The US electricity grid is built to deal with rain, snow, winds, and lightning. But it couldn’t handle Hurricane Sandy in 2012. Across the northeastern coast, more than 8 million homes lost electricity at some point during the storm. In Connecticut, more than one in five residents lost power.
A hurricane-proof way to make sure the lights never go out is to use backup microgrid energy. Instead of the typical long, overground cables (which can snap under the weight of a fallen tree) connected to large power plants, a microgrid has short cables (often buried underground) connected to small power generators that operate independent of any given region’s power grid.
Still, it’s far from perfect. At small scales, fossil-fuel power is inefficient, causing noise and air pollution. Diesel generators are still used in many cities to power buildings the size of hospitals, but people want pollution-free alternatives. Renewable energy from solar or wind would be ideal, but both require tons of real estate and expensive batteries to provide continuous power.
In Bridgeport, the largest city in Connecticut, a company is starting to prove it has a technology that could be the future of hurricane-proof electricity and may even make a dent in reducing the greenhouse-gas emissions driving climate change.
This article is part of The Race to Zero Emissions series investigating carbon-capture technology. You can also read our feature laying out the case for using the technology to fight climate change.
The cleaner alternative
Outside Bridgeport’s train station, I was greeted by Kurt Goddard, the vice president for investor relations at FuelCell Energy. My phone conversations before the visit had left me thinking the technology sounded too good to be true. So Goddard came prepared with an itinerary to convince me: we’d tour three FuelCell generators, each showing a different reason to believe in the company’s product.
The first stop was a remediated industrial site. On an acre and half, FuelCell had built a natural-gas power plant that feeds into Bridgeport’s city grid. It produces 15MW of power, enough for 1,500 American homes. Just blocks away, I saw rows of suburban homes.
Typically, you wouldn’t want a house that close to a fossil-fuel power plant in order to avoid exposure to harmful gases containing sulfur and nitrogen. FuelCell, as its name implies, sells fuel cells, similar to those in hydrogen-powered cars. But instead of hydrogen, FuelCell’s products burn natural gas without the harmful emissions.
Ultimately, burning fossil fuels is nothing but a chemical reaction that exchanges electrons to create heat. The heat produced in a coal power plant is used to make steam, which then runs turbines that convert mechanical energy to electricity. At each of those steps, however, energy is lost. Fire is a wild chemical reaction and it produces heat inefficiently. That’s why only about a third of the energy in coal, for example, actually gets converted to electricity. (Diesel, a fossil fuel often used in small generators, is even less efficient.)
Fuel cells run the same chemical reaction but in a controlled fashion. They use metal electrodes to enable the exchange of electrons. And because there aren’t multiple steps involved—no fire, no steam, no turbines—a lot more energy from the fossil fuel is converted to electricity. FuelCell Energy generators can reach 66% efficiency.
These characteristics make fuel cells an ideal choice for space missions. During the 1950s, NASA worked with private companies to develop fuel cells for use in space during the Gemini missions (precursors to the Apollo missions that took humans to the moon). Since the 1990s, fuel cells have been used terrestrially to power large buildings, such as hospitals and universities. But those that use fossil fuels, such as the ones from FuelCell Energy, still put out carbon dioxide, a greenhouse gas that threatens to change our planet irrevocably for the worse.
FuelCell’s power plants have already eliminated sulfur and nitrogen emissions. Now, its technology has advanced so that it also captures carbon dioxide—all at a cost that makes it financially feasible.
Heat and power
“That house belongs to the university’s chief financial officer,” Goddard said, pointing to a beige-colored home at the second site of our visit. Less than 10 ft (3 meters) away was a tennis-court sized FuelCell Energy generator. It provides key parts of the University of Bridgeport campus with both electricity and heat.
Heat is a necessary byproduct of fossil-fuel use. In the case of FuelCell’s generator, some of this heat is consumed by the fuel cell itself, which works using a molten salt that shuttles the electrons between electrodes. The liquid state of the salt is necessary for the system to work, and that requires temperatures of about 700°F (or 370°C). Some of the heat produced in the reaction is used to maintain those temperatures, while the rest can be converted into electricity using an external generator, or transferred to an external heating system if there’s use for it.
Goddard says Fuelcell’s product saves the university $300,000 per year in energy costs. During summers, when people in Bridgeport are running air conditioners, the city has to fire up its coal plant. The old power plant was Bridgeport’s main source when it was an industrial town in the 1970s, but those blue-collar jobs have disappeared. Today, with a smaller population to serve, the city doesn’t need the plant most of the year. On hot days, however, Bridgeport can’t get enough energy from the state’s power grid, so it pays the coal-power company 10 to 20 times market price to fire up the plant and give it the needed electricity. Those prices are reflected on Bridgeport residents’ energy bills. Thanks to FuelCell Energy, the university relies less on state power and thus pays something like 10% less on electricity than it would otherwise.
Crucially, FuelCell’s plant would also act as a microgrid in emergencies. When Hurricane Sandy hit, University of Bridgeport students had to go days without power. If the campus is hit with another storm, FuelCell’s microgrid is ready to power some dorms and an auditorium—enough to let people charge their phones, stay warm indoors, and get hot water.
