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Precourt Institute for
Energy
Precourt Energy
Efficiency Center
TomKat Center for
Sustainable Energy
Seed Grant Portfolio
2010-2013
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Precourt Institute for Energy 2010
Better Models for Applying Hydraulic Fracturing to Geothermal Systems
Roland Horne, Energy Resources Engineering; David Pollard, Geological & Environmental Sciences
This award-winning research could lead to overturning 25 years of conventional thinking about the
basic mechanism of hydraulic fracturing, or stimulation, for enhanced geothermal systems, (EGS).
Instead of EGS stimulation inducing slip of preexisting fractures, this project and its follow-on work
suggests that in many cases extensive propagation of new fractures occurs. This has major
implications for site selection, design, economics and safety. The student this grant supported, now
in a tenure-track position at the University of Texas, developed a computational model for EGS. The
model fully describes the stresses induced by fracturing in complex networks with thousands of
fractures in a reasonable amount of time on a single computer. The model demonstrated how
different mechanisms can control stimulation, depending on geological setting. The researchers
also showed how field measurements can diagnose the best stimulation mechanisms. The research
should lead to greater safety of fracturing for both geothermal and natural gas. The model couples
fluid flow with highly realistic rate and state friction earthquake modeling, the first of its kind. The
model identified two strategies that could reduce the size of the induced events. Continued work at
Stanford and Texas includes development of 3D software and application to natural gas production,
which has drawn interest from four gas companies and Schlumberger.
Developing Surface-Modified Metal Electrodes for Turning CO2 Into Fuel
Matthew Kanan, Chemistry
This project developed surface-modified metal electrodes to improve the efficiency of electricity to
turn CO2 and water into a carbon-based fuel. Researchers then found that copper metal particles
derived from a copper oxide layer dramatically improved selectivity, stability and energetic
efficiency for CO2 reduction compared to all other copper materials that had been studied to date.
(Copper is the most intensively studied electrode for CO2 reduction, and no substantive
improvement to its catalytic properties had been made previously.) The project then experimented
with “oxide-derived” metal electrodes for three other metals: gold, silver and palladium. Each
greatly improved CO2 reduction properties relative to their standard metal electrode counterparts.
This work continues under a three-year grant by the Global Climate & Energy Project. Researchers
are analyzing the structural features of the new copper electrode, exploring its potential use in fuel
cells, and developing strategies for producing a liquid fuel from the CO2 reduction.
Solar Fuels: Using Composite Metal/Oxide/Semiconductor Anodes to Split Water
Paul McIntyre, Materials Science & Engineering; Christopher Chidsey, Chemistry
This work found a solution to a major technical problem for using solar power to produce hydrogen
fuel from water. The research resulted in publication in Nature Materials, a U.S. patent, a pending
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patent, and a three-year research project selected for funding by the Global Climate & Energy
Project a year ago. The project discovered that ultra-thin titanium oxide layers permit electronic
carrier movement while protecting high-quality semiconductors during water splitting.
Photovoltaic electrodes that use sunlight to help drive this reaction are usually made of silicon,
which corrodes and fails when exposed to the oxygen, as do other high-quality semiconductors.
This research used atomic layer deposition to coat silicon with ultrathin and pinhole-free layers of
titanium dioxide and iridium. The result was a corrosion-resistant and efficient solar cell for
splitting water far exceeding the performance of previously reported silicon photovoltaic anodes
for water splitting. The protected silicon anode may prove to have other possible applications, such
as producing other kinds of fuels by using other feed stocks, possibly even carbon dioxide.
Using Paper- and Cotton-Based Materials for Grid-Scale Energy Storage
Yi Cui, Materials Science & Engineering; Zhenan Bao, Chemical Engineering
The researchers made inexpensive, high-performance supercapacitors by coating renewable
resources—paper and cotton—with nanoscale conductive materials. Supercapacitors hold high
charges temporarily and can smooth
power flows on transmission
systems, considered a growing need
as wind and solar power become
greater portions of electricity supply.
In this project, graphene, which is a
one-atom-thick highly conductive
sheet of bonded carbon, was
combined with manganese dioxide and a conducting polymer. This was applied to a textile to
produce a high capacity, high power supercapacitor. Second, the investigators showed that
excellent supercapacitors can be fabricated with a graphite pencil in a precise pattern on paper. The
shear peeling of graphite produces multi-layer graphenes with a high proportion of conductive
edge structures. These supercapacitors show stable long-cycling performance and an area
capacitance much higher than previously reported. The paper supercapacitors demonstrated here
could lead to the development of all-paper electronics that are low cost and highly versatile. On the
side, the project also developed a novel hydrogel material for energy storage.
