Fuel cells as a power generator simply look too good to be true. They're quiet, they don't produce criteria pollutants, and they're efficient electricity producers. They can be placed right next to a building without adding miles of transmission lines, and they won't bother passers-by any more than a fire hydrant or a dumpster—less than a dumpster.
But they're not the perfect power source, not yet. They cost too much for some applications, lifetime issues still need to be resolved, and some units are too large for their desired applications. So although the technologies have powered buildings and busses for years (even lighting the Academy Awards last year), there are challenges to meet before they fulfill their potential.
That's where Lawrence Berkeley National Laboratory's (Berkeley Lab's) Fuel Cell program comes in. Located in the Environmental Energy Technologies Division, Berkley Lab's fuel-cell researchers work with the U.S. Department of Energy and industry partners to address fuel-cell challenges. Adam Weber, program manager and one of the two primary principle investigators for Berkeley Lab's fuel-cell work, is confident that they will play a strong role in providing energy in the twenty-first century.
"Performance is getting better, and there are viable devices for a lot of applications," he says. "There is a rich market out there today for fuel cells in fleet and industrial applications, and many more opportunities in the future."
Some prominent corporations tend to agree. Google, Staples, FedEx, and eBay are all using fuel cells to power facilities. In 2011, healthcare leader Kaiser Permanente plans to install fuel cells at seven of their facilities around California, amounting to a total of 4 MW of capacity.
Weber's program has expanded over the past four years. While much of the research is funded by the Office of Fuel Cell Technologies of the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy, some of the funding increase is the result of partnerships with commercial enterprises interested in improving fuel-cell performance to meet their products' needs.
"We've established a number of successful partnerships with companies such as Toyota, 3M, and Ballard," says Weber. "It's interesting work."
Fuel-cell research at Berkeley Lab is divided into roughly two areas. Weber's area concentrates on performance and diagnostics issues, using such techniques as mathematical modeling to examine transport within cells, and on establishing diagnostics to evaluate performance. John Kerr heads the other group, which studies membrane synthesis and new materials development for non-precious metal catalysts. Collaborations are an essential part of Berkeley Lab's fuel-cell work. Both groups collaborate extensively with outside national laboratories, industry, and academia, as well as with internal collaborators from the Earth Science, Materials Science, and Chemical Science Divisions.
Although a variety of fuel cell technologies exist, most fuel cell research at Berkeley Lab focuses on proton-exchange-membrane fuel cells (PEMFCs), with some work also being done on solid-oxide fuel cells (SOFCs). Berkeley Lab researcher Michael Tucker heads the SOFC work, which he brought over from the Material Sciences Division.
Currently, seven projects are underway, and others are being developed, to help solve practical fuel-cell issues. For example, fuel-cell performance is reduced at low temperatures, especially with the nanostructured thin-film catalysts that are an order of magnitude thinner than traditional catalyst layers. These thin-film catalysts perform as well as traditional ones, but allow the fuel cell to require less platinum. However, at subzero temperatures, there is a possibility of ice formation. This complicates the already complex water and thermal management issues of keeping the membrane hydrated and conductive without flooding the catalytic reaction sites with water. Researchers are evaluating PEMFC performance at low and sub-zero temperatures with the goal of finding solutions to this critical barrier.
In another two projects, Berkeley Lab is working with Los Alamos National Laboratory (LANL) to understand fundamental PEMFC degradation mechanisms. One issue they are examining is the fundamental nature of the proton exchange membrane, PEM, which is the heart of the fuel cell. Studies in Weber's lab and at Berkeley Lab's Advanced Light Source are revealing insights into PEM water-sorption behavior and combined mechanical and chemical durability. The activities with LANL also include analyzing the efficacy and real-world applicability of accelerated lifetime tests. Researchers are gathering fuel cell data from buses in field service and linking that information with lab data to see how well the protocols evaluate lifetime performance.
