2023 Research Magazine

RESEARCH

THE WORLD LOOKS TO MINES FOR WHAT’S NEXT

For nearly 150 years, the world has looked to Colorado School of Mines to solve some of the biggest challenges in science and engineering. Founded in 1874 with specialties in mining and metallurgy, Mines has long been a leading research university in these fields worldwide. But we also have expanded our portfolio over the years to become a global leader in key emerging technology fields. And as an R1 designated university with very high research activity, our work helps create and support lasting positive change in nearly every major industry.

We break down tough challenges and explore solutions that improve how the world works. We are a community of inventive and disciplined thinkers who revel in the process of solving problems. We lead meaningful innovation, make promising discoveries and present new ideas that ensure a sustainable and prosperous future.

The world turns to Mines for what comes next.

Learn more about Mines research at research.mines.edu .

THE WORLD LOOKS TO MINES

In 1874, when Colorado School of Mines became the first public university of the U.S. territory of Colorado, the name “Mines” signified research and education focused on the technologies that mattered most to jobs and economic prosperity. That focus hasn’t changed over the years as the world continues to look to Mines to bring the best minds together to solve the planet’s most pressing and complex challenges.

Policymakers and leaders from around the world count on Mines’ unbiased and relevant expertise. Our researchers bring together a deep understanding of areas such as worldwide supply chains, critical materials, manufacturing processes and product technologies, energy and environmental solutions, and more, bringing context and insights to their societal impacts. Designated as an R1 institution by the Carnegie Classification of Institutions of Higher Education, Mines is a community of high research intensity, attracting top faculty and students to this team-oriented, interdisciplinary culture of research excellence.

At the core, it’s Mines’ agility in establishing and nurturing collaboration that allows the university to bring special advantages to its research. Through extensive partnerships with other universities, corporations, international entities and entrepreneurs and leveraging our proximity to the largest concentration of federal laboratories outside the Washington, D.C. area, Mines enables broad access to R&D capabilities, fostering technology transfer and innovation.

Mines, as ever, connects closely with industry today. Corporate funding makes up about 20 percent of Mines’ research volume, manifesting the university’s reputation as an ideal partner with industries in transition. Our portfolio of use-inspired research provides fertile ground for inventions and start-up companies, representing a pipeline of future opportunities for companies and investors.

in total research awards in FY22

$95M 32 1 shared instrumentation facility

active research centers and industry consortia on campus

I find great inspiration in Mines’ spirit of innovation, our vibrant research partnerships and the unparalleled skill of our faculty and students. I hope you also will be inspired by the Mines research highlighted in this collection. Look to Mines for what is most important to you: great education, world-leading pragmatic expertise, policy insights, research collaborations, innovative technologies, investment opportunities and much more. We invite you to visit. Get to know the Mines of today—and partner with us to innovate for a better world.

Walter G. Copan Vice President for Research and Technology Transfer

Understanding critical materials deposits within the subsurface

Decarbonizing the metals industry

Understanding water’s role in climate change

Social responsibility in engineering, demystified

Finding the energy balance

Tackling the lithium supply chain

Green hydrogen: Empowering the future of energy

Cracking open enhanced geothermal energy

6 | SUSTAINABILITY

How can we overcome critical challenges to reduce greenhouse gas emissions, preserve natural resources and promote sustainable development and engineering?

14 | ENERGY

How can we help the world meet growing energy demands and diversify the U.S. and global energy portfolios?

Harnessing data to discover and design materials

Customizing additive manufacturing for materials R&D

3D-printed metal parts take a dip

Teaching robots how to think and share information

Concrete solutions to infrastructure challenges

Bridging the interoperability gap in cities Protecting infrastructure and privacy

Cover: The world looks to Mines to solve the latest science and engineering challenges. Illustration by Zachary Anderson

research.mines.edu

mines.edu/news

President

Paul C. Johnson

Vice President for Research and Technology Transfer

Walter G. Copan

28 | ADVANCED MANUFACTURING

What new technologies and systems can we develop to promote a robust and sustainable manufacturing R&D infrastructure?

36 | INFRASTRUCTURE

With national and global systems becoming more complex and interconnected, how can this infrastructure be strengthened or redesigned to be more secure?

Director of Materials and Energy Initiatives

Michael Kaufman

Director, Research Development

Lisa Kinzel

Director, Technology Transfer

Will Vaughan

Research Compliance Officer

Scot Allen

Shared Instrumentation Facility Director

David Diercks

Research Proposal and Development Manager

Alyssa Von Lehman Lopez

Editor

Ashley Spurgeon

Contributing Writers

Jenn Fields

Sarah Kuta

Jasmine Leonas

Jen A. Miller

Ashley Piccone

Emilie Rusch

Ashley Spurgeon

Anna Squires

Photography

Agata Bogucka

Cyrus McCrimmon

Graphic Design

Gretchen Kershner

RESPONSIBLE ENGINEERING

Mines is a leader in overcoming critical challenges to build a more sustainable and prosperous future.

When looking at the world’s biggest goals today, sustainability is near the top of the to-do list. Governments, communities and industries around the globe are searching for the latest solutions and creative approaches for furthering innovation while being mindful of the wellbeing of our environment, our people, our economies and more.

At Mines, our world-class researchers are taking an interdisciplinary, collaborative approach to this goal. We have teams working on issues such as decarbonization; water resource management; critical material supply chains; carbon capture, utilization and storage; and more. By working across disciplines and addressing all sides of an issue, our researchers are able to think holistically and take a wellrounded approach in their work. This also enables unique partnerships with national labs and government agencies that allow us to make significant advancements in technology and find solutions faster. And all of this work is governed by responsible engineering practices that put communities first and ensure maximum benefit for the people these solutions aim to support.

In the following pages, you can read about some of the projects we’ve been working on to support a more sustainable future and the partnerships that are making this work possible.

When seeking the next step toward a more prosperous future, Mines is helping lead the way.

research centers and industry consortia related to subsurface characterization

11 5 research centers and industry consortia related to water

RESEARCH CENTER SNAPSHOT

Center for Advanced Subsurface Earth Resource Models (CASERM)

A collaborative venture between Mines and Virginia Tech, CASERM aims to solve research challenges in the development of 3D subsurface geological models for mineral deposits. CASERM forms part of the National Science Foundation’s Industry/University Cooperative Research Centers program.

CASERM’s research includes:

• Development of novel instrumentation, analysis and interpretation methods for enhanced characterization of rock properties

• Integration, scaling and inversion of geological, petrophysical and geophysical data types of dissimilar spatial resolution and distribution to identify and characterize subsurface resources

• Development of machine learning methods to predict subsurface properties, quantify uncertainty and de-risk decision making

• Development of graphical and exploratory data analysis solutions and visualization tools for 3D subsurface features

$1.5 million in total research volume per year

Visit

UNDERSTANDING CRITICAL MATERIALS DEPOSITS WITHIN THE SUBSURFACE

Finding efficient, sustainable workflows to improve the critical material supply chain

BY ASHLEY PICCONE

A renewable, green future full of electric cars, wind turbines, solar panels and smart technology is on the horizon. But for the sun to rise in this new dawn, these devices must be manufactured. Doing so requires a supply of certain minerals—often rare earth elements—with unique magnetic, catalytic and luminescent properties.

These critical materials are essential but often difficult to obtain. The supply chain issue is twofold: some minerals are rare and hard to find, while others are challenging to mine at a profit. This explains why critical minerals have historically been mined mostly as byproducts.

Thomas Monecke,

professor of geology and geological engineering, are exploring mineralogy across scales to better understand deposits of critical materials within the subsurface. They aim to develop and implement a workflow to explore for minerals in the most efficient and sustainable way possible.

“We want to figure out which deposits have elevated critical mineral concentrations and how these are distributed within the deposit,” said Monecke. “And, as a scientist, I care about the why. What are the processes that make certain deposits enriched while others are not?”

The team brings together techniques from the micron to kilometer scale. At several sites within the Idaho Cobalt Belt, which may become an important domestic source for cobalt as a battery material, they conducted a drone-based hyperspectral survey of the potential future deposits. In addition, they analyzed the drill core with an X-ray fluorescence core scanner, a device that is entirely unique in North America, to determine the geochemical composition of the ore and waste. Using a state-of-theart hyperspectral core scanning system, they will also determine the mineralogical composition of the core. Optical and electron scanning microscopes will allow them to examine samples at the smallest scales.

“Generally, we just don’t know that much about critical minerals,” said Pfaff. “This work is helping us understand where they really occur, how we should look for them and how we can assess what is available.”

The end goal of the project is to develop a 3D model of the subsurface. This will require synthesizing the different datasets, a task the researchers are working on with machine learning algorithms and in conjunction with Mines’ Applied Mathematics and Computer Science departments.

“Our project is really broad. It reaches from early exploration, throughout a mine life cycle, all the way to remediation afterwards,” said Pfaff. “We would like to use minerology across scales and our knowledge of the subsurface to predict what mining would look like before diving in.”

By truly understanding what minerals are beneath the surface and the processes that created them, Monecke and Pfaff aim to make domestic mining economically feasible while focusing on sustainability and community engagement.

professor of geology and director of the Center for Advanced Subsurface Earth Resource Models, and Katharina Pfaff, research associate

These heat and topographic maps were part of a hyperspectral survey of Iron Creek in the Idaho Cobalt Belt.

Using drones equipped with hyperspectral cameras, scientists can survey potential mineral deposits.