Development of a New High-Temperature Proton Exchange Membrane for Fuel Cells
Curtis Frank, Chemical Engineering; Michael Toney, SLAC
This project began the development of a low-cost, high-performance alkaline exchange membrane
to replace the conventional water-based membrane for use in fuel cells. Previous alkaline exchange
membrane technologies degraded and conducted hydroxide ions poorly. After initial study, this
project developed a new membrane material that does not rely on water for proton conduction. The
researchers used a copolymer structure composed of water-attracting and water-repulsing micro-
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sections. The hydrophobicity mismatch between the polysulfone and the polyethylene glycol was
expected to drive micro-phase separation of the membrane into water-rich, conductive domains.
The project demonstrated the concept, showing conductivity in the first phase of development in
line with expectations. Further refinement of the membrane material continues in a follow-on
project with Thomas Jaramillo, (Chemical Engineering). The follow-on project, funded by the
TomKat Center, is developing a fuel cell that can store electricity by producing hydrogen from
water and later produce power when the hydrogen is allowed to recombine to make water.
Potentially Low-Cost Crystalline III-V Thin Film High Efficiency Solar Cells
Jim Plummer, Electrical Engineering
Solar photovoltaic cells made from compound semiconductors known as “III-V,” like gallium
arsenide, are comparatively efficient but expensive. This project aimed to dramatically improve the
cost/performance tradeoff of III-V photovoltaics with rapid melt growth technology, which was
developed at Stanford for high performance computing. This project concluded that the rapid melt
growth approach is likely more difficult to use to implement full wafer III-V photovoltaic devices
than had been hoped. However, the results the project obtained are exciting in other applications.
The III-V materials the researchers were able to integrate successfully on silicon using rapid melt
growth have drawn great interest for integrated circuits. The work enabled by Precourt Institute
funding has led to follow-on funding from Intel Corp. to pursue these applications.
2011
Novel Hybrid Materials of Carbon for Lithium-Air Batteries
Hongjie Dai, Chemistry
This project has successfully developed several novel materials for metal-air batteries and other
types of electrocatalysts that could be useful in energy generally. First, researchers developed
multi-walled carbon nanotubes riddled with defects and impurities on the outside to replace
expensive platinum and palladium catalysts used in lithium-air batteries, and other types of
batteries not in the original proposal. Then the researchers invented single-use and rechargeable
zinc-air batteries using the carbon nanotube catalyst for oxygen reduction and a nickel-iron catalyst
for the cathode. These catalysts exhibited higher catalytic activity and durability in concentrated
alkaline electrolytes than precious metal catalysts. The single-use battery showed high discharge
peak power density, current density and energy density. The rechargeable battery in a tri-electrode
configuration exhibited an unprecedented small charge/discharge voltage polarization, high
reversibility and stability. This work may lead to zinc-air batteries for electrical vehicles. Second,
the investigators chemically synthesized a nickel−iron carbon nanotube complex as a catalyst for
the electrochemical oxidation of water. It demonstrated higher catalytic activity and stability than
the benchmark commercial iridium-based catalysts for this purpose. This was a breakthrough in
the search for a non-precious metal catalyst for the electrochemical oxidation of water. This project
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has resulted in additional funding from Amperex Technology Ltd., (a major battery company), and a
grant from GCEP to further develop the rechargeable zinc-air battery. The primary investigator is
discussing the potential licensing of resulting battery materials to a U.S. battery company.
Raising Efficiency in Dye-Sensitized Solar Cells at Electrode-Electrolyte Interface
Daniel Stack, Chemistry; Michael McGehee, Materials Science & Engineering
Dye-sensitized solar cells use a special dye sandwiched between two semiconductors to convert
sunlight into electricity. To make the process more efficient, the researchers have synthesized new
dyes to better keep the negative charge carriers in one semiconductor away from the positive
charge carriers in the other semiconductor. Since the last update, two different dye-sensitized solar
cells with the same absorbing dye, yet chemically assembled by a different sequence of steps,
provide a 30 percent enhanced efficiency. Extension of these principles to more efficient dyes is the
investigators current objective.
Designing Micro-Combined Cooling, Heating and Power
Lambertus Hesselink, Electrical Engineering
This project is developing a novel, highly efficient and economical energy system combining
heating, cooling and electricity in a small unit for residences or small businesses. The research team
has modeled a Stirling thermo acoustic heat engine and is evaluating fundamental system
performance issues through the use of three-dimensional simulations. Researchers have identified
a promising system architecture that may be mass manufactured at low cost. They have raised
significant funding for further research and commercial development.
2012
Polymer Gels for High-Performance Batteries
Zhenan Bao, Chemical Engineering; Yi Cui, Materials Science & Engineering/SLAC-Photon Science
This project is developing specially designed nanostructured polymers for a new generation of
battery materials. The project has three main tasks. First, the
researchers developed an electrode of silicon nanoparticles
suspended in a highly conducting polymer hydrogel. Silicon can
hold 10 times the charge of the common graphite electrode used
in lithium-ion batteries today, but silicon materials have not
been created to overcome the rapid expansion and contraction
silicon undergoes during charging and discharging. Second, the
research team is developing self-healing polymers, which will
address the capacity decline of new battery materials due to
volume change and fracture. Finally, they will develop all-
Silicon nanoparticles in a three-dimensional
conductive polymer gel network.
