Hydrogen may hold key to storing wind power

Jun 29 - Houston Chronicle

A system that could make renewable sources of power more reliable has begun operating in Germany, marking a milestone for a new energy storage system, the companies involved say.

The plant converts surplus power from wind turbines into energy-dense hydrogen gas and is one of several efforts in the area of energy storage that are attempting to boost renewable power sources.

A major barrier to wider adoption of renewables has been the inconsistency of obtaining energy from wind that doesn't always blow and sun that is hidden at night.

Germany's new power-to-gas system, built by Canada-based Hydrogenics for E.ON, a German utility, takes advantage of the wind's tendency to blow hardest at times when there isn't a lot of power demand, according to E.ON.

The 2-megawatt facility uses the excess power from wind turbines to fuel a chemical reaction that produces hydrogen from water, Daryl Wilson, CEO of Hydrogenics, said in an interview.

The plant then feeds the hydrogen into natural gas pipelines, where it mixes with natural gas. The mixture then can be burned in natural gas turbines to generate electricity when needed, Wilson said. The "green gas" displaces natural gas, resulting in less fossil fuel combustion and ultimately more power generated from renewable sources, he said.

The approach has great potential, he said, because existing pipelines can hold enormous quantities of hydrogen.

Other systems being developed to store renewable power have limitations. Battery systems, for example, can store large amounts of power, but can be drained in a matter of minutes.

Stored hydrogen, by contrast, can fuel existing gas generation plants to provide power when demand rises, Wilson said.

E.ON said the plant operated properly earlier this month during tests. The plant is the largest of its kind and cost about $2 million, Wilson said.

While the technology holds promise, it takes a lot of wind power to produce the hydrogen gas, said Haresh Kamath, program manager for energy storage at the Electric Power Research Institute.

The process converts about 50 percent of the excess wind power into hydrogen, with the remainder required to fuel the chemical reaction, Kamath said. In addition, the hydrogen, when burned, produces power at about the same rate as natural gas, with a maximum efficiency of around 60 percent, Kamath said.

The system also depends on natural gas turbines, meaning that it does not do away with the need to burn fossil fuels, though the hydrogen does provide a renewable replacement, he said.

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