Though FuelCell’s current generators are “ultra-low emissions”—that is, they produce no sulfur, nitrogen, or particulate matter pollution—they still do generate carbon dioxide. By the Atlantic coast in Bridgeport, Goddard showed me one last installation, and explained how the company figured out a way to capture that last bit of emissions.
The company’s fuel cell takes in natural gas (methane, or CH4) and air (containing oxygen or O2). Then an internal reaction aided by a metal catalyst converts the methane and water to hydrogen and carbon dioxide (CO2). Next, at the positive electrode (which draws in electrons), the CO2 reacts with oxygen and is converted to carbonate (CO3 ion), which is the molten salt that transfers charge from one electrode to another. Finally, at the negative electrode (which releases electrons), hydrogen reacts with carbonate to form water and CO2.
Excess water can be dumped into sewers without treatment. The last step is to capture the CO2 produced at the negative electrode.
In testing, FuelCell saw that the CO2 emissions from the plant typically contained some hydrogen and water. The company’s solution was to attach a condenser to remove the water (through a cooling process) and a compressor to separate hydrogen from carbon dioxide (by applying pressure so one liquefies before the other). The excess hydrogen is fed back into the cell and the compressed CO2 is collected.
Obviously, something must be done with this carbon dioxide. In small scales, the CO2 can be sold to beverage makers. At large scales, it could be sent offshore to store in underground aquifers, or sold to oil companies for use as a detergent-like compound to extract oil from depleted fields. FuelCell has succeeded in capturing carbon dioxide in small prototypes; Goddard took me to the coastal installation not because it’s a successful zero-emission fuel cell generator, but to show how a future system could capture CO2 and then send it through pipelines to bury it beneath the ocean.
Even with these additional extra steps, the overall energy balance in the zero-emission fuel cells is still better than it is in traditional carbon-capture technology. FuelCell’s cost of capture comes to about $40 per metric ton, according to Tony Leo, FuelCell’s vice president for technology. That’s pretty good compared to current carbon-capture costs, which tend to run higher than $60 per metric ton. The cost-savings come from energy savings. For example, a coal-fired plant can capture all its carbon dioxide but has to sacrifice about 20% of the electricity it produces. With FuelCell’s technology, there is no energy loss because the capture process is built into the system.
The promise of FuelCell’s innovation is so huge that ExxonMobil believes the startup can help the oil giant scale up its carbon-capture efforts. In 2015, ExxonMobil captured 6.9 million metric tons of carbon dioxide, about as much emitted by a million cars in a year. That was all with conventional carbon-capture technology.
ExxonMobil knows it must keep scaling up carbon capture, but it also has to find more financially viable ways to do it. After the company had a public change of heart and accepted that climate change is real, it realized the size of the problem. The world needs to capture as much as 6 billion metric tons of carbon dioxide by 2050, according to modeling done by the International Energy Agency, a Paris-based intergovernmental organization focused on energy and climate change. ExxonMobil has to support the IEA’s goal; the energy giant’s shareholders are pressuring the company to take steps to ensure climate change doesn’t convert their investments into stranded assets. And to scale up, the cost of carbon capture needs to come down.
ExxonMobil is now working with FuelCell Energy to develop a version of the latter’s technology that could produce fossil-fuel electricity while also capturing all CO2 emissions. The current thinking is that they could inject the fuel cell with exhaust from a natural-gas power plant, instead of the air used in current generator models. This exhaust gas is rich in carbon dioxide, but will have enough oxygen for the normal chemical reactions in the fuel cell to occur. The electrodes would do their job and help separate carbon dioxide, both from the power plant’s exhaust and from the fuel cell’s own reactions.
The two companies won grants from the US Department of Energy to test the technology at the Barry Power Station in Alabama. The construction work is set to begin early next year.
Too good to be true?
Fuel cells have a long history, so there’s little doubt they can provide microgrid solutions. FuelCell Energy has built the world’s largest fuel-cell park in South Korea, producing 59 MW of electricity, enough to power more than 6o,000 households, and recently received an order to build a 40 MW plant on Long Island. It shows that there are clearly customers for their product.
ExxonMobil’s hope is to build FuelCell plants that are much larger, perhaps hundreds of MW, to enable carbon capture on even larger gas-fired power plants. At that scale, however, the price of the plant will start to bite. For example: the 15 MW FuelCell Energy plant in Bridgeport cost $60 million to build, or $4,000 per kW. That’s higher by a significant margin than the cost of building any other type of large power generation.
It’s already a price worth paying for a clean and reliable way to keep the lights on during natural disasters. But the price becomes even more palatable for potential large-scale use when it includes carbon capture—especially if in the process you don’t lower the output of the main power plant—and even more so if the FuelCell add-on helps produce even more electricity, which we’ll certainly need to support a growing global population and a move to electric cars.
You can sign up to our newsletter for more stories on the challenges and opportunities of low-emissions technology. The reporting was supported by a fellowship from the McGraw Center for Business Journalism at the City University of New York Graduate School of Journalism.