Bulletin of the American Physical Society
2006 APS March Meeting
Monday–Friday, March 13–17, 2006; Baltimore, MD
Session G5: Advanced Materials for Solar Energy Utilization |
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Sponsoring Units: DMP FIAP Chair: Julia Hsu, Sandia National Laboratories Room: Baltimore Convention Center 309 |
Tuesday, March 14, 2006 8:00AM - 8:36AM |
G5.00001: Scientific Challenges in Sustainable Energy Technology Invited Speaker: This presentation will describe and evaluate the challenges, both technical, political, and economic, involved with widespread adoption of renewable energy technologies. First, we estimate the available fossil fuel resources and reserves based on data from the World Energy Assessment and World Energy Council. In conjunction with the current and projected global primary power production rates, we then estimate the remaining years of supply of oil, gas, and coal for use in primary power production. We then compare the price per unit of energy of these sources to those of renewable energy technologies (wind, solar thermal, solar electric, biomass, hydroelectric, and geothermal) to evaluate the degree to which supply/demand forces stimulate a transition to renewable energy technologies in the next 20-50 years. Secondly, we evaluate the greenhouse gas buildup limitations on carbon-based power consumption as an unpriced externality to fossil-fuel consumption, considering global population growth, increased global gross domestic product, and increased energy efficiency per unit of globally averaged GDP, as produced by the Intergovernmental Panel on Climate Change (IPCC). A greenhouse gas constraint on total carbon emissions, in conjunction with global population growth, is projected to drive the demand for carbon-free power well beyond that produced by conventional supply/demand pricing tradeoffs, at potentially daunting levels relative to current renewable energy demand levels. Thirdly, we evaluate the level and timescale of R{\&}D investment that is needed to produce the required quantity of carbon-free power by the 2050 timeframe, to support the expected global energy demand for carbon-free power. Fourth, we evaluate the energy potential of various renewable energy resources to ascertain which resources are adequately available globally to support the projected global carbon-free energy demand requirements. Fifth, we evaluate the challenges to the chemical sciences to enable the cost-effective production of carbon-free power on the needed scale by the 2050 timeframe. Finally, we discuss the effects of a change in primary power technology on the energy supply infrastructure and discuss the impact of such a change on the modes of energy consumption by the energy consumer and additional demands on the chemical sciences to support such a transition in energy supply. [Preview Abstract] |
Tuesday, March 14, 2006 8:36AM - 9:12AM |
G5.00002: High-Efficiency, Multijunction Solar Cells for Large-Scale Solar Electricity Generation Invited Speaker: A solar cell with an infinite number of materials (matched to the solar spectrum) has a theoretical efficiency limit of 68{\%}. If sunlight is concentrated, this limit increases to about 87{\%}. These theoretical limits are calculated using basic physics and are independent of the details of the materials. In practice, the challenge of achieving high efficiency depends on identifying materials that can effectively use the solar spectrum. Impressive progress has been made with the current efficiency record being 39{\%}. Today's solar market is also showing impressive progress, but is still hindered by high prices. One strategy for reducing cost is to use lenses or mirrors to focus the light on small solar cells. In this case, the system cost is dominated by the cost of the relatively inexpensive optics. The value of the optics increases with the efficiency of the solar cell. Thus, a concentrator system made with 35{\%}- 40{\%}-efficient solar cells is expected to deliver 50{\%} more power at a similar cost when compare with a system using 25{\%}-efficient cells. Today's markets are showing an opportunity for large concentrator systems that didn't exist 5-10 years ago. Efficiencies may soon pass 40{\%} and ultimately may reach 50{\%}, providing a pathway to improved performance and decreased cost. Many companies are currently investigating this technology for large-scale electricity generation. The presentation will cover the basic physics and more practical considerations to achieving high efficiency as well as describing the current status of the concentrator industry. \newline \newline This work has been authored by an employee of the Midwest Research Institute under Contract No. DE- AC36-99GO10337 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes. [Preview Abstract] |
