Integrating bioenergy options into the global forest products market for climate benefits
Sijia Zhang, J. Keith Gilless, and William C. Stewart
Woody bioenergy releases carbon that has been absorbed by plants from the atmosphere in the recent past, therefore reduces the amount of geologic carbon released into the atmosphere. The object of this project is to model how increased use of wood-based bioenergy, in the forms of fuelwood, cellulosic ethanol from woody biomass, electricity and industrial heat produced from wood, will interact with global markets for wood products; liquid, solid, and gaseous fuels; and electricity. We endogenously modeled demand for woody bioenergy by modifying the U.S. Forest Products Module of the Global Forest Products Model (USFPM/GFPM). Our results project a substantial increase in demand for wood-based cellulosic ethanol in the U.S. for the next 20-30 years, under a high oil price scenario, providing evidence that part of the projected demand for bioenergy could be met from sustainably managed forests that produce products and energy for a globally integrated market.
 Using fecal sludge as a renewable energy source in sub-Saharan Africa
Jeonseuk “Louis” Kang and Lauren Steinbaum
Despite its economic status as a mid-income country, Ghana lacks adequate human waste management. Fecal sludge from pit latrines and septic tanks is dumped into ponds or landfills at best, and may even be discharged to surface waters. However, the composition of fecal sludge makes it a potentially attractive resource for generating alternative energies, such as solid industrial fuel and biodiesel. Various technologies converting fecal sludge into fuel were tested in Ghana, with results proving that the conversion is possible and may even be financially viable. Most promisingly, industrial fuel can be created that is as energy-dense as sawdust and can be used in cement kilns and boilers in Africa, where solid fuel is increasingly scarce and costly. Converting fecal sludge into alternative energy has the potential to address both the problems of inadequate sanitation and increasing energy demand in a rapidly developing world.
 Developing a synthetic biology tool box for metabolic engineering of ralstonia eutropha
A complex tool box was constructed for engineering Ralstonia eutropha (R. eutropha), allowing controlled expression of metabolic pathway of multiple genes. The toolbox makes it possible to produce high octane directly from hydrogen and CO2. Broad host plasmids, pCM62 (IncP), pBBr1 (IncQ) and pKT (ATCC 37294) were able to be transconjucated and replicate in R. eutropha. Mutations were made to increase plasmid copy numbers of the pCM plasmids. Promoters such as PBAD, PT7, Pxyls/pm and PLacUV5Y were evaluated and engineered to create an array of promoters with different strengths upon induction. Especially important is a set of PCbbr promoters that respond to autotrophic condition were engineered for inducer-less induction. RBS sequences derived from E. coli, R. eutropha and an RBS calculator (salis.psu.edu/software) were compared for expression. Additionally, a 5’ stem loop structure sequence was found to increase expression of the downstream gene in R. eutropha. This tool box has the potential to be applied to broad range of microbial hosts.
 Engineering efflux pumps to enhance microbial secretion of biofuel-relevant inhibitors
The microbial conversion of sugars to biofuels is a promising new technology, but the fuels are usually inefficiently recovered from the microbial production host. Furthermore, the byproducts of biomass pretreatment processes and the fuels themselves are often toxic at industrially-relevant levels. One promising solution to these problems is to evolve efflux pumps to secrete fuels and inhibitory chemicals from the cell, increasing both fuel titer and microbial tolerance. We have isolated variants of the Escherichia coli AcrB efflux pump that enhance the growth of E. coli in the presence of n-butanol by approximately 30%. The single amino acid changes in AcrB responsible for the enhanced growth phenotype have been identified. Furthermore, we found that these variants enhance tolerance to isobutanol and straight-chain alcohols to n-heptanol. Moving forward, we will test if these pump variants enhance production of butanol from producing strains and screen our AcrB libraries against additional biofuel-relevant inhibitors.
 Integration of chemical catalysis with extractive fermentation to produce fungible fuels
Acetone, a product of the acetone-butanol-ethanol (ABE) fermentation, harbors a nucleophilic α-carbon, which is amenable to C-C bond formation with the electrophilic alcohols (ethanol and n-butanol) produced in ABE fermentation. This functionality enables the formation of higher molecular weight hydrocarbons similar to those found in current jet and diesel fuels. Here we describe the integration of biological and chemocatalytic routes to efficiently convert ABE fermentation products into ketones, ranging from 2-pentanone to 6-undecanone, by a palladium-catalyzed alkylation. Tuning of the reaction conditions permits production of either predominately gasoline or jet and diesel precursors. Glyceryl tributyrate was used for in situ selective extraction of both acetone and alcohols to enable simple integration of ABE fermentation and chemical catalysis. This process provides a means to selectively produce gasoline, jet, and diesel blendstocks from lignocellulosic and cane sugars at yields near their theoretical maxima.
 Engineering ionic liquid tolerant cellulase enzymes
Ionic liquids (ILs) are capable of solvating biomass and separating lignin and hemicellulose from cellulose. It is likely that (partially) dissolved cellulose could be very rapidly hydrolyzed. Aslo, ILs prevent contamination during the enzymatic hydrolysis step in cellulosic biofuels production. Cellulase activity in neat IL has not been demonstrated due to the IL’s denaturing effect on the enzymes. In this work, we searched for and found a more IL-tolerant cellulase via a mutant library generated with DNA shuffling for the purpose of hydrolysis of the cellulose in the presence of the ionic liquid (with water added).
 Membrane science for liquid organic fuel cells
This study was aimed at understanding the interaction of liquid organic fuels with Nafion® membranes. Carbocyclic compounds, O-containing and N-containing heterocyclic compounds were investigated as fuels. We report the properties of PEMs, such as solvent uptake, proton conductivity and fuel cell performance in the presence of such liquid organic fuels.
 Optimization and kinetic modeling of saccharification of non-edible plants for bioethanol production
Over the past decade bioethanol has been recognized as a potential fuel source by the scientific community around the world, including India. India’s growing population and scarcity of arable land have been important concerns for many years now. This has engendered a need to develop a fuel- generation process that does not compete with the food source and this is the motivation behind using non- edible lignocellulosic biomass for bioethanol production. The focus of this project was to optimize and model the kinetics of the enzymatic saccharification stage of the bioethanol production process using Cotton Stalk as the substrate. Optimization was performed for parameters such as temperature, operation time, and substrate concentration while analysis of the kinetics allowed us to identify possible inhibitory effects of the enzyme. This study can aid in upscaling when this bioethnaol production procedure is implemented on an industrial scale.
 Screening metagenomic libraries for a novel xylanase
Susan M. Lee
Biofuels have great potential to reduce our fossil fuel dependency, and Brazil has harnessed much of this potential as one of the world’s leading bioethanol producers. At the Brazilian Bioethanol Science & Technology Laboratory (CTBE), we screened metagenomic libraries for novel enzymes to improve the lignocellulosic biofuel production process. This project’s target enzyme was a novel xylanase. We used Xyl Pat, a degenerate primer, to anneal to conserved regions in the xylanase gene. These efforts to discover novel enzymes effective at biomass degradation have a goal of increasing efficiency and decreasing costs of bioethanol production. Additionally, metagenomic screening can contribute to a greater understanding of natural soil microbial communities.
