Energy and Environment

Cleaner Coal Technologies

Coal-Based Power Generation
Edward Levy, Hugo Caram

Slightly more than 50 percent of the electricity used in the U.S. is generated in coal-fired power plants, which, in turn, are responsible for producing approximately one third of U.S. CO2 emissions. Developing the technologies needed to achieve a meaningful reduction in the carbon footprint of coal-fired power plants is the largest challenge facing the coal research community. Meeting this challenge will require that breakthrough technologies be developed to increase the thermal efficiency of coal-fired power plants and to capture and sequester the CO2 generated by burning coal. Lehigh research interests related to coal-fired power generation include development of technologies for carbon capture and sequestration, development of methods to increase power plant efficiency and reduce pollution from power plants, development of technologies to reduce consumption of fresh water for power plant cooling and development of improved materials for use in boilers and other power plant components.

Alternative Energy Sources

Fusion Research
Professor Arnold H. Kritz, Professor Eugenio Schuster

The Lehigh University Fusion Research Group is widely recognized in the international fusion community for developing and applying integrated modeling computer codes to predict the temperatures and densities in hot magnetically confined plasmas and for its research on control of theses plasmas. Members of the Lehigh group work closely with leading researchers at the largest fusion laboratories in Europe and the United States. The Lehigh group is playing a central role in using computer simulations, thoroughly validated against experimental data, to predict the expected performance of the ITER fusion experiment, which is supported by seven international partners and is currently under construction. It is estimated that the ITER experimental project will cost about $10B and the ITER device is predicted to produce ten times the energy input. Since each pulse in ITER is expected to cost about a million dollars, there is a compelling need for the reliable whole device simulation capability that is required to optimize discharge scenario planning and control. The goal of this project is to create high-performance software designed to use petascale computers to carry out accurate simulations relevant to ITER and other toroidal fusion devices.

Photovoltaic Energy Production
N. Tansu

Solar energy is one of the most promising sources of energy, and photovoltaic is an important technology for converting solar energy into electrical energy. The annual human energy consumption can be fulfilled by one hour of total irradiation energy from the sun on earth, but low-cost and high- efficiency solar cells are required for enabling the technologies to become an important alternative means for energy generation. High-efficiency solar photovoltaic cells would also have a broad impact in the developing world, to provide efficient energy generation solutions. Two important types of photovoltaics are: 1) inorganic semiconductor photovoltaic, and 2) organic photovoltaic. Both research areas are of great interest for energy applications, with different advantages and limitations. The current state-of-the-art Inorganic semiconductor photovoltaic cells are robust, moderate efficiency, and widely implemented, but the high cost and lack of high efficiency solar cells remain important challenges for inorganic solar cells. The organic solar cell has advantages in its flexibility and low cost, however the low efficiency and reliability issues remain important limitations for organic solar cells.

Key technical challenges and approaches on solar photovoltaic cells include:

Novel device concepts to improve the photon-to-electron conversion efficiency in semiconductor photovoltaic solar cells
Improving the light collection efficiency of semiconductor solar cells
Novel growth or fabrication techniques to reduce the cost of the solar cells. Several techniques include:
Fundamental material physics and understanding of material issues in inorganic III-V / III-Nitride semiconductor solar cells and organic solar cells

Household/Business Energy Reduction

Energy Reduction Strategies for Home and Business
Dork Sahagian, Sharon Friedman, John Gatewood, Steve Cutcliffe, Al Wurth, Chad Briggs