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polymer batteries: anodes, cathodes and electrolytes. Such batteries will be flexible and stretchable
for novel form factors, and could be manufactured at very low cost, making them potentially
feasible for grid storage requirements. Ultimately, researchers expect this project to evolve into a
new world-class energy storage research program at Stanford.
Hybrid Minerals for Reversible Capture of Atmospheric CO2
Hemamala Karunadasa, Chemistry
An unexplored and potentially inexpensive approach to capturing atmospheric CO2 may be to
develop organic-inorganic hybrid materials to exploit electric potential swing cycles. This study is
using metals to make synthetic materials with electronic properties that enable the controlled
capture and release of CO2. The material needs to be both porous and conductive, two properties
that typically arise from diametrically opposite structures. A hybrid material could meet both
requirements. The project has started with hybrid perovskites, which have been successfully used
in electronics with demonstrated ability to tune their transport properties. The successful
modification of hybrid perovskites for conductivity, porosity and inclusion of substrate binding
sites could open this class of materials to a wide range of applications in the fields of sustainable
energy and pollution management.
Water Splitting Using an Inorganic Proton-Conducting Membrane
William Chueh, Materials Science & Engineering/Precourt Institute; Nick Melosh, Materials Science &
Engineering
Most solar-driven water-splitting experiments are conducted in photo-electrochemical cells at
room temperature using either a liquid or a polymer solid electrolyte. This project is developing a
water-splitting device that operates at high temperatures (up to 400° C) by replacing these
conventional electrolytes with a
hydrogen-conducting ceramic
membrane. The higher temperature
can lower the energy required to
split water, and it provides better
mechanical and chemical stability.
The researchers are building a
proof-of-concept photo-
electrochemical cell using a
perovskite-oxide-based proton
conductor, operating at about 300° C. The solid-state approach ensures the rapid removal of
hydrogen gas molecules from the photo-electrode surface, suppressing unwanted recombination of
the water molecules. Researchers are examining and engineering the interface between various
earth-abundant light absorbers and proton-conducting membranes.
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Ultrathin Light Absorbers for Solar Cells
Stacey Bent, Chemical Engineering; Mark Brongersma, Materials Science & Engineering
One way to lower the cost of solar power is to dramatically reduce the thickness of light-absorbing
layers in solar cells. This project is addressing the fundamental question of what minimum amount
of material is required to absorb most of the light incident in the useful part of the solar spectrum.
Atomic layer deposition is being used to create nanocomposites combining plasmonic nanoparticles
with ultrathin semiconductor layers and light trapping structures to generate the right conditions
for maximum light absorption. This proof of concept demonstration could potentially reduce the
absorber layer thickness 100-fold compared to conventional thin-film solar cells. The results could
lead to production of low cost, efficient solar cells using minimal materials.
2013
Functionalized Graphene-Platinum Composites for Fuel Cells
David Goldhaber-Gordon, Physics; Fritz Prinz, Mechanical Engineering and Materials Science
The investigators plan to use a new material system they have recently developed to reduce
dramatically the amount of expensive platinum needed in fuel cells. They can grow dispersed
platinum nanoparticles on graphene, (one-atom thick sheets of carbon), without damaging the
electrical or structural properties of the graphene. This may enable catalysis of key energy
conversion reactions for fuel cells with high efficiency, in addition to reducing platinum use.
Self-Regenerating Fuel Cells Running on Natural Gas
Robert Sinclair and William C. Chueh, Materials Science & Engineering
Certain types of fuel cells can convert natural gas into electricity and back again with very high
efficiency, eliminating the traditional fuel cell’s production of hydrogen from natural gas as the
energy source. However, the catalysts used by such fuel cells degrade quickly, so the cells stop
working after a few years. Attempts to develop self-regenerating catalysts for these devices have
fallen short. Using Stanford’s Titan environmental transmission electron microscope—the only one
in the United States—this project seeks to illuminate the fundamental chemical and structural
transformations needed for developing self-regenerating catalysts for elevated-temperature
ceramic fuel cells and electrolysis cells.
An Electricity/Carbon Market Simulation Incorporating Renewables:
Mark C. Thurber, Program on Energy & Sustainable Development; Frank A. Wolak, Economics.
Research using games often reveals effects of human actors in economic outcomes that standard
economic models do not foresee. In a Graduate School of Business class last year, this project’s
investigators created a simulation in which teams of students tried to maximize profits from
portfolios of power plants operating in California’s markets for electricity and CO2 emission
permits. Among other surprises, they found that in some situations power producers benefited by
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boosting emission permit prices, which raised electricity costs dramatically. This new project will
further develop the game by adding non-hydroelectric renewable power plants into the market,
reflecting the state requirement that utilities obtain a certain amount of their electricity from
renewable sources. The refined version of the game will also let consumers respond to higher
prices more quickly. The researchers will then run multiple, controlled experiments involving a
broader swath of the Stanford students playing the game. The project could produce valuable
insights for policymakers, while providing a unique educational experience for students.
