Solar power depends on the solar cell. Wind power, the wind turbine.
The key to the green hydrogen economy is a little-known machine with a name out of 1950s sci-fi — the electrolyzer. And after a century of obscurity, the electrolyzer’s moment has come.
The device uses electricity to split water into hydrogen and oxygen. If that electricity comes from wind turbines, solar panels or a nuclear reactor, the whole process gives off no greenhouse gases. Factories, power plants, even jet aircraft can then burn that hydrogen without warming the earth.
A Plug Power employee inspects a stack in Concord, Massachusetts. Photographer: Adam Glanzman/Bloomberg
There are other ways to make hydrogen fuel, from natural gas or even coal. But the methods to do it carbon-free, with no emissions that need to be trapped and stored, rely on the electrolyzer.
“I don’t think people grasp what an electrolyzer is,” said Andy Marsh, chief executive officer of Plug Power Inc., which makes the devices. “It is the building block of green hydrogen.”
Unlike wind turbines and solar cells, electrolyzers aren’t immediately easy to understand. Larger ones can look like a jumble of tubes and pipes, while smaller, more modular versions are collections of electronics and machinery crammed into boxes the size of a shipping container or even a fridge.
The Plug Power electrolyzer stacks shown here use a technology called “proton exchange membrane” or PEM, which features a solid electrolyte. Photographer: Adam Glanzman/Bloomberg
Scientists discovered the process the electrolyzer employs — electrolysis — more than two centuries ago, and commercial electrolyzers hit the market in the 1920s. They were the main way to produce hydrogen until the 1960s, when a process using steam to strip hydrogen from natural gas supplanted them. Almost all of the hydrogen used around the globe today — in oil refineries, fertilizer plants and chemical facilities — comes from natural gas. Demand for electrolyzers dried up.
That has now changed — in just the last few years. Measured by the amount of power the machines consume, worldwide electrolyzer sales doubled from 200 megawatts in 2020 to 458 in 2021, according to BloombergNEF, a clean energy research group. They’re expected to triple this year, reaching anywhere from 1,839 megawatts to 2,464 megawatts, BNEF predicts. It may be the kind of hockey-stick moment solar power experienced a decade ago.
“It’s going to be difficult to supply all the demand,” said Amy Adams, vice president of fuel cell and hydrogen technologies at Cummins Inc., a veteran engine maker that has jumped into the business.
Even more explosive growth likely lies ahead. Electrolyzer “gigafactories,” each able to make enough electrolyzers in one year to use at least 1,000 megawatts of power, have been announced in Australia, China, India and Spain.
“When somebody says they’re going to build a gigafactory, they’re talking about in a year having more capacity than is installed in the world today,” said Patrick Molloy, a manager in the climate aligned industries program at the US-based RMI energy and climate think tank.
These electrolyzer stacks, made by Cummins Inc., use “alkaline” technology. Photographer: Source: Cummins Inc.
Electrolyzers come in three basic flavors — alkaline, proton-exchange membrane (PEM), and solid oxide — with different pros and cons. All involve water reacting with oppositely charged electrodes and an electrolyte, sometimes liquid, sometimes solid. Competitors are vying to perfect each technology. They’re paring down the use of such expensive catalysts as iridium and figuring out better ways to build a product that, until now, was largely assembled by hand.
Driving all of this is the need for a clean, carbon-free fuel. Solar and wind power now cost less than new fossil fuel generation in much of the world, but storing that electricity in bulk remains difficult and expensive. And some things, like steel mills and jet planes, can’t easily run on electricity. A molecule that can be produced, stored, shipped and used without pumping heat-trapping carbon into the atmosphere would work far better. Governments and companies worldwide are betting hydrogen will be that molecule.
Plug Power has smaller stacks used for testing new materials at high temperatures and pressures. Photographer: Adam Glanzman/Bloomberg
For many hydrogen advocates, the electrolyzer is the missing piece to fulfill renewable power’s promise. It can take the excess electricity streaming from solar plants at noon and turn it into a fuel for use any time.
“That’s one of the things about electricity — we as consumers want it when we want it, and renewables don’t always work that way,” said Ian Russell, Bloom Energy’s director of development engineering.
Each type of electrolyzer has its selling points. Alkaline electrolyzers tend to be the least expensive and have become the technology of choice for Chinese manufacturers. They’re trying to undercut their global competitors on price — just as happened with solar cells a decade ago. PEM technology uses more rare metals and costs more, but it can start faster than alkaline, something worth considering if the power source is as variable as the sun and the wind.
The customers could, in the end, span many industries. Semiconductor and LED factories use hydrogen and could benefit from on-site production. Owners of solar plants and wind farms may want to add electrolyzers, just as they’re adding batteries to their projects today.
“We’re just at the beginning of where this industry’s going,” said Ole Hoefelmann, general manager of Plug Power’s electrolyzer business.
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