Tuesday, March 14, 2006 9:12AM - 9:48AM |
G5.00003: Nanowire based solar cells Invited Speaker: |
Tuesday, March 14, 2006 9:48AM - 10:24AM |
G5.00004: Bio-inspired constructs for solar energy conversion Invited Speaker: Solar energy input to the biosphere is about 10$^{24}$ joules/year. This makes human needs of even a projected 10$^{21}$ joules/year a deceptively achievable goal. One key to global-scale use of solar energy is the synthesis of energy-rich fuel materials such as hydrogen and reduced carbon compounds. The latter have the almost inestimable advantage that the energy infrastructure for distribution and use is in place. The photosynthetic and respiratory enzymes provide paradigms for all of the important energy converting processes humans would need to achieve sustainable energy production and use. These include water oxidation, O$_{2}$ reduction and oxidation of energy dense organics at room temperature. These processes are carried out by biological catalysts at near thermodynamic efficiency without the use of precious metals. Copper, manganese, iron and nickel are typically used at their active sites. Energy rich organics such as ethanol and larger reduced-carbon compounds offer energy densities comparable to that of fossil fuels yet technology has not produced a low temperature catalyst for breaking carbon-carbon bonds. Biology offers myriad examples of such catalysts. Electroreductive synthesis of organics from CO$_{2}$ is also templated by Nature's catalysts. The challenge is clear: we must understand the structures and chemical reactivity of these catalytic sites and co-opt their essential features for human use. A number of parameters are involved and will be discussed. Even considering an artificial catalysts comprising only the atoms necessary for catalysis, the footprint is relatively large and, since biological turnover rates are often low, achieving current flows adequate for human needs in industry and transportation is problematic. A detailed understanding of efficiently coupling electromotive force to the active sites of redox enzymes will be one key to designing efficient hybrid catalytic devices. A model system for solar-driven reforming of biomass to H$_{2}$ will be presented. [Preview Abstract] |
Tuesday, March 14, 2006 10:24AM - 11:00AM |
G5.00005: The Status and Outlook for the Photovoltaics Industry Invited Speaker: The first silicon solar cell was made at Bell Labs in 1954, and over the following decades, shipments of photovoltaic (PV) modules increased at a rate of about 18\% annually. In the last several years, the annual growth rate has increased to $\sim$ 35\% due largely to government-supported programs in Japan and Germany. Silicon technology has dominated the PV industry since its inception, and in 2005 about 65\% of all solar cells were made from polycrystalline (or multicrystalline) silicon, ~ 24\% from monocrystalline silicon and $\sim$ 4\% from ribbon silicon. While conversion efficiencies as high as 24.7\% have been obtained in the laboratory for silicon solar cells, the best efficiencies for commercial PV modules are in the range of 17 – 18\% (the efficiency limit for a silicon solar cell is $\sim$ 29\%). A number of companies are commercializing solar cells based on other materials such as amorphous silicon, microcrystalline silicon, cadmium telluride, copper-indium-gallium-diselenide (CIGS), gallium arsenide (and related compounds) and dye- sensitized titanium oxide. Thin film CIGS solar cells have been fabricated with conversion efficiencies as high as 19.5\% while efficiencies as high as 39\% have been demonstrated for a GaInP/Ga(In)As/Ge triple-junction cell operating at a concentration of 236 suns. Thin film solar cells are being used in consumer products and in some building-integrated applications, while PV concentrator systems are being tested in grid-connected arrays located in high solar insolation areas. Nonetheless, crystalline silicon PV technology is likely to dominate the terrestrial market for at least the next decade with module efficiencies $>$ 20\% and module prices of $<$ \$1/Wp expected by 2020, which in turn should allow significant penetration of the utility grid market. However, crystalline silicon solar cells may be challenged in the next decade or two by new low-cost, high performance devices based on organic materials and nanotechnology. [Preview Abstract] |
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