Does hydrogen have any hope as a clean fuel?

This story is part of Recode by Vox’s Tech Support series, which explores solutions for our warming world.

Between the battery electrics, plug-in hybrids, and radar-festooned self-driving cars on the streets here in San Francisco, the slick red Toyota Mirai doesn’t turn many heads.

That’s despite it being one of the most technologically advanced cars in the world and one of the rarest. Since it went on sale in 2015, Toyota has sold only about 10,000 of the sedans in the United States (out of a total of approximately 290 million registered cars in the country). Yet it easily blends in with traffic.

The Mirai takes styling cues from Toyota’s more mundane offerings, like the Corolla and the Camry. Inside the cabin, it has the fit, finish, noise isolation, and heated seats of a luxury car. Behind the wheel, the Mirai has the torquey pull of an electric motor, launching up steep streets and feeling far more nimble than its 4,200-pound weight would suggest.

It’s only when you pop the hood that you can see what sets the Mirai apart: a tidy silver block with the Toyota logo and the words “fuel cell.” And behind the back seat is a tank filled with hydrogen gas — the most abundant element in the universe, and potentially a clean fuel whose main “waste” product is water.

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The world is desperate for more ways to curb carbon dioxide pollution. According to the Intergovernmental Panel on Climate Change, global greenhouse gas emissions have to peak and decline by 2025 to keep warming this century below 1.5 degrees Celsius. That’s less than 1,000 days away, yet global emissions are still rising. And transportation alone accounts for 20 percent of global emissions.

That’s where hydrogen energy comes in — companies like Toyota think it could be the future, or at least a part of it (“Mirai” means “future” in Japanese). While other clean energy technologies like battery-powered vehicles have gained momentum, they aren’t rolling out fast enough or cheap enough. Hydrogen could help get the world to its climate goals faster by powering not only cars like the Mirai, but also ships and aircraft in the near future.

Hydrogen has potential uses beyond vehicles, too: It can make synthetic fuels and store power for the electricity grid; it can also clean up industries that are notoriously hard to decarbonize, like steel manufacturing.

These promising use cases have driven interest and investment in hydrogen as fuel in the past, which is why you may have heard about it before: Presidents George W. Bush and Barack Obama touted hydrogen and invested government money into researching and developing the fuel. But the hype faded each time as high production costs, practical challenges, and a limited infrastructure for hydrogen-powered vehicles got in the way. For hydrogen-powered cars to truly take off anywhere, they’ll first require a vast network of fueling stations, pipelines, and producers — essentially a hydrogen economy — to compete and win against fossil fuels. The US has never gotten close to building something like this.

But for now, the momentum behind hydrogen energy is once again building as its demand grows and the technology behind it improves. According to 2018 data, hydrogen fuel cells have dropped 60 percent in price since 2006, while their durability increased fourfold.

In 2021, Toyota sold more than 2,600 Mirais in the US, a record. Other hydrogen cars have entered the market too, including the Hyundai Nexo and the Honda Clarity. As of March 1, more than 12,000 hydrogen fuel cell vehicles have been sold or leased in the US. Meanwhile, Delta Airlines and Airbus in March signed an agreement to develop hydrogen-powered aircraft. New hydrogen production plants are in the works in the US. In February, President Joe Biden signed an executive order pledging close to $10 billion to boost hydrogen production, infrastructure, and research.

Overseas, China announced plans to produce as much as 200,000 tons of carbon-free hydrogen per year to help run a fleet of 50,000 fuel cell-powered vehicles by 2025. The United Kingdom is aiming to double its hydrogen production. Globally, hydrogen production and transportation has received more than $80 billion in investment.

In a moment when the urgency of the climate crisis cannot be understated, hydrogen is getting another chance to help clean up the planet.

The hydrogen palette, explained

Like many clean technologies, hydrogen has tricky nuances, especially when it comes to its “clean” credentials. For one thing, many researchers and engineers would argue that hydrogen is not an energy source; it’s an energy carrier. It’s analogous to a battery, which can hold energy but still needs another way to charge it. While hydrogen is the most abundant element in the universe, it’s usually attached to other molecules here on earth.

To use it as a fuel, you must first form hydrogen gas, H2 (two hydrogen atoms stuck together), which requires a source of hydrogen atoms and an energy input. Hydrogen gas is more of a middleman between an energy source and its use in a car, boat, or power plant. It often takes more energy to make H2 than you get from using it, similar to how a battery requires a bit more energy to charge up than it releases in use. According to the International Energy Agency, hydrogen production accounts for 830 million metric tons of carbon dioxide emissions per year, equivalent to the footprint of the United Kingdom and Indonesia combined.