DECARBONIZING THE METALS INDUSTRY

In the U.S. and around the world, there’s a push to cut greenhouse gas emissions by the metals industry

BY JASMINE LEONAS

In May 2021, the United States and the United Kingdom launched the G7 Industrial Decarbonization Agenda (IDA) to reduce greenhouse gas emissions from heavy industries like steel, cement and chemicals. IDA is meant to guide the global economy toward industrial decarbonization and make meaningful steps forward to fight climate change.

Decarbonization in the metals industry has already begun in the United States, and we’re one of the cleanest steel industries in the world, said John Speer, director of the Advanced Steel Processing and Products Research Center and professor of metallurgical and materials engineering.

“We’re not at the end point, but in some ways, we’re farther along at the beginning of this effort compared to other countries,” he said.

For example, Speer explained how the electricity used in the process of making steel can come from renewable sources, such as solar or wind, eliminating the need for carbon. But electricity is the basis for recycling steel, not for converting iron ore into raw steel. In steel production from iron ore, oxygen is stripped from iron oxide and often carbon, coming from coal, is used in that process. But new ways of making steel—like using hydrogen-based fuels instead of coal—are being adopted, and electrolytic processes to reduce iron ore using electricity are also being explored.

But Speer said the efforts to become carbon-free during steel production are just part of a bigger picture. There’s still carbon being used at other steps along the way, maybe in the mining or heating processes when making other materials such as aluminium.

“It’s not enough just to use electricity,” Speer said. “You have to have renewable electricity as well, or nuclear power, before you can actually take the carbon out of the system.”

Though processes are becoming more sustainable in the U.S., another problem lies in how companies are recording and reporting their carbon use and greenhouse gas emissions.

“There is unfortunately no standardized way to measure decarbonization, and that makes it hard for companies to know what to focus on,” said Jordy Lee, former program manager at the Payne Institute for Public Policy at Mines. “A lot of companies want to prove they’re sustainable, but they’re not sure what kind of data to report.”

Lee is part of the Coalition on Materials Emissions Transparency, an effort with the Rocky Mountain Institute and the Massachusetts Institute of Technology Sustainable Supply Chains initiative, to standardize how companies report their greenhouse gas emissions, including the steel industry. He said because Mines has the right experts to lend technical expertise to the effort, we’re the ideal partner.

“Mines is a great place for a lot of this work,” Lee said. “Having the Advanced Steel Processing and Products Research Center, faculty with mining expertise, good relationships with many different companies across sectors—all these assets put us in a place that makes Mines an ideal place to work on decarbonization efforts. We’re a very trusted voice, and I think that’s something that's going to be of value in the future.”

UNDERSTANDING WATER’S ROLE IN CLIMATE CHANGE

downstream,” said Adrienne Marshall, assistant professor of geology and geological engineering at Mines. “Both of those things change depending on precipitation changes and snowpack melt, which are being—and will continue to be— affected by climate change.”

BY JEN A. MILLER

Climate change is altering water resources in the western U.S., especially when it comes to snowpack: how much snow there is, how it’s melting and when. These factors have profound effects on reliable sources of both water availability and hydropower.

“When I think about water resources, I think about how much water we have in our rivers and then how changes to our climate affect the timing of when that water flows

Marshall’s research, which is supported by a National Science Foundation IGERT grant and the Carnegie Institution of Washington, focuses on understanding how climate change impacts snow hydrology, such as how snow drifts change and how precipitation intensity mitigates or exacerbates the effects of warming on winter snowmelt.

She hopes that her work leads to better management of hydropower. While hydropower only accounts for 6.3 percent of total U.S. electric generation right now, it will play a bigger and more key role in a decarbonized electrical grid, particularly in

As emissions change snowpack melt, hydropower generation could fail in the near future

the western U.S. For example, water elevations at Lake Powell reached historic lows in 2022. If the water level drops too low, the Glen Canyon Dam, which typically supplies electricity to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada and Nebraska, won’t be able to generate hydropower. The Bureau of Reclamation estimates that without any changes to how water is used, there’s a 23 percent chance the dam won’t make any power by 2024—or sooner.

“If that happens, it will be a massive problem, because so many people throughout the region depend on it to keep the lights on,” Marshall said.

But hydropower is a major player in the U.S.’s energy future when combined with other energy sources. “As we get more solar and wind power online, hydropower becomes especially important because it can turn on relatively quickly to fill gaps when the sun isn’t shining or the wind isn’t blowing,” she said. Hydropower can also be turned on without another power source, which is critical during outages.

A key to better hydropower management is understanding how snow pack has changed and is likely to change, which will affect the availability and timing of water used for power. In one study, for example, Marshall looked at the probability of the western U.S. having two low snow years in a row and then how much more common those multiyear droughts are likely to become under a high-emissions warming scenario. She and her team found about a six-fold increase in that risk, which would lead to “considerable changes in the snow pack,” she said.

This information will change “how we operate dams given what we can expect in changes to stream flow and timing,” she said. If dam operators know that snow pack will melt in a different way—like earlier in the season, or that there will be less of it to melt—they can better plan that.

Her work is also contributing to the mountain of evidence that climate change will continue to change our world if emissions do not change. “There are a lot of creative people working on how we can adjust our management of our water systems and forest management to try to account for these changes and try to adapt, but we really need to reduce emissions,” she said.

Marshall is part of Mines’ tradition of being a leader in nationwide water research. For example, Mines is one of 14 founding university members of the Cooperative Institute for Research Operations in Hydrology, funded by $360 million from the National Oceanic and Atmospheric Administration.

“As scientists, we need to lead the way for society to have a better understanding of how climate change is affecting our water resources,” she said. “Being able to say these changes are ahead with confidence is important for understanding this problem and that there are very good reasons to work on mitigation solutions.”

The Glen Canyon Dam supplies electricity to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada and Nebraska, but if the water levels drop too low, it won’t be able to generate hydropower.

“As scientists, we need to lead the way for society to have a better understanding of how climate change is affecting our water resources.”

SOCIAL RESPONSIBILITY IN ENGINEERING, DEMYSTIFIED

Jessica Smith explores how working engineers manage the social and public accountability dimensions of their careers

BY SARAH KUTA

“Mines is unique among engineering schools, because we have innovative social scientists who study science, technology and engineering and use that knowledge to collaborate with our peers. This means that as an institution, we have a real opportunity to lead the practice of interdisciplinary, transformative research that really makes a difference.”

Working engineers solve technical problems on a daily basis—that’s a big part of why many choose to go into the field in the first place. But they also regularly grapple with sometimes less obvious questions that deal with the social, environmental, economic, cultural and ethical facets of their work.

As an anthropologist and professor of engineering, design, and society at Mines, Jessica Smith wanted to learn more about how engineers understood the public accountabilities of their profession. She spent years getting to know engineers in the field, learning about how they thought about their work in the broader context of their community and the planet. The result is Extracting Accountability: Engineers and Corporate Social Responsibility, a book published open access by The MIT Press in 2021 that synthesizes interviews with 75 anonymous engineers and executives, as well as her analysis of various historical documents and archival materials.

Smith shared more about the role of corporate responsibility in engineering.

What does social responsibility encompass? And why do engineers need to care about it?

Jessica Smith: One way to think about it is creating shared social, environmental and economic value— and that depends on adapting to the particular context. In places that have a history with the mining and oil and gas industries, many people want well-paying, safe jobs. In other places, there’s more concern about environmental impact. There’s also commonly a desire for transparency. People want to know what’s happening, what decisions are being made and how they impact them. Is there going to be an expansion? When might this operation shut down? What will that mean for us?

There is a clear need to go beyond just aspiring to a “social license to operate,” in which people allow a company’s activities to proceed. The most visionary engineers I met were thinking about how they and their companies could contribute to the well-being

FUNDING PARTNERS:

National Science Foundation

Shultz Family Fund for Leadership in Humanitarian Engineering

Collaborators:

Virginia Tech

South Dakota School of Mines & Technology Marietta College

of the planet and the people who live next to their operations. Mining and oil and gas can be powerful engines for sustainable development if social and environmental wellbeing are embedded into core business practice.

What key themes emerged from your interviews and research?

Smith: For many engineers, the intersection of social and technical issues was the most exciting part of their careers. They wanted to be where there were challenges, as well as opportunities, for them to stretch beyond a narrow technical focus and to think about how they could make a positive difference in the world through their engineering practice. That is a very powerful position to be in. Even though there’s often a formal community relations team, engineers actually have a lot of power to make decisions that ensure that these companies and their facilities are good neighbors.

What critical lessons should engineers working in industry keep in mind when adopting social responsibility practices into their decision-making processes?

Smith: No. 1 is that engineering is socio-technical by nature: Whatever decision you’re making, whatever process you’re designing, whatever thing that’s going to be built, it’s embedded in the world and is going to shape how people live and how people experience and think about your company. You have to think about your engineering in this wider context. It’s never just technical.

No. 2 is that integrating social concerns into engineering decisionmaking requires deep, contextual listening. This is not just listening for information—it’s listening for how someone views the world and their position in that world. You’re trying to understand not just what people think, but why they have a particular worldview.

What role do engineers play in the broader realm of social and corporate responsibility?

Smith: As one of my interviewees eloquently said, engineers are the ones who live out a corporation’s values. He said that while it was his job as a CEO to set those values and express the mission and the vision of the company, the engineers are where the rubber meets the road. It’s through their decisions that the company actually exists in the world. Social responsibility is crucial because you want the engineer who is drawing the line for where the road is going to be or the engineer who is setting up the shift schedule to be thinking about those broader values so that they are baked into the everyday business of the company.

