Helping the Hydrogen Economy Break Even
By Eileen McCluskey
In WPI's Fuel Cell Center, chemical engineering researchers Ravindra Datta, left, and Nikolaos Kazantzis are working to overcome the practical and theoretical challenges that stand in the way of the widespread deployment of hydrogen fuel cells.
When Welsh scientist Sir William Robert Grove built the first fuel cell in 1839, he could scarcely have imagined how big a promise his invention would hold for the world 168 years later.
Today, companies, universities, and governments worldwide, recognizing the urgent need to decrease humanity's reliance on fossil fuels and divert the catastrophe of global warming, strive to realize a hydrogen fuel cell–powered economy.
WPI scientists work at the forefront of this field. From the university's Global Clean Energy Center to its Fuel Cell Center, in classrooms and in the field, faculty and students drive fuel cell science, and its integral policy and economic issues, toward greater clarity in the hope of fostering a new energy paradigm.
"Fuel cells are of great interest as low-polluting, high-efficiency power sources for applications ranging from the laptop to the automobile," says Ravindra Datta, professor of chemical engineering and director of WPI's Fuel Cell Center. "This work is gratifying because it's become increasingly clear that we can't keep doing things the way we've been doing them, in terms of energy use."
Fuel cells are essentially high-tech batteries, except that they don't run out of energy as long as they receive a continuous flow of fuel. The most common type uses a proton exchange membrane (PEM) as its electrolyte. In a PEM fuel cell, hydrogen is fed into the anode side, where a platinum-coated catalyst separates it into electrons and protons (hydrogen ions). The ions pass through the membrane and, reacting on the catalyst, mix with electrons and oxygen on the cathode side to produce water, the cell's only "waste" product, which flows out of the cell. The electrons, which cannot pass through the membrane, produce an electric current as they travel to the cathode through an external wire.
To optimize the performance of fuel cells, Datta and Kazantzis have developed an analytical framework that sees the cell's complex chemical systems as a set of interacting subunits. The catalytic reaction networks are represented as circuits, shown here, in which each step in the reaction is represented as a directed branch interconnected at nodes, so that all conceivable reaction paths can be traced.
Datta and his team in the Fuel Cell Center work toward improving the cathode's catalytic activity, and to increase the anode's tolerance for carbon monoxide, which easily poisons today's fuel cells but is difficult to eliminate from hydrogen fuel. They also experiment with making the membrane thicker and more durable without sacrificing its ability to conduct ions under dry conditions. And they study the chemistry of platinum with an eye toward reducing its use. "Platinum is the fuel cell's workhorse," explains Datta, "but there's only so much of it around, and it's expensive. To use less, or to replace it, you need to understand how it reacts, which is a key goal for us."
When Datta dove into fuel cell research 14 years ago, PEMs were made from powdered platinum. "This was very wasteful," he says. "I could see that chemical engineers, few of whom were involved in fuel cells at the time, had the right skills to develop a more efficient form of platinum for the fuel cells." Datta's latest PEM uses carbon cloth and the high-tech plastic Nafion, which is coated with supported platinum nanoparticles.
Nikolaos Kazantzis, associate professor of chemical engineering, works closely with Datta. By using an analytical framework that views the fuel cell as a set of complex systems comprising a number of interacting subunits, Kazantzis helps further illuminate ways to enhance and optimize fuel cells' performance. "It's exciting to address the fragile interface between energy production and environmental protection using a systems-based analytic approach," Kazantzis says.
"We're developing much clearer understandings of the most basic science behind how membranes, catalysts, and fuel cell systems operate," Datta notes, "so that those who make the fuel cells can reap the benefit." For example, "the fuel cell's membrane and catalyst account for two-thirds of its manufacturing cost. With better membrane and catalyst design, fuel cells would become more viable economically."
So when might a hydrogen economy establish itself? "The fuel is the kicker," Datta comments. "Hydrogen, unlike fossil fuels, is an energy carrier that you have to produce from something else. Producing hydrogen on site, on demand, in small quantities, in compact units for a broad range of applications, including on-board cars, is 15–20 years down the road."
The research team led by Ed Ma has been working for 10 years on a reactor that uses a palladium membrane to separate hydrogen economically from natural gas or corn. Much of the funding came from divisions of Shell, which will use it in what it hopes will be the nation's first hydrogen refueling system. In 2004, Shell installed the first hydrogen pump at a retail gas station, in Washington, D.C. Photo courtesy of Shell Hydrogen.
Solving the fuel problem has been the quest for the past decade of Yi Hua "Ed" Ma, Frances B. Manning Professor of Chemical Engineering, and his large, well-funded research team in WPI's Center for Inorganic Membrane Studies. Ma knows that the hydrogen economy will depend on a supply of hydrogen pure enough to power fuel cells without poisoning their catalysts and cheap enough to compete with fossil fuels.
To meet that daunting challenge, Ma and his team have developed a novel chemical reactor built around an ultrathin membrane made from the metal palladium.
