The humble water heater could be the savior of our energy infrastructure woes

Lots of good discussions about water heating in this thread. But it's such a tricky topic.

Tankless water heaters are pretty efficient, but when you need hot water, you briefly use huge amounts of energy. It's for this reason that they almost always use natural gas. Electric tankless heaters are a great way to cause brownouts. They're roughly the size of a microwave oven, so they can fit in pretty much any kind of dwelling.

Water heaters with tanks, on the other hand, take up huge amounts of space and require frequent (but lower) energy input. This can use heat from a variety of sources, including low quality/unrealiable heat sources like solar heat pipes.

Then there's space heating. Unless you live in a Passivhaus, keeping a comfortable indoor temperature is challenging. Central heating using hot water and radiators is the most common approach where I live. But this again relies on burning hydrocarbons. Or, increasingly, on heat pumps, which require a lot of space, are noisy, and drop in efficiency as the temperature drops.

As far as I can tell, there are no silver bullets in either space heating or water heating. If you have a really big house, a big tank is probably a good solution for hot water. But living in a really big house is horribly inefficient in its own way. So I'm guessing that's not the greener approach. Living in a smaller dwelling is more efficient. But it seems there are basically zero good ways to heat small living spaces and hot water for a family of 1-2 living in small houses.

> Good heat pumps aren't of the air conditioner type. Our heat pump uses two 60m deep drilled holes. Thus heat exchange happens in the ground, which is always more or less 10 degrees Celsuis.

Good point. The source and destination of heat can be air, water, or "ground source". But it's still all just the same concept as A/C units. Pump heat to one place, using less energy than what it would take to heat it using resistance heating. There is nothing special about ground source heat pumps, except that they're a pain to install in densely populated areas.

All types of heat pumps, unfortunately, often leak. Depending on the type of refrigerant they use, this can be a serious climate concern as well.

Tankless are also useless if you don't have perfect water, and even if you do you have to descale them every year. The calcium, iron, and others in your water builds up in the small copper pipes, and an acidic cleaner is required to remove it. If youve ever used a Keurig it's similar.

Propane water tanks are pretty bulletproof. Even with bad water they just truck, and require no electricity to operate, unlike some other gas appliances.

Am I the only one that find this article incredibly confusing?

It starts off talking about wanting to move energy production to renewable sources. Great, I'm with you so far. A major issue with renewable energy (solar and wind) is that they're variable, not constant. This results in uneven power. The wind doesn't blow, it's cloudy or it's night time. So we need a way to convert this variable renewable energy into constant energy that's accessible around the clock. An obvious solution to the problem is to convert the renewable energy into stored potential energy. This is what pumped hydroelectric dams are all about. Use the variable energy to pump a bunch of water up behind a dam, then release it when you need a more constant supply of energy.

Great, so we've got that much figured out. The world needs a way to convert renewable energy into constant energy.

And the solution to this problem is... the distribution of more efficient water heaters.

Wat

How do more efficient water heaters in any way, shape or form help solve the renewable variable rate energy to constant energy problem? I feel like I must be missing something obvious. Are we able to somehow store energy in heat-pump based water heaters and then extract that energy to run other items in our homes? When you store energy in a heat-pump based water heater does it not need to run at night when renewable energy sources are lowest?

Can anyone explain to me what the heck this article is talking about?

I feel like I'm missing the larger picture, but I don't see how these two concepts (energy storage and appliance efficiency) are related.

Yes and add to that the ability of many of these large-battery vehicles to self-drive. For example when the owner is working during the day, the vehicle could drive to a regional charging station. This could help with the distribution component e.g. in rural areas with no power lines for the last few miles — the vehicle simply drives the power from where it’s available to where it’s needed.