Manufacturing costs can make or break an energy technology's marketability, and fuel cells are no exception. In collaboration with the National Renewable Energy Laboratory (NREL), Berkeley Lab is examining PEMFC manufacturing to develop ways to detect defects such as pinholes in membranes and platinum-loading variations. The project is working to develop online diagnostics and to better understand how these defects affect performance.
Department of Energy-funded fuel cell research has traditionally focused on transportation applications, and much of Berkeley Lab's fuel-cell work has shared that focus. However, DOE is expanding that vision to include industrial equipment such as forklifts, and the Lab is a big part of this research. In collaboration with Nuvera Fuel Cells, Berkeley Lab is conducting a project to improve PEMFCs for both the automobile and forklift markets. The concept is that one can reduce cost if fuel cells can be operated at higher current densities and slightly lower efficiency from smaller cell size. However, there are implications for heat and thermal management. They include membrane dehydration and too much self-heating. To evaluate those issues, Weber's group is developing submodels of membrane and catalyst layers that work with a model developed at the University of Tennessee, Knoxville. Modeling has shown that the thin coating of membrane in the catalyst layer can result in unexpected mass-transport limitations, where reactant oxygen gas cannot reach the reaction site, an effect that is especially apparent with lower platinum loadings. The study has also shown that extrapolating from high-loading to low-loading situations does not produce accurate performance measurements; performance is fundamentally different at high and low loads.
"The primary application of most of the work is transportation," says Weber. "But if it works for transportation, it can work in stationary applications as well."
While most of Berkeley Lab's fuel cell projects address current challenges faced by the fuel-cell industry, some look at more basic science. For example, the Lab is currently engaged in a project with Sandia National Laboratory to model how water exits a PEMFC gas-diffusion layer. The research team is developing an experimental technique to quantify the energy required for a droplet to leave the surface, with the aim of optimizing water removal and increasing fuel-cell performance.
A hydrogen fueling station is slated to open in Emeryville, California (near Berkeley) soon, and once it does, Weber's group is in talks to get a fuel-cell vehicle from Mercedes Benz for technical validation and to evaluate its real-world response under daily driving conditions. "Once we get the vehicle, I'm interested in having people drive it as much as possible, to give fuel cell vehicles more visibility in the community," says Weber. "These vehicles show great performance and good long-term durability, and when mass-produced in high volumes, the stacks are expected to cost in the range of $50/kW."
In addition to the primary PEMFC and SOFC systems, Berkeley Lab is also working on very similar systems that use essentially the same framework (and sometimes materials) as those of fuel cells. Examples include work now ongoing on hydrogen/bromine flow batteries for grid-level energy storage. This work is funded by DOE's Advanced Research Projects Agency - Energy (ARPA-E), which seeks innovative and game-changing research ideas.
"The hydrogen/bromine flow battery is essentially a reversible fuel cell, with many of the same components but different issues," says Weber.
Another system similar to a fuel cell is a design being considered in the Joint Center for Artificial Photosynthesis (JCAP), one of DOE's Energy Innovation Hubs, led by CalTech in association with Berkeley Lab and other California research institutes. The produced hydrogen from the artificial photosynthesis can be used in typical PEMFCs, and the actual cell design is similar, except that the electricity is generated internally within the membrane from solar irradiation.
Competition in the fuel cell market has increased, with worldwide fuel cell shipments now surpassing those of the United States. In recent years, Japan, China, Korea, and Germany have all increased production of fuel cells and their underlying hydrogen infrastructure. In Japan, they are even selling fuel cells for residential use. Called ENE-FARM, they are marketed as a natural-gas-fueled home cogeneration that produces electricity and hot water.
"There are so many applications for fuel cells—in transportation, industry, appliances, and buildings. Their potential growth is immense as a clean energy conversion technology," says Weber. "Our work here is fundamental in supporting that growth by helping to diagnose and eliminate performance and durability problems."
This research is funded by the Office of Fuel Cell Technologies of the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy and partnerships with companies including Toyota, 3M, and Ballard.