It has become clear through a multitude of analyses that the fastest way to achieve major reductions in fossil fuel burning and associated emissions, and thus become less dependent on foreign (and domestic) oil, coal and other fuels, is to enhance energy efficiency in our homes, businesses, and other structures. There are numerous measures that can be taken immediately using readily available technology and practices that would dramatically reduce energy consumption, and thus provide the necessary time for development of a broad portfolio of renewable energy resources that will ensure energy security into the distant future. As such, energy efficiency and conservation is the "low hanging fruit" that can provide the most immediate benefit in matching energy supply and demand. Strategies for reducing energy utilization in building were highlighted at the 2009 "Green Builders EXPO" hosted by Lehigh University. While far more efficient measures exist than are commonly being used in homes and businesses, most people simply do not know about them, and thus continue using outdated, inefficient technologies for lighting, heating, insulation, appliances, and systems. Further, most buildings could greatly reduce energy consumption without impacting functionality if the occupants could determine where energy is being used most productively, and where it is primarily wasted. This requires a mechanism for "home energy inventory" that can be conducted cheaply and easily by the home or small business owner. Creation of such a simple system for home energy inventory requires expertise in architecture, policy, communication, sociology, engineering, and economics, while implementation and widespread use and benefit from such a system involves public and community relations, marketing and education. Lehigh possesses expertise in each of these areas that can be brought to bear on the problem. While there is a technical aspect to energy inventory, an additional issue arises in providing incentives to reduce energy consumption and waste, particularly in the ubiquitous rental properties in urban areas. In many cases, control of lighting, heating and air conditioning is not in the hands of those who are paying for energy, and thus there is no financial incentive to conserve in any way. This is most evident in apartment buildings in which tenants pay energy bills, but the infrastrucure that could reduce energy consumption (insulation, better windows, etc.) is the responsibility of a landlord who does not bear the cost of inefficiency. Through well-designed policy, this disconnect can be repaired, providing financial incentives/disincentives for improvements in efficiency in rental situations, thus preventing finger-pointing regarding systems efficiency vs. end-user conservation.

Solid State Lighting
N. Tansu

Solid state lighting has tremendous impacts on high-efficiency energy applications, in particular as lighting consumes approximately 21% of the electrical energy usage in the United States. The use of solid state lighting will have tremendous impacts to achieve electrical-to-light conversion efficiency of approximately 50%, which is approximately 10-times and 4-times more efficient than those of incandescent light bulbs and fluorescent light bulbs, respectively. Significant efforts have been invested in universities, national laboratories, and leading industries in U.S., Europe, and Asia. The goals by U.S. Department of Energy (DOE) is to realize the solid state lighting be implemented by 2013 as the solution of efficient lighting in U.S. It is expected the use of solid state lighting in U.S. alone will result in energy saving by approximately $21 billion per year. This technology will also have tremendous impacts in other regions of the world in particular in third world countries, where energy demand will increase very rapidly with the growing population and GDP income.

Major issues related to physics and technology of InGaN QW LEDs for solid state lighting include:

The low radiative efficiency InGaN-based active regions LEDs emitting in the 'green' regime is considered as the most important limitation for enabling high power conversion efficiency of LEDs. High radiative-efficiency green-emitting LEDs is considered as one of the important technologies for enabling solid state lighting.
The second major challenge for high power LEDs is 'efficiency drooping' in LEDs at high current density operation. The 'efficiency drooping' is defined as a reduction of quantum efficiency phenomena in LEDs at high operating current density, which is crucial for high power operation. The physics and mechanisms of efficiency drooping in LEDs still require further investigation. The improved understanding of device physics of 'efficiency-drooping' in LEDs will be crucial for designing 'droop-free' InGaN-based LEDs.
Improved understanding of recombination mechanisms in polar and non-polar InGaN quantum wells / dots active regions require further investigations. Complete studies in the recombination processes in these active regions will require understanding of the time-resolved photoluminescence / cathodoluminescence, structural characterizations, and correlations with LEDs device characteristics.
Improved growths of III-Nitride LEDs using low-cost substrates are important for reducing the cost of LEDs. The use of nano-patterned AGOG and Silicon substrates will enable the growth of low- dislocation density materials. The use of Silicon substrates will enable significant reduction of LED cost, which is important for implementation of solid state lighting.
The large index contrast of GaN / air interface results in low light extraction efficiency. The availability of low-cost and practical approach to enhance the light extraction efficiency of InGaN- based LEDs is important for solid state lighting.

