On April 14, Adam Weber, a staff scientist in Lawrence Berkeley National Laboratory’s Environmental Energy Technologies Division (Berkeley Lab), stepped up in the East Room of the White House to shake hands with President Obama. Weber was one of 102 young scientists this year receiving the Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed by the United States Government on science and engineering professionals in the early stages of their independent research careers. Weber was honored for his work on fuel-cell diagnostics and modeling activities as well as his leadership in coordinating scientific collaborations in these areas.
A graduate of Tufts University and the University of California, Berkeley, Weber is familiar with prestigious awards—he has also been the recipient of a Fulbright scholarship to Australia, the 2008 Oronzio and Niccolò De Nora Foundation Prize on Applied Electrochemistry of the International Society of Electrochemistry, and the 2012 Supramaniam Srinivasan Young Investigator Award of the Energy Technology Division of the Electrochemical Society.
Though Weber is honored by the recognition, and he enjoyed meeting the other recipients and taking his family to Washington, DC, for the awards ceremony, he maintains a steady focus on his day-to-day work in the laboratory. His current research revolves around three main topics: understanding and optimizing fuel-cell performance and lifetime; examining redox-flow batteries for grid-scale energy storage; and analysis of solar-fuel generators at the Joint Center for Artificial Photosynthesis.
Scientists like Weber believe that the proton-exchange-membrane fuel cells being studied at Berkeley Lab and improved by Berkeley Lab industry partners are becoming an important part of our energy future—fueling cars and fleets, industry, appliances, and buildings.
Unlike batteries, fuel cells do not store electricity, they convert it from primary fuels like hydrogen—a plentiful and renewable resource. The main byproduct of the chemical conversion is water.
Working to make these fuel cells more durable, efficient, and effective, Weber uses mathematical computer models to provide an approximate idea of the distribution of heat, fuel, and water within different parts of the cell and to understand how these distributions affect the cell’s power output. Through these simulations, Weber can identify exactly what goes on inside the fuel cell with the aim of optimizing its performance.
“A lot of our core competence is on the physics-based mathematical modeling of the complex phenomena,” Weber said. “On the computer we can look at each of the components in the process and understand exactly how it works—where the water goes, where the hydrogen and oxygen go—and we can ask how we can make it better,” he said.
Right now he’s working on next-generation fuel-cell designs and materials, finding less expensive options to improve the technology and overcome stumbling blocks, such as improving the ability of fuel cells to operate at below-zero temperatures, making fuel cells more durable, and examining how to reduce cost without decreasing performance.
“Advancing fuel cells is important and it’s happening right now,” Weber said. “Hyundai is releasing a fuel-cell car this year, and Toyota will next year. But on the engineering and material side, there is still work need to be done for the Generation 2 designs,” he said.
Improving the Ion-Conducting Membranes in Fuel Cells
Fuel cells work by generating protons and electrons from a fuel (such as hydrogen) and moving the protons through an ion-conducting, polymer membrane while the electrons flow through an external circuit as electricity. The understanding and improvement of fuel-cell membranes is a major focus of what Weber and his colleagues are doing.
“We want to understand the processes, find the bottlenecks and ways to overcome them,” Weber said. “We’re looking for a viable way to have a carbon-neutral power source,” he said.
One of his projects is to understand how cell membranes function when used in the electrodes as a binder. The small thicknesses—as thin as 10s of nanometers of polymer—demonstrate different performance that may be key to allowing fuel cells to reduce their precious metal catalyst amount. Such study requires new analysis techniques.
Then they make recommendations to industry and laboratory partners for improving the membranes.
“We can tell them, ‘if you double the amount of the flow of this gas, or change the size of the device, or use have a material with these properties, these are the results you could obtain,’” he said. “Our results allow them to prioritize the research they are doing,” he said.
His team has also been working with Los Alamos National Laboratory on durability issues in fuel cells and with the National Renewable Energy Laboratory on detecting and understanding manufacturing defects of membranes and electrodes. In this latter work, Weber said, the joint team has developed new infra-red-based techniques to determine thickness variations and have begun to model how such defects impact performance.
Improving Fuel-Cell Operation at Low Temperatures
Weber’s work to improve the ability of fuel cells to work effectively at low temperatures—something critical to starting a fuel-cell-powered car in wintertime in a cold climate—was one of the specific reasons he was granted the Presidential Early Career Award. And this research is the subject of a journal article Weber recently co-authored in the Journal of the Electrochemical Society.
In the paper, Weber and his co-authors report findings about research studying the nucleation and growth of ice crystals forming in the catalyst layer of the fuel cells.
It’s all about removing the water produced in the conversion process fast enough, Weber said, which freezes at low temperatures and stops the fuel cell from producing electricity.
“Right now manufacturers have a lot of engineering solutions for this—they dry out the systems to keep the water from flooding the system,” Weber said. “If we understand what’s happening, we can find a passive solution rather than an active solution, like a blower, that is inefficient,” he said.
Weber said that they started with experimental lab work, and then used the results in their computer simulation.
“For example, we filled the backing layer of the cell up with water and put it in a machine to measure the heat flow in the layer,” he said. “When things freeze, they give off a lot of heat. We set the temperature down to -10 degrees Celsius, and then we waited for the heat release when the water changes from liquid to solid. We did this a lot of times,” he said.
Weber and his team have taken the results of these experiments, and put them into models. Results have shown that, depending on how much below zero the temperature goes, it takes a long time for the water to freeze—longer than other models (which rely on a thermodynamic-based approach) have used. Put another way, cell-failure time increases with increasing temperature due to a longer required time for ice nucleation.
“We can put the numbers into models, and then we’re able to tell manufacturers, with more accuracy than before, “if you’re at -10 degrees, you have this much time to raise the temperature until the cell shuts down and won’t work,’” he said.
Then, they take the diagnostics and results from the modeling to their industry partners. Weber said he’s been working with industry giant 3M for the last few years to see how their fuel cell operates in low temperatures.
“Working with a diverse team of industry, academia, and national laboratories, we’ve shown how we can increase performance of a 3M cell by removing the liquid water from one side of the cell, showing how it operates and how it works better,” Weber said.
Artificial Photosynthesis: Creating Fuels from Sunlight
Another project attracting attention for Weber is his work with artificial photosynthesis—producing fuels, like hydrogen, from sunlight. Weber is the team leader for the modeling and simulation team at the Joint Center for Artificial Photosynthesis—a U.S. Department of Energy-funded innovation hub combining team members primarily from California Institute of Technology and Berkeley Lab.
Weber and his team are working to model and understand the various physics to design integrated photoelectrochemical cells that can efficiently produce hydrogen gas or maybe even liquid fuels from the atmosphere and water. He thinks this technology might have the efficiency needed to “close the fuel-cell loop,” producing the hydrogen that is then used in other fuel cells to produce electricity.
Looking Into the Future
Weber is enthusiastic about the future of his work at Berkeley Lab, pointing to his work on hydrogen/bromine redox (reduction-oxidation) flow batteries—a system that uses essentially the same framework (and sometimes materials) as those of fuel cells.
“The hydrogen/bromine flow battery is essentially a reversible fuel cell, with many of the same components but different issues,” says Weber.
Except that these cells can store electricity from wind and solar electric generation for grid applications in order to curtail their inherent intermittency.
As it was intended to do, his recent award has provided good incentive for his future work.
“It was very inspiring to see the people getting awards and hear the breadth of the research being done,” Weber said. “Getting the presidential award was a vote of confidence—not just for what we have already done, but for what we can do in the future. They are telling us, ‘Your best science is ahead of you and we’re looking forward to seeing what you can do next,’” he said.