Gas Power Technology J O U R N A L Bi-weekly news
12 March 2014
U.S. needs new policy to tackle power plant cyber attacks Security at power plants in the United States is under threat from cyber-attacks, according to a recent report from the Bipartisan Policy Center (BPC). “Evidence collected by the U.S. Department of Homeland Security (DHS) suggests that cyber-attacks on key energy infrastructure—and on the electricity system in particular—are increasing, both in frequency and sophistication,” said Margot Anderson, lead author of the report and director, at the BPC. ut of a total of 256 cyber incidents reported to DHS in 2013 across all critical infrastructure sectors, 59% involved the energy sector and in particular electricity generation. A large-scale cyber attack on the electric grid would present governance and coordination challenges potentially destroying country wide communications, food and water supplies, health provision and fuel delivMargot Anderson eries. In 2007 the Aurora event
at a U.S. DOE’s Idaho facility demonstrated the capability of a cyber attack to infiltrate a generator control system and led to the destruction of the generator and started a fire.
Electric Power System and Control Communications
Cybersecurity to cost $7 billion by 2020 The report, titled ‘Cybersecurity and the North American Electric Grid’ addresses new policy approaches that the BPC advises are necessary to counteract attacks. The report’s authors suggest that in the U.S. alone utilities will spend
about $7 billion on cybersecurity by 2020. “An important question is how the costs of these investments will be distributed among utility shareholders and customers,” Anderson said. “The challenge for regulators lies in determining whether a particular investment is prudent, or whether other needed investments are being overlooked.”
EU research improves GT combustion to avoid flame instability Improving the reliability of the combustion process in gas turbines (GT) can potentially save operators tens of millions of euros. “Although failure due to flame instability is extremely rare, a single event can cost in excess of €10 million - so research to improve reliability is vital” Professor Jim Kok, project co-ordinator for the Limousine group told Gas Power Technology Journal. he Limousine project group, a consortium of European universities and industries, includes industrial partners Siemens and Electrabel and has taken a multi-variant approach to study instabilities in gas turbine combustion. It will publish its findings over the course of the coming year.
AGENDA FUEL CELLS World’s largest fuel-cell plant (59 MW) opens in South Korea AES launches battery to replace smaller gas power 3 LNG TO POWER GE develops gas power solution without pipelines Wärtsilä sees rise of single purpose LNG terminals to supply power plants 4 CCS ON GAS-FIRED GENERATION Peterhead shares £100m to develop world’s first gas CCS technology 5
Reducing thermo-acoustic instability helps prevent turbine failure The aim of this research has been to predict the mechanical vibration in a gas turbine engine and help prevent fatigue and damaging failure. At present variations in the burner flame can frequently create unwanted thermo-acoustic pressures of
continued on page 2
SELECTIVE LASER MELTING 3D metal printing of turbine parts to cut repair times by 90% 6 Test rig of Limousine Group
between 4,000 and 40,000 pascals, a range which can be fatal for components. continued on page 2
GAS TURBINE RESEARCH TU Vienna thermo-power research offers output boost for turbines 7
12 March 2014
Top story, continued from page 1
The report highlights a number of urgent priorities, suggesting that costs may be far higher than the projected figure of $7 billion, if adequate steps are not taken now to create a countrywide policy to tackle complex threats. “New polices and public-private partnerships are needed to address the growing threat of cyber-attacks on the North American electric grid,” he added. “Power sector companies need tools and incentives that will enable them to invest in cybersecurity in ways that benefit the broader system and to support the development of advanced cybersecurity solutions.” The first step identified by the BPC is to strengthen existing protections for the distribution system as well as the bulk power system. This must then be matched with enhanced coordination at all levels and development of robust protocols for response and recovery in the event of a successful attack.
New industry body needed to co-ordinate risk management
Greater information sharing ‘essential’
One key recommendation to come out of the report is the establishment of a new industryled body, comprising power sector participants across North America, modelled on the nuclear power industry’s Institute of Nuclear Power Operations (INPO). “We believe such an organization could substantially advance cybersecurity risk-management practices across the industry and, in doing so, serve as a valuable complement to existing NERC standards,” Anderson commented. Such a body would develop cybersecurity performance criteria and conduct detailed cybersecurity evaluations at individual facilities. It would also be responsible for analysing systemic risks, particularly on the distribution system, analysing cyber events as they occur and providing technical assistance, such as the use of new cybersecurity tools.