Environmental Impacts of Energy Production

Environmental Impacts of Alternative and New Energy Resources in Pennsylvania
Frank J. Pazzaglia, Dork Sahagian, Ben Felzer, Steve Peters, Don Morris, Kristen Jellison, Bruce Hargreaves, David Anastasio, Derick Brown, Tae-Sup Yun

Emergence of alternative and new sources of energy, a long predicted consequence of growing energy demand as fossil fuels reach or pass global peak production, will generate far-reaching environmental impacts. Similarly, the need to mitigate the effects of carbon loading in the atmosphere and related undesirable climate change has inspired carbon sequestration solutions that have related environmental impacts. The exploitation of fossil fuels has led to a spectrum of environmental problems ranging from local pollution and acid mine drainage, to global climate change. Alternative energy resources will be associated with a different suite of environmental impacts that need to be explored and understood in order to design energy systems for greatest energy production with minimum environmental impact. Pennsylvania is a state rich in energy and energy-related resources including fossil fuels, water, agricultural lands, and wind. Furthermore, its location, concentration of power generation, and geology make it a prime candidate for carbon sequestration strategies. For these reasons, it is important that the environmental impacts of alternative and new energy resources, as well as carbon sequestration, are explored and understood in the context of developing management practices consistent with sustainability and environmental health. An integrated approach involving geoscientists, climate scientists, geochemists, hydrologists, and social scientists will be required to meet the challenges and new activities related to alternative energy will require new regulatory strategies and best management practices. The Environmental Initiative and Energy Research Center at Lehigh University are positioned to meet these challenges and assume a leadership role as it applies to environmental impacts of emerging energy resources and needs.

Environmental impacts of bio-fuels

Pennsylvania is blessed with productive soils that can be used to grow crops as feedstock to a growing bio-fuels industry. Ethanol made from corn is a bio-fuel that is already marketed in several mid-western states, but there are concerns regarding its limited efficiency and impact on the cost of food. In Pennsylvania, there has been greater interest in developing warm-season grasses as a potential source of ethanol as well as combustible pellets as an alternative fuel. Currently, a warm-season grass like switch grass can be harvested to produce four tons of combustible grass pellets per acre of farmland at $200/ton. When burned, it produces 1 therm (100,000 BTU) at a cost of only $0.12/therm. In comparison, natural gas cost $1.20 per therm. Furthermore, the dense root systems of warm-season grasses represent a significant sink for bio-matter and can be managed to sequester atmospheric carbon. Converting agricultural lands to warm-season grasses has environmental impacts at the watershed scale as they relate to runoff, hydrology, and ecologic health of constituent channels. Smart growth practices would have to be adapted to account for the shifting value of land use from suburban or urban development to agricultural or even from forest to cultivated grassland.

Environmental impacts of wind energy

Much of Pennsylvania’s topography is characterized narrow, elongate, forested ridges separated by wide agricultural valleys. The forested ridges provide contiguous habitat for a range of wildlife and provide ecosystem services related to the overall environmental health of the state. By some accounts, Pennsylvania’s forests are healthier now than they have been in the past 200 years when a formerly extensive logging industry severely compromised forest health and surface water quality. Pennsylvania’s forested ridges are also potential sites for wind-generated energy as evidenced by the operating wind farm on Moosic Mountain in Lackawanna and Wayne Counties. Pennsylvania is already the leading wind power generator among eastern states with some 153 MW currently being produced, and there are several more wind farms in the planning stages. Although a clean source of energy, wind farms represent breaks in the otherwise contiguous wildlife and ecosystem corridors that characterize Pennsylvania’s ridges. Furthermore, the road and transmission line systems that need to be built to install and maintain wind farms have related potential impacts on watersheds and water quality. The overall environmental impacts of rapidly expanding wind-based energy in Pennsylvania remain to be fully explored.

