On another note, I wonder how resisitve heaters compare to heat-pumps. The article states that heat-pumps can react faster, but are more efficient. What about putting a battery in front of the heat-pump to accelerate the response?
And in fact a well-insulated modern tank is a very efficient store for energy that you're going to use at some point anyway. It makes perfect sense to use it as a flexible load to buffer grid management.
> On another note, I wonder how resisitve heaters compare to heat-pumps.
Heat pumps are sort of an orthogonal trick. Ultimately they work by using a lower temperature state to "steal" energy from the cooler outside temperatures. They don't make "heating" any more "efficient" per se. But if you have such an outside environment (i.e. colder than whatever the operating temperature of the heater is, but still warm enough to provide energy to the coolant) they are worthwhile.
The reason they are over unity is they are taking heat from one place and moving it somewhere else. If they are pulling heat from outside air they are basically solar assisted. Technically anything above absolute zero has heat energy, even very cold outside air has plenty of heat to pump into your living space. Temperature is not heat, you can raise temperature by putting the same amount of heat in a smaller space, its like using a transmission to increase torque by lowering rpm.
They definitely do make it more efficient at least in the ways that matter to people, less energy paid for the same heat.
I guess all technology is a trick, but normally that denotes its not really doing what is said, which you reinforced by saying it is not more efficient.
Air source heat pump water heaters and direct solar water heaters are similar in they both utilize solar energy to heat water. Then again if you really get down to it you could argue everything is indirectly solar powered, just some forms you must pay for the energy, while heat pumps and solar collectors get it directly from outside your home heat pumps just require some energy to collect it.
The advantage of the heat pump is that we are, for, say, 3 joules of energy, heating part of the system by 5 joules and heating the other part of the system by -2 joules.
This is great for home heating and the like because we don't care about making the outside slightly colder.
This comes with the downside of leaking energy a lot faster than batteries. Moreover, the more energy stored, the faster the leakage.
All that is not to say this is useless. Just to say the role played by heaters is different from batteries. Notably, neither are a good solo solution to the volatility of renewables.
I know that in the Netherlands, stuf like this would require infrastructure upgrades. There is simply not enough copper running to consumer houses to handle the amperages.
One-way conversation of energy to heat is a very common use-case: Warm water, heating are all things a lot of people use. Currently, most of that conversion happens on-demand, when someone turns on the tap. Heat is a form of energy that is fairly easy to store. Have a large bucket of water, well insulated and you’re mostly set. It’s dead cheap. There are similar concepts that use a generator to provide electricity for buildings on demand and store the waste heat for warm water and heating.
> Calling such a one-way sink a battery is even worse.
The article does not. They are a replacement for batteries in some use cases. The article may overstate how often that’s the case but it does not pretend you could regain the energy stored as electricity.
If heating loads are a significant amount of the total load, then this would help reduce the need for peaker plants or battery energy storage. And, if done properly, it provides a cost savings to the utility user too.
You can also use the same principle to store cold in summer: Cool down a vat of coolant (though water likely won’t do) at times when you have electricity surplus and use it later.
Certainly, that not solving all problems, but it can kill battery usage for some cases.