alt Hacker NewsBottom line: 40% efficiency, which is better than I expected but the competition is batteries at 80+% efficiency. It's a hard sell, especially as continual improvements in battery storage will continue to eat away at their niche.
5,000 W/kg sounds great on paper compared to 150 W/kg for batteries and is even in the same ballpark as gasoline at 12,000 W/kg, but I think that's just the figure for the fuel. I don't think it includes storage, the solar panels, the burner, etc... The cost is an open ended question as well. Maybe this will pan out for aircraft?
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If that is 40% efficient as in 40% of the theoretical energy input comes out as electricity then it's quite incredible but I find that hard to believe. It would put it in the same range as diesel engines.
The better comparison is Fuel Cells and vehicle based electrical generators. So you could put this in a vehicle or remote location, run it off hydrogen or natural gas, and get better efficiency. Potentially this could be a much better option for longer term storage in remote areas as well, where excess solar/wind could be used to crack hydrogen which then gets stored and later burned in one of these instead of a much much larger battery installation.
Battery densities are going towards > 500 wh/kg. There's some talk of batteries of several kw/kg long term. And since we're talking technology that is very much in the early stages of development (see the helpful image in the article), that would be an apples to apples comparison. 500wh/kg is basically a done deal. Several battery companies have announced products that are shipping in the next 2-3 years. From there to 1kw/kg seems very feasible. Several companies have hinted at that being a goal for them.
It's useful for grid storage. Very large amounts of hydrogen are already stored in salt domes[0]. Current salt domes have volumes in the range of hundreds of cubic kilometers and can support pressures around 50-150 bar, translating into storage of thousands of tons of hydrogen. Along the texas gulf coast, there are hydrogen storage facilities that each store enough hydrogen to translate to around 100 GWh chemical energy. Being able to convert that chemical energy with 40% end to end efficiency means one site could store 40 GWh. In comparison, in 2023 the entire world had only around 56-200 GWh of battery storage capacity[1] installed.
[0]https://energnet.eu/wp-content/uploads/2021/02/3-Hevin-Under... [1]https://www.rethinkx.com/blog/where-is-all-the-battery-stora...
Rechargeables/battery packs have inefficiencies due to the grid and/or solar cells though, in terms of where to measure inefficiency?
It might not be a hard sell compared to home generators. Forget hydrogen. Think natgas.
Do you mean watts or watt-hours?
How is efficiency for say, propane? No need to worry about hydrogen embrittlement or invisible flames around residential areas.
The gasoline vs H2 ballpark is a little wider because storage is not trivial for H2 -- you need to carry around a cryogenic and/or high pressure vessel instead of a plastic box -- which will detract from your p/w ratio. It also wants to leak out, so H2 is maybe better for fleet vehicle applications where they can refill daily. Granted, anything is better than burning more hydrocarbons!