Environmental Impacts of the Marcellus Natural Gas Reservoir

Black, organic-rich shales are a common sedimentary rock in the Pennsylvania and these shales are known to be the source of hydrocarbons found in sandstone and limestone reservoirs. One of these black shales, the Middle Devonian Marcellus Fm has been known to be both a source and reservoir for natural gas for over 75 years; however, it has not been until recently as new drilling and reservoir development technologies were developed that the Marcellus resource could be fully realized and exploited. The estimates of how much natural gas is within the Marcellus Formation in Pennsylvania is highly debated with one recent study suggesting that there is at least 50 trillion cubic feet recoverable. That translates to approximately 9 billion barrels of oil, or the size roughly of the Prudhoe Bay oil field in Alaska, the largest known field in the United States. The economy of the state stands to benefit enormously should the Marcellus gas reservoir prove its potential worth. One potentially environmental sensitive reality of the Marcellus gas reservoir is that to extract the gas, numerous, tightly-spaced wells need to be drilled to take advantage of the low fracture-porosity of the reservoir. From a resource exploitation perspective, expertise in Pennsylvania geology, both in the surface and subsurface will be required. From an environmental perspective, development of the field(s) will require careful environmental consideration ecological function, habitat continuity, and watershed, water, and forest resources impacted by the dense road and pipeline infrastructure that will need to be constructed.

Environmental Impacts of Micro-Hydro.

Among other things, the 20th century will be known for the building of large dams and reservoirs for hydropower and water resource management. The environmental, social, economic, and political impacts of large dams has led to a marked decrease in their construction in the 21st century, with an alternative being considered in low-head dams and in-stream generators for decentralized micro-hydro electricity production. While the environmental impacts of such systems are presumed to be much less than of large dams, proliferation of microhydro in Pennsylvania’s many river systems will not be without consequence, which may include fish migration issues, turbidity alterations, bank disturbance and erosion, and other localized impacts.

Environmental Impacts of carbon sequestration

The state of Pennsylvania has been a national leader in exploring ways to mitigate carbon emissions to the atmosphere through various carbon sequestration strategies. The results of Pennsylvania’s leadership are detailed in a report by the Carbon Mitigation Advisory Group (CMAG) (http://www.dcnr.state.pa.us/info/carbon/documents/final-report-050708.pdf). The key recommendations of the report as they apply to sequestration include developing a pilot project to demonstrate geologic sequestration in depleted oil and gas reservoirs in western Pennsylvania, develop a pilot project to demonstrate geologic sequestration in conjunction with coalbed methane extraction in the anthracite fields of northeastern Pennsylvania, and manage forest and other lands to serve as a natural vegetation carbon sink. These and related carbon sequestration strategies will require geologic and engineering expertise, innovation, and training.

CO2 Sequestration

Carbon Capture and Sequestration
Hugo Caram, S. Sircar, E.K. Levy, B. Koel, I. Wachs, W. Schiesser, A. McHugh, A.Sengupta, David Anastasio, Frank Pazzaglia

Carbon dioxide emissions to the atmosphere are considered to be one of the main causes of global warming, climate change and ocean acidification. Nearly 30% of CO2 emissions are contributed by the commercial energy sector (e.g. combustion of coal and natural gas for electricity production). CO2 is currently vented into the atmosphere as a waste (flue) gas after the necessary scrubbing and removal of acid gas contaminations (SOx and NOx). However, the CO2 removal targets are set, respectively, at 15, 30 and 80% by the years 2015, 2025 and 2050 by the electric power generation industry (EPGI). The flue gas from a pulverized coal fired power plant typically mostly consists of 13-15% CO2 in N2 with dilute amounts of O2 (1-3%) and traces of the acid gases at a near ambient pressure and a temperature of 130-180oC. Furthermore, the gas is generally saturated with water. The need for developing an efficient and economic method for recovering the CO2 from such a flue gas and its subsequent compression and sequestration in geological formations (e.g. under ground caverns, fossil fuel reservoirs) or water bodies (e.g. lakes, oceans) has been a subject of much debate and discussions during the last decade.

Some of the crucial technical issues for the separation of CO2 from a flue gas include:

The flue gas is generally produced at a near ambient pressure (low CO2 partial pressure of ~ 0.15 atm), and the volumetric flow rate is large. The separation process must not require much or any compression of the gas to be economically viable.
The separation process must be very efficient under the low CO2 driving force condition.
The gas is saturated with water. Use of a separate drier prior to CO2 removal from that gas (other than simple condensation of water) may be costly.
It may be beneficial to treat the gas at its source temperature of 130 – 180 C.

