Caltech faculty pursue research on a wide range of topics linked to energy, climate, water, and sustainability.
I am a chemical oceanographer interested in using trace metals as tracers of environmental processes. Most of my current work is centered around the geochemical investigation of past climates. I am primarily concerned with the last few glacial/interglacial cycles (spanning a few hundred thousand years). It is in this time range that we have both a relatively accurate and precise understanding of age models (though they are always improving), together with large climatic shifts that require mechanistic explanation. In particular, we have an amazing record of the rapidity and magnitude of climate change from polar ice cores.
The last 10,000 years, the Holocene, is marked by relative climatic stability when compared to the preceding glacial period, where there are large and very fast transitions between cold and warm times. As an oceanographer, I try to understand the coupled ocean/atmosphere system during these shifts by monitoring the deep ocean's behavior. Much of my work to date has focused on developing a new climate archive--deep-sea corals--that has the potential to revolutionize the types of information we can obtain about oceanographic climate change.
We stand on the brink of a cellulosic ethanol revolution. This will bring growth and change to the energy industry and to the diverse fields comprising the energy research community. Lignocellulosic biomass is converted to ethanol through a three-step process: pretreatment, hydrolysis of cellulose into glucose, and fermentation of glucose to ethanol.
The hydrolysis of cellulose following pretreatment can be accomplished through the use of a team of cellulolytic enzymes. The glucose produced by these cellulases may be fermented to ethanol using an appropriate microorganism, such as S. cerevisiae. The Frances Arnold lab is working to engineer superior cellulases for use in the hydrolysis of cellulose to glucose.
The Atwater research group is engaged in interdisciplinary materials and device research, spanning photonics and electronics and with applications in renewable energy: in particular : thin-film photovoltaic materials.
Sustainable energy has emerged as the most pressing challenge facing humanity in the 21st century. Fuel cells, because of their high efficiencies and benign emissions, will likely play an important role in a sustainable energy future. In our work we attempt to leverage new materials discovery against tailored architectures in order to obtain unprecented fuel-cell power outputs.
One goal of the fuel cell research carried out in the Haile group is to develop fuel cells that do not require hydrogen as the input fuel. Of course these fuel cells function well on hydrogen, but by eliminating the need for hydrogen, the many benefits of fuel cells (high efficiency, zero regulated emissions) can be realized without having to wait for a hydrogen infrastructure to be developed.
Work in the Lewis lab focuses primarily on the chemistry of semiconductors that are technologically important and that have band gaps appropriate for efficient capture of solar energy for use in energy conversion systems. A primary interest of this research is the use of these materials in solid/liquid junctions to convert sunlight into stored electrical energy and/or chemical fuels. Semiconductor/liquid junctions comprise the most efficient wet-chemical means for storing solar energy known to date, with efficiencies in excess of 16% in the most efficient systems.
Prof. Lewis is also a well-known lecturer on the scientific challenges in sustainable energy technology. You can view video of one of his lectures and download slides at http://nsl.caltech.edu/energy.html.
Basic climatic features--such as the pole-to-equator surface temperature gradient, the thermal stratification of the atmosphere, and the distribution of atmospheric water vapor--are maintained by turbulent fluxes that interact with large-scale radiative processes. For example, the surface temperature gradient between pole and equator results from an interaction between differential heating of the Earth's surface (the equator is heated more strongly than the poles) and turbulent heat transport.
My research, based on theoretical considerations, simulations with climate models of various complexity, and analyses of observational data, focuses on the development of theories of the turbulent fluxes of heat, mass, and water vapor that maintain the global-scale climate. Such theories help us understand the changes in the atmospheric climate that have occurred over the Earth's history and that are likely to occur in the future.
The goal of our research is to gain a fundamental understanding of atmospheric chemical and physical processes that govern the dynamics and distribution of gases and particles (aerosols) from urban regions to the global atmosphere. We are motivated especially by the desire to understand the role of atmospheric aerosols in global climate and air quality.
My research group applies traditional physical chemistry techniques to study the mechanisms of chemical transformation in the Earth's atmosphere. Through these studies, we wish to understand the oxidative chemistry of the atmosphere and how this chemistry is influenced by, and in turn influences, the biosphere. An important component of this research effort is to understand the influence of anthropogenic activity on the global atmosphere.