Condensed-Matter and Materials Physics The Science of the World Around Us (2007) / Chapter Skim
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3 How Will the Energy Demands of Future Generations Be Met?
3 How Will the Energy Demands of Future Generations Be Met?
Pages 53-69
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From page 53... ...
In the United States, there is a pressing need to develop energy sources in order to reduce dependency on fossil fuels while minimizing carbon emissions and other sources of harm to the environment. Promising technologies for solar energy, hydrogen fuel cells, solid-state lighting, supercapacitors, rechargeable batteries, and improved nuclear power will play critical roles, but fundamentally new scientific approaches are also needed.
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From page 54... ...
Many of the issues are political and/or economic in nature and therefore lie outside the scope of this report, but for the transition to renewable energy sources to occur on the required timescale, many scientific and technological breakthroughs will be necessary. These are global challenges, of course, but as the world's most prolific energy consumer, the United States bears a responsibility to demonstrate leadership.
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From page 55... ...
sectors at right. SOURCE: Energy Information Administration, Annual Energy Review 2006, available at http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf.
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From page 56... ...
The latter, for example, could address the need for independent control of increased hydrogen adsorption and faster kinetics for hydrogen release in the hydrogen storage needs of a hydro gen economy. In the sections below, the committee highlights some of the ways in which the CMMP community can develop cutting-edge science that will strongly influence future developments in energy conversion, energy storage, and end-use energy efficiency.
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From page 57... ...
An additional challenge is that many conducting polymers are unstable in the presence of light and oxygen owing to the formation of reactive oxygen radicals, so strategies for minimizing this problem are urgently needed, especially through the design of new materials. One approach for improving the cost-effectiveness of the more expensive solar cells is to use them in combination with concentrators that can harvest the sunlight from a large area and focus the incident energy onto a small area of active cells.
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From page 58... ...
Fuel Cells Fuel cells, which are an integral part of the concept of renewable chemical fuels, already have an advantage over the internal combustion engine in terms of their efficiency, but to make this technology viable, substantial further increases in fuel cell efficiency are needed, as well as dramatic improvements in hydrogen generation and storage capabilities. Fuel cells present a number of difficult technical challenges to the CMMP community.
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From page 59... ...
The development of inexpensive catalysts to replace platinum would have a significant impact, and further CMMP research is needed in this area. Theoretical models have recently shown that catalysts made from Pt-Ni alloys, for example, require less platinum and achieve improved performance.
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From page 60... ...
for the optoelectronics indus try, power generation applications for space vehicle propulsion, energy harvesting from the waste heat in cars, and the utilization of geothermal energy. Biofuels The production of so-called biofuels from renewable biomaterials, such as palm oil and sugar, is attractive from many perspectives.
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From page 61... ...
The technology roadmap for this initiative is aimed at designing systems that address a number of societal concerns, including sustainability, economics, safety, and reliability, as well as issues relating to security and proliferation. The materials-related challenges associated with the various reactor designs under consideration are discussed in A Technology Roadmap for Generation IV Nuclear Energy Systems. Research areas of great opportunity include the transmutation of intermediate-lived actinides into shorter-lived or stable nuclides by means of irradiation, the development of materials with good temperature stability combined with superior resistance to fast neutron fluxes and fluences, the design of novel refractory fuel concepts with enhanced fission product retention capability, and the development of advanced glassy materials for nuclear waste disposal applications.
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From page 62... ...
Energy Storage In addition to energy generation, energy storage represents an important and challenging element of the overall energy strategy. The principal means of storing energy at the present time include the use of batteries; chemical storage in high energy-density synfuels such as hydrogen, ethanol, and methane, ideally produced in a renewable manner as discussed in the previous subsections; and the use of supercapacitors.
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From page 63... ...
hydrogen storage at reasonable pressures and ambient temperatures. The ideal medium for automotive applications would be a storage material, probably a solid or a liquid, that could reversibly adsorb and desorb hydrogen without the physical removal of the storage medium from the vehicle. The most common storage media are porous solids that adsorb hydrogen through a physisorption mechanism and metal hydrides or chemical hydrides that bind hydrogen through a chemisorption mechanism.
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From page 64... ...
Even though EDLCs are now being used in various types of electronic device applications, such as for memory backup in vehicle computers, their intrinsically low energy density limits their impact on the energy storage market. The present challenge is to increase energy storage density and to lower fabrication costs through the optimization of the cell design and the development of improved electrode materials.
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From page 65... ...
in combination with yellow phosphors using Ce3+-garnets give a reasonable quality of white light that is good enough for off-grid lighting applications, flashlights, traffic lights, and a utomotive lighting (Figure 3.3)
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From page 66... ...
Lighting consumes approximately 22 percent of the electricity that is generated in the United States, and solid-state lighting has the potential to reduce energy con sumption for lighting requirements by about 60 percent by 2025. Success in this area would therefore reduce electricity consumption in the United States overall by around 13 percent over the next 20 years, making it a very important element of the nation's energy strategy and virtually guaranteeing that solid-state lighting will emerge as a multibillion-dollar industry worldwide. In addition, when combined with solar panels, the solid-state lighting approach can provide lighting for homes and villages in remote, off-grid locations in developing countries (Figure 3.4)
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From page 67... ...
While these may not match the lifetimes of the inorganic materials, which are aiming for 100,000 hours of continuous operation, they are likely to be much cheaper and will be preferred for area illumination requiring large emissive surfaces. Smart Windows The development of smart windows based on novel nanocomposites represents an entirely different opportunity for end-use energy efficiency and an area in which CMMP is already playing an important role.
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From page 68... ...
The search for a room-temperature superconductor is certainly one of the elusive "holy grails" for CMMP, as is the quest for a better understanding of the mechanism of high Tc superconductivity. Other, more immediate possibilities include improving the power efficiency of computers by inventing new materials for the current computing paradigms and by developing new computing paradigms based on optical signaling and low-power computing.
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From page 69... ...
There are no quick or singular solutions to meeting the growing global energy requirements; the cost-effectiveness of solar energy remains unresolved, the efficiency of the photochemical splitting of water is still very poor, fuel cells suffer from longevity problems, bioethanol and biodiesel fuels compete with the food chain, and society has still not embraced nuclear energy. A sustained effort on a broad range of options is therefore required.
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