 Metabolic profiling and systematic identification of hydrocarbon next-generation drop-in biofuels and its precursors in wild-type and transgenic tobacco leaves using GC-MS
A novel method utilizing gas chromatography-mass spectrometry (GC–MS) was developed for the large-scale and systematic identification of hydrocarbon and its precursors in tobacco leaves. Today, some scientists are working on engineering tobacco plants with cyanobacteria and algal genes so that they use energy from sunlight to produce various biofuels directly in their leaves, which could then be harvested, crushed and the fuel extracted. It becomes important to understand how the carbon flux through the fatty acid and alkane biosynthesis pathways finally leads to the accumulation and/or secretion of notable amounts of hydrocarbon molecules. Under optimized conditions, we were able to simultaneously quantify and identify fatty acid-based compounds including free fatty acid, fatty aldehydes, fatty alcohols and fatty alkanes. All identifications were based upon mass spectral characteristics of ion fragment, mass spectral data, compared with mass spectra reported in the NIST mass spectra library, and confirmed through the co-characterization of authentic compounds. Comparative metabolic profiling of wild-type and transgenic tobacco leaves will be then performed and hopefully reveal significant differences in the fatty acid-based composition of these two lines.
 Expanding the uses of soybeans: anti-HIV microbicide, spider silk proteins, biodiesel
Improving the sustainability of soybeans extends to developing more uses of the plant other than as a food and vegetable oil source. As a versatile vehicle for producing recombinant molecules, soybeans are potent bioreactors for plant-derived biopharmaceuticals and industrial macromolecules. They are capable of producing cyanovirin, a cyanobacterium protein shown to inhibit the human immunodeficiency virus (HIV), as well as spider silk proteins—specifically the Major Ampullate Spidroin. In addition, since no nitrogen fertilizer is required, soybean is an ideal feedstock for biodiesel as it generates more energy in the derived biodiesel than required for its production. The ongoing research attempts to further improve the fatty acid content in soybean seeds for a more oxidatively stable oil. Using recently developed research tools and purification systems, significant progress is made in the preliminary characterization of the proteins produced by transgenic soybeans.
 Metal-organic frameworks: synthesis and gas sorption studies
David Gygi and Mary Anne Manumpil
Increasing alarm regarding the environmental effects of current and predicted carbon dioxide emissions have motivated investigation of more sustainable energy sources. Until an economically viable alternative can be introduced and implemented, however, the development of metal-organic frameworks for carbon sequestration is being pursued to reduce the environmental consequences of current energy-related pollution. Metal-organic frameworks boast large internal surface areas, potential for functionalization, and thermal as well as chemical stability—all of which lend to the ability of the frameworks to selectively adsorb and store gases. These frameworks are also capable of storing large amounts of hydrogen gas that have the potential to be used in fuel cells. In this way, metal-organic frameworks may provide current and future relief from environmental contaminants.
Energy Economics and Policy
 Poverty, growth and the demand for energy
Paul Gertler, Orie Shelef, Catherine Wolfram, Alan Fuchs
We argue that countries with pro-poor economic growth will experience much larger increases in energy demand than countries where growth is more regressive. When poor households’ incomes go up, their energy demand increases as they buy energy-using assets for the first time. The speed at which households come out of poverty affects their asset purchase decisions. We find that transfers from Mexico’s conditional cash transfer program had a large effect on asset accumulation among the low-income program beneficiaries, and is substantially greater when the cash is transferred over a shorter time period. We find that assets, not cash transfers drive household electricity usage. Using country level aggregate energy data, we show that the correlation between energy use and income is nearly double in countries where growth has been pro-poor than other countries. These results suggest that forecasts grossly underestimate future energy use in the developing world.
 What changes energy consumption…and for how long? New evidence from the 2001 Brazilian electricity crisis
Incentives are often disregarded as unable to spur sufficient, immediate and long—term demand response in case of energy crises, more prevalent in developing countries. I study the 2001 Brazilian electricity crisis when consumption had to decrease by 20% over 9 months. I find that average electricity consumption per customer dropped by 33% in areas subject to private and social incentives. Using individual billing data for 3 million customers, I show that the reductions came from large responses by most customers. Using variation in individual incentives and indirect inference techniques, I show that a “regular” price elasticity must be increased fivefold to explain conservation efforts by the private incentives only: social effects likely exacerbate consumers’ responsiveness in times of crisis. Finally, I find that consumption has been reduced by 11% in the long—run. Survey data reveal that both short and long—run responses arose partly from behavioral changes.
 Do the poor respond to environmental messages? Experimental evidence from Brazilian favelas experimental evidence from Brazilian favelas
Both prices and non-pecuniary approaches have been used to encourage the adoption of energy efficient technologies. In this paper, I investigate the effect of these approaches on a poor population from a
developing country. Using data from a randomized experiment in 18 favelas in Rio de Janeiro, Brazil, I study the effect of providing an environmental message to poor individuals on the take-up of an energy
efficient light bulb (LED). By randomizing three price levels and whether individuals receive an environmental talk, I am able to identify the effect of the environmental talk on LED take-up and the price level at which it operates. On average, receiving the environmental talk significantly increases LED take-up by 6 percentage points (12.5%). At the middle price (R$11), the effect of the environmental talk increases to 13 percentage points (19%). In another comparable laboratory experiment with UC Berkeley students, I find similar results.
 2012 analysis of the U.S. solar photovoltaic (PV) energy market
Over the past summer at the Bosch Solar Energy (Bosch SE) headquarters in Germany, the business development team researched and designed a US market strategy based on future US market demand for solar photovoltaic (PV) energy. The strategy was developed through analyzing market drivers and barriers at the federal, state, and local levels. The strategy comprised of models that projected future solar PV demand for each market segment (residential, commercial, utility) from 2012-2020, and also included a comprehensive state ranking system for wholesale and retail solar energy markets, in which market attractiveness was quantitatively analyzed for all 50 states based on different variables affecting each state’s demand for solar PV. The finalized research findings also contained a detailed analysis of political factors affecting solar energy policy and incentives, residential solar energy system finance, and downstream solar energy project integration in the US market.
 Electrifying China’s power sector with efficiency: quantifying the potential impacts of power sector policies
Nina Zheng Khanna, Nan Zhou, David Fridley and Jing Ke
China’s electricity demand has grown at double-digit rates in recent years with doubled installed capacity from 2000-2007. Policies have started to focus on supply-side non-fossil energy development, but the impacts of individual policies are not well known. This study evaluates and quantifies the energy and emissions reduction potential of China’s power sector policies through 2050 using bottom-up end-use modeling and scenario analysis. Policies evaluated include renewable targets, environmental priority generation dispatch, demand-side management (DSM), coal-fired efficiency and CCS technology upgrades, increased natural gas generation and transport electrification. We find that energy efficiency is and will continue to be a crucial resource for China’s power sector with DSM having the greatest impact on reducing electricity demand and power sector CO2 emissions. Renewable targets and environmental dispatch also have crucial and interlinked impacts on energy and emissions reductions, including changing the shape and peak year of the long-term power sector emissions outlook.
