Green Technology: Environmentally Friendly Pursuits for a Better Tomorrow
by Zachary M. Bauer
Mr. Baldauf HVAC 204 14 March 2011
Bauer 2 Zachary M. Bauer Mr. Baldauf HVAC 204 14 March 2011 Green Technology: Environmentally Friendly Pursuits for a Better Tomorrow In the last three years alone, the advancements made in green technology have been massive. Already there are examples of green technology that have been made readily available to residential consumers at affordable rates with realistic reimbursements through reduced billing amounts, tax breaks, and increased efficiencies. The science of green technology continues to grow however, with more environmentally friendly and efficient methods of accomplishing everyday tasks on residential, commercial, and industrial levels. The green energy technologies that are shaping tomorrow are the concepts of various green energies, dynamic green buildings, and the breakthroughs in nanotechnology. There have been countless forms of green renewable energy advancements in the last decade, ranging from biomass energy to geothermal energy. Through biomass research, technologies have been developed to convert biomass—plant matter such as trees, grasses, agricultural residue, algae, and other biological material—to fuels. The National Renewable Energy Laboratory claims that “These biofuels will reduce our nation's dependence on foreign oil, improve our air quality, and support rural economies.”, although realistic implementation of this technology has yet to been uncovered (Science & Technology). Another source of energy yielded from the earth is geothermal. Geothermal has various applications, all using the natural heat emitted from the earth that lies beneath the surface. “We use the geothermal reservoirs of hot water and steam to generate electricity and for direct
Bauer 3 applications, including aquaculture, crop drying, and district heating. We also use the constant temperature that exists at very shallow depths for heating and cooling buildings with the energyefficiency technology of ground-source heat pumps” (Science & Technology). The heat within the earth is all-renewable; having no chance to be extinguished by human use. The energy generated is found through hot water steam aquifers. The two most popular methods of renewable energy also happen to be among the least used in America; solar and wind power. Solar and wind combined amount to just 0.84% of all energy produced in the United States (Summary Statistics). Photovoltaic technology has been enhanced, however. New third generation solar cells are designed to possibly overcome the Shockley-Queisser limit of 31 to-41% for single solar cells. The Shockley-Queisser limit refers to the maximum theoretical efficiency of a solar cell using a p-n junction to collect power from the cell (“Applied Physics” 14). These new third generation solar cells are projected to be able to reach efficiencies up to 65%, and are considered to be much more cost-efficient; being more accessible to the general public having less of a price tag (“Third Generation Photovoltaics”). Wind and water technology has progressed little in the last decade, although hydro-electric power plants account for 6% of the total power generated in the U.S. and an impressive 60% in Canada. Wind power uses the basic principles of induction coils to generate power, just as a gasoline generator would. The perk of wind energy is of course however, its renewable nature. The second category in green technology breakthroughs are green buildings. The concept of building green is described as “the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building's life-cycle from siting to design, construction, operation, maintenance, renovation and deconstruction”. The most basic forms of green building simply use sustainable materials in their construction, create healthy
Bauer 4 indoor environments, and feature landscaping that reduces water usage (“Green Building”). These practices are used mostly to conserve and efficiently apply energy usage. More advanced methods of building green include building practices of tactical building siting, energy efficiency, materials efficiency, and water efficiency. Strategic building siting in commercial application is used not so much for the sake of energy conservation, but to promote green technology. Green buildings are sited in areas that take advantage of mass transit, and use the natural environment to grow plants that will thrive rather naturally using undomesticated precipitation to implicate a cosmetic effect (“Green Building Basics”). Energy efficiency is defined as using less energy to provide the same level of energy service. For example, a building can be designed passively in order to dramatically affect building energy performance. These measures include building shape and orientation, passive solar design, and implicating the use of natural lighting. Energy efficiency in buildings will also be achieved through high-efficiency lighting using motion sensors, as well as geothermal heating and cooling systems used in conjunction with thermally efficient buildings; having high R-value insulation, maximizing light colors on building shell, and minimizing glass exposure on the east and west sides of the building exterior (“Green Building Basics”) Another method of green building is to conserve materials through material efficiency. Green buildings are constructed with low toxicity sustainable materials that can be easily recycled and ensure longevity and durability throughout the building life. Usage of efficient materials develops markets for recycled materials, as well diminishing the need for new materials to be manufactured. The third goal of advanced green building is water efficiency. Green technology engineering allows for design of dual plumbing systems to use grey water, an
