ExxonMobil and FuelCell Energy have formed a pact worth up to $60 million to optimize carbonate fuel cells to capture carbon dioxide. FuelCell Energy uses a molten carbonate salt as the electrolyte in fuel cells that convert fuel into electricity. The two firms have worked together since 2016 to test running power plant exhaust rather than air through the fuel cells. While the cells produce electricity, their membranes also concentrate CO2, doing so more efficiently than the amine solvents often used to capture CO2, ExxonMobil says. The oil company is also working with Mosaic Materials on metal-organic frameworks that capture CO2 (see page 38).