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This is unrealistic: >It shouldn’t be hard for my fridge or hot water heater to buy a kwh of electricity anytime over the next 7 hours to do it’s thing. Fridg

This is unrealistic: >It shouldn’t be hard for my fridge or hot water heater to buy a kwh of electricity anytime over the next 7 hours to do it’s thing. Fridges lose a ton of cool air when you open them. You're going to end up with bad food if refrigeration can't kick in for 7 hours. >Same for dishwashers and clothes dryers: I’m 100% okay with pressing “Clean/dry within 8 hours” setting. Waiting 8 hours to dry clothes is a great way to end up with dirty clothes again because of the moisture trapped in from the washer. >Hot water heaters are effectively thermal banks. Not really. Unless you effectively turn them into boilers, you max out at boiling temperature. Given that's barely twice the normal setting, it's not going to last for any long period of time that way. >It shouldn’t be hard to convince people to replace their AC with a unit that makes ice overnight if it cuts their electricity bill in half. Ice is useless for people that need air conditioning. I think you vastly underestimate how much ice it would require to replace a large air conditioner cooling a single family home by 30F or so for 6+ hours.

Scoundreller 8y ago
For the fridge: you use excess cooling in the freezer to keep the whole thing cool. Or a reservoir of compressed refrigerant. Or phase change materials. The point wasn’t to be off for 7 hours, but to look at the current and projected prices and decide when to run at a normal rate or when to kick into overdrive (2C fridge and deep freeze) or when to run at normal rate (maintain 4C and -18C). For the dryer, depending on electricity price, you run it at a slower or faster rate. Indeed, when I line dry, it can take a while, without the issues you bring up. If there’s a gust of wind, dial it up. When it’s calm, dial it down. Since wind goes in a direction, we have some idea of when turbines will put out more power that’s cheaper. Hot water heaters here have thermostatic mixing valves, so as long as we’re not boiling, we have a lot of margin to work with without scalding anyone. Finally, the nice thing about ice is that water is cheap. It’s already a commercialized tech, just not cheap enough for residential use.... yet. The point isn’t to use these reservoirs for 100% of needs, but size them up to be fully utilized on a regular basis buying electricity at low prices to offset higher prices. Sometimes that’s less efficient from a thermodynamic standpoint (the hotter hot water heater does shed more heat), but made up for in reduced op costs.
crote 8y ago
Fridges: energy loss isn't that bad, especially when your fridge is decently filled. Most of the heat capacity is in the contents, not in the air. My current fridge is already off for multiple hours at a time. With a couple degrees of margin and a little bit of high-heat-capacity padding, this is realistic to do. Clothes dryers: Agree, don't start a wash cycle, then wait 8 hours after finishing to start the drying cycle. But delaying both at once does work. Hot water heaters: Already being done at a smaller scale, look up Quooker. Given known usage pattern, the replenishment of hot water can also be delayed. Ice cooling: The math checks out. The temperature difference of 200 gallons of water from 5F to 70F provides over 400.000 BTU of heat capacity. A quick Google tells me that the upper size of air conditioning capacity is 14.000 BTU / hour, so that's more than enough. Given proper isolation, this can probably be lowered by at least an order of magnitude. 20 gallons isn't that much, in my opinion. Besides, this is already being done in practice, using the underlying soil as heat buffer. It has enough capacity for a whole season. It's not ideal, but mathematically it checks out.

Scoundreller 8y ago

For the fridge: you use excess cooling in the freezer to keep the whole thing cool. Or a reservoir of compressed refrigerant. Or phase change materials. The point wasn’t to be off for 7 hours, but to look at the current and projected prices and decide when to run at a normal rate or when to kick into overdrive (2C fridge and deep freeze) or when to run at normal rate (maintain 4C and -18C). For the dryer, depending on electricity price, you run it at a slower or faster rate. Indeed, when I line dry, it can take a while, without the issues you bring up. If there’s a gust of wind, dial it up. When it’s calm, dial it down. Since wind goes in a direction, we have some idea of when turbines will put out more power that’s cheaper. Hot water heaters here have thermostatic mixing valves, so as long as we’re not boiling, we have a lot of margin to work with without scalding anyone. Finally, the nice thing about ice is that water is cheap. It’s already a commercialized tech, just not cheap enough for residential use.... yet. The point isn’t to use these reservoirs for 100% of needs, but size them up to be fully utilized on a regular basis buying electricity at low prices to offset higher prices. Sometimes that’s less efficient from a thermodynamic standpoint (the hotter hot water heater does shed more heat), but made up for in reduced op costs.

crote 8y ago

Fridges: energy loss isn't that bad, especially when your fridge is decently filled. Most of the heat capacity is in the contents, not in the air. My current fridge is already off for multiple hours at a time. With a couple degrees of margin and a little bit of high-heat-capacity padding, this is realistic to do. Clothes dryers: Agree, don't start a wash cycle, then wait 8 hours after finishing to start the drying cycle. But delaying both at once does work. Hot water heaters: Already being done at a smaller scale, look up Quooker. Given known usage pattern, the replenishment of hot water can also be delayed. Ice cooling: The math checks out. The temperature difference of 200 gallons of water from 5F to 70F provides over 400.000 BTU of heat capacity. A quick Google tells me that the upper size of air conditioning capacity is 14.000 BTU / hour, so that's more than enough. Given proper isolation, this can probably be lowered by at least an order of magnitude. 20 gallons isn't that much, in my opinion. Besides, this is already being done in practice, using the underlying soil as heat buffer. It has enough capacity for a whole season. It's not ideal, but mathematically it checks out.