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Precourt Energy Efficiency Center 2010
Paying for Good Deeds: Using Financial Incentives to Achieve Energy Efficiency
Matthew Harding, Economics
This project helped establish several fundamental findings in the developing research area of
energy and behavior. The researchers conducted experiments with utility customers in Chicago and
Massachusetts to determine the extent to which financial incentives, and reward schemes in
particular, can achieve energy efficiency. Partnering with a leading energy efficiency company,
Efficiency 2.0, the researchers found that some behavioral nudges, when well designed, can cut
energy consumption significantly. Goal setting was particularly potent. In Chicago, households
saved on average about 8 percent immediately after adoption, but savings over a 12 months period
slipped to just 2-3 percent. Households that chose realistic goals of 1-15 percent reduction, saved
almost 10 percent, and the effect persisted. Households that chose unrealistic goals saved for a few
months, then gave up. Families that
joined the program for the financial
incentives saved only for a limited
period of time, though this may
have been due to poor construction
of the rewards. The experiment in
Massachusetts showed that giving
families information about how
they can save energy is not
sufficient for significant savings.
Also, combining goal setting and
neighbor comparisons worked very well. Rank comparisons did not work. With support from
NRDC, this work has continued in a large program implemented by OPower and Facebook.
Reducing Barriers to Diffusion of Energy-Saving Technologies in the Building Industry
Raymond Levitt, Civil & Environmental Engineering; Erica Plambeck, Business
Up to 34 percent of energy used in buildings is wasted, despite available technologies. This project
identified the key organizational, inter-organizational and industry barriers to widespread
adoption of energy-saving technologies in the building industry. The project’s case study of the
company ZETA Communities documented examples of government regulations and incentives, as
well as corporate strategies, that have successfully overcome these barriers. ZETA Communities
integrates architecture, engineering, functional construction to produce zero-net energy homes for
15–20 percent less cost than conventional homes. The project also developed preliminary
hypotheses about strategic and policy interventions that can overcome these barriers. The project’s
results showed that integration of supply chains from manufacture through maintenance can help
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overcome the barriers of the decentralized U.S. building industry. This represents a business
opportunity for penetrating mature markets with integral innovations. The work also found that
modular innovations are implemented almost three times as often as integral innovations. In
follow-on work, researchers are investigating strategies to increase implementation of integral
innovations. They are also working with Johnson Controls’ booming energy efficiency division.
Improving Airflow Parameterizations in Energy Simulation Tools
Gianluca Iaccarino, Mechanical Engineering; Martin Fischer, Civil & Environmental Engineering
This project developed a building energy model using the current best practices in computational
fluid dynamics, coupled with heat transfer information from an existing energy simulation tool. The
project also applied the tool to Stanford’s Y2E2 building’s nighttime air purge, which was
underperforming expectations. Initially,
researchers found that cost savings for
cooling Y2E2 could be increased from
15 percent to 20 percent savings by
modifying the night purge algorithm.
Ultimately the study found that detailed
computational fluid dynamics
simulations can provide a flexible tool to
parameterize geometry and flow-
specific coefficients, specifically those for discharge though openings. This study found that the
popular EnergyPlus software used a formula to calculate the effective area of pivoted windows that
tended to underestimate the flow rate through such openings by up to 50 percent. A modification to
this expression was proposed that takes into account the airflow through the sides as well as the
bottom of an open, horizontally-pivoted window. Both computational fluid dynamics results and
data from window manufacturers agree well with the modified formula.
Santa Clara County Jail—Energy Efficiency Retrofit, Monitoring, and Modeling
Martin Fischer, Civil & Environmental Engineering
Santa Clara County Jail is one of four buildings studied by PEEC to compare simulation models of
energy use with actual outcomes in order to improve the models. This project dealt with the more
complicated and less well understood modeling of retrofits. The researchers collaborated with the
jail on energy retrofits—within a modest budget—to reduce the operating costs of the jail and its
greenhouse gas emissions. The team recommended a set of cost-effective efficiency improvements
after extensively monitoring the building’s energy consumption, analyzing historical data and
simulating 30 possible retrofits. In a smaller, follow-on project funded by PEEC, investigators are
analyzing outcomes of the retrofits made and comparing them with earlier simulations.
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2012
Experiments with Appliance Choice
Brian Knutson, Psychology
This study is examining whether some groups of consumers alter their decision-making process
when buying major household appliances due to behavioral nudges, such as eco-labeling. The study
is characterizing consumer classes and monitoring neural activity in each group via brain imaging
with functional magnetic resonance imaging. Observations of shifts in the manner of decision
processing would imply a need to reassess policies for behavioral nudges. Current approaches
assume that nudges do not alter the decision-making process a consumer employs, for example,
switching attention from financial to environmental concerns. If the work finds that some
consumers do alter their decision-making process in response to nudges, behavioral economic
policy design and analysis will need to consider the impact of policy on the distribution of decision-
making processes and the normative implications of subsequent choices. Moreover, if differences
are found between the neural structures recruited for financial decision-making and those for
appliance decision-making, this work would provide insight into the unique cognitive or affective
processes engaged when consumers are making appliance purchase decisions.