Any new body would also be required to facilitate information sharing between utilities, between industry and government and across government agencies. While the BPC believes government and industry are doing a better job of sharing information on cyber threats, commercial organisations are often reluctant to share data. Without suitable regulatory framework in place utilities may not share data for fear of triggering regulatory non-compliance actions, violating privacy or antitrust protections, or potentially disclosing proprietary or confidential business information. “Our recommendations target these issues as well as the need for enhanced information sharing with international and state-level counterparts, and across critical infrastructure sectors,” the BPC said.
revenue but large penalties as well if they are operating in a capacity market or under a contract for delivery. Altogether a single event can cost between €1 million and €10 million.
entire system as a whole. "We now know that the methane number plays a large part in stability and manufacturers increasingly want turbines that can operate with a range of fuels" Kok commented. Recent European funding to integrate gas networks may increase the variability of gas content as supplies arrive from a range of sources.
continued from page 1
As a result of instable pressure waves blades can snap, destroying the entire turbine's operation. Not only does the lead to costly repairs, with individual blades costing in the order of €20,000 each, but downtime can add significant costs to operations. Independent Power Producers (IPPs) face not only a loss of Gas Power Technology Journal Publisher Stuart Fryer Editor Anja Karl Tel: +44 (0)207 0173417 email@example.com Senior Reporter Malcolm Ramsay Tel: +44 (0) 207 0173 413 firstname.lastname@example.org Asia Correspondent Ramadas Rao Tel: +91 80 4219 0096 email@example.com Advertising Narges Jodeyri Tel: +44 (0)207 2533406 firstname.lastname@example.org Events Barbara Canals Tel: +44 (0)207 173410 email@example.com Subscriptions Stephan M. Venter Tel: +44 (0)207 0173407 firstname.lastname@example.org Production Vivian Chee Tel: +44 (0) 20 8995 5540 email@example.com
Researchers design new generation of burners To investigate the phenomena of burner instability identical copies of a combustor were sent to five different laboratories to be analysed through different approaches. One of the key results from the University of Twente (UT) research has been the discovery that instability can cause severe intensification of the flame. "This focuses the combustion process in a compact volume, due to high acoustic velocities, and has proven the importance of chemical kinetics and transient heat loss in predicting instability events." Kok said. As a result of this insight the team have been able to develop an atmospheric combustor that can operate in either stable or oscillating combustion. "We used saturated amplitude limit cycle oscillations and induced acoustics and vibration in a gas turbine type combustor to study the operating conditions inside the combustor" Kok added.
Accurately predicting GT operating conditions Although initial funding for the project has now ended, follow on research is already underway. Researchers are now looking at means to understand more wide ranging aspects of engine operation and study the
Industry partners spur commercialisation Using the models derived from the research, Siemens, one of the industrial partners, has already taken the first steps to creating a new generation of gas burner. The new design takes advantage of a more distributed flame, greatly reducing instability and reducing the risk to operation. "The Limousine project has involved industry partners as research fellows, helping to boost cross-over for commercialisation," Kok said, adding "Our results have been used to analyse the latest Siemens low NOx combustor design and to investigate the thermo-acoustic performance of a full size gas turbine in use by Electrabel/GDF Suez." The Limousine group includes the universities of Twente (UT), Keele, Brno and Zaragoza as well as Imperial College London, DLR Stuttgart, CERFACS Toulouse and IfTa in Munich. Between these various groups measurements were taken with respect to acoustics, chemiluminescence, vibration, transient velocity field, transient heat transfer and instability growth rates.
12 March 2014
World’s largest fuel-cell plant (59 MW) opens in South Korea U.S. manufacturer FuelCell Energy (FCE) has completed the world’s largest fuel-cell plant at the Gyeonggi Green Energy site in South Korea, generating 59 MW of output from hydrogen formed out of natural gas. The fuel-cell park, located in Hwasung City in the north west of the country, provides baseload electricity to the South Korean electric grid as well as heat to a local heating system and is powered by 21 hydrogen fuel cells each generating 2.8 MW. he stationary fuel cell modules employed in the plant are capable of operating on a variety of hydrogen, methane, or other hydrogen-rich fuel gases such as natural gas, coal gas, propane and biogas from wastewater treatment, food processing, or landfills. The fuel cell stack reacts electrochemically with oxygen in ambient air to produce electric current, heat and water and since the exhaust steam from the first stage of a Molten Carbonate Fuel Cell (MCFC) is around 400C, there is the potential to use a secondary heat converter to achieve electrical power generation efficiency up to 60% in combination. "The scale of this installation is contributing to the power and heating needs of an urban population and generating the electricity in a highly efficient and ultra-low emission profile
that supports our national renewable portfolio standard," commented Tae-Ho Lee, chief executive of Gyeonggi Green Energy. Gyeonggi Green Energy is owned and operated by Korea’s largest independent power producer POSCO Energy and the 5.1-acre facility for the first time provides similar output to a small conventional power plant.