 Marketing solar photovoltaic in developing countries
Solar photovoltaic systems offer a clean, reliable, and local energy source for developing countries as demand for energy increases and political instability can cause energy imports to be less reliable. At Suntech in China, I researched and analyzed the solar photovoltaic markets, managing the solar energy adoption data and comparing renewable energy policies in developing countries in the Asia Pacific, Middle East and Africa regions. I helped develop marketing materials that demonstrated how shifting to renewable energy, including solar photovoltaic systems, on a large scale can help lead to economic growth and a green future for developing countries.
 Implications of carbon management on supply chain design issues
Companies normally focus on transportation tactics to reduce carbon emissions of their supply chains. However, this may lead to suboptimal decisions due to the lack of considerations of other supply chain activities, such as warehouse operations. An integrated supply chain design model was constructed to investigate the trade-offs between warehouse and transportation carbon emissions. A multi-objective problem that minimizes both cost and carbon emissions is also investigated in this research.
 Spin-dependent band structure and ultrafast spin dynamics with potential applications for energy efficient spintronics
Understanding spin dynamics on the femtosecond time scale is a great emergent challenge in solid state physics and is of crucial importance for the development of revolutionary computing technologies. A one-of-a-kind spin- and angle-resolved photoemission spectrometer allows for rapid high-resolution mapping of materials’ spin-dependent electronic bandstructure. This system has been used successfully to study the spin-polarized surface states of 3D topological insulators and Rashba systems. When used with the pump-probe technique, it will reveal ultrafast spin dynamics in ferromagnetic materials. For example, it has been shown that magnetic bits in GdFeCo can be written with a laser pulse shorter than 0.1 trillionths of a second, rather than with a large magnet. The added information of spin, time, momentum, and energy resolution can reveal how these electronic states evolve during this process and how they can be manipulated to yield energy efficient and high speed devices and applications.
 The Global Equipment Energy-Use and Cost Database (GEEC-DB)
The Global Equipment Energy-Use and Cost Database (GEEC-DB) contains a large and hitherto uncollected set of efficiency and price data for 16 in-building equipment types for the commercial, residential and industrial sectors, and currently covers the EU, US, China, India, Japan and Korea. The GEEC database evaluates cost-effective energy savings potential based on price and efficiency cost curves and the utilization of the cost of conserved energy metric. The GEEC-DB evaluates potential for affordable higher efficiency equipment such as refrigerators and HVAC systems, and by doing so allows for a wide range of efficiency policy analyses. The GEEC-DB has proven particularly useful when its cost-effective technology targeting is used in tandem with the energy demand forecasting model BUENAS, to produce national efficiency scenarios. These forecasts have been a component of the Clean Energy Ministerial’s Super-efficient Equipment and Appliance Deployment initiative, as well as contributing to several other national and international research efforts.
 Efficient direct battery interface for modern ICs or a method of area reduction and power saving
Consumers always demand electronic systems (e.g. portable gadgets) more functionalities and at the same time lower power, longer battery life, thinner and lighter. While other functional ICs are in a great effort of integration to save power and leave more space for battery, power management has been slow in renovation. Power management IC (PMIC) together with associated off-chip components requires a board area that is fixed and/or not scaled as fast as other ICs with technology scaling, making its relative area consumption increase (e.g. ~10% of total board area in iPhone 3 to ~20% in iPhone 5). Unlike this conventional solution, our efficient direct-battery-interface power management unit is fully integrated onto functional chips, freeing board space and yielding a >20x-smaller power management for portable devices. In addition, benefitting from the co-integration it enables ultra-fast voltage/power scaling, reducing the overall system power consumption (~40%) by saving power in low-power/shut-down mode.
 Cooperative appliances increase efficiency, quality of life
Household appliances are often designed and sold together on the basis that they complement one another aesthetically. Even though these machines serve different purposes (washing dishes, heating food, etc.), they often utilize similar processes (controlling water, transferring heat to or from some medium, etc.). This system of independent operations is sub-optimal both in terms of energy demand and in terms of service provided to the user. Using the cold water input to a water heater as a heat sink for a refrigerator, for example, would drastically increase the efficiency of each appliance, saving the average household $250 annually. This does not include the benefits of reduced fan noise in the kitchen and reduced demand for air conditioning due to the elimination of the refrigerator wasting heat into the kitchen. The gains in industrial and laboratory settings would be substantially larger. Such is the potential of appliances designed to work together.
 A regional assessment of solar heat management via dynamic window coatings
With building heating and cooling accounting for approximately 14% of national energy demand, buildings provide an obvious target for energy and carbon savings. Windows have a significant influence in achieving these savings, and advancements in dynamic window technologies, such as electrochromic coatings, are helping to realize this potential. With a small applied voltage, electrochromic coatings can dynamically tune their optical properties to either block or transmit solar heat, reducing heating and cooling loads. Conventional electrochromic coatings exhibit broadband switching, reducing overall solar heat gain and visible transmission in unison. This can adversely affect daylighting and building aesthetics. Recent research efforts have demonstrated a new “transparent electrochromic“, which modulates solar heat gains exclusively in the near-infrared range, while maintaining high visible light transmittance. This investigation presents a regional analysis of performance requirements for a transparent electrochromic to achieve market success against existing technologies. It identifies regions well-positioned for deployment and determines best-case energy savings potential in commercial and residential applications.
 Break-even price thresholds for transparent electrochromic coatings
The economic viability of a novel, nanoparticle-based, electrochromic window coating was assessed for U.S. commercial buildings using two simple economic metrics: simple payback period and net present value. Using the economic models, price targets were set for achieving thresholds of simple payback less than two years and net present value greater than zero.The dynamic window film, being developed by the Milliron Research Group at Lawrence Berkeley National Laboratory, is shown to have the best economic performance in cli- mates with significant temperature variation, like the upper midwest. Price targets are very near parity with competing static window technologies that are commonly used in new building design. Limitations of the study and possible future refinements are discussed.
 High performance computation for exploration of low energy information processing materials
We report the development of a massively parallel simulation platform for energy efficient information processing materials exploration. Our numerical model scales up to thousands of processors and calculates both short and long ranged electrostatic and elastic interactions with arbitrary boundary condition. The non-linear dynamics of correlated materials can be simulated up to diffusive time scale.
The micron size device structures that we have simulated is 100X larger than the state of the art. Using this simulator, we studied the switching dynamics of magneto-electric devices and showed that they have the potential to switch at 10X lower power compared to alternative routes. This study underpins the fundamental advantage of using multi-functional devices as information processing elements. The simulator is also useful for understanding non-linear dynamic processes in biology and nano-materials.