Hydrogen itself is an odorless, colorless gas no matter how it’s produced, but the various ways to make hydrogen are typically categorized by color. The main types of hydrogen to pay attention to are gray hydrogen and green hydrogen.

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In the US, 95 percent of hydrogen is gray hydrogen, which is made with steam-methane reforming. The process uses steam as hot as 1,800°F to react with methane under high pressure, yielding hydrogen, carbon monoxide, and carbon dioxide. It’s cheap, but it has a carbon footprint: Every kilogram of gray hydrogen results in about 10 kilograms of carbon dioxide.

Green hydrogen, on the other hand, draws on renewable energy to split water into hydrogen and oxygen, a process called electrolysis. It produces zero carbon dioxide emissions, but it’s upward of twice as expensive to produce as gray hydrogen and it accounts for less than 1 percent of the world’s hydrogen production.

There are other colors too — blue, pink, turquoise, black, white — distinguished by where the hydrogen comes from and how much carbon dioxide the process emits.

For hydrogen to truly help with confronting the climate crisis, the world must figure out how to produce cleaner hydrogen at larger scales and lower cost. Last year, the US Department of Energy launched a research program called Hydrogen Shot with the aim of making clean hydrogen for $1 per kilogram in 10 years.

As for using hydrogen, there are two main ways to put it to work. One is to burn it like any other gas in engines, similar to conventional internal combustion engines that run on fuels like gasoline and diesel. Unlike those fuels, hydrogen doesn’t release harmful emissions when you burn it. The other way is to send hydrogen through a fuel cell. This device separates hydrogen into protons and electrons, with the electrons generating a current to power a motor and the protons reacting with oxygen in the air to make water.

Fuel cells actually have a long history dating back to the 1800s. But only in recent years did their cost, efficiency, and durability reach the levels needed for more widespread use.

With both fuel cells and combustion, hydrogen’s uses can scale from small unmanned aircraft to storing and dispatching electricity on the power grid. Its potential to reduce emissions is very real — but a lot has to fall into place first.

What it’s like to own a hydrogen fuel cell car

The ins and outs of owning a hydrogen-powered car illustrate the fuel’s promise, but also the immense hurdles it will have to overcome in order to take a bite of greenhouse gas emissions and anchor a new clean industry.

There are big advantages to a hydrogen car: It can refuel in five minutes, compared to sometimes hours of charging needed for a battery electric car. You also don’t need access to a car charger, but rather a pump similar to one used for gasoline, often at the same station.

That’s one reason that motivated Darren Higuchi of Alameda, California, to buy a Mirai last year. Since he lives in a multifamily building, Higuchi said he doesn’t have the option to install a car charger at home. “I see people lining up for [the Tesla supercharger nearby], parking and waiting, and that’s more maintenance than I want to deal with,” he said.

Hydrogen fuel cell cars have the same smooth and quiet electric drivetrain as battery-powered cars, which also brings lower maintenance costs compared to gasoline and diesel engines. Drivers can use carpool lanes in most states as well.

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There are financial incentives, too: Mirais come with a factory rebate, a federal tax credit, and California’s clean vehicle credit, which drops its out-the-door price from around $60,000 to $35,000. Toyota also gives owners $15,000 worth of hydrogen fuel for free. Out of pocket, filling up a Mirai costs between $70 to $100 and provides close to 400 miles of range.

But for all the work Toyota put into making an appealing hydrogen car, its biggest drawbacks are beyond the company’s control.

Most of the hydrogen fueling stations in the US are in California. The state has 52 hydrogen stations, including two in San Francisco, and 121 in development, according to the California Fuel Cell Partnership. But the stations are mainly concentrated around the San Francisco Bay Area and Southern California. There’s just one hydrogen station on the 340-mile I-5 stretch between the Bay Area and Greater Los Angeles.

On a road trip to San Diego in his Mirai, Higuchi said he gamed out the locations of hydrogen fueling stations, how fast he wanted to drive, and how much we wanted to test the range of the car. “I mapped out where I would go and paired that to anxiety levels,” he said.

Right now, hydrogen infrastructure is caught in a rut. With so few hydrogen cars on the road, it’s hard to convince companies to invest the approximately $2 million it typically costs to build a single hydrogen station. But with so few stations, it’s tough to sell drivers on a hydrogen car.