technology in South Korea, the company also announced groundbreaking for the 19.6MW Godeok Rolling Stock Management Office fuel cell park, consisting of seven DFC3000 fuel cell power plants that each provide 2.8 megawatts of power.
Fuel cell market to reach €4.8 billion
Investment in novel energy technology is booming in South Korea following strong support from President, Park Geun-hye. The country has high urban population densities, a growing economy and rapidly rising energy demand and as a result the government has committed to invest in "energy storage systems, smart grids and energy [load] management systems" in order to boost efficiency." South Korea will take the lead in transforming into a creative energy economy," Park said. As part of this strategy the South Korean Ministry of Trade, Industry and Energy (MOTIE) recently announced the introduction of the second phase of its Renewable Portfolio Standard, tightening regulations for major commercial energy users by 2016. The government has stated an aim of reducing greenhouse gas emissions by 30% by 2020, and has mandated that the largest utilities obtain 10% of their energy from renewables by 2022.
The quiet operating characteristics and modest land-use needs mean that demand for distributed fuel cell generation in urban settings is growing. There are currently 7 global markets for natural gas based fuel-cells and 4 global markets for biogas with mid-market potential of €3.2 billion and €1.6 billion respectively, according to FuelCell Energy Solutions GmBH, a partnership between FCE and Fraunhofer IPK. "Costs typically are related to scale of the project and source gas quality / composition and therefore can range from well below €3000/kW to above €7000/kW for a fully turnkey solution ready to produce power,” Klaus Ullrich, director business development, FuelCell Energy Solutions said, commenting on Artist’s rendition of the 59MW Gyeonggi Green Energy the benefits for larger fuel cell parks. fuel-cell park Reinforcing the appetite for fuel-cell
Korea’s “creative energy economy” embraces gas power fuel-cells
AES launches battery to replace smaller gas power .S. power provider AES has launched a new modular battery product designed to deliver energy to the grid at comparable rates to smaller gas-fired power plants. The Advancion solution allows companies to combine multiple battery units to achieve output similar to a 50MW peaking plant with the option to grow incrementally. The Advancion product was launched by subsidiary AES Energy Storage and is a fourth generation of the technology.
Storage cost competitive with peaking power AES battery systems are already widely installed around the world with 200 MW of storage resources deployed and in construction and over 1.5 million MWh of service delivered. However, most existing projects have been one-off or first-of-a-kind developments aimed at providing off-grid power storage. “The Advancion storage offering is a natural
extension of our business platforms, serving utilities, power systems, and their customers,” said Chris Shelton, president at AES Energy Storage. “Looking at the challenges faced by utilities and power markets today, we developed a complete and cost-effective battery-based solution for power reliability.” The modular nature of the batteries means that utilities can easily add more capacity and costs are relatively low. AES estimates a target capital cost of $1,000 per kilowatt or less as compared to a cost of Comparison of battery and gas-fired peaking power about $1,350 per kilowatt for a typical gasfired peaker plant in California. Demand for battery based solutions The plug and play nature of the technology heats up means that AES offers Advancion as a turnkey Demand for battery based power is expected to solution that includes delivery of arrays, siting grow as grid operators seek to mandate ways to and permitting, interconnection, facility design, balance intermittent renewables. The Califorand fully managed engineering, procurement nia Public Utilities Commission (PUC) last and construction. AES currently operates the year voted in legislation that will require operworld’s third largest battery park, the 32MW ators to provide 1,325 megawatts of energy Laurel Mountain facility in California. storage by 2020.