The reactor uses steam reforming and catalysts to extract hydrogen from natural gas or renewable sources, such as corn. Pure hydrogen passes freely through the palladium membrane and is collected; carbon dioxide, the other major product of the reaction, is sequestered.
The work has been funded by major research awards from Shell International Exploration & Production Inc. and Shell Hydrogen, which plans to use the technology to supply hydrogen for what it hopes will be the nation's first successful hydrogen refueling system for fuel cell–powered vehicles. The work has also been supported by the U.S. Department of Energy, which recently selected Ma's team as one of six research groups in the nation to share nearly $10 million for work aimed at promoting the production of hydrogen from coal at large-scale facilities.
The technology, which has been turned over to Shell, offers a number of advantages over existing hydrogen production systems. For one, it combines, in a single device, the processes of generating and separating the hydrogen, which will dramatically cut both operating costs and the size of the reactor. It is also able to operate at significantly lower temperatures than conventional reactors, which means it can be made from less-expensive materials. "Now you can put it in a gas station," Ma recently told the Financial Times.
In a new seminar, Isa Bar-On and faculty in the Global Clean Energy Center teach students about the science behind technologies like fuel cells, left, but also about the social and regulatory issues that surround them.
While most of the buzz surrounding fuel cells has focused on technology for vehicles, mechanical engineering professor Isa Bar-On does not see fuel cell–powered automobiles as a feasible first step. "From a manufacturing cost perspective, the nearest-term likelihood will be the development of fuel cells that replace the standard battery in portable devices," she says, noting such change could come within two years. (In fact, Ravi Datta's Fuel Cell Center is working on direct methanol fuel cells that may be well suited for powering laptop computers and other electronic devices.)
To help accelerate the pace of change and thwart global warming, Bar-On and her colleagues examine the full gamut of alternative fuels from a range of interdisciplinary perspectives, including economics, environmental impacts, and public policy issues. Toward these ends, Bar-On and 10 other WPI faculty members formalized their ongoing teamwork in mid-2006 by establishing WPI's Global Clean Energy Center. Bar-On directs the center, which includes the Alternative Fuel Economics Laboratory, and engages faculty from the departments of Chemical Engineering, Civil and Environmental Engineering, Mechanical Engineering, and Social Science and Policy Studies.
Students demonstrate a lively interest in the center's approach: When eight professors from the Clean Energy Center announced a new graduate-level seminar in July 2006, 16 students immediately signed up. "That's a high number for a first-time graduate course offering," says Bar-On.
To gain a macro understanding of alternative energy issues, students participating in the seminar took a global view, literally, of other countries' alternative fuel uses. They learned, for example, of several European countries' recently adopted policy to increase—to 5.75 percent by 2010—their bio-fuel portion of transportation fuels. "But we also learned that these countries buy their palm oil—bio-fuel's raw material—from Indonesia and Malaysia, which are cutting down rain forests to grow the palms," notes Bar-On. "So we see how critical it is to consider the entire production system when measuring environmental costs associated with various fuels."
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"We face a fascinating and interrelated set of issues in the world today regarding how we might continue to fuel our economies," agrees J. Scott Jiusto, assistant professor in the Interdisciplinary and Global Studies Division. "These issues immediately lead to all the major questions regarding environmental change, geopolitics, the very way we see the world and experience our daily lives.
"To be able to make the leap from a fossil fuel–dependent lifestyle to one that uses what are today considered alternative fuels," Jiusto continues, "will require imagination and daring from many, including policy makers." Indeed, Jiusto approaches fuel cell technology from a policy perspective, having written and taught extensively about technology-related policies since 1989 and recently addressing cross-border power flows and carbon emissions accounting practices.
Jiusto sees the most promising U.S. alternative energy policies springing up at the state level. "This isn't like the 1970s, when the federal Clean Air Act and Clean Energy Act provided important new tools to deal with our most pressing environmental problems," he notes. "For two decades, it's been more difficult to move alternative energy at the federal level, because there's so much entrenched power and sunk capital in the oil economy. These days, those interested in efficient and renewable energy systems find it easier to make progress at the state and local levels. Massachusetts and California, for instance, are at the forefront of policies to regulate and reduce greenhouse gas emissions.
"Nationally," Jiusto says, "we need a suite of policies to encourage renewable energy. We need to experiment, try to get enough, for instance, of a hydrogen fueling infrastructure going. It takes many cycles of innovation to move things along."
Realistically, even the most far-reaching policies are likely to bring about "a mixed energy system, with hydrogen fuel cells as part of a highly layered energy economy," he says. Policy menus at the state level could become the basis for a national program.
"Meanwhile," says Jiusto, "carbon emissions continue to climb. We need to take much larger steps, and quickly. The next round of innovation and creativity could help remake the world. If we in the U.S. want to be on the cutting edge, we have to get moving. We have the resources; hopefully, we'll make the right choices."