this post was submitted on 17 Nov 2024
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We also should consider HVDC lines. The longest one right now is in Brazil, and it's 1300 miles long. With that kind of range, wind in Nebraska can power New York, solar in Arizona can power Chicago, and hydro all around the Mississippi river basin can store it all. We may have enough pumped hydro already that we might not even need batteries, provided we can hook it all up.
HVDC is much more expensive than Hydrogen pipelines, which doubles as storage and transmission, and can provide continent wide resilience, even when local renewables provide much cheaper power when it is available than either long distance electric or H2 power.
The studies on hydrogen pipelines tend to assume there's some existing reservoir of hydrogen. Making hydrogen in a green way is expensive, and that completely ruins its economic viability.
The expense part gets taken care of with OP's solar prices. Battery costs help too.
Not at all. Hydrogen electrolysis efficiency is about 70-80%. When turning it back into electricity, fuel cells are 40-60% efficient. That means your electricity costs are about double for the complete round trip.
Conversely, lithium batteries (and most other types) are over 90% efficient and directly give you electrons.
The difference is that the electrolysis can be done at producer convenience. Sometimes wholesale electricity prices (midday due to high solar penetration) are negative or ultra cheap. Transporting H2, even by truck, can be cheaper than the US typical 8c/kwh electric transmission charge. For many areas, enough solar in winter has 3x more summer production and essentially unusable. A balance of solar and H2 produced in summer, can provide the cheapest necessary energy for winter. An alternative is summer exports with winter imports.
Batteries alone are also subject to curtailment, or not enough charging in winter. H2 can be stored at $1/kwh, where a pipeline is free transmission of withdrawals different from deposit locations. The energy efficiency round trip is less important than the $ efficiency of energy delivery.