How green hydrogen could power industries from steel-making to farming

Hydrogen, the most abundant element, releases energy when combined with oxygen, and the only byproduct is water. That’s why politicians have touted it as the Swiss army knife of climate change, capable of powering a vast range of vehicles and industrial processes currently running on fossil fuels.

However, 99% of the current hydrogen supply is “gray” hydrogen, produced by the breakdown of methane or coal seam gas, a process that releases carbon dioxide. To achieve net zero emissions, many countries are considering relying instead on “blue” hydrogen, where this CO2 would be captured by the chimney and injected underground, or “green” hydrogen, produced by splitting water with renewable electricity.

Green hydrogen is “an important bet that Western countries should make” to compete with China in clean technology, UN chief Antonio Guterres said at a Dec. 3 conference.

The problem is that low-carbon hydrogen is at least twice as expensive as gray hydrogen. Scaling up production so that it becomes cheaper will require government subsidies. As countries like the European Union support the industry, President Donald Trump has begun canceling low-carbon hydrogen hubs planned as part of a $7 billion program in the United States.

As a result of these headwinds, analyst firm BloombergNEF has halved its forecast for low-carbon hydrogen production, to just 5.5 million tonnes by 2030, or about 5% of current gray hydrogen consumption. With supply limited, governments and businesses should focus only on uses of clean hydrogen that make the most sense for the climate and the economy, experts say.

“Hydrogen can do just about everything, but that doesn’t mean it should,” says Russell McKenna of ETH Zurich in Switzerland.

In a recent study, McKenna and colleagues analyzed the CO2 that would have to be emitted to produce and transport low-carbon hydrogen in 2,000 planned projects around the world, comparing it to the CO2 emissions that that hydrogen could replace. They found that hydrogen could have the greatest positive climate impact in the steel, biofuels and ammonia sectors.

On the other hand, the use of hydrogen for road transport, electricity generation and domestic heating would not reduce emissions as much.

Steel

In a blast furnace, coke made from coal provides not only heat to melt iron oxide ore, but also carbon for a reaction that removes oxygen from that ore. It is therefore not enough to heat the metal with renewable electricity. You need something to replace the carbon in the reaction, which hydrogen can do, emitting water rather than CO2.

“The technology we have today will make it possible to make iron on a large industrial scale from iron ore without producing CO2, this technology is hydrogen,” explains David Dye of Imperial College London. “Everything else requires inventing many future technologies.”

Stegra, a green steel startup, is building a factory in northern Sweden that plans to produce steel with an electric arc furnace and green hydrogen produced from river water on site by the end of 2026, becoming the first carbon-free steel mill. Projects are also underway elsewhere in Europe, Asia and North America.

But cheap, renewable electricity must be available to produce green hydrogen and power the arc furnaces. ArcelorMittal, a multinational steel company, this year refused 1.3 billion euros in subsidies to convert two steel mills in Germany to hydrogen, saying electricity prices were too high.

Ammonia

To grow, plants need nitrogen in the form of nitrates, but the soil contains a limited amount. However, in the early 20th century, chemists Fritz Haber and Carl Bosch developed a process for reacting abundant nitrogen in the air with hydrogen to produce ammonia, which can be converted into a variety of fertilizers.

This enabled a revolution in agriculture and a boom in the world’s population, and hydrogen is now widely consumed for the production of ammonia, as well as for oil refining. About 70 percent of all ammonia is used as fertilizer, while the rest is used to make plastics, explosives and other chemicals.

“We can’t electrify that… because it’s a chemical reaction that requires that input,” McKenna explains. “So we need hydrogen, but it has to be carbon-free hydrogen. »

Countries like Saudi Arabia have started building factories to produce hundreds of thousands of tons of green ammonia using solar and wind power, mainly for export. Meanwhile, start-ups are developing small, modular factories that produce green hydrogen and ammonia on-site on farms across the United States. But for now, all of these approaches rely on government investments or tax credits.

Alternative fuels

Ammonia can also be burned in an engine. While cars and many trucks can run efficiently on electricity, long-distance transportation like heavy trucks, ships and planes can struggle to transport and recharge batteries. Hydrogen will likely be crucial for making low-carbon fuels for this sector.

McKenna and his team’s study found that producing hydrotreated vegetable oil was one of the most efficient uses of hydrogen. This involves treating used cooking oil with hydrogen to break down fats into hydrocarbons that can be burned.

Ammonia and hydrotreated vegetable oil are being considered to replace heavy fuel oil in shipping, which accounts for 3% of global emissions. Aviation, with its similar carbon footprint, could also switch to ammonia.

But hydrogen could also be used to make synthetic aviation fuel, which could power any plane today, because it is almost identical to kerosene, produced only without petroleum.

Longer term, researchers at institutions like Cranfield University in the United Kingdom are designing planes with ultra-strong tanks to hold compressed hydrogen. While hydrogen or ammonia produces nitrogen oxide pollution when burned, they can combine with oxygen in a fuel cell to produce electricity and water. Fuel cell aircraft are the ultimate goal, says Phil Longhurst of Cranfield University.

“Hydrogen is the cleanest, most zero-carbon fuel we can get,” he says, “so it’s kind of the holy grail.”