I read an article, which I cannot find now, that said that water heaters can be retrofitted to provide a more cost effective energy storage system when compared the electrochemical battery storage systems. Basically, excess renewable energy would be used to heat water in residential water heaters. But, I don’t understand how the energy is later extracted for use or if it was only for the purpose of providing hot water.
In: Engineering
>But, I don’t understand how the energy is later extracted for use or if it was only for the purpose of providing hot water.
If the system uses hot water as a storage mechanism then it will simply just function to provide hot water when needed. Basically this would just be a system where you heat up the water when electricity is cheap and then save it for your later hot water needs. So this is a electricity to thermal battery.
There are electricity to electricity thermal batteries too, but these operate at very high temperatures because then you can extract the energy by superheating stream which can be put into a turbine to generate electricity. Typically this is done by heating objects like rocks to thousands of degrees.
Technology Connections has some interesting takes on this. Especially how the water heater actually had a hot and cold side with a stratified layer in the middle. It kinda blew my mind. He’s also shutting off his hot water tank when power is more expensive.
If I ever build a house from zero, it is getting the mother of all energy storage tanks in the basement. I’m a stainless fabricator so I’d be welding up something out of 316 stainless that would last a hundred years, with removable heat exchanger coils that drop in from the top.
When combined with a ground (or air) source heat pump and some solar hot water panels on the roof you have yourself one hell of an energy storage system. It will need some serious valve manifolds to pipe around the heat on demand.
Yes, exactly! Consider your water heater as a resourceful method of utilising surplus solar or wind energy. Your water is heated when clean energy is abundant. By heating water when there is an abundance of power, you avoid using the energy later on. It’s a wise decision that lowers demand during peak hours, balances the energy grid, and may even result in cost savings. Thus, while it doesn’t store energy like a battery does, it is a clever method of maximising the use of renewable resources. Well, that’s a neat solution.
My heat-pump water heater runs during the middle of the day to heat my water. Not only is that the time my solar panels are generating the most power, it’s also the time the air is warmest, making my heat pump most efficient.
Hot-water storage tanks are big enough and well insulated so they will stay hot for at least a day. Water also requires a large amount of energy to heat. So just heating them at the best time saves renewable energy. The energy is only “extracted for use” in the sense that you use the hot water; it’s never turned back into electricity.
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