A Mechanism for Electric Vehicles to Support the Power Grid of the Future
Yinyu Ye, Management Science & Engineering
Plug-in electric vehicles likely will be integral to the reliability of the future power grid for two main
reasons. Charging stations at home and work will create the ability to shift significant power
demand in time when needed. Also, in the future these vehicles likely will be able to transmit
electricity back to the grid, creating a network of
millions of distributed batteries for supply when
needed. However, realizing this vision requires
overcoming several barriers. Various technologies
still need development, as does the optimal market
mechanism to organize this distributed trading.
New business and service industries may be
needed. This project aims to address these
challenges. In particular, the researchers are
building an automated demand response
mechanism for a fleet of electric vehicles. A demand-response aggregator, a new kind of energy
service company, will communicate energy needs between the fleet and the utility, and it will
regulate electricity use. The aggregator being developed uses a simple price equilibrium to instantly
and automatically determine feasible energy exchange schedules for tens of thousands of vehicles
as they plug-in to the grid, based only on a relatively small amount of aggregated historical data.
Such a system would not only benefit grid stability, but reduce charging costs for consumers.
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The Dynamic Effects of the Light Bulb Ban
Mar Reguant and Lanier Benkard, Business
Economists have long pondered “the light bulb puzzle,” which asks why consumers appear to make
poor financial decisions when continuing to use inefficient light bulbs. However, new regulations
effectively ban incandescent light bulbs in much of the world, and lighting alternatives—compact
fluorescent, LED, halogen incandescent—have flourished. The researchers are exploring whether
the new choices cause consumers to consider not only immediate prices but long-term costs. Or will
the light bulb puzzle persist? On the producer side, this project is examining whether the
incandescent bans were essential to the spurt in lighting innovation and whether previous
manufacturer inertia was due to consumer inattention. The project’s findings may illuminate the
role of government policy in spurring innovation. The researchers are developing an econometric
dynamic industry model that takes into account the interaction of consumers and firms to quantify
the effects of various policies in a comprehensive fashion.
2013
Trip Estimation Techniques to Better Manage Hybrid Vehicle Batteries:
John D. Fox, SLAC; William Dally, Computer Science; Jonathan Levav, Business.
The environmental and economic value of hybrid vehicles is maximized by using the least amount
of fossil fuel and exhausting battery power before recharging. Most hybrid cars use simple
protocols for managing the battery. This project will develop techniques to predict the most
probable trip a car is taking while the vehicle is in motion based on the driver, time of day, starting
point, and other parameters. Such predictive ability combined with mapping of charging stations
and real-time traffic data could direct the hybrid motor to use its electric charge optimally.
Improving Predictions of the Efficiency of Natural Ventilation in Buildings
Gianluca Iaccarino, Mechanical Engineering; Martin Fisher, Civil & Environmental Engineering
Designing buildings that rely on natural ventilation for temperature control is a relatively new
science. Due to limited analytical tools, such buildings to date have too often resulted in
uncomfortable occupants. This work seeks to improve the design and operation of such buildings to
yield increased overall building efficiency (in mixed-mode ventilation) without sacrificing comfort.
The researchers will use high-fidelity simulations and rigorous sensitivity analysis based on
available weather and building data to inform designers on the amount of time in a year the
building is not operating in the mode expected. The tools developed will also evaluate and
incorporate mitigation strategies, and identify what to monitor in order to assure building
performance.
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Better Decision Making for Policies and Programs to Reduce Electricity Use
Roy Pea, Education; Michael Bernstein, Computer Science; Martha Russell, H-STAR
This project seeks to aid decision making in energy-efficiency initiatives from government policies
to business campaigns. Researchers will first create a crowd-sourced process for feedback on
critical assumptions in residential energy conservation. Then they will develop analytics and
metrics to identify critical changes in factors influencing public opinion regarding efficiency
technologies and their adoption. The end product will also include visualizations of the data for
easy access by targeted decision makers and group processes for augmented decision systems.
Visualization of smart meter data for critical peak pricing for commercial energy consumers
Ram Rajagopal, Civil & Environmental Engineering; June A. Flora, H-STAR
Most electric utilities have multiple programs offering customers
financial incentives for using electricity efficiently and reducing use
when power demand is very high. But utilities often do not know what
programs are effective, or how to market the specific incentives to the
customers most likely to respond. Working with PG&E, the
investigators have developed a system using data from 200,000 smart
meters to identify residential customers who are good targets for such
incentives. This new project will extend their system to 2,000 small and medium business
customers of PG&E and, to a lesser extent, the Los Angeles Department of Water & Power. In
addition to its data analysis component, the system includes a visualization and interaction front
end for engaging selected users via email, the Internet and print.
