[zparky]

rough math: 1000 kwh / mo / house, ~30kwh/kg hydrogen so 30kg H per mo per house. idk how long winters would be, 8 months is 240kg of hydrogen, which if compressed to 10 bar is roughly 300 cubic meters of storage. kinda a lot of space. compressed to 100 bar is like 10kg/m3 which sounds more manageable

[Retric]

Round trip efficiency on hydrogen is horrible. Local hydrogen production could make sense because importing fuel into remote off grid communities is extremely expensive.

Rather than building 10x as much solar in the north + battery systems + winter hydrogen storage etc long distance HVDC to cities and the surrounding grid just makes so much more sense. Even better because the state is huge and the population is tiny they can go nearly 100% hydro.

Where batteries could be useful is operating those long distance power lines at nearly 100% 24/7 then load shifting via batteries to match local demand.

[pfdietz]

> Round trip efficiency on hydrogen is horrible.

For seasonal storage, round trip efficiency is mostly irrelevant; the relevant metric is capex per unit of stored energy.

[Retric]

That could be generally true, but it’s not true in this specific instance.

A panel in Alaska only collects so much sunlight over the summer before considering efficiency losses from Hydrogen. It would require buying panels that effectively get ~1 month of use over the entire year due to efficiency losses + limited gathering period, and solar isn’t that cheap.

So in Alaska you’re just better off only using panels directly in the summer which at least provide several months of electricity per year. In say Texas on the other hand you get energy from a panel year round so a marginal panel purchased to generate hydrogen at say 20% round trip efficiency gets 30% * 9 months + say 70% of average production for the 3 winter months = 4.8 months of winter electricity per year. Of course you also need to pay for the hydrogen generating machine and the hydrogen burning device, but that’s not necessarily problematic.

[pfdietz]

If the alternative were, say, diesel, I think a RTE of 40% (which you might get with hydrogen) would be fine in this case, if the capex of the storage system is low enough.

It is certainly the case that hydrogen would be better than batteries for this storage use case in Alaska.

[Retric]

If the baseline is ~2c/kWh solar in a good location and they are forced to buy 10x as much solar panels to cover winter use they are now spending ~20c/kWh on solar panels but on top of that they also need to pay for hydrogen generating equipment which only gets used for a few months a year, hydrogen storage equipment, and hydrogen specific generators plus presumably a backup diesel or gas based generator + storage system.

In 20 years it might make sense but today green hydrogen is several times more expensive than gas even when you can use cheaper electricity, can make use of the equipment year round, and have the benefit of larger economies of scale. Even if the goal is completely about climate change locating that same equipment in the lower 48 states is just a much better idea.