Xcel sells electricity made by wind turbines, and NREL develops cutting-edge "green" energy technologies. Wind energy has stubbornly remained more expensive and less reliable than traditional power sources. A key problem always has been how to store wind energy so it can be used to make electricity at any time.

That puzzle might be solved if Xcel and NREL can engineer affordable ways to make hydrogen from wind turbines. The physics are well known: Wind turbines generate electricity, and electricity is used to break apart water molecules, leaving just oxygen and hydrogen. The hydrogen can be stored in battery-like fuel cells or burned in combustion engines similar to those that use natural gas or propane. (Despite its reputation, hydrogen isn't more dangerous than other, commonly used flammable fuels such as natural gas, propane and gasoline.)

When hydrogen is burned, it recombines with oxygen to make water. Unlike fossil fuels, the process doesn't emit carbon or other greenhouse gases. It sounds ideal except for an annoying fact: At each step, some energy is lost and so the costs rise, making such projects commercially unattractive.

But the $1.75 million, two-year experiment at NREL's wind farm south of Boulder seeks to improve the economic equation. If Xcel and the lab can improve the efficiencies of both wind generation and hydrogen storage, then hydrogen storage of wind energy may be financially feasible.

While Xcel just wants to make electricity, there's another possible use for wind-made hydrogen. BMW makes a prototype hydrogen-powered car, and Shell Oil is opening hydrogen fuel stations in some U.S. cities. While widespread use of hydrogen as a vehicle fuel is many years away, a tiny market already has started to emerge.

Today, the ultimate goal of much global energy research is how to make affordable hydrogen fuel from "green" sources like wind.

Thus much more could be at stake in the Xcel-NREL partnership than whether one company can make its wind farms more profitable. At stake may be part of the answer to America's energy supply woes.