By George Moffatt
Just as we are beginning to appreciate emissions-free electrical vehicles (EVs), hydrogen-powered vehicles (HVs) also are vying for consumers’ attention. In theory you can hop into an HV and start motoring down the road with no concerns about greenhouse gas or nitrous oxide (NOx) emissions, although the hydrogen you use should come from a “green” source.
After careful review, the Sierra Club has concluded that “hydrogen should not be used to power most vehicles” and it should be sourced only from solar or wind energy.
HVs use hydrogen gas and fuel cell stacks—multiple specialized cells—that create the electricity that powers electric motors, unlike EVs that use lithium-ion batteries. And unlike gasoline engines, HVs have clean tailpipe emissions—just water and oxygen.
HVs generate their own electricity through electrochemical reactions with hydrogen gas, known as reverse electrolysis. This chemical reaction uses hydrogen gas and oxygen to create electricity, with water as a byproduct. The chemically created electricity powers the HV’s motor, which is refueled with more hydrogen gas.
HVs are pollution free, have few moving parts, are easy to operate, and are reliable and quiet. They also feature quick refueling (3-5 minutes), low maintenance, simple repairs, steady acceleration (sorry, no pedal-to-the metal), and consistent power.
However, HVs are pricey, beginning at $50,000 to $65,000, and options for refueling them are very limited. There are just 54 refueling stations in the United States, and all but one are located in California. The other is in Hawaii. Hydrogen fuel is not cheap: $5.00 to $8.50 for an amount equivalent to a gallon of gas in California.
If you’re willing to travel only in California and Hawaii, you’ll get about 350 to 400 miles on a tank of compressed hydrogen.
As far as safety goes, hydrogen gas, like gasoline, is explosive; but it is 14 times lighter than air and 57 times lighter than gasoline vapor. This means leaking hydrogen quickly floats upward as it dissipates, making explosions less likely, while heavier gasoline fumes concentrate on the ground.
As a fuel source, green hydrogen produced by electrolysis from wind or solar energy is the ideal. Fossil fuel–based techniques for producing hydrogen cause pollution, greenhouse gas emissions, inefficiencies, and hydrogen leakage into the environment. Hydrogen is a much more powerful greenhouse gas than carbon dioxide.
Energy or hydrogen produced from biomass or biogas is not technically renewable, as it, too, involves greenhouse gas emissions, although it is often falsely promoted as a renewable form of energy.
Hydrogen is found only in combination with other elements, such as water (H2O), methane (CH4), electrolyzed water, natural gas, and—no kidding—cow manure. Of all the techniques used to create hydrogen gas, the dominant process is steam methane reforming (SMR), which amounts to 10 million tons annually or 99 percent of all hydrogen produced industrially.
Unfortunately, SMR requires steam at 1,300°F to 1,800°F, which is created by burning gas, coal, and even wood. As a result, SMR releases 8 to 10 kilograms of CO2 per 1 kilogram of hydrogen, or about 915 tons of CO2 a year. About 76% of these emissions come from using natural gas, 22% from coal gasification, and 2% from electrolysis. They also consume 6% of the world’s natural gas and 2% of its coal.
SMR hydrogen is known as “blue” or “gray” hydrogen, as opposed to genuinely “green” hydrogen that is created by sustainable wind or solar energy, which is favored by the Sierra Club.
Unfortunately, the energy industry “has been pushing for blue hydrogen development with the dubious argument that investing in sub-optimal (or harmful) hydrogen infrastructure today might allow the deployment of green hydrogen in the future,” wrote Cara Bottorff, managing senior analyst for the Sierra Club. Very few pipeline distribution systems in the United States are suitable for hydrogen delivery, as hydrogen molecules degrade steel pipes and leak into the environment.
For now, hydrogen fuel cells are probably best employed in the long-distance trucking industry, where prototype trucks are still in development, Bottorff wrote.
Nevertheless, HVs today are where EVs were in the 1990s: taking their first steps toward emissions-free transportation.