 Real-time disaggregation of composite power usage data into device-level loads
Kevin Weekly, Zhaoyi Kang, Jimmy Wu
Energy conserving smart buildings of the future will benefit from a dense and real-time knowledge of the buildings’ demands and usage. Using a Hidden Markov Model (HMM) observer, we are able to determine the individual power usage of devices sharing one physical sensor, such as a power strip plugged into a power measuring device. We also implement an infrastructure to inteface algorithms with real-time sources such as Simple Measurement and Actuation Profile (sMAP) servers and Cosm. To determine the parameters for the HMM, we have also designed and built a modified power strip which can individually measure the devices plugged into it. Learning sets from these devices can also be integrated into the model in real-time. This project is part of the Singapore Berkeley Building Efficiency and Sustainability in the Tropics (SinBerBEST) effort.
 A novel integrated building energy controller and optimization scheme for demand response automation
Michael Sankur and Jason Trager
Commercial demand response has traditionally consisted of a building manager manually reducing lighting and HVAC power consumption at the appropriate time. We present a new paradigm in which commercial demand response is automated and uses an optimization program to maximize power savings while minimizing occupant inconvenience and discomfort. This work is an integral part in the i4Energy DIADR (Distributed Intelligent Automated Demand Response) project. A central building controller (CBC) acts as a supervisory controller for the building’s energy consumption. It uses algorithms to create bids, based off plans of action for lighting and HVAC. The bids consist of a power savings time profile and calculated occupant inconvenience. A modular mixed integer program is used to find the optimal solution, minimizing the inconvenience incurred on occupants while meeting a budgeted power savings profile. This architecture has been tested several times in SDH with success.
 Personal Comfort Systems (PCS)
Ed Arens, Hui Zhang
Professors Ed Arens and Hui Zhang are developing an integrated system of personal thermal devices that improve the comfort of occupants while at the same time unlocking substantial net energy savings at the building level. As you may have experienced first-hand, in large indoor work-spaces it is both difficult (and expensive) to get the room temperature right for everyone, especially because people can have differing preferences. The team have developed 3 energy efficient devices to help solve this problem; a fan, a foot-warmer and an air-conditioned chair. The idea is to allow the individual to control the climate in their personal work space and thereby greatly improve their level of comfort through both physical and psychological effects. At the same time, total energy consumption can be significantly reduced- up to 40% in some climates.
 Cost and energy consumption optimization of product manufacture in a flexible production environment
Manufacturing activities comprise approximately one-third of the United States’ energy consumption. Previous work has limited its scope to characterizing manufacturing processes or simulating facilities with fixed process routings in order to reduce energy consumption. This project aims to develop a methodology for simulating part production in a manufacturing environment where parts have flexible process routings. The simulation accommodates low to high production volumes, low to high product mixes and could also be downgraded to manufacturing facilities with fixed process routings. We focus on the process planning stage for product manufacture and implement green scheduling techniques in a discrete-event simulation environment. It outputs data from the perspective of the individual part, manufacturing cells and the facility as a whole. Lastly, alternative facility designs are evaluated in which the number of machines tools in a manufacturing cell is varied to lower expenses related to non-value added activities in the facility.
 Comparison testing of Haitian cookstoves
Kathleen Lask and Jennifer L. Jones
In April 2010, Lawrence Berkeley National Laboratory (LBNL) organized a team of scientists and engineers to undertake a fact-finding mission in Haiti to assess the needs and potential impacts of fuel-efficient cookstoves. Based on data collected from interviews with Haitians and non-governmental organizations, the team identified and recommended stove performance testing and comparison as a high priority need that could be filled by the Gadgil Lab – Stoves (GLS) at LBNL. A total of six charcoal stoves intended for use in Haiti were tested at the GLS facility. Both Water Boiling and Controlled Cooking Tests were conducted, testing time to boil, thermal efficiency, specific fuel consumption, and emissions of carbon monoxide (CO) and carbon dioxide (CO2). The results and comparisons drawn from them are presented in this poster.
 Household cooking with solid fuels is a source of fine particulate ambient air pollution (PM2.5)
Smoke from household cooking with wood, charcoal, dung and coal is an important, but often overlooked, source of outdoor air pollution across much of the world. This research shows that fine particulate matter attributable to household cooking with solid fuels (PM2.5-cooking) constituted >15% of anthropogenic PM2.5 in eight world regions (home to 4.5 billion people) in 2010. The contribution from PM2.5-cooking remains negligible in six higher-income regions. Approximately 2.8 billion people cook with solid fuels—a number that has not significantly decreased over time, despite the fact that exposure to indoor air pollution from cooking smoke causes about 2 million premature deaths each year. Efforts by developing countries to meet air quality guidelines must more explicitly address access to cleaner fuels and improved cookstove to succeed.
 Solving San Francisco’s housing crisis with floating energy-independent neighborhoods
Ruth Miller, Jean Michel Monier, and Maude M. David
Our cities are in crisis: the working class that powers our metropolitan cores cannot afford the steep cost of urban housing. Further, the density of urban areas makes the replacement of antiquated infrastructure difficult. New, dense, efficient urban neighborhoods could break the urban cycle of renewal and blight. Building micro-apartments offshore, we could create whole carbon-neutral, energy-independent neighborhoods. Taking advantage of their location, these communities could be powered by biofuel cells, tides, solar, and wind. Because the neighborhoods would be built around new and intelligibly organized infrastructure, they could use wastewater for biofuel and gas production for local use. New, real-time monitoring technologies would guarantee water and air quality. This vision starts off the coast of San Francisco. Between their considerations of 220 square foot “micro-apartments”, the dissolution of redevelopment agencies, and the failure of the America’s Cup to attract coastal investment, the political environment is ripe for experimentation.
Energy Harvesting and Storage
 Synthesis and characterization of sodium titanate (Na 2Ti6O13) for sodium ion batteries
Sergio Alfredo Hidalgo
Large renewable energy installations, such as wind or solar, are expanding worldwide but how do we store this energy when it is not needed? Sodium-ion batteries are a potential storage alternative because of its higher power density and the abundance of sodium. Sodium titanate (Na2Ti6O13) arises as a prospective anode material for sodium ion batteries. Although sodium titanate is usually synthesized using traditional solid-state methods, a soft template method is explored to create a mesoporous material potentially giving higher charge capacity. Performance of the sodium titanate in half-cells is compared against its impure state (containing rutile titanium dioxide) and against different electrolytes.
 Performance improvement of a hydrogen-bromine flow battery
Kyu Taek Cho
Redox flow batteries (RFB) are getting attention as promising candidates for grid-scale energy storage and load leveling including renewable-generation firming. However, due to challenging issues such as low cell performance, durability and high electrolyte cost, their wide-spread adoption has not occurred. Previously, we introduced a RFB operating with hydrogen and bromine and exhibiting good charge/discharge performance as a candidate for solving these challenges. In this study, we are developing the H2-Br2 RFB further to meet the requirements for application by increasing cell performance and durability. Cell performance was greatly enhanced by activating the bromine carbon porous electrode and utilizing the proper cell and operating conditions. The effect of activation and structure of the carbon porous electrode and operating condition on cell performance will be presented. For durability, cell potential decay at OCV and at constant current was investigated with various membrane structures. The cause of degradation and ways to mitigate it will also be discussed.