The more and more these industries evolve in terms of their public engagement, the more they see the intrinsic value of being responsible and being inclusive. It’s the right thing for these industries to contribute to sustainable development—it’s not just a box that should be checked.

SHAPING OUR GLOBAL ENERGY FUTURE

Mines researchers are working on the latest technology to help diversify the world’s energy portfolio and offer the best solutions to today’s energy challenges.

Today’s energy demand is a global challenge. The world’s energy portfolio is becoming more complex and diverse, looking vastly different than it did a century ago. And those with the expertise in energy resources and technology are being called upon to determine the best ways forward and develop what comes next for our energy future—and Mines is leading that effort.

At Mines, we recognize that a one-size-fits-all answer to the energy challenge does not exist. We work closely with industry, government agencies, international organizations and communities to understand and address all sides of this issue. Our researchers are actively pursuing the latest energy pathways, whether that’s finding sustainable ways to source geothermal energy, efficiently build hydrogen fuel cells or develop other advanced energy systems. We’re even investigating the impacts on critical materials supply chains and how the energy transition affects global systems and economies.

Here, you will find only a few examples of the work Mines is leading in this effort and the part we play in nearly every aspect of the energy transition. We are an ideal partner made up of dedicated collaborators and enthusiastic problem-solvers that will help the world successfully meet the energy demands of today and tomorrow.

When the world looks for energy solutions, Mines has the answers.

GLOBAL ENERGY FUTURE INITIATIVE

This Mines-led initiative connects energy innovators, industry leaders and policy makers to advance scientific and datadriven solutions for the energy transition. We are providing innovation and thought leadership in areas such as:

• Oil and gas

• Decarbonization and renewable energy

• Minerals and metals

• Clean water innovation

• Carbon capture, utilization and storage

• Supply chain transparency

Learn more about this initiative and Mines’ impact on our energy future and get involved at mines.edu/ global-energy-future.

TACKLING THE LITHIUM SUPPLY CHAIN

Researchers are closely monitoring energy supply chains to ensure resource availability

BY EMILIE RUSCH

THE ISSUE

Lithium-ion batteries are essential to electric vehicles, but there’s broad concern about whether the production and availability of lithium will increase quickly enough to keep up with the explosive growth of technology reliant on the extra light, energy dense material—and at prices that U.S. customers will be willing to pay.

Currently, all three stages of the lithium supply chain— resource extraction and initial processing (upstream), intermediate processing (midstream) and battery production (downstream)—lack geographic diversity, which puts the supply of this critical material at risk for geopolitical disruption. Chief among the issues is the fact that some 80 percent of all midstream lithium processing currently happens in China. Even if additional domestic sources of lithium can be brought into production, those upstream resources would still likely have to travel to China for midstream processing, at least in the short term, before they could become batteries.

THE PLAYERS

Rod Eggert, Viola Vestal Coulter Chair of Mineral Economics at Mines, is the deputy director of the Critical Materials Institute, a multi-institutional, multidisciplinary consortium and Energy Innovation Hub of the U.S.

Department of Energy focused on innovation to assure supply chains for materials critical to clean-energy technologies.

“To meet the deployment targets for electric vehicles, we are going to need a lot more lithium. The long-term issue is, will the market be able to respond quickly enough to develop new supply chains at prices that we’re willing to pay?”

Eggert said. “Some are concerned about the risks of physical unavailability, but perhaps more important is the affordability of the battery material.”

“Ideally, we’d like the lithium supplies to be sufficient in a quantity sense. We’d like them to be affordable, and we’d like them to be secure so they’re not vulnerable to disruptions like we’ve seen over the past couple of years,” he said.

“There’s tension between minimizing costs today and making sure your supplies are secure. Security requires diversity in supply—if you’re a battery manufacturer or electric vehicle manufacturer, security of supply comes from having options for sources. But sometimes having options costs more money than relying on a single source.”

THE SOLUTIONS

Mines researchers affiliated with the Critical Materials Institute are tackling the lithium-ion battery challenge, as well as other critical material challenges, in a variety of ways.

Eggert’s work focuses on economic analysis—including how to explain battery material substitutions from an economic perspective—and long-term lithium availability. One of his current projects aims to create an alternative decision framework that monetizes the environmental impact of different sources of lithium.

“The engineering community is very good at quantifying environmental impacts in physical terms—what are the emissions to water or the emissions into the air or the land use requirements for different types of production. But each of those impacts has a different unit of account, which can make comparisons difficult,” Eggert said.

Monetization has the potential to help inform decision making in both the private sector and in government. In the private sector, companies are primarily focused on commercial costs, but what has come to be termed ESG (environmental, social and governance) considerations are also very important in making a commercial investment decision.”

FINDING THE ENERGY BALANCE

Control systems expand the scope of renewable and hybrid energy technologies

BY JEN A. MILLER

Innovations in renewable technology are rocketing ahead, but they can only advance so far without control systems, which manage and regulate how a technology operates. A car, for example, is full of control systems: fuel injection, anti-lock brakes, cruise control, to just name three. The same is true for mechanisms that harness and transfer renewable energy into usable energy.

For hybrid energy systems, “you need to supply it with just the right amount of fuel and right amount of cooling systems in order to operate,” said Tyrone Vincent, professor of electrical engineering. “The control system is keeping that power generation system happy.”

In work funded by the Advanced Research Projects Agency (ARPA-E), Vincent and his team are working to create a control system that allows a fuel cell’s waste to be turned into more energy through an attached combustion engine.

“In order to avoid side chemical reactions that would damage the fuel cell, you have to let some of the fuel slip out, so there’s always going to be usable energy leaving the fuel cell,” he said. “If we can recover that energy in a hybrid system and use it an internal combustion engine, that’s a new hybrid system.” The end result would be hybrid fuel cells that could become a generator for an office complex or hospital, or, if efficient and

effective enough, become the main source of energy for that structure that would then use the grid as a backup.

Control systems are also necessary to expand the scope of what renewable energy technology can do, said Kathryn Johnson, professor of electrical engineering. That’s especially true with wind turbines. Also through ARPA-E, she is working on a project testing the feasibility a 50-megawatt turbine. The project started in in 2015 when 13 MW was the most powerful turbine in operation.

Control systems are key to that success. “Structures as big as 50-MW turbines get all sorts of wind speed across the motor blades. Wind pushing harder on one spot and causing bending and could damage the structure” she said. “A control system is critically important in making these kinds of advancements possible and feasible.”

In another ARPA-E funded project, Johnson is working on enabling floating off-shore wind turbines. Right now, these structures must be anchored to the ocean floor, but that’s missing nearly 60 percent of wind energy—equal to the entire U.S. annual electricity consumption—because it blows across waters more than 200 feet deep. Johnson is creating control systems that would enable those turbines to work while floating on the water instead.

Control systems are critical to advances in renewable technology because they “enable new designs of individual devices that aren’t currently possible,” she said. “We can reach those next steps, if control systems are in place to make those theoretical technologies reality.”

Tyrone Vincent, professor of electrical engineering, and Chris Cadigan, research assistant professor, work with a fuel cell in a lab in the Colorado Fuel Cell Center on the Mines campus.

GREEN HYDROGEN:

EMPOWERING THE FUTURE OF ENERGY

A closer look at hydrogen’s role in the energy transition

BY MINES STAFF

Hydrogen has emerged as a key player in the energy transition, identified by the International Energy Agency as a “versatile energy carrier” that has a diverse range of applications and can be deployed in a variety of sectors. But is hydrogen a moonshot? Or does it really have the potential to change the energy game?

At Mines, teams of researchers are working on the hydrogen problem—from developing electrolyzers to separate hydrogen from other energy sources to developing and testing the ceramic materials in fuel cells and making them commercially viable and cost-effective. And they will tell you that hydrogen truly has the potential to supplement the world’s energy profile in meaningful ways and help us successfully navigate the energy transition.

We talked to researchers working on projects across the scope of this issue to take a deeper dive into hydrogen technology, the challenges researchers are facing in this work today and how they’re overcoming them and what the future looks like when powered by hydrogen.

COLORADO FUEL CELL CENTER

Created in 2005, the Colorado Fuel Cell Center is a research center housed on the Mines campus that seeks to advance fuel-cell and electrochemical research, development and commercialization to address demands in electricity generation and storage. Mines faculty across disciplines actively perform research and bring diverse perspective to the field, and close ties with industry partners enables the center to meet today’s technological development needs.

Scope

• Proton-conducting ceramic fuel cells and electrolyzers

• Solid-oxide fuel cell (SOFC) development and testing

• Fuel processing

• Modeling and simulation

• Advanced materials processing and evaluation

• Manufacturing technology development

• Systems integration

HOW DO HYDROGEN ELECTROLYZERS WORK?

The Colorado Fuel Cell Center has been exploring—and expanding— the possibilities of fuel cells and electrolyzers for a variety of inputs, outputs and applications for more than 15 years now.

But what’s got Neal Sullivan, associate professor of mechanical engineering and the center’s director, really excited these days is using the technology to create green hydrogen at scale.

“Colorado School of Mines is uniquely positioned to develop the building-block technology behind these electrolyzers, or what I like to call flow batteries,” Sullivan said. “Our faculty are experts from many complementary scientific perspectives. We’ve got fundamental material scientists looking at how we design the optimal materials to get highest possible performance and widest possible range, and by the end of this year, the Colorado Fuel Cell Center will turn on a 30-kilowatt fuel cell system. Most universities are doing 1W or 2W. Because we’re able to handle that level of technology, spanning from fundamental materials discovery at the sub-Watt scale, to complete electrolyzer systems at the tens-of-kW scale, we can study things that most universities cannot. We can partner with commercial developers and help them get to where they want to go.”