Efficiency and Group Behavior in Power Distribution Networks
Ramesh Johari, Management Science & Engineering; Ram Rajagopal, Civil & Environmental
Engineering
The electricity system of the future is expected to include many local energy devices that can either
generate electricity, like rooftop solar panels, or store energy, like electric cars. Such distributed
energy resources could reduce power losses in the traditional central power plant paradigm and
reduce purchases of backup power supplies. A potential complication to the hoped-for gains in
efficiency, however, is that the owners of these resources—homeowners and small businesses—
likely will form groups in order to have more leverage in negotiating deals with their local utilities.
Researchers in this project will investigate the nature of such “micro grids” likely form, in terms of
size and geographical proximity of the members, as well as whether such groups will improve the
overall efficiency of the power system. The researchers will also study whether the efficient
operation of a network with many distributed energy resources requires a communication system
much more robust than what the researchers see emerging currently.
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TomKat Center for Sustainable Energy
2010 - Smart Grid
GridSpice: A Virtual Platform for Modeling, Analysis, and Optimization of the Smart Grid
Abbas El Gamal, Stephen Boyd, Benjamin Van Roy, Amit Narayan and Dan O'Neill, Electrical
Engineering
The electrical network of the future will have many devices, such as generators, fixed demand,
flexible demand and storage devices, and each device will have its own objective and dynamic
limitations. This project supported the development of GridSpice, an open-source, cloud-based
platform for modeling and simulation of the smart grid. GridSpice was developed in collaboration
with industry mentors at Cisco Systems. This research project also developed a messaging system
for quickly optimizing a dynamic system based on a
great deal of data. Maximizing the efficiency of the
total network over an instantaneous time horizon,
subject to device and line constraints, is a large
optimization problem. Stephen Boyd’s research group
developed a decentralized method for solving this
problem. At each step, each device exchanges simple
messages with its neighbors in the network and then
solves its own optimization problem, minimizing its
own objective function, augmented by a term
determined by the messages it has received. The
method is completely decentralized, and needs no
global coordination other than synchronizing
iteration. The method can solve a problem with over
10 million variables in 17 minutes for a serial implementation; with decentralized computing, the
solve time would be less than one second. More than 20 groups from industry and other academic
institutions have submitted project proposals to the researchers to be considered for use in the
next version of GridSpice. The research team is adding several applications to the platform, such as
energy storage and electric vehicles, and they are standardizing the software to the electric power
industry’s Common Information Model.
Improving Wind Power Operations with Sensing, Statistics and Control
Ram Rajagopal, Civil & Environmental Engineering
This project developed three approaches to enable high penetration of wind energy by reducing the
planning, safety and operating costs due to wind’s uncertainty. The three approaches developed:
novel control for power dispatch by the system operator, improved forecast algorithms for wind
power generation and improved sensing for wind energy generators. The dispatch algorithm
researchers developed reduces the costs of integrating wind power up to 60 percent by using
forecast information appropriately. The algorithm addresses the full market model and includes the
possibility of network congestion. It can be directly implemented in existing system operator
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software. The forecasting method developed is able to predict wind generation with reasonable
accuracy for the next day without complex computing tools. The researchers have also developed
the first wind ramp detection and characterization methodology to improve dispatch against large
swings in wind production. Finally, the researchers began development of an airborne wind sensor
that is less expensive than those currently used because it does not require a tower. The concept is
that these sensors can be deployed in greater quantity and at greater distances from the wind
power farms to more accurately forecast production. The researchers have worked with the
California Independent System Operator and other grid operators to implement their research.
Facilitating Renewable Energy in a Wholesale Market by Expanding Transmission
Frank Wolak, Economics; Stephen Boyd, Electrical Engineering; Mark Thurber, Program on Energy &
Sustainable Development
This work quantified the economic benefits and costs of expanding a transmission system operating
in a wholesale power market environment. The work found that transmission expansions increase
competition among power suppliers, who offer electricity to the wholesale market at prices closer
to their variable costs of production. The researchers also performed a cost/benefit analysis for
Alberta’s wholesale power market. The analysis found positive net benefits for transmission
upgrades that would not be built without accounting for these financial benefits. Also, the
researchers found that the intermittent nature of renewable resources such as wind and solar
energy increases the expected magnitude of the competitiveness benefits. However, as the share of
renewable resources on a given system increases economically, beneficial expansions may not be
undertaken if this source of economic benefits is not accounted for. The researchers also examined
a zonal-pricing market where transmission congestion is explicitly priced. Using data from
Australia’s national power market, they implemented an enhanced version of the methodology to
quantify the competitiveness benefits of several proposed transmission expansions in Australia.