 New frontiers in high resolution imaging with laser techniques
Jaroslaw Syzdek, Alexander S. McLeod, Ivan Lucas, Elas Pollak, Vasilia Zorba, Dmitri Basov, Robert Kostecki, Rick Russo
Lasers cover a wide range of frequencies, light intensities and time domains (ultrafast pulses through continuous wave). Harnessing different spatial and temporal capabilities lasers have, gives us endless opportunities for material characterization. Using different time and space domains we can characterize materials in three space dimensions, in time and provide chemical information. Utilizing high power femto-second laser pulses we were able to characterize very volatile surface layers at unprecedented 7nm depth resolution. Using near-field techniques we provided for the first time tomographic information on materials that are sensitive to X-Rays and electron beams, at 20nm resolution using Quantum Cascade IR lasers.
 Conductive polymer binder based silicon composite anode for high energy lithium ion battery
Si material has 10X lithium-ion storage capacity than that of the state of art graphite materials. But the large-volume change associated with lithiation and delithiation severely hinders the practical application of Si in anode. Electrically conductive polymer binders can solve the volume-change issue of the Si for anode application. A class of new conductive polymers was designed and synthesized with optimized properties as electrode binder. The polymer maintains both electric conductivity and mechanical integrity during the battery operation. Therefor, the alloy particles and conductive polymer composite anodes do not require using other conductive additives such as acetylene black. More importantly, this conductive polymer matrix is compatible with the lithium-ion slurry manufacturing process. Pure Si particles without carbon coating are used with the conductive polymer binder, and exhibit extraordinary cycling performance. Si can be reversibly cycled at its theoretical capacity limit.
 Near Zero
Togay Ozen, Marwan Rammah, Sadegh Asefi, David Olmos, David Atkins-Maters
The rapid growth of solar and wind power in the United States strains our electricity grid’s ability to provide ancillary services that maintain grid stability. Near Zero is developing a mechanical storage technology capable of efficient and rapid charge and discharge rates over a very low maintenance 30-year operating life. These advances are achieved through a high efficiency coreless brushless DC motor design coupled with a near zero loss magnetic bearing system. The lack of cogging torque in the coreless motor/generator enables high efficiency charging and discharging at all speeds, including the 40,000 RPM operating limit.The magnetic bearing system utilizes two pairs of cylindrical NeFeB magnets to provide axial lift and radial centering forces that are stabilized by a fast acting electromagnets. Simulation and early stage prototyping has demonstrated a 92% roundtrip motor efficiency and only 5-10 watts of parasitic losses in the magnetic bearings, positioning Near Zero far ahead of other storage alternatives. Near Zero’s storage solution is aimed at increasing the profitability of providing ancillary services, while lowering the barrier for renewables integration.
 Stirling engine for solar thermal generation and storage
This project focuses on the design, development, and testing of a Stirling engine for converting thermal energy into electricity for the purposes of generation from renewable or other thermal sources while incorporating energy storage for reliable output. The key advantages of the technology include the ability to store thermal energy in a cost-effective manner, accept multiple input thermal streams, and perform more efficient conversion at lower temperatures than other technologies. Targeted applications include distributed solar generation, primary generation in developing regions, waste-heat recovery, and backup generation. The incorporation of thermal energy storage made possible by the technology improves the reliability of its power output, reduces intermittency and variability, and enables generation at all hours of the day.
 MEMS piezoelectric vibration energy harvesters for powering wireless sensor nodes
Lindsay M. Miller
Wireless sensor networks (WSNs) have the potential to transform engineering infrastructure, manufacturing, and building controls by allowing condition monitoring, asset tracking, demand response, and other intelligent feedback systems. Today, wireless sensor nodes are typically powered by a standard single-charge battery, which becomes depleted within a relatively short timeframe depending on the application. This introduces tremendous labor costs associated with battery replacement, especially when there are thousands of nodes in a network, the nodes are remotely located, or widely distributed. Piezoelectric vibration energy harvesting presents a potential solution to the problems associated with too-short battery life and high maintenance requirements, especially in industrial environments where vibrations are ubiquitous. This research presents results of a prototype micro scale device that can harvest energy from vibrating machinery, as well as optimization of that device, and steps towards integrating the harvester with power conditioning and energy storage components.
 Nanostructured block copolymers for use in solid-state lithium metal batteries
Alexander A. Teran, Daniel T. Hallinan Jr., Nitash P. Balsara
Nanostructured block copolymers (BCPs) with a mechanically robust block and an ion-conducting block doped with a lithium salt have proven promising for use as electrolytes in rechargeable lithium metal batteries. These materials exhibit high ionic conductivity at elevated temperatures, excellent stability against lithium metal, and the ability to retard dendrite growth. Using these BCPs as electrolytes to create completely dry solid-state lithium metal cells offers the possibility of very high energy density system with no volatile components. These materials have been cycled in symmetric lithium metal cells, as well as full electrochemical cells with lithium metal as the negative electrode and several different active materials in the positive electrode.
 Batteries for grid scale energy storage
Venkat Srinivasan, Adam Weber, Vince Battaglia, Marca Doeff, Jordi Cabana, Mona Shirpour, Kyu Taek Cho, Paul Ridgeway, and Sophia Haussener
The growing complexity of the electrical grid requires close coupling of energy generation with storage, particularly as reliance on renewables increases. Researchers at Lawrence Berkeley National Laboratory are currently working on two types of potentially very low-cost batteries intended for grid storage applications. Both systems, a hydrogen-bromine flow battery and a sodium-ion battery, employ low-cost chemistries without resource limitations. For flow batteries, the goal is to develop a low-cost, high power device with 80% efficiency or better. Work on improving membranes, catalysts and electrolytes for this system has resulted in the highest power flow battery reported to date. The sodium ion battery can be engineered much like the already commercialized Li ion analog, but requires different electrode materials and an aqueous electrolyte for reasons of cost. We have recently demonstrated the first reversible sodium ion battery with an aqueous electrolyte, and have discovered two new classes of anode materials.
 International microgrid assessment: Governance, INcentives, and Experience (IMAGINE)
In performing this International Microgrid Assessment, we provide an avenue to understand the Governance of a grid environment where microgrids can succeed and to form the INcentives needed to capture the benefits microgrids provide, by cataloging the international Experience to date. The assessment reviews both the key drivers for microgrid development and outlines the main barriers that microgrid demonstrations have faced to date. It highlights two well-known demonstration projects: the Santa Rita “green jail” in Dublin, CA and the Sendai microgrid in Japan. Specific technology and policy pathways for microgrid development to get from the “land of penalties” to the “land of payments” are proposed. Finally, the assessment leads to policy recommendations for starting a microgrid demonstration program that can eventually scale up to deployment, with a specific focus on China which is planning to launch a demonstration program for 30 microgrids.
 Real-time automated demand response for commercial buildings
Joyce Kim and Rongxin Yin
In order to ensure reliable and affordable electricity, demand-side resources need to respond to grid reliability requests and wholesale market conditions. Automated demand response (Auto-DR) enables commercial buildings who are under dynamic energy pricing to provide continuous energy management and the ability to curtail loads during demand response events without human in the control loop. This project is focused on the development of control algorithm for Auto-DR to provide practical, robust, and optimal solutions to commercial building operation in real-time. First, we establish the communication model between the grid system operator, utilities, and facilities to send and receive reliability and pricing information. Second, we populate and categorize control strategies that can respond to energy prices, outside weather, building system constraints, and operation conditions. Finally, we integrate the control algorithm into the existing building control system via a user interface that allows the facility managers to modify and fine-tune control strategies.