Here, Sullivan walks through the process that turns intermittent wind and solar energy into hydrogen that can be stored, transported and used whenever it is needed for chemical production, clean steel manufacturing, transportation and more.

“What makes green hydrogen ‘green’ is what is not in it—there’s no carbon in this green-hydrogen process,” Sullivan said.

Wind turbines and/or solar panels generate renewable electricity.

Renewable electricity goes into an on-site electrolyzer, and water is supplied.

Hydrogen and oxygen flow into separate tanks

Hydrogen (and oxygen) tanks are transported for use anywhere and anytime. Potential uses for green hydrogen include:

• Transportation

• Synthetic fuels

• Upgrading oil/biomass

• Ammonia/fertilizer

• Metals production

• Chemical/industrial processes

• Heat/distributed power

Illustration by Zachary Anderson

The electrolyzer uses the renewable electricity to split the water vapor into hydrogen and oxygen, with no additional byproducts. Water vapor enters one side of the electrolyzer and is hit with a voltage, causing it to dissociate and break into hydrogen and oxygen. The hydrogen goes across the electrolyte membrane (located in the middle of the electrolyzer) and the oxygen doesn’t. Now separated, the hydrogen and oxygen travel into their own tanks.

DISCOVERING NEW CERAMIC MATERIALS TO SUPPORT THE HYDROGEN ECONOMY

Electrolysis plays a significant role in sourcing hydrogen for use in fuel cells and other energy technologies. But the ceramic materials used in the electrolysis process must withstand unique stresses and conditions to operate efficiently.

We sat down with Ryan O’Hayre, professor of metallurgical and materials engineering at Mines, to learn more about the ceramic materials he and his team of researchers at Mines are developing for this purpose and the many factors he must contend with when advancing this technology. Here’s what we learned.

Walk us through your research and how materials discovery relates to green hydrogen. What do you aim to do in your work?

Ryan O’Hayre: We’re developing a new class of materials called proton-conducting ceramics, or protonic ceramics. These have applications in all sorts of electrochemical energy conversion technologies. As it relates to hydrogen, you can use these in ceramic electrolyzers to take clean, renewable energy from solar or wind and water and split that water into hydrogen and oxygen.

There are some electrolyzers based on polymer materials that are great at operating at room temperature, and there’s also older ceramic materials used in solid oxide electrolysis cells that work at really high temperatures. The protonic ceramics we’re developing at Mines are in the medium temperature space, between 400 and 600 degrees Celsius. Being able to do electrolysis at these medium temperatures has a lot of potential benefits, because it’s a sweet-spot temperature-wise if you want to make more valuable things other than just hydrogen. These protonic ceramics are particularly attractive for making green synthetic fuels. We can do this by co-electrolysis where you don’t just split water into hydrogen, but you can split carbon dioxide into carbon monoxide at the same time. Then at these same magic intermediate temperatures between 400 and 600

degrees, you can do some clever chemical engineering to convince the carbon monoxide and hydrogen to react to make valuable fuels, such as alcohols and hydrocarbons.

What factors do you have to take into account when developing these ceramics?

O’Hayre: There’s a couple things we’re working on when developing th e electrolyte, which is the ion-conducting membrane that’s the heart of the electrochemical device. This membrane has to conduct protons, but it needs to be electrically insulating. Just like in batteries, where a lithium ion conducting membrane is needed to serve as the heart of the battery, so same idea here.

For this membrane material, we want it to be as highly ionically conductive as possible but have very, very low electronic conductivity. It also needs to be mechanically strong enough to survive thermal cycling. We also need to figure out a way to make it as thin as possible, because that decreases the ionic resistance, so it makes the device more efficient. We can make these protonic membranes as thin as about 10 microns, and eventually we hope to be able to go down to maybe three or four microns.

And then on either side of this thin, dense membrane are electrodes that are also made out of ceramic materials, but they have to be porous so the reactants can diffuse into the electrochemical cell and the products can diffuse out. The electrodes must be electrically conductive and exceptionally catalytically active.

We’re developing new electrode materials starting from the periodic table and looking at different doping elements that we can put into these ceramics to make them more catalytically active and more electronically conductive. We create new ceramic compositions as paste or powders, and then we fabricate test cells that we test in our lab to develop the materials and see how well they perform and how durable they are.

Another key element of this is that we want these devices to not only run for a couple of hours—we want them to run for thousands and thousands of hours because that’s what you need for a commercial product. So we do these tests on the small scale in the lab, and once we’ve identified really promising materials, we pass them over to [other researchers on campus] who start making larger cells and stacks and do more long-term device testing.

What are the challenges you’re seeing when developing these ceramics?

O’Hayre: Just like with any other ceramic, they’re very fragile, and although you want to design an electrolysis device that’s going to run for 20 or 30 years, it can sometimes be challenging to get these ceramic devices to survive lab testing for more than a couple days. So mechanical strength, durability, reliability, lifetime, these are the biggest challenges.

Another challenge is thermal cycling. An electrolyzer has to be able to follow the electric supply up and down depending on intermittent energy sources. It has to be able to ramp and sometimes it has to turn off completely and sometimes has to be operating full speed and sometimes it’s in between. These ceramics don’t really like having to heat up and cool down all the time, so that kind of thermal cycling can be a real problem. It’s these robustness and reliability issues that are the biggest constraint, the biggest challenge for ceramic electrolyzers.

How do you mitigate those challenges?

O’Hayre: It starts with fundamental property measurements in the lab. We measure their thermal characteristics. Like most materials, when you heat our ceramics up, they expand, so if you’re going to make an electrolyzer where you have these ceramic cells and are packaged inside some kind of metal frame which gets packaged in some type of box, if you don’t want to run into problems, then, ideally, all the different components in that box have to have the same thermal expansion characteristics so they all expand and contract at the same rate.

There’s also the fundamental measurements of the mechanical properties. We will make a bunch of cells and break them on purpose to measure how much strength, how much force it takes to break them and then figure out modifications to make them stronger.

What would green hydrogen enable for the future of the energy transition and how we’re using energy?

O’Hayre: This is probably the single most important question, and it’s something the public really needs to understand. There have been a couple surges of interest in hydrogen that have fizzled out and everyone thought we’re going to be driving around fuel cell vehicles and clearly that’s not going to happen. So do we really

need hydrogen? The answer is absolutely, yes. But it’s probably not for reasons that are readily apparent to the general public.

For a lot of our economy, we can pursue direct electrification—buildings, cars, lights—you can just use renewable electricity and use the grid and batteries, but there are certain sectors of the economy that are impossible to electrify. If we want to decarbonize those hard-to-decarbonize, hard-to-electrify sectors, that’s where hydrogen comes in. The big four industries are fertilizer production, plastics, cement and steel. Today, those four sectors are responsible for about 25 to 30 percent of all CO2 emissions, and you can’t only use electricity to produce them. The only way to remove fossil fuels from those big four sectors is with something like green hydrogen.

Why is Mines the ideal partner for solving the hydrogen challenge?

O’Hayre: We’ve had a long history in this field. The Colorado Fuel Cell Center has been around for close to 20 years, so we have a huge amount of infrastructure for electric chemical testing that’s almost unequaled by other universities in the U.S., spanning from the small button cell test stations that I have in my lab up to the 10, even 50, kilowatts scale test capabilities. At Mines, we have expertise in this field going all the way from the basic materials that go into these electrolysis devices all the way to the system-level engineering—allowing us to study how you would design a commercial system that would operate in the real world. That’s a really unique capability, and it’s a result of 20-plus years of investment in this field.

CREATING HYDROGEN MEMBRANES FOR USE IN NUCLEAR FUSION POWER PLANTS

Fusion, the process that powers the sun and the stars, has long been a part of the conversation about low-carbon sources of electricity. Unlike nuclear power generated through fission, less waste is generated as a byproduct of fusion. However, there isn’t currently a process that successfully produces power through fusion in a way that is cost effective, efficient and safe.

“Fusion is the technology that’s always been 20 years away,” said Colin Wolden, professor of chemical and biological engineering. “However, scientists have recently advanced the fusion gain energy factor to the breakeven point where the power released by the fusion reactions matches that required to sustain the plasma. ITER, the international research collaboration located in France, has targeted achieving the level necessary for practical power generation by the end of the decade. The U.S. startup Commonwealth Fusion Systems has raised more than $2 billion to commercialize this technology within a similar time frame. Wind and solar are the bridge for the next 20 to 50 years, but fusion power could be the ultimate solution to the sustainable energy question.”

A project led by Wolden that began at Mines in January 2021 and is funded by the Advanced Research Projects AgencyEnergy (ARPA-E) might be a key part in making fusion a realistic source of clean energy in the future.

The project’s focus is not on the fusion process itself, but on generating and purifying the hydrogen isotopes that are the fuel for a fusion reactor. In the sun, four hydrogen atoms are fused together to form helium, which is accompanied by a very small loss of mass that generates tremendous amounts of energy as described by Einstein’s theory of relativity equation. On Earth, this process is recreated in

a magnetically confined plasma using the hydrogen isotopes deuterium and tritium. In the plasma reactor, only a fraction of these isotopes are converted into helium, so a critical requirement for practical deployment is to efficiently separate the unreacted isotopes from helium and recycle them back to the fusion reactor. Wolden’s team is developing composite membranes for this purpose.