Three different generic separation technologies have been extensively studied for capture and recovery of CO2 from flue gases during the past fifteen years:

Absorption of CO2 in a physical or chemical solvent followed by regeneration of the solvent for production of CO2.
Selective permeation of CO2 through a porous or non-porous membrane.
Physical or chemical adsorption of CO2 on a solid adsorbent followed by regeneration of the sorbent to produce CO2.

Some of these technologies are fairly well developed for the application of interest and they continue to be further developed. The present proposal deals with the use of a solid chemisorbent for selective sorption of CO2 from a flue gas and its recovery as a compressed gas. Once the CO2 has been captured and purified it is expected that most of it will be geologically sequestered in underground aquifers, inaccessible coal seams or for enhanced oil recovery. There are other alternatives that can take advantage of the chemistry of the CO2 but because of its low energetic state only a limited number of reactions are possible that will produce carbonates.

Hydrocarbons

Materials for Energy Production and Efficient Utilization

Structural Materials for Energy Applications
J. DuPont, H. Nied, W. Misiolek, E. Levy, T. Delph, J. Grenestedt, G. Harlow, R. Sause, C. Kiely, B. Koel, S. Pessiki, J. Ricles

Structural materials are expected to play a vital role in sustaining both near-term and long-term energy from a variety of sources, including coal, natural gas, oil, nuclear, and wind. For example, many coal and nuclear plants are near or beyond their original design life. The cost of constructing new plants has escalated significantly, thus placing demand on life-extension of existing plants. This will require a fundamental understanding of the long-term degradation mechanisms of materials under a wide range of conditions. In addition, new plants are being designed that will operate under extreme conditions of stress, temperature, corrosion, and irradiation (for nuclear) that are unprecedented. Successful implementation of these newer plant designs will require advances in structural materials and will need to involve materials of all classes (metals, ceramics, intermetallics, and composites). Gas turbines are expected to require similar needs as operating temperatures climb to improve efficiency and as more corrosive fuels that are derived from coal are utilized. Research needs also exist for the safe transportation and long-term storage of spent nuclear fuel. In this case, materials need to be developed with high neutron cross section, excellent toughness, and corrosion resistance that is maintained into geological time frames (up to 10,000 years). New materials with high strength/weight ratios will also be needed to accommodate the development of lightweight vehicles aimed at energy conservation. The research requirements associated with reliable generation and utilization of energy point to the need to develop a fundamental understanding of the behavior of advanced materials under extreme conditions of stress, temperature, corrosion, and irradiation. This information needs to be applied to develop new structural materials that will support both existing and future sources of power. In addition, many advanced energy applications will require efforts that go far beyond the conventional development of new materials. Lehigh has a strong reputation in structural materials that crosses a wide range of length scales, from the world-class facilities in electron microscopy and materials characterization at the micro and nano scale (primarily in the Materials Science and Engineering (MS&E) Department), to the study of inherent material properties associated with fatigue, fracture, creep, and corrosion (which include faculty in the MS&E and Mechanical Engineering and Mechanics (MEM) Departments), to realistic simulation and evaluation of the full-scale behavior of large structural systems (in the ATLSS Center and Civil Engineering (CE) Departments). There is also significant research underway to study the fabrication characteristics of advanced materials in the areas of deformation processing, powder processing, welding/joining, casting, and composites, to name a few.

Exploring the fundamental potential of organic photovoltaics through single-crystal organic semiconductors
Prof. Ivan Biaggio

