Before she begins her talks about hydrogen’s potential at eco conferences and other events, Environmental Defense Fund (EDF) senior climate scientist and Princeton Ph.D. Ilissa Ocko likes to ask how many people in the audience have seen the Hollywood film, Glass Onion.
A show of hands—and murmurings about whether or not attendees enjoyed it—ensues.
In the movie, Ocko continues, a reckless billionaire has found a solution to earth’s climate woes: a hydrogen-based clean fuel.
It’s a novel—and layperson-friendly—way to get into a sticky subject. Hydrogen has, in real life, been touted as a cure-all when it comes to creating a net-zero economy. Tens of billions of dollars from public and private spheres have been pledged to projects and within the next decade the amount is expected to grow to hundreds of billions. Those include $8 billion the Biden administration has set aside for the creation of clean hydrogen hubs, where producers and consumers can soon test out the most promising among them. But as Ocko and other experts know it’s, well, complicated.
First, the good news. Hydrogen comprises 90 percent of the universe’s atoms and is present in plants, animals, water and even our very selves—binding our DNA. So it’s abundant. It’s also carbon-free in the form we use it (as two hydrogen atoms bonded together). It’s versatile too. Hydrogen can be burnt as fuel, converted into electricity, used to refine or make other fuels, and to create chemicals used in everything from household cleaning products to butter.
But despite hydrogen being cited as a potential solution in almost all past energy crises, enthusiasm is typically short-lived. Why? Essentially: It’s always proven too expensive when compared to nonrenewable energy. Ocko is blunt when asked what’s different now: “Today, we have a crisis unlike anything we have ever known,” she told attendees at the Techonomy Climate conference in March. “And the entire world desperately and urgently needs to get off fossil fuels.”
But its problems don’t end with cost. For one thing, hydrogen rarely occurs on its own in nature and is often tied up in larger molecules like water, so it needs to be made. That process is rife with potential for greenhouse gas emissions. There are two fairly clean processes that are currently available: “Green” hydrogen is created using renewable electricity and water, and “blue” hydrogen uses natural gas—a fossil fuel—but captures most of the CO₂ created in the process. Still, the methods aren’t foolproof. In the former case: Renewables are limited and using them to create hydrogen could cut into wind- and solar-generated electricity needed to decarbonize the power grid. And in the latter case: today’s carbon capture technology varies widely in efficiency, sometimes only grabbing 65 percent of the emitted CO₂. Because blue hydrogen creation involves natural gas, which contains methane, and methane emissions from human actions are causing at least a quarter of the planet’s warming, leaks are problematic.
Hydrogen, while indeed being carbon-free, also isn’t climate neutral. Translation: It too can warm the planet. The process through which it does so is different than that of carbon dioxide, which itself traps heat. Hydrogen warms the earth as the result of reacting with molecules in the atmosphere—which trigger effects that ultimately lead to more greenhouse gasses. But it’s potent. Over a 20 year period, hydrogen emissions are roughly 40 times more powerful at warming the climate than an equal amount of carbon dioxide. Its effects though are short-lived, which again makes it different than CO₂, which can cause warming for centuries. But the leaks which lead to them are likely.
Is hope lost? Absolutely not, say Ocko and colleagues. But controlling leaks, as well as intentional venting and purging during hydrogen operations, is crucial. This may not be simple. Current sensors only monitor large leaks that threaten safety because they could lead to explosions. Detecting smaller leaks, like those that lead to hydrogen warming effects, is not possible, so getting a handle on the problem is challenging. Estimates of emissions rates across the value chain vary widely, ranging from less than 1 to 20 percent. The overall amount will make a difference. If green hydrogen leaks are kept to the minimum almost all warming can be curtailed and even if leakage is high at 10 percent, warming impacts from fossil fuel systems can be reduced by 80 percent over a 100 year period (the typical temporal metric). When considering the effects of 10 percent leakage in the next 20 years, however, green hydrogen lowers warming impacts by only 65 percent. That’s still beneficial but not ideal. When it comes to blue hydrogen the picture is worse. Keeping leaks of hydrogen plus the methane involved in that process to 1 percent would deliver a 75 percent reduction in emissions over 20 years. Again, that’s not bad. But if the emissions are 10 percent for hydrogen and 3 percent for methane, it could lead to 25 percent more warming than fossil fuels.
The key is to keep researching, innovating and adapting, Ocko says. At the top of EDF’s list of recommendations: Make sure green hydrogen is made without cutting into renewables used to decarbonize the electricity grid. Make sure blue hydrogen is made with the best carbon capture and storage techniques, and set a high bar for cutting methane emissions. And design systems strategically to minimize hydrogen leakage. (This will entail developing sensors to detect small leaks. EDF is partnering with the company Aerodyne, which is developing a first-of-its-kind instrument to do so. EDF will test and use the product.) Finally: Only use hydrogen in cases where it’s the most climate-friendly solution. When it comes to powering cars and heating homes, for example, direct electrification can be up to 9 and 16 times more efficient, respectively.
Ocko says, “Hydrogen has an important role to play” in a clean energy future. But it’s not a simple panacea, “and people need to be aware of that more.” To urge caution, she ends her talks by going back to Glass Onion. In the final scene protagonists sit in the dark, having made a series of disastrous decisions. An alarm keeps sounding.