Energy Conversion, Transmission and Storage
Most of the energy we use today is generated by burning fossil fuels, with negative consequences for the environment, our economy, and our geopolitical relations. That makes finding sufficient supplies of clean energy a critical challenge. In addition to improving the efficiency of the devices we use, the Institute for Energy Efficiency is focused on developing clean sources of energy that reduce the need to burn fossil fuels.
Sunlight is an excellent carbon-neutral energy source. As much energy from sunlight strikes the Earth in one hour (4 × 1020 J) as all the energy consumed on the planet in a year. However, solar electricity provides less than 0.1% of the world’s electricity because the cost per watt of delivered solar electricity is too high. Although silicon-based photovoltaic devices are available commercially, their fabrication cost is high, and there are vast improvements in efficiency possible. At UC Santa Barbara, the research groups of Nobel laureate Alan. J. Heeger, Kwanghee Lee, Guillermo Bazan, and other scientists are developing solar cells that can be painted, printed and mass-produced like photographic film or even woven into clothing. Making solar cells out of plastic is a cost breakthrough compared to single crystal materials and it could be a critical step to achieve “grid parity”, the point at which the price of electricity from solar cells is no greater than that of power from conventional sources. In the longer term, researchers hope to provide large increases in solar cell efficiency while keeping costs low. The secrets to doing so lie in controlling the nanostructure of the photovoltaic device, optimizing collection of sunlight across its entire spectrum, and ensuring the full collection of all the electricity generated. Greater efficiency may be found through the use of new semiconductor materials, as Umesh Mishra is doing, and constructing the optimal nanostructure can be made reliable and low-cost through the bio-templating techniques Evelyn Hu is exploring.
Efficient, economical and reliable energy storage is another important component, because of the intermittent nature of the sun, wind and waves. Brad Chmelka, Ed Kramer, Eric McFarland, Horia Metiu, Steve Buratto, Michael Doherty, Dan Morse and Galen Stucky are using nanostructured materials for high efficiency, high power density electrochemical devices, including batteries and fuel cells. The objectives are to develop new materials that overcome the power density and stability limitations faced by existing state-of-the-art materials in the conversion and storage of electrochemical energy. Emphasis is focused on areas where recent advancements in the design and optimization of materials at nanometer length scales present new opportunities for overcoming current performance constraints, especially targeting energy inputs from sustainable or renewable sources. These are: (1) fuel cells, (2) lithium ion and flow batteries, and (3) ultracapacitors and electrodes, which are expected to benefit from new platform technologies that can be derived from self-assembled inorganic-organic nanostructured solids and the versatile compositions, structures, and processing options that they allow. The development and optimization of new functionalized nanostructured materials are expected to enable new technological advancements in sustainable electrochemical energy conversion and storage.
Thermoelectric materials are used to generate electrical power from temperature differences. Thermoelectric power generators can be used to charge car batteries by using the waste heat from catalytic converters. They can also be used to power remote sensors and alarms by using the temperature difference between the air and the subsurface ground. Thermoelectrics can be used as solid-state refrigerators, and it may someday be possible to replace our bulky refrigeration units with more efficient, compact, solid-state thermoelectrics. John Bowers and Art Gossard have been investigating modifying materials to improve their thermoelectric performance. Placing erbium arsenide (ErAs) nanoparticles inside materials has led to dramatic increases in thermoelectric performance of compound semiconductors. This approach is being extended to other materials to improve the efficiency of thermoelectrics over a range of temperatures.
