4 ms·

Should this kind of observation be especially surprising for anyone? There are some round-trip inefficiencies to any energy conversion and/or storage system, so

Should this kind of observation be especially surprising for anyone? There are some round-trip inefficiencies to any energy conversion and/or storage system, so using electricity directly if you can is always going to be better than storage - that doesn't mean storage is bad or less important, but it's a tool that we should try and reserve as much as possible for when it's really needed. It's easy to demonstrate the same thing on a small scale - at my house with hot water heating for example, I run my electric (heat pump) storage hot water heater in the middle of the day, and it almost always runs 100% from solar power (sometimes with extremely cloudy or rainy weather it uses some grid power). I don't have a battery system yet, but I'm doing the sums - and if I relied on instantaneous electric hot water heating so was heating water on demand mostly outside solar hours, even before thinking about the lower round-trip efficiency I'd need a far bigger (and therefore much more expensive) battery system than I will now for the same hot water load. If you're in an area that has less sunshine but more wind energy, the principle is basically the same, you just have to time it for when there's excess wind energy, but it just seems very obvious that if you can shift high energy use tasks to those times that's always going to be more effective than using batteries, and doing so makes the battery storage cheaper for the electricity use that you really need it for...

hedora 3y ago
I think you’ll find the kWh used by any water heater will be negligible, but that the peak kw of the on demand one would force you to buy giant batteries. We ended up getting a hybrid heat pump water heater. It is very efficient, but we have to wait for the water to warm up at the tap. If it were easy to change, I’d probably put in a recirculating system that keeps the water hot in the pipes (not sure how much electricity that wastes though).
tlb 3y ago
The question is whether the round-trip inefficiency of storing energy is greater than the cost of having energy-consuming equipment that sits idle when the sun isn't shining and gets stopped and started frequently. For example, aluminum production is famously energy-intensive, but I've read it's not good for the equipment to start and stop it frequently because the reaction happens in molten aluminum salts and it hurts the equipment when you stop and it solidifies. And while Bitcoin is energy-intensive, it's also capital intensive for the chips so it's not cost-effective to run it only part-time. Reverse osmosis may have a good combination of high energy:capital ratio (so it doesn't waste a lot of capital on idle equipment) and not requiring complex startup/shutdown sequences.
- hitchstory 3y ago
  In Germany they vary aluminium production rates in response to electricity supply (i.e. produce much less when it's less sunny and windy). They just dont turn it off completely, ever. There's probably a lot more low hanging electricity demand shifting fruit like this.
  - wkat4242 3y ago
    That will make production a lot more expensive, if you have production capacity laying unused for a long time. The rent, write-off etc still had to be paid but is now offset against less profit.

hedora 3y ago

I think you’ll find the kWh used by any water heater will be negligible, but that the peak kw of the on demand one would force you to buy giant batteries. We ended up getting a hybrid heat pump water heater. It is very efficient, but we have to wait for the water to warm up at the tap. If it were easy to change, I’d probably put in a recirculating system that keeps the water hot in the pipes (not sure how much electricity that wastes though).

tlb 3y ago

The question is whether the round-trip inefficiency of storing energy is greater than the cost of having energy-consuming equipment that sits idle when the sun isn't shining and gets stopped and started frequently. For example, aluminum production is famously energy-intensive, but I've read it's not good for the equipment to start and stop it frequently because the reaction happens in molten aluminum salts and it hurts the equipment when you stop and it solidifies. And while Bitcoin is energy-intensive, it's also capital intensive for the chips so it's not cost-effective to run it only part-time. Reverse osmosis may have a good combination of high energy:capital ratio (so it doesn't waste a lot of capital on idle equipment) and not requiring complex startup/shutdown sequences.

hitchstory 3y ago
In Germany they vary aluminium production rates in response to electricity supply (i.e. produce much less when it's less sunny and windy). They just dont turn it off completely, ever. There's probably a lot more low hanging electricity demand shifting fruit like this.
- wkat4242 3y ago
  That will make production a lot more expensive, if you have production capacity laying unused for a long time. The rent, write-off etc still had to be paid but is now offset against less profit.