Membranes are often used to purify hydrogen for fuels cells or in the chemical process industry, but the ones Wolden and his team are creating are tailored to operate in the environment of a fusion power plant. The composite membranes are based on low-cost metal foils, such as vanadium or iron, whose surfaces must then be modified to facilitate the transport of hydrogen while withstanding exposure to plasma radiation and high-temperature molten salts. Wolden’s group is using tools of the semiconductor industry, such as reactive sputtering and atomic layer deposition, to modify surfaces and create the catalytic layers that enable such performance.

Wolden said creating a successful membrane could enable a lower cost and more secure fusion energy system and potentially aid in making fusion power plants a reality. Working in collaboration with other teams and industry partners within the ARPA-E umbrella, the goal is to have efficient isotope processing technologies ready for deployment as fusion energy systems advance.

“Fusion has the potential to be an infinite carbon-free power source,” Wolden said. “This may be the longterm solution.”

THE COST OF GREEN HYDROGEN TECHNOLOGIES

The appeal of green hydrogen is clear, but before hydrogen fuel cell and electrolyzer technologies can be adopted on a commercial scale, questions of cost, durability and performance still need to be addressed.

Svitlana Pylypenko, associate professor of chemistry, is looking for answers at the microscopic—and even nano—scale.

In collaborations with partners in industry, national laboratories and academia, Pylypenko is leading cuttingedge characterization work to improve understanding of low-temperature polymer electrolyte membrane (PEM) water electrolyzers and fuel cells, two leading technologies for green hydrogen production at scale and hydrogen conversion to electricity.

For fuel cells, work on fabricating high-performance electrodes and understanding the complex relationships between various fabrication and processing parameters, the resulting electrode’s structural properties and the electrochemical performance is well underway. Pylypenko’s partners include the University of Connecticut, the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), Germany’s Fraunhofer Institute for Solar Energy Systems, Pajarito Powder and Forge Nano.

Additionally, the team also hopes to accelerate the development of high-volume fabrication of catalysts with tunable properties for a wide variety of applications. “When our industrial partner makes a new catalyst, they might have clients that want to purchase that catalyst for a different application, and they need to know how that catalyst will perform under those different applications,” Pylypenko said. “Understanding those structure-processing-performance relationships is important.”

On the electrolyzer side of the equation, Pylypenko is collaborating with NREL as part of Hydrogen for Nextgeneration Electrolyzers of Water (H2NEW), a consortium of nine DOE national laboratories focused on making large-scale electrolyzers more durable, efficient and affordable. With a focus on both low- and high-temperature technologies, H2NEW’s goal is to achieve the required cost, durability and performance targets to enable $2-per-kilogram green hydrogen by 2025.

“Expensive catalysts weren’t an issue before—as long as the electrolyzer performed under certain conditions and produced hydrogen, it was OK to be expensive,” Pylypenko said. “But now that our community is trying to scale these technologies up, we need to reduce cost and use cheaper components when possible and make sure they are reliable for many, many years.”

Mines is home to multiple research facilities available for this type of characterization work, including the Pylypenko Research Group lab, and user facilities, such as the Multiscale Materials Characterization Facility in the CoorsTek Center for Applied Science and Engineering, which has several unique tools for advanced characterization.

“If we want to address global warming, we need to do everything—we need to do solar, we need to do wind, we need to do fuel cells, we need to do electrolysis and multiple types of electrolysis, because they all will have different niches,” Pylypenko said. “If you want to address the issue globally, we also have to think about how a device will work in the U.S. versus a device working in another country, because of the different contaminants in the air and humidity levels. And that’s where there is still a lot of work to do.”

Jasmine Leonas, Emilie Rusch and Ashley Spurgeon contributed to this piece.

IMPROVING MATERIALS AND MANUFACTURING

Despite the workforce and supply chain issues we’ve seen over the past few years, manufacturers worldwide continue to build capacity and strength— which is critical to keeping up with societal demand. The world requires an overhaul in how we think about manufacturing and the processes by which we produce materials and products. We are entering a new phase in manufacturing, led by advanced computing and robotics, that has the potential to complete tasks faster, cheaper and more efficiently than ever before.

With top experts in advanced manufacturing and materials, Mines is working on ground-breaking research that can take manufacturing to the next

level. We’re optimizing technology and 3D printing novel materials. We’re using artificial intelligence and advanced computing for materials discovery to replace slower, more invasive processes. We’re teaching robots how to think and communicate with each other. We’re even improving post-processing for 3D-printed products that’s faster than ever before.

Read on to take a closer look at just a few of the projects Mines researchers are working on to further what is possible in manufacturing. When industry or governments are looking for solutions to their biggest engineering challenges, they turn to Mines—and we deliver.

RESEARCH CENTER SNAPSHOT

Alliance for the Development of Additive Processing Technologies (ADAPT)

A multidisciplinary additive manufacturing research center and industry consortium, ADAPT brings together research in materials development and characterization; processing-structure-property relationships; advanced manufacturing process control and part qualification; machine learning and big data mining; and data informatics.

ADAPT has 22 industry partners, and members gain the following benefits:

• Early access to leading additive manufacturing research at Mines

• Access to monthly networking and professional development events

• Student recruitment opportunities

• Membership discount on professional development short course

• Co-funding of Mines student projects

• Proposal teaming opportunities

• Industrial advisory council membership to shape future research direction and membership benefits

Learn more about ADAPT and get involved at adapt.mines.edu.

Mines has research centers related to materials and manufacturing 10

We are pioneering new materials and processes to build a more robust and sustainable manufacturing R&D infrastructure.

HARNESSING DATA TO DISCOVER AND DESIGN MATERIALS

Mines researchers create new and improved tools for materials discovery with artificial intelligence and advanced computation

BY ANNA SQUIRES

Chemical separations, such as the processes that fuel water purification and oil refining, are among the most energy-intensive processes on Earth. They’re necessary, but costly. But what if you could use artificial intelligence to reduce the energy they require tenfold?

That’s a question at the heart of nanosponge research by Diego GomezGualdrón, associate professor of chemical and biological engineering. And it’s emblematic of research underway at the National Science Foundation’s Institute for Data-Driven Dynamical Design (ID4), housed at Mines, which aims to accelerate findings in material science by harnessing artificial intelligence.

Gomez-Gualdrón’s work on nanosponges—which can be made of materials known as metal organic frameworks—centers on their porous nature, just like the sponge in your kitchen. But nanosponges can be formulated to attract specific molecules while leaving others behind. The right nanosponge, exposed to a mixture, can extract the components of interest using 10 times less energy than traditional methods.

“The problem is that exhaustively synthesizing and testing nanosponges until one finds the right nanosponge for every separation in the chemical industry would require trillions of experiments—an impossible gambit,” Gomez-Gualdron said. That’s why his research leverages machine learning, which can predict the separation properties of millions of materials nearly instantaneously. At play is

not just a significant reduction of global energy expenditure. It is also the potential reduction of a trillion-year project into an instant—and an entirely new predictive method, offered as open-source software for fellow scientists.

“We want a machine learning model that can instantly predict adsorption of any molecule at any process condition. The idea of a ‘universal’ equation that would predict adsorption in any scenario was first pursued in the early 20th century, but the equation was becoming too cumbersome,” Gomez-Gualdron said. “With our current ability to generate and collect lots of adsorption data, machine learning now seems like a plausible way to achieve the same goal.”

This is just one of the transformative research projects underway at ID4. The cross-cutting collaboration, funded with $15 million from the National Science Foundation, has brought together data scientists, engineers, physicists, chemists and material scientists from 12 institutions across the U.S. Fueled by Mines’ materials science program, ID4’s goal is to harness the power of advanced computation and artificial intelligence to accelerate discovery in material science. It aims to push experimentation to the speed of theory—and along the way, create visionary new technologies for industrial and commercial use.

It’s a lofty ambition. But Eric Toberer, professor of physics and director of ID4, breaks it down to a question of tools.

“When we were creating the seedling of the idea that became ID4, we asked ourselves, ‘What are the problems that have historically felt extremely intractable,

but with advances in computation and machine learning, is there an opportunity to move the needle? And how could we bring in human expertise and artificial intelligence jointly to address these problems?’” Toberer said.

“Computation today is producing more data than the human brain can comprehend,” he continued. “And we need tools to help us make good decisions in physical sciences and engineering, given this giant wave of complicated data. This Institute is about building those tools.”

The engine at the core of ID4 is its interdisciplinary faculty. Inspired by the Materials Genome Initiative, an Obama-era project that partnered experimental and computational researchers to discover material twice as fast as traditional methods, ID4 brings together both material and data scientists who collaborate across four material science sub-domains and on core data science needs.

“Computation today is producing more data than the human brain can comprehend. And we need tools to help us make good decisions in physical sciences and engineering, given this giant wave of complicated data.”

“If the Materials Genome Initiative had never happened, we never would have become the scientists we are, who could conceptualize being part of this Institute,” Toberer said. “When you do collaborative research between computational groups and experimental groups, you create findings that are more than just the sum of the two parts.” That collaboration explains how the Institute is poised to transform the methods and speed at which we discover materials—and tackle some of the world’s most pressing challenges along the way. Gomez-Gualdrón’s nanosponge research, for instance, could have an impact on methods to trap C0 2. The Institute’s photocatalysis researchers are working to create sustainable chemical reactions by harnessing visible light as fuel. Its ion-trapping group will

be critical in creating next-generation solid-state batteries, electrolyzers and fuel cells.