LNG TO POWER
12 March 2014
GE develops gas power solution without pipelines Indonesia’s PLN Enjiniring and GE are developing a “comprehensive marginal gas-to-power solution” with no pipeline infrastructure. Termed as a “virtual” pipeline, the pilot project in remote islands of Indonesia will use GE Oil & Gas’ LNG-In-A-Box technology. hrough this joint-packaged solution, small volumes of gas now can be liquefied, transported, stored and regasified at a distanced demand location with no pipeline infrastructure to produce fuel for small-scale distributed power plants," GE announced in Jakarta this week at the launch of its new global distributed power business. Papua, and other remote locations in Indonesia where it is extremely difficult and expensive to lay conventional pipelines, are earmarked to host a pilot scheme of the LNGIn-A-Box technology. GE has not yet disclosed a specific timeframe for realising this first project.
The pilot model is said to address diesel replacement, peaking power plants and remote generation and therefore is ideal for an archipelago such as Indonesia, which has 17,000 islands. As an alternative to diesel-fuelled generation, the solution will help to cut costs by reducing subsidy spending by the government, it is claimed. GE's distributed power products include Jenbacher and Waukesha gas engines, aeroderivative gas turbines
and clean cycle waste heat recovery solutions with an output range of 100 kW to 100MW.
Wärtsilä sees rise of single purpose LNG terminals to supply power plants Single purpose LNG receiving terminals (SPT) attached to combined-cycle gas power plants may be profitable solutions for small and medium scale LNG storage in the future, according to Wärtsilä. The Finnish plant and services provider has just signed a contract to supply an LNG terminal to Tornio in Finland and expects a 30% rise in global LNG shipments by 2016. bsolute global LNG production is forecast to grow from 270 million tonnes per annum (mtpa) in 2011 to around 350 mtpa by 2016, boosting development of new gas-fired power plants.
Bright future for LNG single purpose receiving terminals Re-gasification capacity today is around 660 mtpa but the need for SPT to supply gas power plant is increasing because of difficulties developing sufficient pipeline infrastructure between supply and demand zones, the Wärtsilä report finds. The estimates are published as part of a new report examining the economics of "Single Purpose" LNG receiving terminals (SPT). Such terminals typically receive and store LNG for a given region and act as a central point to distribute to users in the local area.
The capacity of such storage facilities ranges from a couple of hundred m3 to around 20,000m3. Wärtsilä studied three power plant sizes with electrical outputs of 50 MWe, 100 MWe and 300 MWe at 35°C ambient conditions. Results suggest that investment in a combined LNG SPT and power plant is profitable provided there are additional off-takers in the system to help reduce cost. The report concludes that the price is heavily dependent on the volumes consumed and the import LNG prices.
Wärtsilä’s analysis shows larger volume LNG project can be more profitable
Asia drives demand for LNG storage These findings are in line with the latest investments in LNG infrastructure which are largely in locations where demand outstrips domestic supply and high fuel prices reign. In Asia this differential is particularly acute with some of the highest LNG prices in the world. Since early 2013, energy companies have been boosting investment in LNG storage and regasification projects along Asia's coastal region. At the end of December, Chinese gas distributor Shenzhen Gas announced plans to raise $264 million for a comprehensive gas project featuring a storage tank with capacity of 80 thousand cubic metres (Mcm), gasification systems and 6 km of pipelines. Huadian Fuxin Energy, another Chinese operator, also recently signed an agreement with Hainan province government to build a 12 mtpa LNG terminal at a cost of around $6 billion. Temasek, the Singapore sovereign funded investment company, has previously stressed its intentions to develop the island state as the central hub for LNG trading in Asia in a bid to help set lower prices. It is hoped that this will tackle disparate pricing on global gas markets that sees some Asian nations paying over $18/MBtu for gas as compared with $4/MBtu in the U.S.
12 March 2014
CCS ON GAS-FIRED GENERATION
Peterhead shares £100m to develop world’s first gas CCS technology The announcement that the Peterhead CCS project will share £100 million of funding has paved the way for testing of the first commercial scale gas-fired power plant with CCS in the world. “This research will better understand the implications of long term exposure and operation of classes of carbon capture materials when functioning in the field,” Dr Mathieu Lucquiaud, a Royal Academy of Engineering Research Fellow at the University of Edinburgh told Gas Power Technology Journal. n initial £20million slice of funding is expected to be used for Front End Engineering Design (FEED) studies at Shell's Peterhead site in the North of Scotland, with researchers eager to develop the novel technology uniquely suited to gasfired power generation. The proposed Peterhead CCS Project aims to reduce CO2 emissions by 10 million tonnes over 10 years.
