Xcel, NREL studying wind-to-hydrogen

Renewable fuel could level electric loads if costs decline

A single wind turbine can generate 1,500 kilowatts of electricity at a given moment, enough to power roughly 1,500 Colorado homes, and without burning even a stocking-stuffer lump of coal. But the wind doesn't always blow between 4 and 7 p.m. on the hottest summer days, when utilities need it most.

Xcel Energy and the National Renewable Energy Laboratory on Thursday unveiled a $2 million wind-to-hydrogen research project to overcome the greatest barrier to wind sweeping into position as a top energy source - its variability. The idea is to use wind-generated electricity to create hydrogen and then burn it in generators or fuel cells when the wind dies down.

Dan Arvizu et al push a button
From left, Xcel Energy chairman, president and chief executive Dick Kelly and National Renewable Energy Laboratory director Dan Arvizu push the start button of an experimental wind-to-hydrogen system at the NREL National Wind Technology Center as part of a dedication on Thursday. Energy generated from a wind turbine powers a hydrogen compressor to store the renewable energy. Joshua Lawton/Daily Camera

The Xcel - NREL Wind2H2 Project, based at NREL 's National Wind Technology Center in southern Boulder County, already is converting breezes to electrons. Although not the first project of its kind, NREL and Xcel officials hope the effort succeeds in the formidable engineering challenge of making wind-generated hydrogen cost-competitive with fossil-fuel-based hydrogen - and perhaps electricity generation.

Without radical, multi-billion-dollar improvements to the nation's electricity grid, utility engineers will continue to view lifting wind's share in the electricity mix above 10 percent as risky. If Xcel could fire up wind-to-hydrogen fueled generators on demand as they do with gas-fired generation today, wind could theoretically provide all the nation's electricity, NREL engineers have calculated. But that would be extremely expensive, and hence the need for the new research, which began two years ago and is slated to continue through 2008.

"We've got to get the costs down," said Xcel CEO Richard Kelly, who described the research project's current per kilowatt-hour cost as unknown, but "really high."

There is certainly political interest in the program. In remarks at the event, U.S. Sens. Wayne Allard, R-Loveland, and Ken Salazar, D-Denver, as well as U.S. Rep. Mark Udall, D-Eldorado Springs, spoke of the promise of wind-to-hydrogen technology in improving energy security, particularly with respect to hydrogen as a way to displace imported fossil fuels.

The Wind2H2 system, completed Monday, connects two wind turbines - a 100-kilowatt turbine and a 10-kilowatt turbine - to three electrolyzers, which zap water with electricity into its component hydrogen and oxygen. The hydrogen flows through a compressor, which crushes it to 3,500 pounds per square inch.

Even at such pressure, equivalent to what a submarine experiences under 1½ miles of seawater, a tank assembly the size of a sedan holds just 85 kilograms of hydrogen, which is the energy equivalent of 85 gallons of gasoline that can fit in two barrels.

Hydrogen is the universe's lightest element.

"Storing it is the challenge," said Keith Wipke, an NREL senior engineer who works on hydrogen vehicles. "It's why they use it in blimps. It wants to go up."

Hydrogen burns in either an internal-combustion generator or a fuel cell. Water vapor comes out the exhaust pipe.

About 10 NREL and 10 Xcel engineers are working on the project, in addition to several equipment suppliers. Well past basic "will it work" research, the project aims to streamline the cumbersome process of converting alternating-current wind energy to direct-current input for the hydrogen-producing electrolyzers, said Kevin Harrison, an NREL senior engineer on the project.

Although the Xcel project focuses on electricity generation, which would minimize the challenge of storing and transporting hydrogen, NREL engineers are most bullish about the use of their wind-generated hydrogen technology to supplant petroleum in cars.

"If you run the numbers, hydrogen for vehicles actually makes a lot more sense," said Ben Kroposki, an NREL senior engineer on the project.