National Grid’s green energy plans look like a carbon-free utopia. In an animation presented as part of the Climate Week NYC last week, the utility—which serves New York and Massachusetts—showed how wind farms off the shore of Long Island would be able to power facilities to produce hydrogen, which could then provide energy for ships, trucks, and aircraft, and back up regional electricity supply when the wind stops blowing. Plus, the hydrogen could heat buildings.
Currently, much of the energy to heat homes comes from fossil fuels. Last year, homes in the U.S. sucked up more than 4 trillion cubic feet of natural gas, producing about 250 million metric tons of CO2 emissions. Part of the solution, according to gas distribution companies like National Grid, is to use hydrogen produced from water and renewable energy to heat homes. It’s an idea not just being promoted in the U.S. but Europe as well, where the gas lobby is trying to boost hydrogen by discrediting increasingly popular electric heat pumps.
But while such initiatives might make sense for gas companies, they might end up costing the public far more in the long run. It’s more efficient and affordable, say experts, to heat homes directly with green electricity rather than using renewable energy to produce hydrogen for home heating. Those were the conclusions of a paper published today in Joule, which summarized the findings of 32 independent analyses on the topic. None of them concluded that widespread use of hydrogen for heating buildings was a good idea.
That’s not to say hydrogen isn’t useful for the energy transition. It’s highly energy dense, making it good for decarbonizing so-called “hard to abate” sectors of the economy where weight and volume are important considerations, like shipping or aviation. It just doesn’t make sense for heating homes when far more efficient solutions already exist, like installing electric heat pumps or connecting buildings together with district heating systems, according to the study.
Much of the reason for the disparity comes down to thermodynamics. You waste some energy when you use electricity to separate water into oxygen and hydrogen, which can then be used as fuel. And when you burn that hydrogen in a specially designed boiler, as some proponents argue we should, you lose more energy. Electric heat pumps, in comparison, can be about five times as efficient, according to the study, partially because of the fewer energy conversions required.
Not only then is heating homes with hydrogen more expensive due to the extra electricity required to make it, but doing so means we have to build even more solar and wind farms to get the same decarbonization result, in effect moving the goalposts of the amount of renewable energy required to decarbonize the economy.
That’s a big deal for anyone eager to see the world zero out its carbon emissions as soon as possible, a point made by the study author Jan Rosenow, director of European programs at the Regulatory Assistance Project, in almost deliberately staid terms. “The required build rate for renewables,” he wrote in the paper, “would be extremely challenging.”
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