Gas CCS to utilise Shell’s Cansolv technology Peterhead is expected to start CCS operations during 2018-20, after 24 months of FEED and will use Shell's Cansolv capture technology. This proprietary technology uses regenerable amines to capture and remove SO2 and CO2 using large-scale aqueous solvents with minimal environmental waste. This technology has
The Peterhead CCS project will be the world’s first commercial scale capture for gas-fired power
now also been installed for commercial operation at Boundary Dam lignite-fuelled power plant where it will start CCS early in 2014. “CCS on gas will become even more important, due to the UK Government’s emphasis on using more gas for electricity generation, and is inescapable if shale gas emerges as a fuel source for the UK,” said Professor Stuart Haszeldine, director at Scottish Carbon Capture and Storage (SCCS). “The Peterhead project is critical to reducing the cost of tackling the UK’s carbon emissions by demonstrating that full-chain CCS offers a viable and safe route to doing so.”
Commercial scale gas-CCS to reach lower levelised cost than coal While the overall process for gas-CCS is essentially similar to coal-CCS, differences in the composition of emissions from gas-fired plants mean that new technology is required to ensure maximum efficiency. There are a number of significant differences between CCS for gas as opposed to coal, not least a lower concentration of CO2 and SOx in flue gases. While this means that gas plants are less polluting it poses different challenges to CO2 capture from coal flue gases. "The overall levelised cost of electricity from gas-fired CCS is lower than coal at current gas prices, even though the cost of capture per tonne of CO2 is higher," said Dr Mathieu Lucquiaud.
CO2 from the Peterhead power plant will be stored in the depleted Goldeneye reservoir in the North Sea
Goldeneye provides obvious choice for gas CCS The newly announced funding will establish a post-combustion capture plant, compression and dehydration facilities at Peterhead Power Station as well as new pipeline to connect the power station to the depleted Goldenneye gas field where CO2 will ultimately be stored. "There are many positive aspects of the Peterhead plant when it comes to CCS," Lucquiaud said. "Its location and existing transport infrastructure makes it an ideal 'low hanging fruit' to commence this first phase of research into commercial gas-power CCS." The Goldeneye field, a deep subsurface site, is extremely well understood because of its geological simplicity and the history of methane gas production from it.
Business case for commercial scale CCS needs policy support – IEA Though the Peterhead project can help prove the technical viability of CCS on gas-fired power generation, rolling out CCS at commercial scale will take more than just a successful demonstration: "It requires smart policies that allow industry to build a business case around the technology," Sean McCoy, analyst at the International Energy Agency (IEA) told Gas Power Technology Journal. emonstration projects like Peterhead are a very important step in building the case that capture on gasfired generation is technically viable and should help industry feel more comfortable with CCS at commercial scale," he said, stressing the need of supportive Sean McCoy policies to foster commercially viable projects.
Lack of pan-European CCS policies So far, coordinated policy support is missing on a European level and demonstration plants have
to rely on national support schemes. "The policies that could make follow-up projects commercially attractive are, by-and-large, missing in Europe and they'll need to be in place if Peterhead is to spark a revolution," he criticized. "The UK is developing a framework that should be able to support power generation with CCS, other European countries have yet to follow suit."
Higher CO2 price vs tougher emission rules A lack of cost-competitiveness has so far hampered the commercialization of coal or gas generation, equipped or retrofitted
with CCS technology. "Pricing should be more efficient, but isn't always going to be a politically viable option," McCoy suggested. Regulation might well be the right stimulus in the short-term as it is unlikely that the carbon prices will move up sufficiently. "Right now additional policies are needed that support CCS technology demonstration, early-deployment and, in particular, facilitate development of the transport and storage chain," he said. Gas generation from CCS equipped combined-cycle plants will be 8% in 2050, according to IEA's Energy Technology Perspectives (ETP) 2012, 2°C scenario.