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The small scales of hydrogen production have also left it vulnerable to shocks. Right now, most hydrogen produced in the US is used for chemical manufacturing. “We’ve been living off of surplus hydrogen that is being taken from other industries and being used for transportation,” said Russ Mobley, a sales manager at San Francisco Toyota and a Mirai owner.

In 2019, a hydrogen explosion at a Santa Clara plant caused shortages across the Bay Area for nearly six months. During that time, Toyota gave Mirai drivers free rental cars to get around. “We didn’t drive our hydrogen cars. They became paperweights at that point in our driveways,” Mobley said.

Compare these ordeals to battery-electric cars, which can charge up just about anywhere there is a power outlet or at one of the fast-charging stations cropping up quickly around the country. So while hydrogen cars themselves may be excellent, the weak infrastructure to support them continues to hold them back.

Hydrogen needs to go big before it can go bigger

The infrastructure hydrogen needs poses its own technical challenges. It requires high-pressure pumps, fittings, and storage containers, many of which are expensive boutique products. The Covid-19 pandemic then threw up another roadblock, disrupting the supply chains for hydrogen construction projects.

“These pumps are all handmade,” Mobley said. “When the entire world shuts down and nobody’s in there manufacturing the bolts and nuts and seals, pretty much we saw the construction halt.”

The hope now is that with larger players like trucking and delivery companies investing in their own hydrogen vehicles, they will drive economies of scale for everyone. With larger vehicles, planned routes, and centralized fueling, these industrial uses might be even a better use for hydrogen than passenger cars. “As we rotate into more of the trucking industry getting into using hydrogen technology, the infrastructure is going to be beefed up considerably,” Mobley said.

Daimler Truck, for example, is one of the world’s largest manufacturers of commercial vehicles, accounting for about 58 percent of the market for large highway trucks. The company has already received approval for a hydrogen-powered truck in Germany and expects to begin delivering hydrogen trucks to customers in 2027. It’s also a shareholder in H2 Mobility Deutschland, a hydrogen fueling station operator that recently raised 110 million euros from investors. In addition, Daimler has teamed up with Volvo to build a fuel cell factory scheduled to begin operation in 2025.

Meanwhile, delivery firms like DHL, Royal Mail, FedEx, UPS, and Swiss Post are currently testing out hydrogen vehicles on their routes.

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As for industrial uses, Swedish steel manufacturer Hybrit last year began delivering steel made with a hydrogen-based process that emits zero greenhouse gasses. Steel production accounts for around 7 percent of carbon dioxide emissions. According to Bloomberg New Energy Finance, decarbonizing the industry with hydrogen would require $278 billion in investment through 2050.

On the production side, green hydrogen also needs to scale up to drive down costs. The question is whether countries and companies can brute force an entire clean hydrogen industry into existence fast enough to meet climate targets.

For its part, California thinks hydrogen is worthwhile. Last October, the California Air Resources Board put out a report on hydrogen infrastructure in the state. Looking at various scenarios, the report concluded California could run a self-sufficient hydrogen network servicing 1.8 million fuel cell cars by 2035 with about $300 million in state funding.

Toyota, meanwhile, is hedging. The company is investing $17.6 billion to produce a line of 30 battery electric vehicles by 2030. Daimler is also pursuing battery-electric trucks alongside hydrogen. Batteries have experienced a stunning 97 percent drop in costs over the last 30 years, and battery-powered vehicles are already gaining ground around the world.

Some analysts are skeptical that hydrogen could ever catch up, at least for cars and trucks. “[T]he window of opportunity to establish a relevant market share for hydrogen cars is as good as closed,” argued Patrick Plötz, coordinator of the energy economy business unit at the Fraunhofer Institute for Systems and Innovation Research in Germany, in Nature Electronics earlier this year.

For trucks, manufacturers and governments need to make stronger and faster efforts to deploy them if they have any hope of hitting highways. “If truck manufacturers do not start the mass production of fuel cell trucks soon to reduce costs, such vehicles will never succeed in low-carbon road transport,” he wrote.

But Plötz said hydrogen still could play important roles in decarbonizing aviation, shipping, and industry.

So even though some of the largest car and truck manufacturers are trying to force a hydrogen economy into existence, it could be yet another false start. After decades of hype and continued growing pains, it’s tough to get excited about hydrogen again. But the potential for hydrogen as a pillar of clean energy is impossible to ignore, and with more investment than ever and the urgent need for tools to slow climate change, this might be the moment it finally ignites.