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Sodium batteries hit 458 Wh/kg: New material closes gap with lithium
(interestingengineering.com)
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this post was submitted on 23 Dec 2024
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Feeling stupid: doesn’t this mean more energy per kilogram is possible with Na cells?
Lithium ion is around 265-280wh/kg but hydrogen is already in the kWh
Isn’t most of the weight with hydrogen coming from the high pressure tank and gas regulator?
My impression is that the gas is light but whole system hydrogen is pretty heavy.
edit: Did some more reading. Hydrogen is still competitive on a Wh/kg basis, but worse on a Wh/L basis. Larger tanks are harder to fit in passenger cars than batteries and hydrogen’s poor whole system efficiency has kept fuel prices high while lithium batteries and solar power keep getting cheaper.
H2 to get weight of tank down and highest density can be liquified. This works best by far for aviation that refuels right before takeoff. Can work for commercial boats as well. Costs more energy to liquify than compress.
This makes hydrogen even more expensive and pushes it further into niches which need maximum range at any cost.
Renewable h2 can be cheaper than gasoline or kerosene. Even with liquifaction. Has to use behind the meter or wholesale renewables instead of fixed utility pricing with transmission costs.
Planes typically spend 100x in fuel over lifetime compared to price of plane
Where are you finding this cheap renewable H2?
Or is this a theoretical future development?
Making h2 at less than $2/kg from renewables is achievable today. 300 bar at $2. Lh2 at $2.50.
Sales prices are much higher because capacity is still low, and toyota bundles some free to its fcev customers, and sales volumes are low such that a high profit margin is required to pay for filling infrastructure.
$2/kg is equivalent range in a fuel cell compared to 1$/gallon gasoline. That is much less than refinery sales prices of gasoline or diesel.
Consumer prices have chicken vs egg problem.
I'm assuming the concept they're thinking of goes something like: Using renewable energy like solar and wind to convert water (or some other source of H2) into liquid H2 for the increased energy density compared to charging lithium batteries or equivalent with those same renewables.
There'd be tons of energy loss along the way, but since renewables are effectively "free energy," I can see that it would work in theory.
Right, hydrogen only makes economic sense if the fuel is free because the whole system efficiency stinks compared to BEVs.
Well, my city operates busses on hydrogen. Must be worth it, otherwise they wouldn't have done it. We also have a hydrogen fuel station.
Edit: for actual numbers - 100km - 6.9kg of hydrogen average usage - 387 PLN. For comparison - diesel - 168 PLN, but it just assumes fuel cost. They explain that filters, maintenance, oil etc isn't factored in and is higher for diesel, where hydrogen is a lot less complicated and requires less consumables to operate.
For something that is just beginning to be introduced, versus diesel which was used since time immemorial, the cost isn't that bad.
For range, they say 450km "full", but one shouldn't completely empty the fuel tank. It takes 25 mins to fuel a bus from zero to full. They're silent as hell, don't need huge electric infrastructure (since they refuel so quick). Long term they predict that fossil fuels will be more expensive, with hydrogen reducing in price. They also get funding from the country for it, since it is a "green" vehicle. Also, zero emissions obviously, but still brake dust and tire particulate
The biggest drawbacks is the current fuel price and the price of the vehicle itself.
Wonder where they get cheap H2 or if it’s being subsidized somehow? It’s like $36/kg here!
We have a private fuel station that does hydrogen, and the busses have two backup solutions. One that is able to fuel it to 100%, and the other they call "flyby" (?) which does 50% max. They get it hauled to the station using "hydrogen carriers" which each can get up to one tonne of hydrogen to the station. Apparently the station itself is electrically self sustaining from solar panels too.
The current cost for personal vehicles is 69 pln (heh) per kg. They say that personal vehicles can refuel in 4 mins for a 650km range. For busses, they paid 56 pln per kg from October 23' to May 24' (that's when the article I'm looking at aggregated the data). In total they paid 1.3 million pln, for twenty busses Now that I read it, 69pln is gross, 56pln is net, so they pay the same as the public. They project ~50k pln each bus will save over the next three years compared to diesels.
Apparently, they got subsidies / EU funding to buy em. 65% of the value. Now they are buying more and they're getting it 100% refunded - they're only paying the tax, totalling 800k PLN, which is a steal. The busses themselves are modern as fuck too, passengers love em and so do drivers. Shit like side mirrors is a thing of the past, they get cameras now. They went through winter like a boss - no issues with them being susceptible to frost / freezing temps (remember, Poland is about as high up in latitude as Canada). Apparently it is sneaky enough to sneak up on motherfuckers, they have speakers mounted to simulate a car going 40km/h so pedestrians don't get run over by it (since they're basically an electric vehicle with a small powerplant on top).