When most people picture greenhouse gas emissions, they think about cars and electricity. That’s because they turn keys, press buttons, and flip switches every day. The good news is, we already have ways to decarbonize these types of emissions (solar, wind, and nuclear power and lithium ion batteries). The bad news is, they add up to only about one third of the total.

The other two thirds—almost 35 billion tons—are much harder for most people to see. For example, we all use products made of cement, plastic, and steel, but most of us don’t manufacture them or load them onto cargo ships. To zero out emissions on these products, we need new technologies. Enter clean hydrogen. It has so many potential uses that some people refer to it as the Swiss Army Knife of decarbonization.

What hydrogen can do

The world already uses 70 million tons of hydrogen each year as a chemical in some manufacturing processes like making fertilizer. Today, nearly all that hydrogen is produced from fossil fuels. If we make that hydrogen clean, we eliminate the 1.6 percent of global emissions that it is responsible for now.

But that’s just the beginning. Hydrogen is pure, reactive chemical energy. If we can bring the cost down far enough and make enough of it, we can also start using clean hydrogen to replace fossil fuels in all sorts of other industrial processes, including important ones like making plastic and steel, liquid fuels, and even food. (It’s called the Swiss Army Knife for a reason.)

In addition, clean hydrogen opens the door to all sorts of possibilities beyond industry. For example, as more and more electricity comes from variable sources, the world will have to get better at balancing energy supply and demand so we don’t go dark when the sun isn’t shining or the wind isn’t blowing. Electricity can be converted into hydrogen through a process called electrolysis, then stored for months at a time, and finally converted back into electricity when it’s needed.

Another potential use for hydrogen lies in heavy-duty transport. Battery-electric vehicles work great for passenger transportation and trucking over shorter distances, but aviation, shipping, and long-distance trucking remain a challenge. And together they account for 8 percent of global emissions. Clean hydrogen has the potential to provide a net-zero solution for moving cargo around the world.

So in theory, clean hydrogen can do a lot of things we need to do urgently. And governments in many European countries, Australia, Japan, and the United States have ambitious plans for using it to decarbonize their economies. But how do we make hydrogen clean in practice?

How to make hydrogen clean

Innovators are working on several different technologies, some of which are more mature than others.

One option is to use solar, wind, or nuclear power to turn water into hydrogen and oxygen. This process, known as electrolysis, was invented in 1800 using the first-ever battery that had just been invented by Alessandro Volta. More than two centuries later, the same basic principle may be the key to massive clean hydrogen production. There are four different electrolyzer technologies being developed, and the price of each one needs to go down to make electrolyzed hydrogen cost-competitive.

Another option is to produce hydrogen using the current methods that burn fossil fuels and then capture the CO2 produced in the process before it’s released in the atmosphere. It may never be economical to capture 100 percent of the carbon released using incumbent technologies, but while we’re waiting for thousands of industrial facilities to retrofit their infrastructure, carbon capture can help drive emissions way down.

Other clean hydrogen technologies are further away.

Methane (CH4) is the primary fossil fuel used to produce hydrogen now. When it reacts with water (H2O) at a high temperature, both H2 and CO2 are produced. However, through a different heating process that happens in the absence of oxygen, called pyrolysis, it’s possible to separate the hydrogen atoms and leave just solid carbon—think of the lead in a pencil.

Finally, there are reserves of hydrogen in geologic formations around the world, and in theory geologic hydrogen has the potential to provide a vast supply of affordable, zero-emissions hydrogen. Scientists are still in the early stages of researching ways to find and extract geologic hydrogen from natural reserves.

Making clean hydrogen cheap

So the potential of clean hydrogen is tantalizing, and its necessity is becoming clearer every day. Take Russia’s war in Ukraine, which has made hydrogen not just a climate change issue but also an energy security issue. The EU has already announced its intention to produce and import 20 million tons of green hydrogen by 2030, enough to reduce its dependence on Russian natural gas imports by at least a third.

But hydrogen faces the same challenge as just about every other clean technology: Can we get the price down far enough, fast enough? If people have to pay too much to be green, change will happen too slowly. But if we get the Green Premiums down near zero, there is a chance to build a prosperous net-zero economy. It’s going to take a big push for collaboration between business and governments, which, together, can make innovation happen much faster than usual by being aggressive with investments and policies.

Breakthrough Energy, the climate initiative I helped start, is supporting the commercialization of clean hydrogen in many ways. The Breakthrough Energy Fellows program funds innovators working on early stage ideas. Breakthrough Energy Ventures invests in companies working on clean hydrogen. And the Breakthrough Energy Catalyst program speeds up the time to market for clean hydrogen, among other climate technologies.

The more everyone gets excited about the many benefits of clean hydrogen, the faster businesses and governments will put in the work to make it a real alternative to fossil fuels. That’s how we avoid a climate disaster.