Bauer 5 arrangement used to recycle water or collect rainwater to flush toilets or for site irrigation (“Green Building Basics”). Similarly, there is another green building arrangement that takes into account the building operation itself. Dynamic architecture is definitely the next generation in green architecture. Take the concepts of the Dubai tower; an entirely self-sustaining skyscraper capable of generating more electricity than the tower would have to consume, producing an impressive ten megawatts. The many floors of the tower will rotate individually throughout the day at extremely slow speeds; in order to avoid inducing motion sickness. This amazing feat is possible thanks to the wind accumulators found in-between the different floors as well as the concentrated solar power armature found on the external of the tower. The third method of gathering energy through selfsustained means is a massive updraft tower, measuring up the height of the entire tower (Dynamic Architecture). This engineering masterpiece will undoubtedly rewrite architecture for many civilizations across the globe. The most intricate technological advancements have been in nanotechnology; which also has the potential to yield the highest resource output. Nanotechnology is viewed as being “an anticipated manufacturing technology that allows thorough, inexpensive control of the structure of matter by working with atoms. It will allow many things to be manufactured at low cost and with no pollution”. The ability to manipulate atoms gives humans the opportunity to fabricate materials and resources with no environmental repercussions. Furthermore, Wilson states that “it [nanotechnology] will lead to the production of nanomachines, which are sometimes also called nanodevices. It is therefore an advance as important as the discovery of the first tool [fire]”. Nanomachines have unlimited uses, from sci-fi inspired medical uses to industrial uses; such as
Bauer 6 to clean up oil spills (currently accomplished by various enzymes) or even to purify air (Wilson et al. 3). The energy efficiencies that can be accomplished with nanotech far surpass the attainable efficiencies that are used today. By the twenty-second century, nanotechnology will have greatly advanced the technologies of medicine, chemistry, information and communication, heavy industry, consumer goods, and energy. Only through research into energy will these other various fields become realistically available, however. Investigation must be concentrated into nanodevices as semiconductors, their use in batteries and capacitors, solar cells, reduction of energy consumption, and the increase of the efficiency of energy production. Increasing energy production will be the largest breakthrough in nanotechnology. This can be accomplished by maximizing the energy output of steam generators, for example. Dr. Gillet explains this phenomenon in his work, Nanotechnology: Clean Energy and Resources for the Future:
Nonetheless, energy could be used vastly more efficiently in technological processes. Present-day energy efficiencies lie anywhere from factors of several to orders of magnitude below the thermodynamic limits. In effect, the high energy densities of conventional fuels are a "brute force" compensation for the inefficiencies with which they are used. The reason, as foreshadowed in the Introduction, is that energy is largely used as heat. "Fuels" are "burned"; that's what fuels are for, at least in conventional thinking. Indeed, "energy" often means just heat—a generally unexamined assumption that might be termed the "Promethean paradigm." It turns out, however, that "burning" a fuel—i.e., converting its chemical energy into heat—discards much of its free energy, the energy available to do work. For an example, let us look at the reaction of H2 and O2 to form water vapor at standard temperature and pressure (STP, 1 atmosphere and 25°C): (R1) H2 + ½ O2 → H2O (g). For processes at constant pressure and temperature, typical of those at the surface of the Earth, the maximum useful work that can be obtained (or alternatively, the minimum energy cost of a thermodynamic transformation) is given by the Gibbs free energy:
(E1) ∆G = ∆H - T∆S = ∆U + P∆V - T∆S.
Here ∆H is the change in enthapy (change in internal energy ∆U, plus any pressure-volume work P∆V done), T is the absolute temperature, and ∆S is the change in entropy. Obviously, ∆G is a function of temperature. Since ∆H and ∆S are functions of temperature and pressure, ∆G is a function of pressure as well. The T∆S term, which has dimensions of energy, represents the "tithe" paid to the
second law. It is a measure of the energy that is lost. Because the ∆S term increases with temperature, the irreversible losses also are larger the higher the temperature at which reaction is carried out. Hence the maximum thermodynamic efficiency is given by ∆G/∆H. For reaction (R1), for example, the Gibbs free energy at STP is some -228.6 kJ/mol, whereas the enthalpy is -241.8 kJ/mol. In the thermodynamic limit, therefore, some -228.6/-241.8 » 95% of the total reaction energy is available to do useful work. This is far more efficient than conventional processes. Combustion heat from this reaction could instead be used to drive a heat engine. A heat engine turns some of the flow of heat from a hotter body to a cooler body into useful work, and the maximum efficiency at which it can do so is the Carnot efficiency: (E2) eC = (Th - Tc)/Th, where Th is the absolute temperature of the hot body and Tc that of the cold. The Carnot limit can be derived rigorously from the second law of thermodynamics (e.g., Moore, 1972, p. 78-85). For example, the heat from stoichiometric combustion of H2 and O2 to form one mole of water could be used to form 3.8
Bauer 8 moles of steam at 550°C (823 K) at a pressure of ~2.1 x 107 Pa (3000 psi), which are typical operating conditions for a modern steam-turbine electrical generating plant (e.g., Peltier, 1995).
