Alternative Energy Supply

The hydrogen economy - proposed as a replacement for our carbon-based economy — has been slow to materialize due to problems of cost, reliability and scale. U.Va. Engineering School researchers are working to find new materials for the electrical contacts within fuel cells that provide the optimal balance of catalysis, conductivity and cost.

Faculty involved:
Assistant Professor Steven McIntosh
Professor Matthew Neurock

It has been estimated that global energy consumption will double by 2050, and that this need could be met by use of fossil fuels. However, in view of the attendant increase in carbon dioxide emission and the need to limit atmospheric CO2 levels, it is necessary to identify renewable and carbon neutral energy resources and to develop a variety of efficient, inexpensive energy conversion devices that are able to efficiently exploit such resources. Two promising energy conversion/generation technologies are solid oxide fuel cells (SOFCs) and photo electrochemical solar cells (PECs). These devices have the potential for commercial development. SOFCs are devices that can cleanly convert the chemical energy in renewable fuels such as bioethanol and biodiesel into electrical energy. These systems are under commercial development, but increases in efficiency and a reduction in operation temperature are required prior to widespread adoption. PEC water splitting with a solar photovoltaic cell, on the other hand, provides the most direct method for the production of high purity hydrogen – a suitable energy vector for fuel cell systems – without the concurrent formation of polluting agents or greenhouse gases. Several possible approaches to photoelectrolysis have been demonstrated; however major obstacles to commercialization remain in the high cost, low efficiency and limited lifetime of the photoelectrodes.

Faculty involved:
Assistant Professor Steven McIntosh
Professor Giovanni Zangari
Associate Professor Despina Louca

The sun provides a free and natural resource that has the potential to power all the world's energy needs. Yet today, the conversion of sun light to electron flow is highly inefficient and expensive. U.Va. Engineering School researchers are investigating the interaction of sunlight and matter at the nanoscale level to better understand charge generation, transfer and transport. With this knowledge in hand, researchers can then develop nanocrystalline materials that, when combined with organic matrix and thin film materials, have the potential to create photovoltaic cells that are more efficient across a wider bandwidth and easier to manufacture.

Faculty involved:
Professor Joe Campbell
Professor Lloyd Harriott
Professor Paxton Marshall
Professor Tatiana Globus
Professor Robert Davis
Professor Ian Harrison

The fabrication of high efficiency solar cells using laser texturing of surfaces could improve solar cell efficiency by (1) enhanced light trapping over broad spectral and angular range (2) enhancement of the solar radiation infrared light absorption beyond band gap due to laser assisted chemical etching process. The morphological, optical and chemical properties of textured surfaces and design concepts of photovoltaic devices using these textured materials are studied by researchers at the School of Engineering and Applied Science and the Dept. of Physics.

Photovoltaic energy conversion in solar cells consists of two essential steps: (1) absorption of light that generates charge carriers (electron-hole pair) (2) the electrons and holes are then separated by the structure of the device to develop a potential difference, which when connected externally, delivers power to an external load. Therefore, efficient solar energy absorption to cause carrier generation in a photoactive material is one of the most important steps for enhancing photovoltaic conversion efficiency. The processing cost and energy payback time of the cells needs to be reduced in order for them to be cost competitive.

Faculty involved:
Professor Mool Gupta
Professor Joe Campbell
Assistant Professor Keith Williams

How can we most efficiently and economically switch our energy supply from complex hydrocarbons like oil to simpler carbohydrates like ethanol and biomass? One approach under investigation at U.Va.'s Engineering School and in the U.Va. Department of Chemistry is the creation of integrated biorefineries that produce both fuels and chemicals.

Faculty involved:
Professor Robert Davis

Research is focused on developing a highly-efficient distributed combined heat and power energy system using micro turbine technology that is fueled with renewable gasified biomass. Excess waste heat from the combustion and energy conversion process will be used to supplement building HVAC systems. The technology is expected to produce efficiency conversions in the 70-80% range.

Faculty involved:
Professor Harsha Chelliah
Cheryl Gomez

The goal of this work is to develop fundamental knowledge related to the use of a model photosynthetic micro-alga, Chlorella protothecoides (CP), as a means to convert atmospheric carbon dioxide into fatty acids suitable for use as biofuels feedstocks. As prices for biofuels continue to soar past their record highs, microbe-mediated fuel production becomes a particularly attractive alternative to the use of higher plants because they are comparatively more efficient at converting sunlight into biofuel. Nevertheless, the technical and economic viability of microbial biofuels remains unclear because several questions have yet to be addressed. Towards eliminating these knowledge gaps, three specific research objectives have been defined: (1) characterization of growth conditions under which CP produces the highest sustained yields of fuel-grade fatty acids; (2) evaluation of CO2 as a viable separation and esterification solvent during conversion of fatty acids to biofuels; and (3) identification of operating conditions that result in the lowest life cycle environmental burdens and the largest economic potential. The scientific impact of this work will be to explore several apparent research gaps related to productivity and harvest of microbe-generated biofuels.

Faculty involved:
Assistant Professor Andres Clarens
Assistant Professor Lisa Colosi
Associate Professor Mark White

Contemporary energy scenarios include many direct and indirect uses of enormous amounts of hydrogen as an energy carrier such as for fuel cells, commercial and residential heating, natural gas substitutes for ammonia, and upgrading heavy oils and coal to fuels. Current methods for obtaining hydrogen utilize carbon-containing fuels, but water decomposition does not emit climate-changing or polluting substances. Investigations are underway into systems involving nuclear and solar energy sources for electrolysis and with complex chemistry to efficiently obtain massive amounts of hydrogen from water. A multiinstitutional project for experiment, properties modeling, and process simulation is underway to establish more reliable design and optimization schemes for the Sulfur-Iodide process, considered the most efficient thermochemical means for large-scale hydrogen production.

Faculty involved:
Professor John P. O'Connell