SELECTIVE LASER MELTING
NEWS NUDGES Sunfire fuel cells receive 7-figure investment German fuel cell developer Sunfire has secured a seven figure euro investment from Total Energy Ventures and Electranova Capital. Sunfire’s product portfolio includes hightemperature solid oxide fuel-cells (SOFC) as well as solid oxide electrolysis cells (SOECs), power-to-liquid and power-to-gas systems. "Technology is at the tipping point of being robust and cheap enough for field applications and most trends in energy technologies over the next decades to come will improve market conditions for SOFCs," Nils Aldag, one of the founders of Sunfire GmbH told Gas Power Technology Journal. The Dresden-based company states that the funding will be used to “consolidate its position” as a technology enabler for the current energy transition in Europe.
Everest Sciences wins turbine inlet ECOChill order Turbine cooling specialist Everest Sciences has announced an order for two of its ECOChill hybrid turbine inlet chilling solutions from energy firm, Kinder Morgan. The company will provide units to chill inlet air on a Solar Taurus 70 and Centaur 40 gas turbine, used as the drivers for a pipeline compression station. “In the case of a gas pipeline such as this one, we are allowing the customer to maintain pipeline pressure, even during the hot and/or humid months of the year, and therefore deliver the contracted gas, at the contracted rate,” Eric Warren, director at Everest Sciences told Gas Power Technology Journal. The cooling units will be installed at Compressor Station 321, known as the Uniondale CS, near Clifford, PA, on the Tennessee Gas Pipeline, to allow consistent winter-like operation from the station also during warm weather days.
3D metal printing of turbine parts to cut repair times by 90% Though 3D metal printing is still at an experimental process for testing prototypes, Siemens and GE are gearing up to turn it into a standard technology for rapidly producing industrial parts. Used for producing burner components, 3D metal printing can cut repair times by up to 90% compared to conventional methods, according to Siemens. peeding up and simplifying the manufacturing process, 3D printing allows Siemens to create the nozzles in a single piece – instead of from 20 separate parts as done with conventional manufacturing methods. GE Aviation, meanwhile, announced that it will first join forces with Swedish company Arcam to produce 3D-printed components for its jet engines while its oil and gas division plans to start pilot production of 3D-printed gas turbines fuel nozzles later this year. Arcam is currently using its electron beam method to manufacture titanium alloy turbine blades for GE Aviation.
Cost effective for small numbers 3D printing, also known as selective laser melting, is slower than casting or molding but far more cost effective if only a small number of parts are needed. The technology concept allows individualised design and manufacturing of items using various materials, including powder or granulate, and a so-called 'printer. Metal powder is
Sulzer forms turbine services JV with China Huadian Swiss engineering and manufacturing firm Sulzer has signed a joint venture agreement with China Huadian (CHD) to provide ongoing gas turbines services. The deal covers field service, component repair, and delivery of new capital parts for CHD's gas power plants in China. The new joint venture will operate under the name of Hua Rui (Jiangsu) Gas Turbine Services Company.
12 March 2014
A smooth transition from round to square at this gas turbine part is difficult to achieve with conventional production methods, but it is simple with 3D printing.
placed on the floor of the printer, and a laser beam moves across the bed of powder. One tiny point at a time, the 'printer' melts and compiles the material into a three-dimensional object. As only a small amount of metal is melted at a time, it solidifies much faster than liquid metal poured into a mould.
Realising intricate geometries "Selective laser melting, allows us to realize geometries that can hardly be manufactured right now. We will see new frontiers for heat transfer and structural integrity," said Nicolas Vortmeyer, the Head of Technology and Innovation for Power Generation at Siemens. Additive manufacturing enables faster manufacturing and repair of gas turbine components, with higher functionality and performance. For example, when producing a pipe section that connects two parts of a gas turbine, a smooth transition from round to square is difficult to achieve using conventional production methods, but it is simple with 3D printing. "A lot of the effort of developing gas turbines involves proper validation; so if we can quickly manufacture our own components, we can try out our ideas really fast," Vortmeyer said. The Siemens Corporate Technology (CT) Division in Berlin is currently already testing some parts that were produced with rapid prototyping, aiming to manufacture innovative materials with business applications. Siemens has started offering SLM for repairing the burners on its SGT-800 industrial gas turbine, instead of replacement. An advanced design burner swirl for its SGT-750 turbine was recently launched that can only be manufactured by SLM.
12 March 2014
GAS TURBINE RESEARCH
TU Vienna thermo-power research offers output boost for turbines apping the searing 2,000°C heat of gas turbine combustion with new man made materials may add fuel efficiency, said Professor Andrey Prokofiev at Vienna University of Technology (TU Vienna). "While according to the second law of thermodynamics some heat will always be lost, we can turn part of this waste heat into useful electricity." A TEG (thermoelectric generation) module containing these new materials could generate small amounts of electricity from the exhaust gas of various thermal engines, such as power plant turbines, industrial or automotive engines, and use it to power the controls.
