It’s lighter than air, more common than carbon, and burns with a bang into a puff of pure water vapor. Some see it as an essential element in decarbonizing electricity, transportation, and even steelmaking. Hydrogen is easy to love—but, for some of the same reasons, hard to handle. Recently, pressure has been building to make more of this gas and to use it to move energy in a form that can burn in power plants and steel mills, energize fuel-cell vehicles and generators, and combine with captured carbon dioxide to make liquid fuels or solid plastics. Japan, Australia, Saudi Arabia, and other nations are touting hydrogen production as a near-term priority and a major element in their long-term plans to decarbonize their economies. In a recent seven-part series on “The race to scale-up green hydrogen,” the Financial Times examined some of the 228 large hydrogen projects—involving $300 billion in capital investment—that have been announced. Hydrogen is high in the hype cycle. But we’ve seen exuberant predictions before that hydrogen’s ascendance was imminent—the Bush administration was bullish on it in the early 2000s—only to see those promises disappear in a flash. Today, the same questions that burst the hydrogen bubble 20 years ago remain unanswered and controversial. Make it from what? Move it how? And at what cost?
© Hydrogen Council
Hydrogen looks just as colorless whether it is split from water by electricity or yanked from fossil hydrocarbons. So what puts the green in “green hydrogen”? The answer is making the stuff from zero-carbon electricity and water. That’s not how it is typically done today. Only about 70 million metric tons of hydrogen are sold each year, and a meager 4% of that is the green variety. The rest is either “brown”—made from coal—or more commonly “gray hydrogen” produced by using superheated steam to strip H atoms off of methane’s CH4 molecules. For every kilogram of hydrogen made this way, 7 kg of carbon dioxide spew into the atmosphere. That’s bad. Less bad is “blue hydrogen,” still made from fossil fuels but with 50% to 95% of the resulting CO2 captured and permanently sunk underground, at substantial cost in both dollars and energy.
1. The ambitious vision is to turn the 4% green hydrogen / 96% gray hydrogen ratio upside down over the next 10 years—and to dramatically increase the total production of hydrogen at the same time. Technology Review laid out the vision in a recent article, noting that growing government mandates and subsidies for both green hydrogen and the cheap renewable power used to make it are reasons for optimism—especially if carbon surcharges erode the substantial cost advantage that fossil gas now enjoys.An eye-opening story in the Wall Street Journal described Saudi Arabia’s $500 billion plan to build a car-free megacity, complete with a $5 billion green-hydrogen plant, in a currently uninhabitable swath of its northwestern desert. The story reports that Australia is considering an equally bold, $36 billion-project to construct 26 gigawatts of wind and solar generation in its arid western state to power production of green hydrogen for export as well as domestic use.
2. But making hydrogen at a scale comparable to natural-gas production will consume enormous amounts of freshwater and vast tracts of land. Figure on zapping apart 10,000 liters of water with 50 MWh of electricity to make each metric ton of hydrogen, New Scientist reckons in a nice explainer of the technical obstacles and opportunities. That’s enough water to fill a small tanker truck and enough electricity to power four or five American houses for a year. Unfortunately, water is often scarce in places—like barren deserts in Saudi Arabia and Australia—where land is cheap and sunlight or wind are plentiful. Those places also tend to be remote. That brings us to the next big challenge….
You might think lightweight hydrogen (atomic weight: 1.008) would be easy to push around. But in fact, concentrating hydrogen and shipping it to end users is so difficult that it’s often hard to answer the obvious question: why not just use electricity instead?
1. It takes a lot of energy to move hydrogen from source to user. Every option available has issues. Gas pipelines work for short distances. But hydrogen is so light that pumping it hundreds of kilometers consumes as much energy as the hydrogen delivers. Germany has been talking to Russia—which supplies most of the natural gas that heats German homes, businesses, and factories—about mixing hydrogen into those streams as a workaround. As the New Scientist and Financial Times articles observe, gas companies like this idea, but many environmentalists do not. Japan is bullish on a second option: liquefying the hydrogen, and then loading it onto tanker ships and trucks. Later this year, Japan expects to receive its first oceanic shipment of 330,000 gallons of liquid hydrogen (the brown variety) from Australia. Kawasaki Heavy Industries reportedly is drawing up plans for hydrogen tankers with 128 times that capacity. But while it may be technically feasible to chill the gas down to a mere 20 °C above absolute zero, where it liquefies, the energy and expensive equipment involved make it very costly. Saudia Arabia says its megacity plant will bond the hydrogen it makes with nitrogen in the air to make ammonia (NH3), which is denser and liquefies at more reasonable temperatures. Concentrated ammonia is toxic, however, so storing and moving hydrogen in this form around cities could raise safety concerns. Then there’s the inconvenient physics that siphons energy away as hydrogen is made, moved, stored, and finally converted back to electricity (see graphic below). For charging vehicles, heating buildings, cooking, and other applications that can use electricity, hydrogen may have a hard time competing as an energy vector.
2. The tech industry may solve some of these problems down the road. Research into safer, more efficient, and more flexible ways to store and move hydrogen has been ramping up, with some encouraging results—including hydrogen goop. Hydrogen-burning planes have already taken flight, and aircraft companies are signalling robust demand that is attracting investment to meet the challenge.
1. Green hydrogen is still too expensive, but costs are falling fast. Although green hydrogen is still three to seven times the cost of gray hydrogen, “that is half of what it cost 10 years ago,” the Technology Review article points out. “And as the cost of wind and solar power continues to drop, and economies of scale around green hydrogen production kick in, it could get a lot cheaper.” The Hydrogen Council, an industry group that includes many of the fossil-fuel majors, recently plotted its aspiration: cutting the price of green H2 more than 60% by 2030. For the cheapest production sites, that might be enough to match the price of gray hydrogen. But fossil gas would still be cheaper, unless carbon pricing makes up the difference.
© Hydrogen Council
2. Green hydrogen will be costlier than it ought to be so long as we have to build way more production capacity than we need. Some argue that green hydrogen could help solve the intermittency problems of renewable power plants by storing energy they make when it is not needed. But the dynamic can flip when solar and wind farms are devoted to hydrogen production. In a sobering paper recently in the International Journal of Hydrogen Energy researchers modeled a national-scale system for Germany that integrated green hydrogen into electricity production. They warn that far more power generation and H2 production capacity would have to be built than is needed, to work around the intermittency of solar and wind power. As a result, much of the equipment would be underused, ruining the economics of the system.
What to Keep an Eye on
Underlying these questions surrounding making, moving, and pricing hydrogen is a crucial, fourth issue: one of trust. New Scientist and the Financial Times both point to a provocative report by corporate watchdogs in Europe, who documented in December that major players in fossil-fuel industries have been lobbying intensely for billion-dollar hydrogen projects that, they say, effectively subsidize existing natural-gas infrastructure and “maintain dependence on fossil gas, with a small volume of hydrogen to greenwash it.” Add to that worry this concern: will Russia and Saudi Arabia be trustworthy in putting only green hydrogen and not gray hydrogen into the pipelines and ships they send to Europe and Asia? More broadly, we’ll need to keep an eye on how hydrogen technology develops and scales up to check that it actually accelerates decarbonization, rather than slowing it down.