“At the end of these five years, we should have a toolkit full of hammers,” Toberer said. “At the end of 10 years, I hope we’re still smashing away with those hammers. There are just so many ways in which you could imagine adoption of our work. For us, a victory would be creating things that the broader scientific community uses on a daily basis and arming our collaborators, in whatever space they’re in, with tools to understand complicated systems and then build better ones.”

Learn more about the transformative work happening at the Institute for Data-Driven Dynamical Design at mines.edu/id4 .

Researchers at Mines, like Associate Professor of Chemical and Biological Engineering Diego GomezGualdron, are using machinelearning models and advanced computation to accelerate findings in material science.

CUSTOMIZING ADDITIVE MANUFACTURING FOR MATERIALS R&D

A Mines research team customized an accessible 3D printer to manufacture specialized materials

BY ASHLEY SPURGEON

3D printing provides many advantages to manufacturing, from the ability to produce specialty parts to streamlining production processes. But it can also be costly, especially when dealing with uncommon materials that require specific printing parameters and is limited primarily to lab settings. However, a team of Mines researchers, led by Veronica Eliasson, associate professor of mechanical engineering and director of Mines’ Explosives Research Lab, found a way to make an expensive 3D-printing process for those specialty materials into a more accessible system.

OPTIMIZING A STANDARD 3D PRINTER

The Mines team is working on a 3D-printing method called direct ink writing (DIW), an extrusion-based additive manufacturing method. A paste-like material is dispensed out of small nozzles under controlled flow rates and deposited along digitally defined paths to fabricate 3D structures. DIW allows almost any flowable material to be printed with enhanced opportunities to mix materials and create gradients. But the 3D printers that allow this kind of extrusion are often expensive and inaccessible.

“The crux of our research is trying to make this more affordable so that more people in academia and other areas of research have access to highfidelity methods of direct ink writing 3D printing,” said Gabriel Bjerke, a materials science PhD student working on the project. “Basically, we were able to take a system that has cost other people $80,000 to $200,000 to produce and reduce the cost to about $5,000 and get a very comparable quality of extrusion.”

The researchers took a standard desktop 3D printer that normally prints plastic film and made modifications and calibrations, changed out some components and ran countless tests to get it to replicate the capabilities of a custom high-end DIW printer—without the high price tag.

“We basically tricked our whole printer into thinking it’s doing normal printing,” said Max Sevcik, a master’s student in metallurgical and materials engineering. “But we ramped up different settings to make it print exactly how we want.”

3D-PRINTING “EXOTIC” MATERIALS, LIKE CAKE ICING

Making DIW printing cheaper and more accessible opens up many doors for manufacturing, particularly when dealing with exotic materials that are more complex to print. But it also comes with unique challenges.

“The materials themselves have to have rheological characteristics that allow them to be printed,” Bjerke said. “If it’s too thick to be extruded, it can be very tricky to modify the formulation so it will actually print. And the material itself is not self-supporting sometimes, especially when we get to the more exotic materials, and won’t keep its shape. You could have 20 different parameters to tune each time you want to make a small change.”

To test this, the researchers have been experimenting with cake icing as a mock material. “It has desirable flow characteristics for DIW printing, but if you just print it just pure, it’s going to start to slump and relax after printing and won’t keep its shape,” Sevcik said. “To combat this, we’ve added extra granulated sugar to increase the viscosity and adjusted our process parameters accordingly to get good control over our extrusion.”

Then when combining materials, those calibrations become even more complex when different materials require different extrusion parameters. “There’s all sorts of thermochemical interactions that have to be taken into account, and we have to completely customize the whole thing,” said Rodrigo Chavez Morales, a postdoctoral researcher on the project.

The process of making, testing and repeating processes in-house makes researching at Mines unique, Eliasson said. “We can make everything here and test them here,” they explained. “We have a whole ecosystem where we can be self-sustaining but invite other people to be part of it, which is super cool.”

PhD student Gabriel Bjerke, master’s student Max Sevcik and Associate Professor of Mechanical Engineering Veronica Eliasson 3D print cake icing—a stand-in material for more exotic materials with similar properties.

3D-PRINTED METAL PARTS TAKE A DIP

Chemical post-processing slashes additive manufacturing costs, keeps printers in the U.S.

BY ASHLEY PICCONE

In laser powder bed fusion, a 3D printer breaks up the design of a part into horizontal slices. It lays down a bed of powder and traces out an image of each slice with a laser, melting the powder in a specific design. Then the platform drops, spreads another sheet of powder and repeats the process until it builds up the entire object, layer by layer.

Additive manufacturing with processes such as this makes it easier to create complex components quickly and is projected to be a $25-billion-a-year industry by 2025. While it is a relatively inexpensive technique, post-processing makes up 46 percent of the cost on average for a 3D-printed metal part. Much of this comes from labor costs, as supporting material is usually ground or machined off.

Owen Hildreth, associate professor of mechanical engineering, has developed a low-cost chemical post-processing method to cut the cost and time required to get a component to a useable state. We asked him more about this technique and how it could help advance the additive manufacturing industry’s prevalence over the next several years.

Why is post-processing so important for 3D-printed materials?

Owen Hildreth : Part of the printing process is creating supports that hold the metal so it can’t curl as it cools down. In post-processing, you have to get rid of those supports. Currently, the go-to technology is a set of pliers followed by a Dremel, which is a big pain in terms of manual labor.

You also need smooth surfaces. When you melt a powder, there’s going to be a line where the powder is fully melted on one side and the other side where it’s just a little bit melted. You end up with these little balls of powder stuck on the surface that increase the roughness. Instead of a machined part that might last 10 years, you might have something that lasts a couple weeks because of that rough surface. So, you have to smooth those surfaces. With a simple geometry, you can just hit that with some sandpaper. But with really complex shapes, it’s hard.

How does your chemical postprocessing method work?

Hildreth: The trick is removing just the supports without changing the overall geometry of the part. The entire part and supports are printed with the same material. After the part is printed, we dip it in a sensitizing agent. When you pull it out, the fluid leaves a coating on all the surfaces and all the supports.

Then you go through a heat treatment step. The sensitizing agent decomposes and diffuses into the top hundred microns of the surface, changing the composition. I’ve chosen the sensitizing agent so that when it diffuses and changes the composition, it makes a really bad metal that can dissolve in, essentially, tomato juice. We dissolve away the supports, which are really thin, and the surface of our structure only loses a little bit of material. So, what we have is a selfterminating etching process.

~$4 million

total project funding, including awards from:

National Science Foundation

CAREER Award

U.S. Department of Energy

NASA

Air Force Research Laboratory

Colorado Office of Economic

Development and International Trade

Collaborators

Asperity Finishing

Honeywell

NASA

Boeing Corporation

Pennsylvania State University

University of Pittsburgh

What impact could this method have for the future of additive manufacturing?

Hildreth: What I think is exciting is the idea of supporting manufacturing in the U.S. For example, a company printing a bunch of parts and sending them elsewhere for post-processing will eventually just start printing elsewhere too. With this technology, there’s almost no manual labor. By getting rid of that cost, we can keep the printers and the manufacturing in the country.

TEACHING ROBOTS

HOW TO THINK AND SHARE

INFORMATION

Machine-learning models help improve manufacturing processes in real time

BY ASHLEY SPURGEON

More and more manufacturing processes today rely on 3D-printed methods and machine learning to produce high-quality products at a faster rate. This requires machines that can evolve and improve over time through learned experience. But getting machines to share knowledge is easier said than done.

In additive manufacturing, there are many parameters and variables that play important roles in a product’s quality— far too many for a human to determine how each alters the outcome. Data-driven machine learning techniques, on the other

hand, can help build correlations among parameters efficiently, where correlations learned by one machine can be shared with other machines to replicate the process and improve products at a much faster rate.

Xiaoli Zhang, associate professor of mechanical engineering, is determining how machines can learn from each other and improve additive manufacturing processes and parameters in real time with machine-learning techniques. We sat down with her to learn more about her work. Here were our main takeaways.

Xiaoli Zhang, associate professor of mechanical engineering, studies an example of the characterization process happening in real time in a 3D printer on the Mines campus.

PRINTING PARAMETERS CAN BE CHANGED IN REAL TIME RATHER THAN POST CHARACTERIZATION.

When 3D printing a part or product, most of the quality control, such as determining the hardness of the printed material, is completed after the part has been completely manufactured. Flaws are only identified post characterization, resulting in inefficiencies with materialusage, time and costs.

Machine-learning models, unlike post-characterization methods, allow scientists and engineers to change control parameters while parts are being printed. The in-printing control parameter tuning capability produces parts with higher quality and gives more detailed material properties. Zhang is developing process-structure-property (PSP) machine learning-based models for better real-time defect monitoring and feedback control for defect prevention.

“If you have this PSP machine learning-based model, you can do the online prediction to predict what kind of hardness you will get, what kind of fatigue property you will get and change those printing parameters in real time,” she explained. “If you can do this in-process with real-time control, then you can improve the quality and reduce the cost, because we can avoid failures.”

TRAINING MACHINES IS LIKE TEACHING HUMAN BABIES.

The first step to getting a machine to successfully adopt PSP models is to feed it data and the machine-learning techniques will explore that data to build PSP correlations on their own. Scientists approach this in a way similar to how humans teach babies to recognize the differences between images of cats and dogs.