 Smart and scalable DC microgrids for developing regions
Achintya Madduri, Javier Rosa, and Ken Lee
There is a strong need to provide a sustainable electricity to over 1.3 billion people who still lack access. Technical and economic barriers prevent the grid extension necessary to meet the needs of this population. We propose a novel DC microgrid that is designed to maximize end-to-end efficiency and reliability for renewable generation and modern DC loads. We base our design choices on recent studies that have tried to find sustainable solutions to rural electrification using a standard AC microgrid architecture. Our choice of designing around a DC architecture is driven by the goal of reducing both capital and operational expenses of rural microgrids. We incorporate the following features into our architecture: (i) DC power generation and distribution, distributed energy storage at end points of grid; (ii) smart load controllers that measure usage and respond to grid voltage to maintain stability; and (iii) end-to-end digital communications to enable demand-response and variable pricing schemes.
 Scenarios for reducing 2050 carbon emissions by 80% in the electric power sector
James Nelson, Ana Mileva, Josiah Johnston
Decarbonizing electricity production is central to reducing greenhouse gas emissions. Exploiting intermittent renewable energy resources demands a new class of power system planning models with high temporal and spatial resolution. We use a mixed-integer linear programming model – SWITCH – to analyze generation, storage and transmission capacity expansion for western North America with hourly resolution. In generator cost and load profile scenarios consistent with California’s target of 20% of 1990 emissions by 2050, greater than 40% of energy from solar and wind is found to be operationally feasible
and economical. The relative shares of wind and solar generation are found to be dependent on the deployment of energy efficiency, heating electrification, and electric vehicles. Electric power sector capital investments are found to increase substantially between the present day and 2050, but are largely counterbalanced by decreased fuel expenditures, causing the projected cost of power to stay relatively constant through 2050.
 Addressing the water-energy nexus in developing countries – a remote sensing feasibility assessment of in-line hydropower in Nepal
Marc F. Muller, Sally Thompson, Slav Hermanowicz
In-line hydropower (IHP), whereby micro hydropower turbines are integrated in gravity fed rural water supply systems, is a promising infrastructure synergy to address the water–energy nexus. Incorporated to water infrastructure, it provides an inexpensive distributed generation opportunity while profits generated from electricity sales can cross-subsidize water supply costs. The concept has been applied in Alpine countries for a century, alleviating mountain poverty. It is likely transferable to developing countries and promises to alleviate both financial constraints that inhibit rural water infrastructure development, and technical constraints that cause load shedding and blackouts. Focusing on Nepal, this project characterizes the feasibility of such a concept at a large scale. Here we present a hydrological modeling procedure to estimate the micro-hydropower potential based on remote sensing data and identify technically promising areas for IHP. We also present preliminary results from feasibility assessments conducted this summer in communities of Western Nepal.
 Ion beam characterization at NDCX-II
Nuclear fusion, an energy source driving our sun and one with great potential for humanity, is a process in need of further understanding. Achieving fusion requires packing hot (energetic) atoms together with high density so their collisions are powerful and frequent enough to get the nuclei of the atoms to fuse while the material ‘burns’ and releases enough energy to provide a large gain over the initial drive. Along the way to this state, a fusion target passes through a regime called ‘warm dense matter,’ of which relatively little is known. Studying this state of matter could help us better understand the process of fusion; the Neutralized Drift Compression eXperiment, or NDCX-II, is a linear induction accelerator planned to do just that when completed at Lawrence Berkeley Laboratory. My work involves imaging the ion beams the accelerator creates to check progress as it’s built, using several diagnostic devices, statistical software, and particle simulations.
 Roadmap for the development of Fluoride salt cooled High temperature Reactors
Lakshana Huddar, Nicolas Zweibaum
In the Nuclear Engineering Department, we are developing an innovative reactor design; the Pebble Bed Fluoride salt cooled High temperature Reactor (PB-FHR). PB-FHRs are inherently safe due to their passive decay heat removal system and high fuel melt temperature margin. PB- FHRs have a high output temperature, increasing the efficiency of the brayton cycle power conversion system. The high temperature output also allows for process heat production, opening up a plethora of markets. The PB-FHR is economical due to its compact size, modularity and superior efficiency. Collaboration with other universities, national laboratories and industry ensures that this promising design does not remain a reactor solely on paper. Through the DOE-NEUP funded Integrated Research Project, with UC Berkeley as a lead, we have produced a roadmap for PB-FHR development, which includes building a test reactor. Our experiments, simulations and engineering design will turn this reactor into reality in the near future.
 Long-term sustainability of nuclear power trough uranium waste utilization
Christian Di Sanzo and Staffan Qvist
Today’s nuclear power reactors, Light-Water-Reactors (LWRs), utilize less than one percent of the natural uranium feed. It takes about 8 to 10 tons of natural uranium to make 1 ton of enriched uranium that is used in LWRs, leaving 7 to 9 tons of depleted uranium (DU) that is discarded as waste. To date, the US LWR program has accumulated more than 600,000 tons of DU “waste”. A new type of reactor technology called “Breed & Burn” (B&B) fueled by this material could satisfy all US electricity needs for at least 800 years. The unique feature of a B&B reactor is that it can breed plutonium in DU feed fuel and then fission a significant fraction of the bred plutonium, without having to reprocess the fuel. B&B reactor technology can provide the US with near limitless emissions-free energy by burning readily available LWR waste without posing proliferation risks.
 Enhanced safety features of fluoride salt cooled high temperature reactors (FHR)
Anselmo T. Cisneros
Fluoride salt cooled high temperature reactors (FHR) are an advanced low-carbon source of heat that can be utilized for electricity production or process heat. FHRs have enhanced safety features to reduce the probability of a severe accident and mitigate radiation release in a hypothetical accident including inherent power feedback mechanisms (negative temperature reactivity), utilization of natural circulation decay heat removal, and immobilization of radiative materials by sorption in the liquid salt coolant. This reduction in risk can be utilized to increase the economics of FHRs by decreasing the fuel fabrication costs and/or reducing the emergency planning zone (EPZ). Reducing the EPZ has the additional benefit of opening up new market to nuclear power including defense applications, co-location of nuclear facilities with industrial processes, and siting proximate to urban centers.
 Solution-processed carbon nanotube networks as transparent electrodes for photovoltaics
We present solution-processed, transparent carbon nanotube networks as an alternative to the conventional solar cell transparent electrode material, indium tin oxide. Carbon nanotube electrodes have been fabricated by spin-coating from two ink formulations: a surfactant-stabilized aqueous dispersion of nanotubes, and an ink formed by spontaneous dissolution of chemically reduced nanotubes in organic solvent. By varying the number of coats of ink used to make these electrodes, we have achieved sheet resistances ranging from 3.4kΩ/□ (with over 95% transmission at 550 nm wavelength) to 250 Ω/□ (75%transmission) to 120 Ω/□ (55% transmission). We have also characterized the changes in structure of the nanotube networks that result from addition of multiple coats. Finally, efficiencies of 2.4% have been achieved for organic solar cells using these electrodes, compared to 2.6% for solar cells with indium tin oxide.
