As a private pilot I am SO looking forward to finally be able to do away with piston engines and fly electric...
I expect short range electric commuters will come first - similar to cars.
There's a Pipistril Velis Electro[1] that shares a hanger with my flight school. It can only fly for about 30 minutes + 30 mins reserve with 2 relatively light pilots. If it had a battery which allowed for 2 hours of flight you've now tripled your range - 1.5hours + 30 mins reserve. That would cover all ab-initio training.
A battery like the one in the article would expand the range further to cross country capability and/or higher useful load, with the complete reconstruction of a piston engine every 2000 hours gone from the equation. Can't wait.
1. https://www.pipistrel-aircraft.com/products/general-aviation...
A gallon of gas weighs about 2.7 kg, so the gas is about 12.3 kWh/kg. If we adjust this type of battery to account for the difference in efficiency, it is about 4.3 (equivalent) kW/kg.
Ok, so that's still a factor of 3 worse. However, all the gas in the Cessna weighs about 336 lbs. The engine weighs about 250 lbs. A comparable electric motor is about 70 lbs. That gives you another 180 lbs, or over 50% more weight to fill with batteries.
Now we're at about 50% of the useful energy of the Cessna. You can also factor in a little bit of gain from "regenerative braking" since the electric airplane can charge the batteries while descending. This may not make a huge difference in range for just point to point flying, but it does add some extra for flight training with lots of landings, and also provides some extra reserve in the case of a missed approach for example.
All of that is to say that this doesn't bring the small electric airplane to parity with gasoline, but it's starting to much more credibly inch in on its turf.
Also, hyper efficient aircraft like the LongEZ (2000mi range on 52usg) become more interesting. Most legacy piston singles are horribly inefficient aerodynamically, to the point where just comparing them by frontal cross section is a completely legitimate strategy. A large amount of thrust is wasted just cooling the engine and the wings on most Cessna's are not flush riveted, seams not covered, etc. People often wonder why multi engine aircraft don't have 2x the performance; they have over 2x the cross section. Composite aircraft have the potential to allow for extremely competitive designs.
I've done estimates before suggesting we don't even need 50% of the performance, but rather somewhere around 30% to start to be competitive. 1.2kw/kg is well beyond viable.
I know hybrids don't make as much sense for planes because the throttle range is typically 50-100% through a flight vs cars where you spend tons of time down at 10-15% throttle and need only bursts of power.
https://hydrogen.aero/product/
Seems promising because they don't have to fully design a new aircraft, they just have to get the new powertrain certified. Though the same end-customer airline (Air New Zealand) is also eyeing off some new-build battery-electric aircraft with 250nm range and 30 min recharge times.
Joby Aviation (the air taxi developer) also bought a company that's been working on a hydrogen fuel cell light aircraft. The power density of fuel cells density would make VTOL air taxis a whole lot more plausible (though you've still got a distinctly nontrivial hydrogen storage problem). [1] There's another startup called HyPoint working on fuel cells specifically for aircraft [2], though they haven't announced a whole lot recently.
[0] https://edition.cnn.com/travel/article/airbus-fuel-cell-engi...
[1] https://evtolinsights.com/2022/07/hydrogen-fuel-cell-company...
Most hydrogen trucks use compressed gas instead. At around 200 bars, the energy density by volume is about 18x that of diesel. So, you need a huge tank for the same amount of energy. And also 200 bar means it needs to be a really strong tank. Hydrogen trucks aren't really competitive with battery electric trucks for this reason.
You need a lot of infrastructure and you add a lot of weight and complexity to the trucks. The handful of hydrogen trucks driving around have in common that they are expensive, don't have a lot of range, and need to be supplied via an as of yet non existent distribution network for hydrogen. If you truck the stuff around, you need 18 trucks for every diesel truck to move the equivalent in energy.
All that volume is a show stopper on planes. We're talking about huge planes that are mostly hydrogen storage tanks with not a lot of room for useful load. Or alternatively really heavy tanks that can keep hydrogen at close to absolute zero. A more likely use for hydrogen in aviation is to use it to produce synthetic fuels that are more dense and easier to handle.
Huydrogen really sucks as a fuel. And it's not a particularly efficient battery either. Storing it is problematic. Transporting it is problematic. The vast majority of hydrogen today is produced and consumed in the same place for this reason. It's main role is as a raw material to produce other things (fertilizers, steel, etc.).