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Energy: Reimagine fuel cells

Investments in solar photovoltaics and wind turbines are soaring as costs fall and governments and companies seek to reduce greenhouse-gas emissions. But fluctuating power from the wind and sun threatens to destabilize electricity grids. As more intermittent sources are connected, the power surges and crashes. This increases variability in voltage, in power and in the frequency of alternating current.

Already, Germany, which produces more than 25% of its energy from renewables, is experiencing problems. Voltage glitches, by tripping crucial components and destroying equipment in factories and plants, have caused hundreds of thousands of euros of damage1. Using coal plants to maintain stability adds greenhouse-gas emissions.

Generation and load must be balanced. Three approaches are in operation: using real-time demand and pricing incentives to control load; ramping natural-gas plants up or down to compensate for fluctuating power; and storing energy. Each has downsides. Repeated requests to reduce demand agitate users and may be manipulated by third parties who stand to profit. Gas turbines and batteries cannot provide rapid (less than a second) high-power responses and supply energy for long periods. Batteries degrade and are expensive to replace. Combinations of batteries require multiple sets of electronics and control systems.

New types of fuel cell on the horizon could eliminate the need for such trade-offs and ease the integration of renewables into the grid. Currently, fuel cells are used to generate only electricity and heat. They can be modified to store energy and produce liquid fuels such as methanol, thanks to breakthroughs in materials and designs. Developing fuel cells with a battery mode is one focus of the programme I direct at the US Advanced Research Projects Agency–Energy (ARPA-E). I lead 13 projects across academia, industry and national laboratories.

Researchers must now demonstrate that fuel cells can perform multiple functions and still generate power efficiently.

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