Hydrogen: the future of electricity storage? US power operators seek to prove the gas can be an on-demand repository of renewable energy. The Okeechobee Clean Energy Center was designed to use the fossil fuel natural gas when it opened two years ago among the lakes of central Florida. Now the power plant’s owner, NextEra Energy, is preparing it to handle a second fuel: hydrogen. They say surplus renewable electricity produced during hours of slack demand can power electrolysis machines to make hydrogen, eventually providing a store of carbon-free energy for dispatch when demand is strongest. The $65m Okeechobee pilot project will “utilise solar energy that would have otherwise been clipped” to create hydrogen to replace some natural gas, Rebecca Kujawa, chief financial officer at NextEra — which last year briefly overtook ExxonMobil as the most valuable US energy company — has said. But producing hydrogen, storing it and then using it to generate electricity, a process known as “power-to-gas-to-power,” is inefficient and expensive. Energy is lost both in breaking the molecular bond between hydrogen and oxygen in water and in burning the resulting hydrogen in turbines. The round trip returns less than 40 per cent of the electricity put in at the start, according to Dharik Mallapragada, research scientist at the Massachusetts Institute of Technology Energy Initiative. Paul Browning, chief executive of Mitsubishi Power Americas, said that while the cost of so-called green hydrogen was expensive compared with natural gas, it was competitive with other forms of electricity storage. “Keep in mind, what we’re really targeting is renewable power that today is 100 per cent wasted when it gets curtailed,” he said. “We know we can do better than that.” The need for long-term storage will become more acute if renewables become the lion’s share of the generation mix. Solar and wind do not run all the time, while lithium-ion batteries empty within hours.
FT 5th April 2021 read more »