Analysis and Control of Smart Electrical Distribution Systems
Sanjay Lall, Aeronautics & Astronautics and Electrical Engineering; Dimitry Gorinevsky, Electrical
Engineering
This project questioned whether a high penetration of distributed generation, like rooftop solar
installations, would make the electrical distribution system unreliable or unstable. The answer,
thankfully, is “no.” The researchers’ model found that for tie-in inverter connection of distributed
generation, the transient oscillations can remain stable and grid frequency disturbances will not be
amplified, so long as the inverter controller is well-tuned. This conclusion holds for a broad range of
parameter values explored in this work, including the percentage of the distributed generation and
transmission line impedance. The team also studied statistical monitoring in power-generating gas
turbines. They developed scalable algorithms that can process the large amount of data generated
by such equipment and flag the anomalous units. Applying statistical process control methodology
to the anomalies could improve reliability and energy efficiency, as well as reduce maintenance
costs. The initial results were very promising. Both efforts stirred interest at GE Energy, and follow-
on research discussions are underway.
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2011 - Large-Scale Solar Power
Storing Electricity: An Alkaline Exchange Membrane Unitized Regenerative Fuel Cell
Thomas Jaramillo and Curtis Frank, Chemical Engineering
The device the researchers are developing is an alkaline anion exchange membrane unitized
regenerative fuel cell (AEM-URFC). Such a device has never been demonstrated previously. The
AEM-URFC uses renewable energy to split water into H2 and O2 when renewable electricity is
available. Later, the H2 and O2 are recombined to provide electricity to the grid. The alkaline
environment of the new AEM-URFCs can avoid the conventional need for precious metals. The team
is researching non-precious metal catalysts and functional alkaline membranes that can work
together in this device. The researchers have developed the first working prototype of a precious-
metal free, low temperature AEM-URFC. They cycled it eight times between electrolyzer mode and
fuel cell mode demonstrating reasonable durability with round-trip efficiencies of 34-40 percent
throughout cycling. The team is now working to improve the key components of the device in order
to boost performance for both round-trip efficiency and durability.
Consuming Renewable Power: Information and Reliability as a Resource
Ram Rajagopal, Civil & Environmental Engineering
In this project the researchers address more efficient ways of offering and consuming renewable
power generation. Current approaches backup the renewable energy generation so it is as reliable
as traditional generators. This approach can significantly increase emissions and cost. Instead, this
research group is developing mechanisms that can benefit from existent flexibility in demand. For
example, demand can be scheduled to follow renewable power profiles in real-time, eliminating the
necessity for reserves. The researchers have designed several smart and simple scheduling
algorithms capable of following random power profiles. The researchers are also in the process of
designing a slotted mechanism that accepts user bids for different time slots offering available
power. Appliances could be programmed with a budget and simple rules to obtain slots for each
day. Finally, the researchers are starting to investigate models that estimate available flexibility in
existing demand from sensor data collected from 1,000 homes when utilizing these mechanisms.
The methodologies reveal that the reductions in emissions required can be drastic, if sufficiently
large populations of schedulable loads are available. As part of the project the researchers have
been building Snowflake, a wireless system capable of implementing the load scheduling algorithms
and interfacing with Zigbee radios present in most appliances and other devices.
Upconverter-Enhanced Molecular Photovoltaics: Cost-Effective, Broadband Solar Energy
Jennifer Dionne and Michael McGehee, Materials Science & Engineering
The conversion efficiency of thin-film solar cells may be enhanced by adding upconverters, which
allow more light from the sun to be absorbed by the solar cell. The researchers have modeled how
up conversion dyes could be used to improve the performance of the most common kinds of solar
cells. These dyes convert low energy photons to higher energy photons that can be utilized by the
cell. The researchers find that coupling up conversion dyes with dye-sensitized solar cells to be
most attractive, because dye-sensitized cells have a larger band gap than the other kinds of cells
16
and can easily be made with two transparent electrodes. Their calculations indicate that
upconverting materials could improve these cell efficiencies significantly. The researchers have also
developed a new process for depositing transparent electrodes on solid-state dye-sensitized solar
cells that involves spraying silver nanowires. The researchers are using these silver nanowires and
related metallic nanostructures to enhance the absorption and emission of upconverting materials,
improving their efficiency.
Market-Based Valuation of Ecosystem Services for Competitive Large-Scale Solar†
Michael Lepech and David Freyberg, Civil & Environment Engineering; John Weyant, Management
Science & Engineering; Stefan Reichelstein, Business
This project captures the benefits of natural ecosystem preservation from large-scale solar power
production by quantifying valuable biological functions such as phosphorus removal. These
functions are valued using option pricing theory to result in a new class of biological assets, which
can be recognized on a generating company’s balance sheet. In cooperation with Combined Power
Cooperative, the research team has quantified the value of nitrogen cycling within the preserved
ecosystem on a concentrated solar power site in southern California. They are adapting financial
accounting tools to recognize this asset class on the cooperative’s balance sheet. The researchers
completed a life cycle analysis of the impacts associated with the materials and equipment
necessary for construction of the site. This was done to determine the effluents, wastes, pollutants
and resources that may alter the ecosystem. Also, by adopting a multi‐nutrient modeling tool, the
effect of multiple ecosystem services when evaluating a single natural environment can be
evaluated. The team has developed a case study on the levelized cost of energy from solar
production. Within this new model, the value of ecosystem services on the solar power generation
facility’s land is now being considered.
