US President Joe Biden has committed $8 billion ($11 billion) to build at least four “hydrogen centers” where the fuel will be produced and used, and nations are preparing for competition. US utility companies now providing natural gas see it as a savior, announcing more than two dozen hydrogen pilot projects in the past two years.
“Now is the time when decisions are made, and money is spent,” Oko said. “We can move on with this problem now, so that it doesn’t become a problem.”
She and others who have sounded the alarm insist there is no reason to give up hydrogen. Instead, thermal hydrogen retention means that any future gas production, distribution and use system must be built to reduce leaks.
Keeping hydrogen leakage rates low
“There is great potential to use hydrogen to save a lot of CO2 emissions, but it’s really important to keep hydrogen leakage rates low,” said Nicola Warwick, lead author of the study in the UK and the National Center for Atmospheric Sciences. at the University of Cambridge.
The hydrogen industry acknowledges the problem, even if companies disagree on the potential scale. Dave Edwards, of industrial gas company Air Liquide, said the effects of hydrogen leakage on the atmosphere should be much less than the conventional fuels they replace. Running cars and trucks on hydrogen fuel cells will have less atmospheric impact than running them on gasoline and diesel, even if the hydrogen making and delivery system is leaking.
Edwards, a director at the company and a leading advocate for hydrogen in the United States, said. He said the hydrogen leak was “remediable problems”.
Hydrogen has great advantages as a clean fuel. Burning hydrogen in a turbine, it will generate power without carbon dioxide. Run it through a fuel cell, and it will produce electricity with water vapor as the only exhaust. Unlike solar and wind energy, it can be stored in large quantities when needed. While the vast majority of hydrogen produced today is stripped from natural gas, in a process that releases carbon dioxide, it can also be separated from water using renewable energy, with no emissions other than oxygen.
Hydrogen can easily slide through equipment
But for all its benefits, hydrogen can easily slip through equipment designed to contain larger molecules like methane in natural gas.
Once it escapes, much of the leaked hydrogen will be absorbed by the microbes in the soil. Some of what’s left in the air reacts with a substance that helps remove methane from the atmosphere. This is a problem, because methane itself is a potent greenhouse gas, with more than 80 times the global warming potential of carbon dioxide over a 20-year period. The reaction between hydrogen and that substance — known as a hydroxyl radical, or OH — leaves little OH available for reaction with methane. So the methane entering the atmosphere will stay longer and do more damage than it would if the hydrogen wasn’t present.
Leaking hydrogen also has other warming effects. In the troposphere, the layer of the atmosphere closest to Earth, it sets off a series of chemical reactions that produce more ozone, another greenhouse gas and a major component of smog. Much higher, in the stratosphere, hydrogen leads to more water vapor, which has the general effect of trapping more heat energy in the atmosphere.
Such reactions occur over a short period of time – a few years. By contrast, excess carbon dioxide causes atmospheric heat to accumulate over centuries. But with temperatures rising rapidly around the world, scientists say the short-term drivers of climate change cannot be ignored.
“These contracts are important,” said Stephen Hamburg, chief scientist at EDF. His group was trying to raise the question of the possibility of hydrogen warming with anyone who would listen, briefing academics, companies and the US Department of Energy. His colleague, Ms. Oko, estimates they have met about 200 people so far. For EDF, this is a logical extension of the group’s work that attempts to draw public attention to short-term climate pollutants such as methane and black carbon, which are often overlooked when focusing on carbon dioxide.
Recipe for leaks
Several utility companies are experimenting with hydrogen blending in their existing natural gas pipelines, the sprawling networks that feed everything from power plants to home stoves.
For Mr. Hamburg, this is a recipe for leaks. He also warns that mass production of hydrogen from fossil fuels could lead to a short-term increase in warming, if hydrogen making and transportation systems leak enough hydrogen and methane. There is still a long-term benefit from reducing carbon dioxide emissions. But over a decade or two, a leaky hydrogen system that relies on fossil fuels can cause temperatures to rise more than usual.
“Over several decades, you could be in worse shape – it’s very reasonable,” Hamburg said.
The case did not prevent gas utilities from exploring hydrogen blending projects. But it could become one of the things those projects are considering. California PG . Benefit&E announced plans last month to test a different blend of hydrogen and natural gas in a dedicated pipeline system separate from the company’s usual gas transmission network, with the blends burning at a power plant south of Sacramento. PG&E spokeswoman Melissa Sobotin said the company’s “Hydrogen to Infiniti” project would study the possibility of leaks.
“Extensive research must be conducted to understand the feasibility of injecting hydrogen into a natural gas pipeline system,” she wrote in an email.
Hamburg said a leak-ridden hydrogen economy would undermine its effectiveness, and would deal less of a blow to climate change than it could. Clean energy advocates point out how methane leaks from natural gas wells and pipelines — which turned out to be more prevalent than previously thought — have undermined some of the benefits of converting coal-to-gas power plants. They don’t want that to happen with hydrogen.
“We are at risk of moving forward with new infrastructure that will essentially repeat all of that past damage,” said Julie McNamara, deputy director of climate and energy policy at the Union of Concerned Scientists. “We don’t have the time or the luxury to get it wrong.”