This June, Nissan announced that it had begun development of a Solid Oxide Fuel Cell (SOFC) system for future use in countries where agricultural feedstocks such as corn and sugar cane are more readily available than petroleum. Unlike the fuel cells used by the Honda Clarity, the Toyota Mirai, and the Hyundai Tucson, which convert hydrogen and air to electricity, the SOFC design contains lower-cost ceramic-based materials instead of expensive platinum catalysts and operates at higher temperatures. Nissan claims its e-Bio Fuel-Cell vehicle marks the first practical use of an SOFC in an automobile.
While Nissan’s approach offers the flexibility of using fuels ranging from natural gas to ethanol to ethanol-water blends, an on-board reformation step is necessary to extract the hydrogen needed for the SOFC from any hydrocarbon fuel. The downsides are that reformation using steam or catalysts consumes energy and produces byproducts containing carbon. In this case, the waste heat from the SOFC can be used in the reformation process.
Carbon-containing reformation byproducts are less of an issue in Third World countries than in the U.S. or Europe, where CO2 is a regulated greenhouse gas. Nissan’s counter to that concern is that growing renewable biofuels, such ethanol derived from corn or sugar cane, draws CO2 from the atmosphere. This fuel-growing and -consuming cycle results in a near neutral carbon output in the so-called well-to-wheels analysis. For now, at least, most of the “pure hydrogen” that powers the aforementioned fuel-cell cars is produced industrially, extracted from natural gas at petroleum refineries in a process that releases CO2. The cars themselves may not emit carbon-containing gases, but in a well-to-wheels analysis, they’re not so squeaky clean, either.
Nissan’s first running prototype, revealed a few days ago in Brazil, is a modified e-NV200 light commercial van with a 5-kilowatt SOFC, a 7.9-gallon fuel tank, and a 24-kWh battery, which serves as an energy storage buffer between the SOFC and the electric drive motor. This arrangement provides a 375-mile range, which is comparable to similar sized gasoline-fueled vans. Attributes shared with the Nissan Leaf and NV200 electric van are silent propulsion, excellent low-speed response and acceleration, and low operating costs.
Nissan’s SOFC initiative is an extension of its Intelligent Power program promoting global use of electrified vehicles. Public road testing has begun in Brazil. Nissan hopes this bio-fuel approach fits well with local infrastructure (Brazil has lots of ethanol) while enabling lower mobility costs and higher driving satisfaction.
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