||KURT ZENZ HOUSE
Department of Earth and Planetary Science
Storage of Captured Anthropogenic CO2 in Ocean Sediment
Advisor: Daniel Schrag
The combustion of fossil fuels is causing a steady increase in the partial pressure of atmospheric CO2. It is widely believed that the increasing density of atmospheric CO2 may result in devastating changes to our planets climatic system. In addition, conventional oil production is forecast to peak within the 30-50 years. Due to the abundance and low cost of coal, coal is likely to substitute greatly for the decline in conventional oil supply after the oil production peak. That shift to more carbon dense fuel (i.e., coal) and more centralized energy production (i.e., hydrogen production) will create both a need and an opportunity for large scale carbon dioxide capture and storage. One potential solution to this is problem is the storage of CO2 in calcium carbonate sediments. The calcium carbonate host-rock will react with the injected CO2 neutralizing the acidic solution through addition of alkalinity to the pore fluids. Furthermore, host-rock dissolution will increase the porosity and permeability of the porous matrix. The temperature and pressure at sub-ocean floor depth should accelerate the dissolution kinetics resulting in a larger pore space to store the anthropogenic CO2. To evaluate the feasibility of CO2 storage in calcium carbonate sediment, the mechanical and chemical behavior of CO2 and CO2-water mixtures injected under a range of pressures and temperatures and with a range of sediment compositions and rheologies is being analyzed.
Energy and Resources Group
University of California, Berkeley
Rethinking Rural Energy Planning in Developing Countries
Advisor: Daniel M. Kammen
My PhD research examines, and will attempt to correct for two biases built into current rural energy planning processes and tools.
The first is a bias towards electrification. The majority of rural energy projects are focused on electrification. While electricity is an important driver of development, there is evidence that the main energy need for economic development in rural areas is heat energy. Currently, no organizations active in rural energy provision plan for the supply of electricity and heat energy in an integrated way. I will demonstrate how this leads to poor technology choice for rural energy provision, which does not meet people’s real needs.
The second bias is a gender bias. I will demonstrate that the tools we use to select renewable energy technologies for meeting rural energy needs have a gender bias built into them. This is because these tools have no means to account for the economic value of women’s work and time expended in collecting fuelwood and cooking using inefficient cookstoves and poor fuel sources.
By correcting for the separation between electrification and traditional energy, and for the gender bias, I believe it is possible to design rural energy planning tools that meet people’s needs effectively and efficiently.
RANDALL H. GOLDSMITH
Department of Chemistry
Optimization of Long Range Electron Transfer for Solar Energy
Advisors: M. R. Wasielewski & M. A. Ratner
Electron transfer (ET) is a critical process in nano-scale electronic and photonic devices including solar cells. Like many natural phenomena, electron transfer is a complex function of many system-specific variables. Our approach entails the synthesis of organic molecules with specific electron donors and acceptors fixed at a well defined distance about an intervening molecule that covalently bridges the donor and acceptor. Using the versatility of organic chemistry to design molecular structures and the probing power of ultrafast transient absorption and nanosecond transient electron spin resonance spectroscopy, we study ET rates as a function of molecular structure, while keeping as many system variables as possible constant and changing only the variable of interest. This procedure allows a logical and methodical approach to studying ET. Most importantly, this effort has the potential to impact the use of organic photovoltaics. Organic photovoltaics have already been shown to possess huge advantages in terms of cost and facile large surface area coverage. However, their efficiency is still lacking, and only by conducting basic research to improve the efficiency of these devices that have ET as their basic step, can organic solar cells fulfill their promise to produce a significant fraction of the world’s energy needs.
ALEX BRANDON FLETCHER MARTINSON
Department of Chemistry
Efficient Organic Photovoltaics that are Interlaced on the
Advisor: Joseph T. Hupp
The global need for affordable, clean energy has spurred interest in organic-based solar cells due to their potential for low-cost manufacturing. The dissociation of excitons into electrons and holes occurs at the interface between two dissimilar organic materials. Efficient photovoltaics must be made thick enough to absorb the majority of incident light, but paradoxically, a thicker absorbing layer decreases the chance that an exicton will reach the heterojunction. Recent efforts in our lab have produced a series of disphosphonic acid chromophores, including a chlorophyll-like macromoleclar square and an electron accepting perylene. Using established zirconium phosphonate chemistry, these molecules have recently been assembled in our lab into well-organized thin films on transparent conductive substrates. Films of each chromophore prepared using layer-by-layer assembly demonstrate control of thickness on the molecular level. More importantly, films of the macromolecular square have been found to be permeable to molecules as large as 16 Å. The molecular width of the perylene is only 6Å, which allows for facile assembly of this material within an assembled film of the electron donating macromolecular square. In this manner, a maximal heterojunction area is achieved between the organic materials to create an interlaced structure on the molecular level.