We seek to gain a deeper fundamental understanding of the processes of charge carrier photoexcitation and transport in high quality organic molecular crystals. It will then be possible to transfer this knowledge to other types of materials. The organic optoelectronics — or “plastic electronics” — field has recently seen many break- throughs, and the ability to develop organics-based photovoltaic cells for wide-area harvesting of the renewable energy of sunlight over a variety of substrates and in many forms has made the un- derstanding and optimization of exciton photoexcitation, exciton diffusion/ionization, and charge- transport in organic semiconductors of primary importance. While many of the organic light-emitting diodes, field effect transistors, and photovoltaic cells that have been demonstrated until now rely on amorphous materials (polymers or small mole- cules), recent achievements in the development of single crystal organic semiconductors have lead to devices with exceptional performance. Even more importantly, the unprecedented quality now achieved by these single crystals allows for the first time to explore the fundamental limits of organic-based devices, and to gain unique and deeper insights into the fundamental properties of charge-carrier photoexcitation and transport in molecular materials. We propose to use several laser-based techniques to investigate the physical processes which will be critical towards developing a solid foundation for the emerging field of organic photovoltaics: These are the photoexcitation of molecular excitons, their efficient ionization into free carriers, and charge-transport. Our laser equipment, know-how, and collaborations make our research team uniquely positioned for this kind of task, as shown also by the new insights we recently into the primary photoexcitation mechanisms in polymers and in rubrene single crystals. The first commercial applications of organic photovoltaics should start appearing in the next 5 to 10 years. At the same time, our investigation into the fundamental properties of photovoltaics in high quality organic crystals should lead to important fundamental insights that will be useful for a new generation of devices.

Materials for Energy Applications: Energy-Efficient Separations in the Biorefinery

A recent report1 by the U.S. Department of Energy (DOE) espouses the idea of the integrated biorefinery as an important part of any comprehensive energy solution. The viability of the biorefinery depends upon 1) the efficient and selective decomposition of renewable cellulosic biomass into liquid biofuels (e.g., ethanol or higher-energy-density butanol), 2) downstream sugar conversion, and 3) recovery of high-value building-block chemicals. In fact, sugar-derived commodity chemicals are critical for the economic viability of the biorefinery. While a range of conventional technologies are being considered for the biorefinery (i.e., thermochemical and enzymatic decomposition, distillation), opportunities exist for engineered materials in three general thrust areas: 1) catalysis, 2) separations, and 3) integrated reaction/separation technologies. Engineering of materials such as functionalized nanoparticles, hierarchically porous inorganic materials, and thin films with controlled morphology and porosity, impact the following areas:

Catalytic and enzymatic reactions Efforts aimed at efficient cellulose decomposition are challenged, on the one hand, by the inaccessibility of the recalcitrant crystal structure of cellulose to bulky enzymes or acid catalysts (e.g., zeolites), and on the other by the low selectivity and neutralization costs associated with conventional mineral acid treatment. While hybrid approaches (i.e., enzymatic/thermochemical) are being developed, nanoparticle-based solid acid catalyst or enzyme mimicking technologies serve as attractive alternatives. Downstream catalysis of sugars (e.g., hexoses) to building block chemicals (e.g., furans), and subsequent furan oxidation are also important biorefining processes. The limited development of technologies outside of low-selectivity mineral acid catalysts opens unprecedented opportunities for the design of hierarchically porous, multifunctional heterogeneous catalysts.
Separations In addition to reaction technology, a critical need for any viable biorefinery is low-energy, high-selectivity molecular separations for reducing the energy footprint and improving the plant-wide net energy production. The importance of technologies (e.g., membranes) capable of realizing low-energy separations is often understated despite separations dominating process costs. Thus, the biorefinery serves as a new platform for developing and leveraging high-flux, high-resolution, and low-energy membrane separations technologies. The importance of such research is underscored by the recently renewed interest by BP Oil in zeolite membrane technologies for water/biofuel pervaporation.
Integrated reaction/separation technology Limited selectivity for high-value chemicals is a persistent downstream challenge in the biorefinery resulting from rapid chemical decomposition (e.g., hydroxymethylfurfural (HMF)) under acidic conditions. We are exploring these issues and equilibrium limitations with integrated reaction-separation technologies capable of rapid, high-selectivity product isolation (e.g., membrane reactors) or simultaneous catalytic conversion and separation (e.g., catalytic membranes, adsorbents).