 Organic photovoltaics performance & anthocyanin content; Co-variations follow a power law model
The purpose of this study is to predict the photoelectrochemical performance of the TiO2 dyes-ensitized solar cells (DSSCs) sensitized by organic dyes based on their anthocyanin concentration in a series of organic fruits. Anthocyanin dye solution was extracted from nine test fruits using water as the extracting solvent. Using these organic dyes, multiple DSSCs were assembled such that sunlight entered through the TiO2 side of the cell. The full current–voltage co-variations were measured at various incremental resistance values. Defining PMAX as the dependent variable, a series of linear, semi-logarithmic, quadratic, and finally power law regression models were used to predict the solar cells energy productions. Dyes extracted from blueberry and black raspberry with the highest anthocyanin content generated higher PMAX with better FF and conversion efficiency. Regression analysis demonstrated that the power law model (R2 =0.86) was the best fit and experimentally sound model to predict the relationship between PMAX and anthocyanin concentration. Based on this model, anthocyanin content and PMAX relation approaches zero for zero concentration and follows a sub-linear increase for higher concentration.
Practical limits on solar cell efficiency improvements due to upconversion
Photon upconversion has attracted attention recently as a potentially cost-effective way of increasing solar cell efficiency by allowing cells to absorb below bandgap light with minimal modification to the actual device structure. In this work, the effect of finite absorption bandwidth upconverters on solar cell efficiency was studied and upper bounds on efficiency improvements are reported as a function of the upconverter absorption bandwidth and location. Due to the Fraunhofer absorption lines present in the AM1.5G spectrum, it is found that there are only two ideal absorption locations for upconverters when coupled with low bandgap solar cells. Since upconverters are designed to be placed behind solar cells, the effect of back illumination on solar cell quantum efficiency was investigated and found to be a critical factor limiting the applicably of upconversion to certain device types. Finally, device specific integration challenges are presented for common solar cell designs.
 Low-cost, high-performance III-V photovoltaics on metal foils
III-V semiconductors deliver the highest efficiencies in photovoltaics, but they cost far too much for wide use. This stems from expensive traditional epitaxial growth techniques as well as expensive substrates. In this project, we get rid of both of these to lower costs, but maintain the electrical and optical quality of this material. This is done by large-scale, uniform, and controllable deposition of poly-InP film on metal substrates, which gives us potential for a huge decrease in production costs of III-V optoelectronic devices. Polycrystalline InP films have been grown on non-epitaxial molybdenum substrates by both MOCVD and close spaced sublimation (CSS). These films with micron-sized grains have similar photoluminescence qualities as single crystal InP and are suitable cheap, >20% efficiency solar cells.
 Hybrid tandem photovoltaics with the potential for efficiencies exceeding 20%
It is estimated that for photovoltaics to reach grid parity around the planet, they must be made with costs under $0.50 /Wp and must also achieve power conversion efficiencies above 20% in order to keep installation costs down. In this work we explore a novel solar cell architecture, a hybrid tandem photovoltaic (HTPV), and show that it is capable of meeting these targets. HTPV is composed of an inexpensive and low temperature processed solar cell, such as an organic or dye-sensitized solar cell, that can be printed on top of one of a variety of more traditional inorganic solar cells. Our modeling shows that an organic solar cell may be added on top of a commercial CIGS cell to improve its efficiency from 15.1% to 21.4%, thereby reducing the cost of the modules by ~15-20% and the cost of installation by up to 30%.
 CdO as a transparent conducting oxide for solar cell applications
Solar cell efficiency is hindered by the use of wire mesh or poor quality transparent conducting oxide (TCO) current collectors. Modern TCOs need to have a variety of properties, including conductivity, transparency, processability and cost efficiency. The best TCO on the market is ITO, indium tin oxide, which is incredibly expensive and in short supply. Cadmium oxide (CdO) is explored as a cheaper and higher performance alternative to ITO current collectors. Current research looks at different dopants, including Al, Zn, Cu, and Ag. Each dopant creates different affects electron concentration, and as a result, can cause large changes in absorbance and resistivity. Annealing and irradiation studies are also conducted to study changes in transparency and conduction. Different low temperature growth techniques, such as sputtering, are also explored.
 Materials considerations for the efficiency of photon-enhanced thermionic emission
Photon-Enhanced Thermionic Emission (PETE) is a promising method of solar energy conversion that is based on thermal emission of photoexcited electrons from a high-temperature semiconductor, making
it attractive for use in tandem with solar thermal systems. Theoretical efficiencies of PETE devices can exceed those of single junction photovoltaics, but experimental tests of the PETE process have displayed low efficiencies. Here we examine this disconnect between experimental results and theoretical promise. We analyze the effects of real semiconductor parameters on the PETE process and relate them to the ultimate performance of a PETE device, directly translating non-idealities of practical materials into constraints on conversion efficiency. We also review experimental that shows increased emission efficiency due to reduced surface recombination, one of the key challenges for realistic solar energy conversion based on PETE.
 Poly-InP photoelectrochemical cells for low-cost solar fuel production
The generation of storable hydrocarbon fuels from light in the manner of photosynthesis is a promising solution to the clean energy problem. To date, the highest efficiencies for hydrogen evolution from the photocathode of a photoelectrochemical (PEC) cell have been demonstrated with crystalline p-InP, a direct bandgap material that has demonstrated energy conversion efficiencies of over 14% with surface nanotexturing and an appropriate catalyst. Unfortunately, the high cost of epitaxial growth substrates and processes inhibits the application of the crystalline p-InP photocathode to a large-scale industrial deployment, requiring cost-oriented innovation despite its high performance. To circumvent these challenges, we utilize non-epitaxial growth methods along with an inspired nanotexturing and ALD protection process to create a viable thin-film, polycrystalline InP photocathode on cheaper substrates with better materials utilization. Long-term stability in acidic environments and reasonable solar-to-fuel efficiencies are demonstrated, with onset potentials and photocurrents comparable to some crystalline results.
 Laser zaps rocks on Mars and Earth: new technology for science and industry
Lawrence Berkeley National Laboratory and Applied Spectra Inc. have developed LAMIS (Laser Ablated Molecular Isotopic Spectroscopy), to analyze the amounts and types of isotopes in a solid, liquid, or gaseous sample under real-world conditions. The instrument operates by focusing a pulsed laser beam onto a sample in ambient air under ambient pressure. LIBS, Laser-Induced Breakdown Spectroscopy is a related technology that provides extremely fast measurements (a few seconds) of a material’s elemental composition without sample preparation.
In addition to being able to analyze any isotope quickly, LAMIS/LIBS is also the only available technology for remote analysis. It can be used in both the laboratory and the field for environmental analysis and monitoring. Applications include solar photovoltaics, energy storage systems, plants and soil, medical and climate change research.
