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Climate change and energy

The 11th Breakthrough Technology of 2023 takes flight

Here’s what aviation and espresso have in common.

experimental hydrogen-fueled plane on the tarmac
Universal Hydrogen

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It’s official—after over a month of open voting, hydrogen planes are the readers’ choice for the 11th item on our 2023 list of Breakthrough Technologies

I’d like to thank the academy, and all of you, on behalf of hydrogen planes. This is an honor, a true honor. (By the way, if you haven’t seen the rest of this year’s list, check it out here.)

It just so happens there’s also some news about hydrogen planes this week. Startup Universal Hydrogen is planning a test flight for tomorrow. If all goes according to plan, it’ll be the largest aircraft yet to fly powered by hydrogen fuel cells.

So for the newsletter this week, let’s take a look at what Universal Hydrogen is up to, why its CEO says he wants to make the equivalent of Nespresso capsules for aviation, and what’s coming up next for hydrogen planes.

Aviation accounts for about 3% of the world’s greenhouse-gas emissions, and the field is growing. Most planes today run on a variation of kerosene, a fossil fuel that generates emissions when it’s burned in aircraft engines. This kind of jet fuel is hard to replace, since it carries a lot of energy in a small amount of space without being too heavy.

There are some options on the table to decarbonize flight. Batteries might work for shorter flights on smaller planes. Sustainable aviation fuels are another option—those can drop into existing planes but might be limited in supply and could be expensive. For more on these possible paths, check out the newsletter from a few weeks ago

Here, though, let’s focus on hydrogen. Efforts to fly planes using hydrogen as fuel date back to the 1950s. Interest has been rekindled recently as concerns about climate change have put a target on fossil fuels. 

Hydrogen is having a moment. More capacity for renewable energy means green hydrogen—generated using renewable electricity—is becoming more available, and cheaper. New subsidies for hydrogen are also coming online across Europe and the US. 

At the same time, there’s been some significant progress in efforts to fly hydrogen-powered planes in recent years. Startup ZeroAvia has been running test flights of small planes partially powered with hydrogen fuel cells. Airbus has also started up a program to test out hydrogen combustion engines. 

And Universal Hydrogen is joining the race this week. The company has a test flight planned for its Dash 8-300, a regional aircraft with over 40 seats. 

The major goal is to test out the propulsion system, which will use hydrogen fuel cells that turn hydrogen and oxygen into water vapor, generating electricity to power the plane. 

The aircraft will fly with hydrogen fuel cells powering one side while a traditional jet engine runs on the other. It’s a standard practice for testing out new systems in flight, says Universal Hydrogen CEO and cofounder Paul Eremenko. 

Even if the test flight is successful, there’s a long road ahead before cargo or passengers will climb aboard a hydrogen-powered plane. That’s because there’s a lot of infrastructure around airplanes, and a broad switch to hydrogen-powered flight may require rethinking a lot of it.

Take fueling, for example. Commercial airports today have an established network to fuel up planes. Jet fuel is carried in, usually on trucks or in pipelines to a central fueling system. Trucks can then pick it up and bring it to a plane as it sits at a gate.  

That whole system might not work so well for hydrogen, Eremenko says. Pipelines carrying hydrogen are prone to leak, and keeping hydrogen in a liquid form requires cooling it down to cryogenic temperatures, which often means there’s a lot of loss when moving it from one container to another. 

The solution, as Eremenko sees it, looks a lot like one of my prized possessions: a Nespresso coffee maker. Universal Hydrogen plans to build and use pods filled with hydrogen fuel that can be loaded and unloaded from its airplanes, preventing the need to transfer hydrogen between different containers. 

The test flight this week won’t use those pods, since the focus is making sure the plane’s propulsion system works as intended. The Dash 8-300 that will be flying will be powered using hydrogen tanks filled up before flight, but future test flights will use the capsule system to test out how that works in the air, Eremenko says.

In the longer term, Universal Hydrogen wants to build a solution for all the hydrogen planes he hopes will be taking off in the years to come. 

(As a side note, in order to fit these fuel capsules onboard, planes might need to get a little longer, Eremenko says. Others say planes might change shape completely to fly using hydrogen.) 

“It’s entirely doable for the [aviation] industry to decarbonize,” Eremenko says. The problem is that it needs to stop taking incremental steps, he says, and make the leap to hydrogen. 

Universal Hydrogen plans to launch planes into commercial service around 2025 with small, regional flights. After that, larger aircraft developers could incorporate room into future designs for the company’s hydrogen pods, and those planes could enter service as soon as the mid-2030s. 

Fresh bio-waste and compost

Another thing

One person’s food scraps could be another person’s treasure.

Companies are rushing to build anaerobic digesters, reactors that use microbes to break down organic materials. It’s the same sort of technology that’s used in wastewater treatment plants, but there’s a growing movement to use anaerobic digestion to cut methane emissions from farm and food waste. For more, on how it works and how it might help the climate, check out the full story

Keeping up with climate

Automakers are weighing how quickly they should go electric, considering mounting pressure to decarbonize along with realistic consumer preferences. (Wall Street Journal)

Toyota is among the companies betting hybrid cars will stick around for a while. For more on the hybrid strategy, check out my story from December. (MIT Technology Review)

Interest in building wind and solar projects is booming. But developers might be stuck waiting four years for approval to hook up to the grid in some places in the US. (New York Times)

Heat pumps are proving the haters wrong by taking off in Maine, one of the coldest places in the US. (Grist

→ Wondering how this tech works to heat and cool homes? I’ve got you covered. (MIT Technology Review)

It’s really hard to make fish-free fish. The tough part isn’t the taste; it’s the texture. But new advances could make your vegan sushi a lot better. (Scientific American)

The EU is introducing new rules for packaging in an attempt to cut down on plastic waste. The moves come ahead of a United Nations summit on such waste scheduled for May. (Bloomberg)

More money for battery recycling. The US Department of Energy awarded a $375 million loan to Li-Cycle to build out its facility in Rochester, New York. (Canary Media

→ Recycling for lithium-ion batteries is one of our 10 Breakthrough Technologies this year. (MIT Technology Review

Harnessing heat from the earth could help pull carbon pollution from the atmosphere. Geothermal power + carbon removal = good for the planet? (Washington Post

Remember that startup dabbling with geoengineering in Mexico? Take a look inside its efforts to launch another balloon. (Time)

→ My colleague James Temple broke the news of the group’s first foray in December. (MIT Technology Review)

Deep Dive

Climate change and energy

These artificial snowdrifts protect seal pups from climate change

The human-built habitats shield the pups from predators and the freezing cold, but they’re threatened by global temperature rise.

How thermal batteries are heating up energy storage

The systems, which can store clean energy as heat, were chosen by readers as the 11th Breakthrough Technology of 2024.

The hard lessons of Harvard’s failed geoengineering experiment

Some observers argue the end of SCoPEx should mark the end of such proposals. Others say any future experiments should proceed in markedly different ways.

Hydrogen trains could revolutionize how Americans get around

Decarbonizing rail transportation is a political problem as much as a technological one.

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