Defects and Defect Reactions in Si Solar-Cell Materials and Processes
Michael Stavola and W. Beall Fowler

The silicon solar cell industry is growing at the remarkable rate of 40% per year. Presently, more silicon is used for the fabrication of solar cells than for the entire microelectronics industry. The maximum theoretical conversion efficiency for a Si solar cell is near 29%. However, solar cells that are commercially fabricated from single-crystal silicon have efficiencies near 20%. And solar cells that are fabricated from multicrystalline Si have efficiencies near 15%, so there is much room for improvement, especially in lower-cost materials. Defects and impurities in silicon solar cells contribute to the reduction of the conversion efficiency, so understanding these defects and the methods used to passivate them have been of great interest. We seek to gain a fundamental understanding of defects and defect reactions that occur in Si solar-cell materials and processes to make possible a rational approach to the defect engineering that will lead to improved efficiency and reduced cost. Some of the questions being addressed include:

What are the concentration and penetration depth of H introduced into high-carbon, multicrystalline Si by methods used to fabricate solar cells?
What defects are formed when H is introduced? And what defects are passivated by H and with what thermal stability?
What is the role played by the very high concentration of C, and how does C interact with dopants, H, and native defects that are introduced during processing?
How homogeneous is the distribution of defects in multicrystalline solar cell materials? For example, can differences in defect properties be detected in the vicinity of grain boundaries?
How might the defect reactions that occur during hydrogenation processes commonly used by industry be modeled so that these processes can be optimized?

The principal goal is to develop a fundamental understanding of defects and defect processes that are important for the fabrication of high efficiency Si solar-cells.

Photoelectrochemical Hydrogen Production
Kyle Wagner and Dmitri Vezenov

One of the most promising alternatives to fossil fuels is the production of hydrogen by direct splitting of water through a photoelectrochemical process using sun light. Hydrogen production driven by solar energy complements traditional solar energy systems (photovoltaic, thermal). Clearly, solar energy is not quite as practical for Alaska as it may be for Florida and obviously not possible during the night; however, if the solar energy is used to produce a fuel, the energy may be used at any time of day and in any weather condition for the purpose of electrical power generation (e.g. during dark periods) or transportation. This work focuses on hydrogen generation by water splitting in the high-efficiency photoelectrochemical (PEC) process using solar energy. The creation of an electron-hole pair during irradiation, followed by their separation and electron transfer reactions at the interface are the basis for the photochemical devices. Intensive research on photochemistry of titania and related oxides has been carried out since discovery of their catalytic activity in water splitting reaction. Photocatalytic production of hydrogen from water on a rutile-TiO2 single crystal is possible, but requires irradiation with ultraviolet light. The photoinduced splitting of water into hydrogen and oxygen using visible light will be the ultimate environmentally benign strategy for generation of a green fuel from a renewable and abundant energy source – ambient sunlight.

Nanocatalysis for hydrogen fuel cell enhancement
David T. Moore

Current designs for polymer electrolyte membrane (PEM) hydrogen fuel cells for transportation applications employ platinum nanocatalysts for the electrochemical oxidation and reduction reactions for molecular hydrogen (H2) and oxygen (O2), respectively. One of the biggest technical problems with using platinum as a catalyst is it is “poisoned”, i.e. its catalytic activity is drastically reduced, by the presence of even small amounts (10’s of ppm) of carbon monoxide (CO) in the fuel stream. Industrial hydrogen production by the steam reforming of hydrocarbons produces a gas that is 1-3% CO, and so techniques must be developed to remove the CO from the fuel stream. It has been known for some time that small gold nanoparticles supported on a metal-oxide substrate are potent catalysts for the oxidation of CO to carbon dioxide (CO2), which is a far less potent poison for the platinum catalyst. Thus there is considerable interest in developing gold nanoparticle catalysts for the CO mitigation in hydrogen fuel streams. Another area where nanocatalysis is finding a foothold in energy research is the artificial photosynthesis of chemical fuels from CO2 and water. Carbon dioxide and water are both low cost renewal resources, so the ability to directly synthesize chemical fuels from these materials using sunlight is a holy grail of sorts in the field of alternative energy. Nanoparticles of titanium dioxide (TiO2) have been shown to have photocatalytic properties, which makes them attractive for use in artificial photosynthesis. When TiO2 nanoparticles absorb UV light of the correct frequency, they undergo a charge separation that can be used to simultaneously drive CO2 reduction and H2O oxidation, both necessary initial steps in artificial photosynthesis.

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