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To keep warm, I'm estimating 2,628 kwh for a month for a home for a family of 3. In our magical Minnesota where everyone lives in houses with 3 people and only
by _ea1k 4y ago
To keep warm, I'm estimating 2,628 kwh for a month for a home for a family of 3. In our magical Minnesota where everyone lives in houses with 3 people and only electric heat pumps, we'd have 1,900,000. This means, we'd need 4,993,200,000 kwh in the coldest month (4.993 Twh).
500,000 kilowatt of panels would produce ~33 gwh in the worst month (January). So, we'd need 151 times that many to have a good chance of doing this with purely solar. That'd mean 75,500,000 kw of solar panels. Assuming that we could install these for $1.50/w, that'd cost 113,250,000,000 and there's still a chance that we'd freeze people to death.
To mitigate that risk, we'd want to add ~500 gwh of batteries (just guessing as to needed capacity here). At a price of ~150/kwh, we'd be looking at ~75,000,000,000 in energy storage prices.
Feel free to check my math, as I did that pretty quickly. The figures are absurdly high due to scaling for the worst case type scenarios. Summer months would correlate with lower demand and more than double the supply.
Sensibly speaking, noone would try to do this. Its like building an offgrid home. You can get 90% of the way there and add a generator, or you can spend 10x more be truly offgrid. Almost everyone chooses the former. Maybe even 80%. Solar is great and very cost effective, but the returns diminish the deeper one goes.
- coldpie 4y agoNice. I just looked up last February's bill for my ~1700sqft detached SFH in Saint Paul. It was apparently 6.8 therms/day (12 deg F average temp for the month). That maths out to about 5916 kWh for the coldest month (6.8 therms * 29 kwh/therm * 30 days), or a little more than double your estimate. March was 5.9 therms/day and Jan was 5.4 therms/day. So I think your costs are on the conservative side of things... or possibly my home is very inefficient :) E: Ah, it occurs to me that you're using electric heat pumps, which are probably much more efficient than my NG boiler.
- _ea1k 4y agoYes, I pulled the estimate for really efficient heat pumps. To convert to all electric heat like that estimate, we'd have to replace a lot of gas heat with electric. Might as well go for the most efficient thing. Compared to the nearly $200B in infra investment that I was estimating, that looks easy, lol.
- foota 4y agoI realize this isn't relevant for a discussion about future investment, but the current "value" of the whole energy infrastructure for a state is probably in the hundreds of billions of dollars, right? It's been built out over decades, of course, so the actual costs per year are much lower.
- _ea1k 4y agoThat's definitely possible. Going based upon the output of something like Catawba, that looks like ~3 nuclear plants. I bet that could be done for less than 100B, though I'd just be guessing. I also don't know anything about operations costs for that. Also, I estimated solar at $1.5/watt. That's probably at least 50% too high.