When babies are given images of cats and images of dogs, they can quickly learn to distinguish them—something machine-learning models need to learn as well.

“We give the data to the machine learning algorithm, and we provide it with a ground truth—we tell the computer the correct answer at the beginning of the training,” Zhang said. “Just like a baby can figure out the difference between a cat and a dog quickly, the computer machine-learning algorithm will also learn how to distinguish them given the ground truth. This way, once a machine-learning algorithm is trained, it will be able to conduct defect classification or quantification tasks, even the given data that are different from the original training data, just like a baby can differentiate new cat images from dog images.”

Once a machine understands these ground truths and the parameters needed to successfully print a part or produce a product in a specific way, it can make adjustments in

“Think about how we develop our human world— we learn from each other and share through the internet. Machines can also have their internet with a cloud-based system. Each machine can post its data and knowledge, run it through the cloud and then it can be assigned to every machine in communication with the cloud. Then they can share and learn from each other.”

real time and avoid mistakes during the characterization process, eliminating the need to complete postcharacterization tests to determine the quality of the product.

GETTING MACHINES TO LEARN FROM EACH OTHER REQUIRES A SHARED BRAIN.

The next step in improving additive manufacturing processes is getting the machines to communicate and learn from each other without humans having to upload data to individual machines. Zhang has a solution that was also inspired by humanity: a system that functions similarly to how humans share knowledge via the internet.

“In terms of the machine knowledge transfer, once we have a model in one printing machine, we want to transfer that to another one,” Zhang said. “Think about how we develop our human world—we learn from each other and share through the internet. Machines can also have their internet with a cloud-based system. Each machine can post its data and knowledge, run it through the cloud and then it can be assigned to every machine in communication with the cloud. Then they can share and learn from each other.”

When a machine uploads a PSP model to the cloud, other machines on that same system can access that model, learn the specific parameters required to produce a part and successfully print the product with the desired characteristics. Humans wouldn’t need to manually upload data or teach individual machines how to make the appropriate correlations from scratch. This interconnectivity and shared knowledge can help manufacturers scale up the number of products and capability for mass production, cut labor costs and decrease production time.

“I imagine we will have less and less labor work to do the monitoring and post-characterization, but that doesn’t mean it’s a negative,” Zhang said. “We can produce products faster, and then the overall workforce development may grow.”

SECURING THE FUTURE

With national and global systems becoming more complex and interconnected, our research is helping to strengthen networks and redesign modern infrastructure to be more secure and efficient.

Existing physical infrastructure are under stress from population growth, extreme weather, climate change and more. Our digital infrastructure is threatened by cyberattacks or lacks the interconnectivity required to be efficient in an increasingly connected world. But new investments in our physical and digital spaces are invigorating innovation and solutions to these challenges, and Mines researchers are ready to face them head on.

Mines faculty and students are developing new materials to help improve our physical spaces, such as advancing construction materials and evaluating existing infrastructure with fast, practical and cost-effective methods. These investigations will help sustain our buildings, transportation systems, grids and more and ensure they remain strong, efficient and secure.

Mines computer and data scientists are also working on the latest technology to improve our digital spaces. By developing technology with practical, real-world applications, it’s easy to see the effects of the work happening at Mines. Our researchers are working on transformative projects, such as standardizing how smart technology communicates between systems and ensuring those systems are protected from cyber threats.

In the next several pages, you will learn exactly how Mines researchers are tackling some of today’s biggest infrastructure challenges and how Mines is providing the expertise to understand the complexities involved in maintaining and securing our day-today lives.

When the world looks for strong and secure networks and systems, it looks to Mines to build them.

RESEARCH INSTITUTE SNAPSHOT Center for Cybersecurity and Privacy

CCSP supports and promotes cybersecurity and privacy education and research at Mines and throughout the region.

The National Security Agency and the U.S. Department of Homeland Security have designated Mines as a National Center of Academic Excellence in Cyber Defense Education since 2016.

CCSP research includes:

• Web, mobile, cloud, cyberphysical, IoT and AI systems security

• Usable security and privacy

• Computer and network security

• Applied cryptography

• Defense and homeland security

• Cybersecurity and privacy education

Collaborators

National Science Foundation

U.S. Department of Defense

Meta Platforms

Red Rocks Community College

University of Colorado Colorado Springs

Regis University

Colorado Technical University

University of Kansas

University of Arkansas at Little Rock

Learn more about CCSP’s work and get involved at ccsp.mines.edu

CONCRETE SOLUTIONS TO INFRASTRUCTURE CHALLENGES

Mines researchers are improving construction materials with sustainability and performance in mind

BY SARAH KUTA

Concrete is the second-most consumed material in the world, second only to water. Used to construct buildings, roads, bridges, dams and many other pieces of vital infrastructure, this versatile material is everywhere. But its widespread use comes at a cost: By some estimates, the concrete production process is responsible for up to 8 percent of the world’s carbon dioxide emissions.

Lori Tunstall wants to change that. As a Mines assistant professor of civil and environmental engineering, she’s developing novel methods of improving concrete to help lower its overall environmental footprint.

The federal government is making a historic investment in rebuilding the nation’s roads, bridges and rails under the $1.2 trillion Bipartisan Infrastructure Law, and innovations developed by Tunstall and other Mines researchers are poised to help address infrastructure challenges and solve some of the country’s most pressing infrastructure issues now and into the future.

Tunstall is tackling concrete sustainability with two different approaches. She’s trying to help make concrete more durable so it can stand up to the punishing freezethaw cycle that exists in many cold climates, as well as other causes of degradation that, over time, cause concrete to crack, crumble and break apart. Concrete that lasts longer doesn’t need to be replaced as often which, in turn, will help reduce the demand for the heavy CO2emitting production process.

To improve durability in the long term, she’s studying the basic material science properties of existing air-entraining admixtures, which create air pockets that provide space for water to grow into ice crystals as it freezes within the concrete.

Lori Tunstall, assistant professor of civil and environmental engineering, handles a carbon-sequestering material called biochar.

“There are still just a lot of unknowns in the concrete industry,” she said. “We haven’t investigated the fundamentals that control the processes because they’ve always just worked—it’s one of those, ‘if it’s not broken, don’t fix it’ kind of things. But now that the admixtures are getting much more complicated, we’re trying to understand the fundamentals.”

Tunstall is also addressing CO2 emissions head-on by experimenting with incorporating biochar, the umbrella term for the carbon-sequestering material produced from biomass sources, such as wood chips and agricultural waste products, into concrete.

“With the incorporation of biochar into concrete, we’re able to replace 15 percent of the cement with this biochar additive, and we estimate that will offset the carbon footprint of concrete by at least 45 percent,” she said. “It doesn’t get us to carbon-neutral, but it gets us in that direction, so perhaps coupled with some of these other techniques, it could actually be a viable way to get us there.”

With the renewed focus on infrastructure, there’s also a greater need for construction materials across the country. Reza Hedayat, an associate professor of civil and environmental engineering, is working to meet that demand while also reducing the environmental impact of another industry: mining. In collaboration with Mines’ Center for Mining Sustainability, Hedayat is exploring how to reuse leftover minerals from mining operations in bricks, tiles, aggregates, ceramics and concrete additives. His research

has the added benefit of helping the mining industry reduce the environmental and economic impact of the 10 billion tons of waste materials, also known as tailings, it produces every year.

But before they begin replacing America’s existing infrastructure, engineers and construction crews first need to evaluate it—and, to do that, they need practical, costeffective techniques that don’t damage the structure or delay its operation. Hedayat is also innovating on that front. By designing and conducting highly controlled experiments, his group is investigating what’s happening inside materials and structures at various points in time—without damaging them in the process. For example, he collaborated with Kiewit Corporation to evaluate and test different methods of detecting potential voids caused by water washout in the grout behind concrete segments of tunnels being built in New York, a process that historically involved drilling verification holes. Thanks to his findings, on-site construction engineers were able to use ground-penetrating radar, which emits an electromagnetic wave pulse and measure the return time and strength of the reflection, to ensure the safety and stability of their projects.

“In some environments, there is a high potential for the grout to wash out behind the tunnel segments that would compromise the integrity of the tunnel support system,” he said. “Detecting the voids behind the segments allows the tunnel contractor to perform secondary grouting and fill any remaining void spaces. The assessment is important to ensure proper support of the tunnel and the ground around it.”

Through collaboration and ingenuity, Mines-led research has the potential to help strengthen and enhance the country’s ports, airports, railroads and highways, while at the same time reducing the impacts of these improvements on the planet.

Tunstall said, “If we’re going to be making an investment in infrastructure, let’s make it better.”

PhD student Cara Clements stress tests a sample of material made from mine tailings.

BRIDGING THE INTEROPERABILITY GAP IN CITIES

BY ASHLEY SPURGEON

We often see it in science fiction films: entire cities that operate with an interconnected ecosystem of smart technology that seamlessly shares data to communicate across a vast network of devices and platforms to maximize efficiencies. These “smart cities” enable a wide array of capabilities that the average person doesn’t even have to think about on a day-to-day basis, such as transportation and access to essential resources. Implicit in this vision is the idea of interoperability—the ability of disparate technologies and systems to interact with one another.

But while we don’t yet live in that sci-fi ecosystem, researchers are working on ways to make that a reality, but integrating this interoperability is more complicated than you might think. It all comes down to semantics.

To use data to understand a large area of an existing built environment, such as cities, buildings and transportation systems, having a good digital representation of that system is necessary. “We need a metadata model, which is a digital description of how the system is put together, how it works, what devices are there and what data they produce,” said Gabriel Fierro, assistant professor of computer science.