Essentially, as the fuel is changed from chemical energy to thermal energy, the nanomachines absorb the traditionally unused heat and convert it into further usable energy. The nanomachines do not use the heat itself for useful energy; however they use the transition of heat energy as it moves from hot to cold as explained in the second law of thermodynamics. This advantage of nanotechnology will allow it to gather increased efficiencies in current energy generation methods (Gillet 12-4) In addition to increasing energy output in power generation, nanotechnology can also maximize power reservoir life in capacitors, batteries, and fuel cells. Nanotechnology will be used to create effective semi-conductors in capacitors and batteries. Fuel cells work by directly converting chemical energy into electrical energy. This has been achieved traditionally by using hydrogen, and coupled with the fuel cell’s limited lifespan caused a stunt in its popularity growth. Both of these problems actually stem from flaws in the fuel cell’s nanofabrication. In order to rectify the fabrication of these fuel cells, two imperfections must be assessed: the catalysts and electrolytes both need improvements. Unsurprisingly, these improvements can only be achieved by way of nanotechnology (Gillet 15) In order for the fuel cell to promote the fuel molecules to react, the molecules must be ionized. The fuel cell fundamentally “catches” electrons transferred during the oxidation process in order to perform useful work. In order to execute this goal, one catalyst must encourage ionization at the anode, while the other catalyst promotes the reduction of dioxygen in electrons with as low of an overvoltage as possible. Because of the non-thermal chemical reactions taking place, fuel cells are much more fragile in how they react to various compounds; limiting their
Bauer 9 construction to just a few compositions, as well as the compatible fuels. With nanomachines and nanotechnology, this fragile reaction could be controlled and the energy output can be maximized at peak stability (Gillet 15-20) New efficient batteries work by generating DC voltage through a coupled set of redox reactions. In these newer batteries, Li+ is used due to the greatly enhanced energy densities. In these batteries, at least one redox-active electrode has an open crystal structure with voids capable of interlacing Li+ ions. In batteries with two of these electrodes, during discharge Li+ is expelled by one electrode and taken up by the other. Through nanotechnology, these crystal structures can be maximized allowing for greatly prolonged battery life and allowing for cheaper reproductions of such formations (Gillet 20). There have been various technological breakthroughs in green energy technology. These concepts have the realistic potential to change the world as it is known today. The implementation of renewable green energy will halt the energy crises and allow for cheaper more accessible means of gathering and using power. Dynamic green buildings will maximize environmental architecture by creating massive structures with such an insignificant carbon footprint that it would help the environment. Finally, advancements in nanotechnology will literally change the world; and in doing so prove to be a technological discovery on par with the wheel. Environmentally friendly technology will continue to grow, just as it has immensely during the last decade. In doing so, more environmentally friendly ways of completing everyday tasks are available in residential, commercial, and industrial avenues. Green technology is economically and environmentally stable, all in the pursuit of a better tomorrow.
Bauer 10 Works Cited “Applied Physics of Solar Energy Conversion.” Rpi.edu. Rensselaer Polytechnic Institute, 2010. Web. 12 March 2011. <http://www.rpi.edu/dept/phys/Courses/PHYS1010/Fall07/Persans.pdf> Dynamic Architecture. Dynamicarchitecture.gov. Dynamic Communications Limited. Web. 12 March 2011. <dynamicarchitecture.net/revolution/> Gillet, Stephen L, Ph.D.. Nanotechnology: Clean energy and Resources for the Future. Reno: 2002. Foresight.org. Web. 12 March 2011 < http://www.foresight.org/impact/whitepaper_illos_rev3.PDF> “Green Building.” Epa.gov. EPA, 2010. Web. 12 March 2011. “Green Building Basics.” Calrecycle.ca.gov. California Department of Resources Recycling and Recovery, 17 April 2010. Web. 12 March 2011 Science & Technology. Nrel.gov National Renewable Energy Laboratory. Web. 12 March 2011 Summary Statistics for the United States. Eia.doe.gov. U.S. Department of Energy, 2009. Web. 12 March 2011. < http://www.eia.doe.gov/cneaf/electricity/epa/epates.html> “Third Generation Photovoltaics.” Pv.unsw.edu.au. University of New South Wales, 12 March 2011. Web. 12 March 2011. <http://www.pv.unsw.edu.au/research/3gp.asp> Wilson, Mick, Kannangara, Kamali, Geoff, Smith, Simmons, Michelle, and Raguse, Burkhard. Nanotechnology: Basic Science and Emerging Technologies. Sydney: University of New SouthWales, 2002. Print.
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