Where is the hydrogen that’s going to power the fuel cell going to come from?
As the H in H20, hydrogen is one of Earth’s most plentiful elements. So why do fuel cells get their hydrogen from natural gas?
The answer is that to separate hydrogen from water is expensive. The process, known as electrolysis, requires passing an electric current between two metal electrodes bathed in water; hydrogen gas is formed at the negative electrode and oxygen at the positive electrode. The problem is, powering an electrolysis reaction takes a lot of electricity. In fact, with existing equipment, the amount of electricity that could be generated by a fuel cell with hydrogen produced by electrolysis is only about half of the electricity that would be needed to actually split the hydrogen from water. And, of course, the vast amount of electricity to run electrolysis is distributed by utilities generally burning fossil fuels, defeating the goal of clean, economical power that fuel cells are supposed to deliver. “It’s very, very expensive to get hydrogen out of water with today’s technology,” says Robert Kripowicz, acting assistant secretary for fossil energy at the U.S. Department of Energy.
Extracting hydrogen from natural gas, on the other hand, is far less costly and doesn’t hog electricity. The most efficient method involves heating the gas with high-temperature steam in the fuel cell’s reformer. In the process, hydrogen is separated from carbon molecules.
At least 20 years’ worth of natural gas reserves are available now, according to the National Petroleum Council, and new technologies are being developed that will soon let suppliers tap enormous resources too deep to get at today.
Nevertheless, natural gas availability isn’t infinite. Yet, only Iceland has so far announced plans to use renewable energy-in its case, abundant hydropower-to remove hydrogen from water and drive the entire nation on a fuel-cell-based electric grid.
There are no efforts in the United States to follow Iceland’s lead. One reason: in the United States, renewable energy sources like hydroelectric dams, solar arrays, and wind farms represent such a small percentage of the electricity grid that even if they were used for electrolysis, not enough hydrogen to power significant numbers of residential fuel cells could be produced. In fact, most experts say that the transition to a hydrogen-from-water fuel cell energy system in the United States isn’t likely before the end of this century. To do better than that, says John Turner, senior scientist at the National Renewable Energy Laboratory in Golden, Colorado, a government laboratory, would require a huge long-term thrust with unyielding support from Washington, D.C., and not a quick fix effort with a short attention span. “I’ve heard people say we need a Manhattan project,” Turner says. “Actually, it would be more like the interstate highway project.”