Buildings are responsible for 40 percent of the energy consumption in the U.S., so they are a particularly rich target for innovations in energy management. However, there isn’t a standard way for describing building systems. Many older buildings have no digital description, and while many modern buildings contain Internet of Things systems, the lack of a standard means that computers aren’t able to interpret that data effectively. Fierro is working on a project to change that by developing a standard way of describing buildings and their data to make it easier to develop software for them.

Fierro said the key to modeling a complex system in a consistent way is to figure out which details matter and which don’t—similar to how you can plug any keyboard, mouse or monitor into your computer and it will still work regardless of what kind of processor or operating system you have.

“I can write the software once and then deploy it for millions and millions of buildings and get the same benefits as if an expert had been there to curate the experience for

each building,” he said. “Having these consistent digital descriptions of this infrastructure makes it possible to provide management in a more distributed fashion without having to involve experts at every level. The software can essentially configure itself to run in a new building without any human intervention, similar to how an automatic car knows how to shift gears at the right time without the driver having to know when to move it back and forth.”

This semantic interoperability would allow for easier software development to provide better energy efficiency, optimize system performance and automatically identify and diagnose faults. This lowers costs for building owners who buy the software, as well as the developers who create it.

Fierro said, “Going forward, I hope to see critical physical infrastructure adopt more modern data management practices so we have greater insight into how these systems are operating. Eventually it would be interesting to explore the idea of municipal data as a public utility.”

“By creating open standards, you create a means of democratizing innovation in that area. The goal of this project is to make data more easily available so that other people can experiment without having to buy an expensive software license. I really enjoy putting things out into the world so other people can improve it beyond what I can think of.”

OPEN-SOURCE INNOVATION

Fierro’s project is centered around collaboration and an open-source community. National labs, universities and companies around the world are using Fierro’s framework and contributing to this research.

Collaborators

University of California, Berkeley

University of California, San Diego

Carnegie Mellon University

National Renewable Energy Laboratory

Lawrence Berkeley National Laboratory

Pacific Northwest National Laboratory

Johnson Controls

Schneider Electric

Standardizing building semantics will help improve efficiencies and performance

PROTECTING INFRASTRUCTURE AND PRIVACY THROUGH CYBERSECURITY

Multidisciplinary approaches tackle new threats as technology becomes more interconnected

BY ASHLEY PICCONE

As today’s networks become more interconnected and complex, security risks become more evident. Malicious attackers can remotely intrude into systems and access sensitive information and manipulate transactions. Phishing emails abound, and smart devices, like cameras and speakers, present even further opportunities to invade privacy. On a larger scale, security breaches in critical infrastructure, such as in natural gas pipelines, transportation, water resources, healthcare, food and agriculture, can have severe consequences.

That widespread and daily relevance is what interests associate professor of computer science Chuan Yue and inspires his research into the security of cyber systems within Mines’ Center for Cybersecurity and Privacy. “The nature of cybersecurity problems remains the same, but the scope is growing much larger,” he said.

Working with Mines’ CSSP, an interdisciplinary collaboration between computer science, electrical engineering, social science, and economics and business faculty, Yue seeks to solve challenges related to web, mobile, Internet of Things and cloud systems and does so in alignment with the Federal Cybersecurity Research and Design Strategic Plan.

CSSP researchers are prepared to defend against, and learn from, malicious cyberattacks. They send browsers to visit tens of thousands of websites, where they gather information about the pages, their protections and their vulnerabilities. Analysis informs another component of their strategy: designing new features and functionalities to protect users.

“Program analysis looks to see if website vulnerabilities are related to the programming language,” said Yue. “That, together with machine learning techniques, helps us analyze what could be wrong and what should be improved.”

Data collection and analysis inform strategies to design better websites and devices to protect users. But perhaps more important is teaching users to protect themselves. Mines researchers from business, economics and social sciences work with Yue to measure user understanding of attacks and determine best practices for their engagement and education.

“Cybersecurity is interdisciplinary,” said Yue. “Hackers have financial incentives, so we have a strong collaboration on the economics perspective. From the social, behavioral side, how attackers perform and how vulnerable people perform are related to human nature.”

Working in the other direction, Yue and his team help with quality control of crowdsourced surveys, which are used to collect important data for the social, behavioral and economic sciences and can easily be manipulated by attackers. Through these collaborations and by allying with other engineering-focused researchers at Mines, Yue hopes to build safer web systems, technology and critical infrastructure from the ground up. That begins at the individual level.

“Largely, security and privacy problems are due to humans,” said Yue. “If we can identify trends in potential risks and educate users, or regular people, about those risks, then when they visit different websites they will be more cautious and keep themselves and others safe.”

“To observe a full-scale tall building with a new lateral system that we believe will be resilient and even damage-free under large earthquakes—that is invaluable, not only for the science community but also the engineering community around the globe. This will add a more sustainable building option for seismically active regions.”

Globally, more than a billion people live in earthquake zones, and the urban population in these areas is expected to grow over the coming decades. The need for earthquake-safe buildings will become increasingly important, but safe structures in seismic zones haven’t traditionally been made from sustainable building materials—another concern for the future.

Shiling Pei, associate professor of civil and environmental engineering at Mines, hopes his research in wood construction will show that using wood materials is a sustainable alternative that’s also seismically sound— even in tall buildings. Pei is a principal investigator on the Natural Hazard Engineering Research Infrastructure (NHERI) Tallwood Project, a National Science Foundationfunded research collaboration between Mines and five other U.S. universities, that is developing a seismic design methodology for wood buildings that, to meet demand in urban areas, climb eight to 18 stories into the sky.

To test their design, Pei and his colleagues spent summer 2022 in San Diego, where the project is erecting a 10-story mass-wood building on the NSF’s outdoor shake table at full scale. When construction is complete in December 2022, the researchers plan to run about 40 seismic simulations on the building, which is constructed with mass timber gravity framing and an innovative lateral system made of wood panels that freely rock to absorb an earthquake’s energy.

Rocking walls aren’t new—Pei said they were first tested and used with concrete construction. But concrete rocking walls tend to crack during large earthquakes and are difficult to repair. “The wood gives it another layer of resiliency guarantee,” he said. The team’s tallwood design uses mass timber construction that, rather than building a frame using smaller dimensional lumber such as two-byfours, consists of large engineered wood panels glued or nailed together. In tallwood building design, the rocking wall is a wood panel with pre-stressed steel tension rods tying it to the foundation.

“The materials—just steel rods and wood panels—they’re not fancy, but with the design procedure developed in

NHERI TALLWOOD PROJECT BREAKDOWN

The shake table use is funded by the National Science Foundation, the primary funder of this project.

The experimental facility is supported by the NHERI program.

USDA US Forest Services is the second-largest funder of this research, supporting testing and related R&D on mass timber research at Mines for close to $1 million over the past six years.

this project, you can target a certain level of earthquake intensity and make most of the building components to remain undamaged,” he said. “Because the post-tensioned steel rods will remain elastic during the earthquakes, the building can always come back to plumb after the shake.” Even though building materials such as concrete and steel have a high carbon cost, using wood as a sustainable building material might still seem counterintuitive. “There’s a forced perception that the lumber industry is cutting down forests,” Pei said. “But in most developed countries, the reputable wood industry companies are typically regulated to use wood from sustainably managed forests. Once you have a well-established industry, sustainability becomes something that they strive to achieve for their own benefit. They own the land, so they would like to keep growing trees again and again to make money out of it for the years to come.” The industry also manages the forests for fire because it will be their loss,” he said. “Especially under climate change, if you don’t have the money and capital going in to take care of the forest, it can end up getting impacted more negatively by climate change.”

Countries that already have a rich tradition of building with timber have already shown their interest in this style of building. “In Europe and Japan, they have heavy timber tradition as part of their history, so they’ll be the early adopters,” Pei said. “I firmly believe in the U.S., we’ll also be a big player in mass timber, because we use a lot of wood material in existing building stock already.”

At full scale, the shake table test of a 10-story building will provide an incredible proof-of-concept for the construction industry and the public in places like California, British Columbia, and earthquake-prone cities in Italy and Japan, where Pei said they have active research and industry collaborators in the project.

Pei said, “To observe a full-scale tall building with a new lateral system that we believe will be resilient and even damage-free under large earthquakes—that is invaluable, not only for the science community but also the engineering community around the globe. This will add a more sustainable building option for seismically active regions.”

Universities on the research team:

Colorado School of Mines

University of Washington

University of Nevada, Reno

Colorado State University

Washington State University

Lehigh University

$3.8 million

Academic collaborators:

Oregon State University

Michigan Technological University

University of California

San Diego

Kyoto University

in funding to test the 10-story building on the shake table

COLORADO SCHOOL OF MINES IS AN R1 RESEARCH UNIVERSITY

Recognized by the Carnegie Classification of Institutions of Higher Education, Mines is in the top tier of research universities in the United States with a Research 1 (R1) “Very High Research Activity” classification, the highest and most prestigious designation granted to U.S. research universities.

Mines is now one of just R1 institutions in the U.S.

146 Research funding has grown 45 percent 20 percent at the university since 2016

Mines receives a far larger share of research funding from industry than most other R1 universities, at roughly

Electrical engineering student Meredith Amrhein places a sample in the Zeiss 520 Versa X-ray Computed Tomography Microscope used for 3D imaging.

Photo by John McKeith