 Transparent conductors for full spectrum photovoltaics
Douglas M. Detert
It is essential that the top electrode layer of a solar cell be both highly conducting and transparent to incident solar radiation. Existing thin film transparent conductive oxides (TCOs) such as heavily doped In2O3:Sn(ITO) and Al:ZnO(AZO) have poor optical transmittance to long wavelength visible and infrared light, owing to optical losses that arise from free carrier absorption (FCA) and plasma reflection. As such, these TCOs cannot be used with photovoltaic devices that rely on low gap absorbers such as crystalline Si and multijunction cells. In this work, we explore the interplay between the optical and electronic properties of doped and undoped CdO, a high electron mobility (µ ~ 100–300 cm2/Vs), highly transparent (band gap = 2.2 eV) oxde. The high mobility permits lower electron concentrations and in turn provides for good transmittance to visible and infrared light, making it an ideal TCO for the full spectrum of photovoltaic devices.
 Novel n-type C3-symmetric discotic materials: synthesis, self assembly and physical properties
David Hanifi, Dannis Cao, Yue Zhang, Evan O’Brien, Victoria Steffes, Yi Liu
In the world of electronic semiconductors, dynamic self-assembled discotics have attracted much attention for a wide range of electronics, such as organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), Dye Lasers and Photodetectors. P-type discotics have been reported with mobilities comparable to or surpassing that of amorphous silicon. In contrast, n-type discotic materials remain largely unexplored. Here we present the design, synthesis and characterization of a new class of n-type
molecules possessing novel planar C3 -symmetric cores, which consist of three fused rings, namely tris(aroyleneimidazole) (TAI). These compounds hold unique regenerative characteristics such as high thermal and oxygen stability. Overall, our approach, by virtue of simplicity in design and functionalization, demonstrates the proof-of-principle and moves one step closer towards creating the desirable nanophase segregated ideal heterojunctions for OPVs.
 Development of a solar-driven electrochemical water-splitting prototype
Karl Walczak, Sophia Haussner, Will West, Chris Karp, Su-Young Ryu, Sean Lin, Kenny Lee, John Stevens, Michael Hoffmann, David Dornfeld, Nathan Lewis
Solar irradiation is one of the most abundant energy sources available and yet humans have not harnessed the ability to use it as efficiently or effectively as Mother Nature. One potential route to improve the use of solar energy through the development of technologies for solar fuel generators, generally referred to as artificial photosynthesis. Unlike solar cells which convert sunlight into electrical energy, the solar fuel generators by photoelectrochemical electrolysis will generate a chemical fuel, for example methanol, which has a greater energy density then electricity. Economically competitive solar fuel generators needs to work multiple times more efficiently than nature, be scalable, and be made of earth-abundant and robust materials.
We use an engineering framework for building a potentially scalable solar fuel generating system. The approach uses a rapid feedback process between design, modeling, fabrication and testing. This allows implementing the newest results gained by fundamental research, continuously incorporating innovative ideas, and using the most efficient absorber and catalyst materials. Designs are conceptually analyzed by numerical models, which allow for feasibility studies, understanding design limitations and predicting performance. The modeling work is accompanied by physical device building via rapid prototyping. The designs are fabricated and tested, providing feedback to the modeling efforts for improved modeling predictions and fidelity. This ensures that the effort is put into useful and viable systems/devices. In this poster, we present small scale prototype designs. We show how the complementary use of modeling and device building helps to improve system performance. First device testing results are reported.
 Surface structural analysis of semiconductor nanocrystals using hetero-metallic ligands
Semiconductor nanocrystals offer a low cost alternative to bulk semiconductors for fabrication of photovoltaic, thermoelectric, and other energy related devices. However, the properties of semiconductor nanocrystals are strongly influenced by their surface‐bound ligands, and relatively little is known about the surface‐ligand interaction. Therefore, a framework to investigate semiconductor nanocrystal surfaces with unprecedented molecular level detail is undertaken here using lead selenide nanocrystals as a model system. To accomplish this goal, hetero‐metallic probe ligands were synthesized and placed at the nanocrystal surface with chemically directed ligand exchange. The spectroscopic and electrochemical signatures of these probe ligands will provide valuable surface structural information in future investigations.
 Solution phase, scalable, surfactant free synthesis of p-type Indium Phosphide nanowires and their application for photoelectrochemical water splitting
Indium Phosphide is an attractive material for use in photoelectrochemical (PEC) water splitting. The 1.35 eV direct band gap of Indium Phosphide allows it to efficiently utilize a large part of the solar spectrum while its conduction band edge position makes it suitable for use as a photocathode. However, the low earth abundance of Indium makes the use of single crystal InP wafers for PEC expensive and impractical. Nano-materials have a much higher surface to volume ratio than bulk materials and, as a result, large densities of reactive sites that allows for the use of much less material when constructing photoelectrodes. Zinc doped, p-type Indium Phosphide nanowires were synthesized via a novel solution phase self-seeded solution-liquid-solid (SLS) method. First, the wires were used for solar driven hydrogen production in an aqueous powder suspension. Next, p-InP nanowires were used to fabricate photocathodes for photoelectrochemical water splitting, using only ~1/3000 the amount of material of a bulk InP wafer. The surfactant free synthesis offers scalability not available with vapor phase growth methods such as vapor liquid solid (VLS) growth or metallo-organic chemical vapor deposition (MOCVD) and the nano-structured morphology of the p-InP photocathodes allows for the use of minimum quantities of photocatalyst material for PEC.
 Functionalized industrial pigments for solution processed organic solar cells
Organic solar cells have attracted much attention in recent years as an inexpensive pathway to fabricating thin and lightweight devices. Industrial pigments are of particular interest for use in organic solar cells due to their abundant nature, low cost, stability, and ease of synthesis and purification as compared to typical polymeric materials. However, due to their low solubility, these materials have traditionally been fabricated via high vacuum vapor deposition. In this work, we report our efforts in developing a series of solution-processable small molecules based on an industrial pigment, quinacridone (QA), for use in organic solar cells. The quinacridone derivatives were designed with consideration to the solubility, as well as the light absorption and charge transporting properties. Bulk heterojunction and multilayer p-i-n organic solar cells were fabricated and characterized.
 Performance of a rolling-cam energy extractor on the WindFloat platform and design of the rotary power take-off mechanism
The possibility of incorporating a wave-energy extractor into a current design of the WindFloat platform is examined. The WindFloat is a tri-legged offshore wind platform developed by Marine Innovation and Technology. To absorb wave energy, a rolling cam shape, with rotary power take-off, is attached to a tubular truss member of the WindFloat located above the waterline. The performance of the system in 3 DOF is obtained using a linearized integral-equation method. It is found that the solution depends on the three-parameter shape of the cam, and more importantly, the prescribed motion of the pivot point. The focus of the experimental work is on an efficient and versatile design of a bi-directional rotator, named the UC Berkeley Double-Ratchet Rotary System, which can produce a unidirectional rotational motiojohnn, thus facilitating the power take off by a generator. Plan for evaluation of the this PTO system is outlined.