Effects of Large-Scale Solar Energy on Land and Water Resources in the U.S. Southwest†
Chris Field, Noah Diffenbaugh and David Lobell, Environmental Earth System Science
Researchers are developing a framework that establishes “big-picture” impacts of utility-scale solar
power plants in the dessert, a popular location. This study is investigating such installations in
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three ways: climate consequences of allocating land to large PV versus irrigated agriculture, which
could be used for bioenergy crops; possible synergies of integrating PV plants with bioenergy
agriculture; and whether some sites may simply be too dusty for large-scale solar, especially given
the expected effects of climate change and the projects’ disruption of local soil. One initial finding is
that, relative to irrigated agriculture, utility-scale PV tends to produce local cooling but warming
farther away. Also, researchers have found that the benefit of using PV-cleaning water to agave
plants would be quite small, approximately one-tenth the direct energy benefit of the cleaner PVs.
† Administered by the TomKat Center; funded by the TomKat Center and the Precourt Institute
2012 Wireless Power Transfer to a Moving Vehicle
Shanhui Fan, Electrical Engineering
In a follow-up to an earlier study, the research team is testing the feasibility of using magnetic
resonance technology to transmit electricity from roads to moving vehicles. In the earlier study, the
researchers showed that efficient wireless power transfer can be achieved in the presence of
metallic plates. In this study,
they have confirmed this earlier
finding experimentally by
demonstrating an efficient
wireless power transfer system.
In two different configurations,
they demonstrated maximum
efficiency exceeding 94 percent
over a distance of 23.6 inches
between the transmitting and
receiving coils. The long-term
goal is to develop roadways that wirelessly charge electric cars and trucks cruising at highway
speeds. The proposed technology could dramatically increase the driving range of electric vehicles
and transform highway travel.
Reliability vs. Cost Tradeoffs in California Renewable Energy Investments
Frank Wolak, Economics; Burton Richter, SLAC and Physics
This project is quantifying the added costs of serving California's electricity demand with an
increasing share of intermittent renewable generation, such as wind and solar energy. The analysis
is accounting for the major drivers of these costs, such as backup generation resources, large
energy storage systems, active demand-side participation and alternatives, such as transmission
upgrades and changes in how the system is operated. The research also is assessing the
management of intermittency under different wholesale power market rules and different
mechanisms for financial support of renewables.
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2013 Electrochemical Splitting of Supercritical CO2
Mark A. Cappelli and Reginald Mitchell, Mechanical Engineering; Tsuyohito Ito, Graduate School of
Engineering, Osaka University
In theory, excess power created by intermittent renewable power can be used to remove CO2 from
the environment and extract carbon monoxide, which can later generate electricity when the wind
is not blowing and the sun is not shining. Previous attempts at breaking the carbon-oxygen bond,
however, have consumed too much energy for an efficient storage system. This project will examine
the fundamentals of splitting CO2 under supercritical temperature and pressure to form CO, which
can be used as a fuel to produce electricity as needed. The researchers hope to establish that the
process can recover much of the energy used in breaking down the CO2 and form the basis for a
carbon-neutral way to store renewable power.
Junctionless solar cell for enabling third generation photovoltaics
Krishna Saraswat, Electrical Engineering
This project will seek to increase efficiency and decrease manufacturing costs of solar photovoltaic
panels by developing junctionless solar cells with transparent electrodes on commonly available
semiconductor materials, such as silicon or germanium. The researchers will eliminate the need for
doped positive/negative junctions by using conducting oxides which form a selective contact for
either electrons or electron holes. Such cells could also be stacked on top of each other to enable
greater than 50 percent efficiencies. The metal-insulator-semiconductor approach has already been
demonstrated to obtain low resistance contacts for nanoscale transistors and photonic devices.
Making Large Wind Farms More Productive, Less Expensive†
Sanjiva K. Lele, Aeronautics & Astronautics, and Mechanical Engineering; John Weyant, Management
Science & Engineering
Power output by large wind farms is typically 25 percent less than what it should be due to rear
windmills operating in the turbulent wakes of those up front. These wakes also increase strain on
the downwind blades and, thus, raise operating costs. This project, funded jointly by the TomKat
Center and Stanford’s Precourt Institute for Energy, will test whether positioning smaller, mixing
turbines among the primary turbines in conjunction with other new management approaches, will
significantly increase output and cut costs. The researchers will also develop an optimization model
for designing new wind farms and operational algorithms based on a given farm’s terrain and
environment.
† Administered by the TomKat Center; funded by the TomKat Center and the Precourt Institute
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