I love movies that use science as an essential plot device. And then I love seeing what the experts say about what the movie got right and wrong.

Now, as a climate scientist studying hydrogen, I have a chance to share my expert take on Glass Onion: A Knives Out Mystery, where hydrogen plays a key role. 

Warning: Spoilers ahead!

Ed Norton holds a piece of solid hydrogen in Glass Onion: A Knives Out Mystery
Ed Norton plays an eccentric billionaire with big plans for hydrogen in Glass Onion. (John Wilson/Netflix)

At the center of this murder mystery, billionaire tech entrepreneur Miles Bron (played by Ed Norton) is about to launch a new solid hydrogen fuel as a climate-friendly, affordable home power solution. He says he's already running his luxurious Greek island villa entirely on hydrogen, and claims his fuel will soon be available all over America. But his friends and business partners who have gathered at the villa have some concerns. 

Like all good fiction, there are kernels of truth to this tale. But the real story of hydrogen is far more complex.

Here’s a quick rundown of hydrogen fact and fiction in Glass Onion.

Hydrogen as a solid fuel: Possible (kind of)

Pure hydrogen in solid form is technically possible, but slipping it in your pocket, as Bron does in the movie, is not. You’d need temperatures around -435 ºF (-260 ºC) at standard pressure to keep pure hydrogen in solid form.

However, it is possible to store hydrogen in a solid state if it's bonded with other compounds, such as salts. Companies in the Netherlands and Malaysia are exploring the use of hydrogen stored in solid form. But for now, the most commercially viable and scalable storage options for hydrogen gas are as a compressed gas or cryogenic liquid.

You probably wouldn’t put those in your pocket either.

Hydrogen-powered homes: Possible, but undesirable 

Bron’s seaside villa in the movie is entirely powered by hydrogen, which is possible in theory. Companies and governments are already pushing ahead with pilot hydrogen homes, using hydrogen fuel cells to supply electricity or swapping out natural gas for hydrogen in a boiler. 

However, using hydrogen in homes is just not a good idea. It's not affordable (as Bron claims) and not necessarily good for our health or the planet.

For one thing, isolating hydrogen is expensive and energy intensive. Also, we can’t use most of our existing natural gas pipes for pure hydrogen unless they are retrofitted. It’s far more energy efficient and affordable to use renewable electricity to directly power a home, than to use renewable electricity to make hydrogen to power a home.

Hydrogen for home heating may be reasonable in certain cold areas where heat pumps aren’t powerful enough, but not for most homes.

The ensemble cast gathered together in Glass Onion: A Knives Out Mystery
Scientist Lionel Toussaint (Leslie Odom, Jr., second from right) and others have concerns about hydrogen. (Netflix)

The whole world will run on hydrogen: Not likely

Bron touts hydrogen as the “fuel of the future” because it produces zero carbon emissions. And in reality, numerous government and industry leaders have made similar claims. This is because when hydrogen is burned or used in a fuel cell, it doesn’t produce carbon dioxide; and hydrogen can be extracted from water using clean, renewable electricity. Even Bron’s claim that his hydrogen is made from seawater isn’t far-fetched. There have been recent breakthroughs in using seawater to extract hydrogen.

However, there are some caveats that make a hydrogen takeover unlikely. Almost all hydrogen produced today is extracted from natural gas or coal, without capturing the carbon dioxide byproduct — far from climate-friendly. And even if we rapidly scale up our ability to produce hydrogen without fossil fuels, hydrogen is a leak-prone gas with a potent climate-warming effect of its own.

Also, when hydrogen is burned, NOx gas — which can cause asthma, bronchitis and increase the risk of heart disease — is created from oxygen mixing with nitrogen in the air.

In reality, a full-fledged global hydrogen economy is unlikely and unnecessary. Cars, homes and many other things currently powered by fossil fuels have more efficient, more environmentally friendly, and more affordable options than hydrogen, such as renewable electricity. 

Hydrogen will be most valuable where we don’t have cleaner alternatives, such as in heat-intensive industries like cement production, or long-haul heavy duty trucks, where electrification is difficult.

Risky hydrogen leaks: It’s not just about explosions it's climate, too

Hydrogen gas molecules are tiny and flammable, so leakage is a concern, as Glass Onion scientist Lionel Toussaint (played by Leslie Odom Jr.) rightly points out. Large leaks are a safety hazard, but we have systems capable of monitoring and minimizing these risks. Hydrogen has been used for decades — with the right equipment and safety precautions — without a major incident.  

But the movie misses a crucial point. Small hydrogen leaks, while unlikely to cause an explosive Hollywood climax, also pose a threat: to the climate. Hydrogen is an indirect greenhouse gas that can contribute to climate change when it leaks. And that’s a risk we haven’t yet addressed. 

We need to be careful not to build out an extensive hydrogen system that is as leaky as our current natural gas system. And right now, we don’t have the technology available to monitor small leaks of hydrogen. 

The bottom line

In an ideal scenario, hydrogen produced using renewable energy could nearly eliminate climate impacts compared with fossil fuels. But it's not a guarantee. I'm glad there are some real-world Lionel Toussaints who are working to make hydrogen safe and climate-positive — with LOTS of testing. 

Did any of this stop me from enjoying Glass Onion? No! I loved it. And frankly I’ve seen far more fictional science plots than this one!