I am a long way from been much of
a fan of fuel cells having watched the technology limp along now for sixty
years or so with no breakthrough that made it useful in the mass market.
However this is a good survey
article and allows us to catch up on the present status of the industry.
What the industry is looking for
is and effective way to produce hydrogen.
That done and then the fuel cell becomes way more interesting as
hydrogen provides a convenient way to store energy until needed.
We have also seen real progress
in that field, so all is not lost and the great days of the fuel cell industry
may well be ahead of us.
by Mark Wilson
Schematic view of a proton-exchange-membrane fuel cell (PEMFC).
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
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.
Fuel Cell Vehicles
A hydrogen fueling station is slated to open in
Fuel Cell-Like Systems
In addition to the primary PEMFC and SOFC systems,
"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.
Worldwide Interest in Fuel Cells
Competition in the fuel cell market has increased, with worldwide fuel cell shipments now surpassing those of the United States. In recent years,
"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."
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