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Comment by stcredzero | Hacker News Reader

If you live in Ohio that is a problem, solar isn't going to keep you warm on a cold night

Houses built to the German Passivhaus standard would do just fine in Ohio. I used to live in Ohio and Western Pennsylvania, so I should know. There was one Minnesota church built with polystyrene panels that had to start running air conditioning in the middle of winter, the insulation was so good.

If you live in the South West though its perfect as Winter nights dont require much heat and the biggest loads are AC at the times when there is lots of sun.

It can get pretty darn cold at night in the desert southwest. Again, insulation is the key.

Of course water is the next problem, but cheap electricity can help that too.

It's 10X as expensive to use techniques like desalinization. It's so much more expensive, that lots of desal plants get built, then get mothballed because it's that much cheaper to get water by other means.

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>Houses built to the German Passivhaus standard would do just fine in Ohio. I used to live in Ohio and Western Pennsylvania, so I should know. There was one Minnesota church built with polystyrene panels that had to start running air conditioning in the middle of winter, the insulation was so good.

You'd have to level most structures and rebuild from scratch to manage that in large parts of North America to make a difference.

Never mind the fact heaters aren't the only thing that use electricity at night.

You'd have to level most structures and rebuild from scratch to manage that in large parts of North America to make a difference.

New construction built like this is a good start.

heaters aren't the only thing that use electricity at night

Know your orders of magnitude. Resistive heating is just ridiculous. Heat exchangers are much better, but are like running Air Conditioners. In a passivhaus, my wife and I would be running a laptop, a clock, and the air filtration/exchanger, and that's it.

Heating water is one of the big energy users, but Solar Water preheat based on heat pipes even works a treat in cloudy, chilly old England.

The biggest challenge probably being the 2x4 walls... if there's one code change to future-proof today's new housing stock, it might be adding 2 inches to the walls, either with 2x6 studs or 2 inches of rigid foam, for R-20 or so. Much of the rest is possible to retrofit, though not always easy.

Actually, while we're on the subject, subslab insulation might be another.

It's a shame that there isn't the regulatory flexibility to subsidize desalination plants, because desalination plants are sort of like insurance policies in that you usually don't need them that much until a drought hits and then you really wish you had them.

That sort of long term risk averse thinking is exactly where the market economy needs to be supplemented.

The market economy would charge the almond cartel and alfalfa growers a lot more money for their water abuse in California, which would instantly eliminate the water problems for the entire state. Versus allowing $10 billion of agriculture industry to hold a multi trillion dollar economy hostage.

Let's add cannabis to the list which will use huge amount of water.

Which plants use a lot of water is irrelevant to the discussion. Unless illegal cannabis growers in California were somehow having their water subsidized, which I do believe to be parent's main point.

Would it make sense to combine California's ability to produce solar and need for water? Build solar plants that run during the day that power desalination plants that fill reservoirs in the western mountainous area which then releases the water at night downhill to the main canal system while turning turbines on it's journey?

is the expense of desalinization the electricity? Which would go down with adoption of solar?

This is a decade old, but I think that the proportions are still about right: https://desline.com/Geneva/Banat.pdf

See the slide "Cost composition for a typical seawater RO (reverse osmosis) plant"

Fixed charges (primarily capital cost): 31%

Energy: 26%

Maintenance and parts: 14%

Membrane replacement: 13%

Supervision and labor: 9%

Chemicals: 7%

Really cheap solar electricity could reduce the second largest expense (energy costs), but right now that's just an improvement for daylight hours. Battery-stored solar electricity is getting cheaper but it's not cheap enough to actually reduce nighttime desalination costs yet. And if you run the plant only during the day, you get less value out of the very largest expense (capital cost).

That's reverse osmosis. In a scenario where energy is very cheap (even if only for part of the day) there are other processes which require less maintenance, but more energy.

The previous slide in that presentation also shows a cost breakdown for a thermal process, multi-stage flash desalination.

Fixed charges (primarily capital cost) 42%

Energy 41%

Maintenance and parts 8%

Supervision and labor 7%

Chemicals 2%

Energy is nearly even with fixed costs for MSF, but fixed costs are even larger here. Leaving this type of plant idle between dusk and dawn would again raise per-unit costs a lot.

I imagine the idea is something more like one way to dump excessive solar capacity would be to desalinate water during the times of maximum power generation.

Or perhaps I just steelmanned the argument.

You also have to maintain equipment, but I think the electricity is the major thing.

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