169. Fuel Cells: What They Are, How They Work, and Why They’re Important
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Fuel cells are not some novel new technology. In fact, most history books credit the invention of the fuel cell to Welsh chemist and physicist William Grove, who, in the late 1830s and early 1840s, conducted experiments proving that electric current could be produced from an electrochemical reaction between hydrogen and oxygen over a platinum catalyst. Yet, fuel cells never really took off as a mainstream source of power. Why is that? “I think the real reason is, historically, we’ve been comfortable with less-clean, lower-efficient but less-expensive technologies, because we haven’t been as focused on air quality and on decarbonization as we currently are,” Tony Leo, executive vice president and Chief Technology Officer with FuelCell Energy, said as a guest on The POWER Podcast. However, as people have become more focused on air quality and climate change, Leo suggested fuel cells are now poised to take off. “That’s why you’re seeing such an acceleration in the deployment of fuel cells and that’s why you’re hearing more and more about them these days,” he said. A fuel cell is a device that makes electricity from fuel and air. Instead of burning the fuel to make heat to drive a mechanical generator, fuel cells react the fuel and air electrochemically, without combustion. The electrochemical approach avoids pollutants that are created by high flame temperatures, and it is a more direct and efficient way to make power from a fuel. Reacting fuel and air electrochemically involves delivering fuel to a set of negative electrodes (called anodes) and delivering air to a set of positive electrodes (called cathodes). The electrochemical reaction of fuel produces electrons. The electrochemical reaction of oxygen in air consumes electrons. Connecting the two produces the current of usable electrical power. Fuel cells are configured in stacks of individual cells connected in a series. FuelCell Energy’s carbonate stacks have up to 400 cells per stack and produce between 250 kW and 400 kW of power. FuelCell Energy’s standard MW-scale module contains four stacks, nets about 1.4 MW of power, and can make electricity for sites such as universities, hospitals, and data centers. The modular design of fuel cell plants allows them to scale up to a specific site’s energy needs. “One big advantage is they’re quiet,” said Leo. “Since they don’t have a big spinning machine and this big spinning generator, they’re quiet compared to traditional power generation, so you can site them in population centers. We have a 15-MW fuel cell right in the middle of downtown Bridgeport, Connecticut, for example, and that just makes a really good neighbor.” The lack of harmful emissions is also a benefit. Another advantage is that while fuel cells are making electricity, they’re also making heat that can be used to produce hot water or steam, or to drive chilling operations. “That further enhances the sustainability because you get to avoid burning fuel in a boiler, for example, if you can use the heat coming off the fuel cell,” said Leo. Additionally, fuel cells don’t require a lot of maintenance or a large operations staff. “They’re unmanned—we monitor them remotely—and so, they take care of themselves and just generate value,” Leo explained.