Cheaper and more efficient materials Satellites running on TEG modules, using radioactive decay as a heat source, don't require fuel, but generate a few hundred watts for 87 years, longer than a fuel cell, with efficiency of 3–7%. Researchers at TU Vienna are exploring a new material, intermetallic clathrates, which may be used in TEG modules to generate electricity from temperature differences. The research explores synthetic material made of clathrate molecules that trap different elements. TEG modules can connect two pieces of clathrate, each with a different type of conductivity and generate electricity when one side is heated to 300°C. Some modules achieve
the highest efficiency when heated over 900°C. The clathrates used are different from the naturally occurring types, such as the hard, white gas-pipeline-clogging substance (gas hydrate) occurring when ice traps methane. Professor Prokofiev has synthesized Barium-silicon-gold clathrates that trap silicon, barium, and goldcerium but hopes these materials can be replaced with cheaper ones. He said, "If you look at materials in the module it contains gold, and of course this is very expensive. Producing this material is very sophisticated so there's no prospect of commercial production. We first have to make it from cheaper elements." "The goal is to achieve higher thermal efficiency of materials and we are working in that direction, but the efficiency is not yet competi-
tive. The efficiency of the best materials about 1/3 that of a gas turbine," he said. "We have observed an increase in efficiency by substituting cerium. At present the efficiency of our material is 3% at operating at 300°C, but this is about 100 percent higher than that of a clathrate sample from same elements with the same electron concentration without Cerium." He said the small size of a TEG module with the material adds to its commercial potential: "We might use a very thin layer of our material covering an exhaust pipe. It's very thin, a few microns of thickness."
TEG modules for the masses Nanoscale TEG modules are close to being commercialised, having a predicted conversion efficiency of around 11 to 15 percent, said Prokofiev. National Institute of Advanced Industrial Science and Technology (AIST) has been behind the launch of 40W commercial TEG units for camping use, generating electricity from the heat of camp fires. Japanese manufacturer Komatsu is reportedly selling, through its distributor KELK, a tiny 50mm square TEG capable of generating 24W from a 280°C industrial furnace at 7.5 percent efficiency and has announced plans to expand its TEG module range to the 10kW class.
Alstom delivers 5% base load reserve for CCGTs to meet peak demand Flexible technology developed by Alstom gives combined cycle gas turbine (CCGT) plants the ability to operate at highest efficiency when at 95% output, allowing for a 5% base load power reserve at times of greater demand. “Our sequential combustion system allows the efficiency peak to be tuned to output, giving operators access to an extra power reserve within the plant base load range in periods of peak load demand or when ancillary services are asked by the electric grid system operator,” Arno Stein, Head of Product Promotion at Alstom's gas business told Gas Power Technology Journal. lstom's sequential combustion technology allows plant operators greater control in adapting performance to demand and gives a flat part-load efficiency curve anywhere between 80% and 100% load, creating a larger window of operation for plant owners close to base load efficiency or even above.
95% matching allows leeway for peak price maximisation Given the option to fine-tune the efficiency peak, many CCGT operators now choose to set the highest efficiency for around 95% plant load, ensuring that the plant can deliver significant load under base-load but allowing a margin to take advantage of higher peak prices on the market when relevant.
"We work closely with our power producer clients to tune plant performance to demand conditions," said Stefan Florjancic R&D director at Alstom. "This is useful for markets where there is tight demand for peak power. This is seen particularly in Singapore where there is a competitive merchant power auction that rewards providers that can deliver extra power reserve Alstom's sequential combustion engines can help deliver a 5% boost in output and similarly in markets with high renewable penetration or ancillary service requirements." exhaust gases from the first turbine feeding the SEV-burners of the second combustor. A fuel/air combination burns in the first Sequential combustion process stage, and radial temperature uniformity is acusing EV-/SEV-burners and complished by pre-mixing compressor air with ring-form annular combustors the fuel in the EV burners and later in the secThe sequential combustion process used in Alond stage by pre-mixing combustion gases stom's GT24 and GT26 gas turbines employs with fuel in the SEV-burners. an annular EV-burner arrangement, with the
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