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Ask HN: Why aren't all heaters computers?

32 points| kyleyeats | 2 years ago

This is kind of a silly question, but waste heat is waste heat, right? So why isn't all waste heat generated by computers?

Obviously I'm talking about electricity here. How do we have something like Bitcoin but then have electric heaters? Won't a Bitcoin miner produce the same amount of heat given the same electricity? You can use heat pumps for extra gains on either, right?

A Bitcoin miner is more expensive to produce and maintain, yes, but over its lifetime shouldn't it pay for itself? I guess it just seems silly that we have datacenters with cooling (which takes even more electricity), and then also heating for homes.

61 comments

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[+] orbital-decay|2 years ago|reply
Datacenter heat reuse is a thing. Mostly in European countries with cold climates. Notably, Finland has a few datacenters like that (Remov, Telia). I believe some countries might even mandate the feasibility study for reusing the heat for new datacenters.

I have no idea why it's not everywhere, but I see some issues right off the bat:

- you need a district heating system to dump the heat into, and to be really close to consumers

- the integration into the heating system isn't free

- heating supply doesn't match demand well (not seasonal; datacenter scaling depends on computing demand, heating is just a byproduct)

[+] jve|2 years ago|reply
> heating supply doesn't match demand well

Yes. However you still must run chillers that would dissipate heat into the environment with or without heat re-use.

I was talking to one of DC technicians about this and mentioned - hey, if a chiller ever breaks down (they are redundant), one can (even in summer), put radiators to max to help dissipate heat from DC rooms. He said yes. I asked whether this is some actionable item on some risk plans or whatever - nop, that is not something that we depend on. And it would just extend the time to do something but not prevent from overheating.

[+] jazzyjackson|2 years ago|reply
as a rule of thumb, electronics will take as much energy to produce as they will use in their lifetime. A silicon chip is a very expensive resistor which has already consumed enormous energy to produce (another rule of thumb, the cost of silicon is double the cost of the energy it took to produce)

disclaimer: i dont know where i heard this

also if you google "bitcoin miner radiator" there's a few attempts. Apparently there's a spa in NYC that heats their water with ASICs

https://kotaku.com/bathhouse-nyc-spa-bitcoin-asics-185095816...

[+] kwikiel|2 years ago|reply
This rule is very wrong for the things like an iPhone which while expensive won’t be using a lot of electricity in its lifetime
[+] thomastjeffery|2 years ago|reply
The specifics of your question have an obvious answer: heat pumps are more efficient, and computers have a high upfront cost relative to their overall heat production, so we wouldn't have enough computers to meet heating demand.

The context of your question is a lot more interesting. Why don't we do something with waste heat? We already have systems to efficiently move it, so why not move it somewhere that it can be captured and put to use? If we were motivated enough to do that, could we?

There are a few realities that get in the way:

- Heat is difficult to trap, and difficult to move. You can't put heat on pause. That puts a hard limit on its travel distance.

- Computers have different distance limits. Sometimes, you want them to be close to each other; other times, you want them close to you. These two things are inversely correlated with the utility of heat production: You are likely to generate more heat from a computer that is near you, but unlikely to have any need to put more computers near it.

If you could game on a datacenter, then that would change this dynamic. If everyone on your block hosted a giant liquid-cooled LAN party, and used the heat to warm a pool...

[+] mathgradthrow|2 years ago|reply
The most efficient heater is a heat pump, and its not even close to heat generators.
[+] ravi-delia|2 years ago|reply
Sure, but if you're gonna have a space heater (and people do) there won't be any difference in efficiency between any possibility, including computers
[+] monocasa|2 years ago|reply
Exactly. Heat pumps work by concentrating and moving heat, which is cheaper than generating it in the first place. There's still heat in 0°F weather if you concentrate it.
[+] starbase|2 years ago|reply
We'd need two orders of magnitude more semiconductors than currently exist. We're already building them as fast as we can.

Global energy use for heating: ~150 trillion kWh/year

Waste heat from semiconductors: ~1 trillion kWh/year

[+] RogerL|2 years ago|reply
Asian countries are already struggling to keep up with energy demands of semiconductor factories.

And then there are the other environmental impacts - waste chemicals, waster water, and greenhouse emissions.

[+] skybrian|2 years ago|reply
Capital costs matter, especially for anything that's only run part-time. Buying servers that sit idle for half the year (during summer) would effectively mean they take twice as long to pay for themselves compared to servers that run all year. So that's at least twice as expensive.

Maybe the numbers would still work, but you have to actually do the math.

[+] someplaceguy|2 years ago|reply
Just send the servers to the southern hemisphere for half the year (when it's summer here and winter there) and then back for the other half. Problem solved!
[+] jve|2 years ago|reply
Well, our datacenter does use heat generated in server room to run heat pumps for our offices. Except there is much more heat in data center and we must still waste energy on cooling.

The premises nearby as far as I know were not much interested in harnessing this heat as that requires doing fair amount of infrastructure.

But I know that a nearby waste plant grows tomatoes and cucumbers by using electricity and heat from biogas (apparently when waste degrades it produces methane gas?!) - sorry for off-topic, just some green thinking went in my mind :)

[+] syndicatedjelly|2 years ago|reply
Computers aren't free, if it costs even $1 to add a computer that generates enough heat (several hundred watts) to be useful as a heater...why not just omit the computer and make an extra dollar of profit, or charge less and undercut competitors that have computers?

Also consider the externalities...making unnecessary computers contributes to e-waste, it increases demand for rare-earth metals that are often mined in extraordinarily bad conditions (slavery and child labor)...

All this for what benefit? Is there a market of people that want to use a computer attached to a space heater? What useful thing is this computer going to do? Maybe it makes sense as a wi-fi repeater or something, but once again as the manufacturer what's easier/cheaper/simpler to design - a computer that generates heat and does some useful software task, or a fat 1500 Watt resistor that converts DC current directly into heat?

All that said, you might be on to something. With some clever advertising and marketing promotionals, I bet you can convert some portion of the space heater market into "premium" users of this contraption, all while make them feel eco-friendly through a greenwashing campaign.

So my answer is, this product doesn't exist for lack of technical creativity - it exists because the advertising industry hasn't sunk to such depths as to market this product yet.

[+] Kuinox|2 years ago|reply
Qarnot, a french startup is selling water heater, and space heater, and are used in some new building in France, and even swimming pools. They also sell cloud services, and market themselves as low carbon compute.

I find the water heater a smart thing, since you also need hot water in summer.

https://qarnot.com/en

[+] rapjr9|2 years ago|reply
Others have explored this space also:

https://braiins.com/blog/guide-home-hvac-heating-bitcoin-min...

https://www.coindesk.com/business/2023/01/03/heatbit-space-h...

https://hackaday.com/2023/05/13/home-heating-with-bitcoin-mi...

Some of the issues are: the noise from the fans, you have to move the heat out of the miner. Miners are computers, they fail in more ways and more often than a space heater does. If you are heating only with miners how do you regulate the heat, by slowing the miner which makes it earn less and is less efficient?

In essence you can easily heat your space with electronics without using crypto miners. Just turn on all your gadgets and lights in the winter and leave them on. It's very convenient to have them on all the time, and the normal heating system will fill in with extra heat to regulate the overall temperature. It may even help your electronics last longer since turning them on/off tends to be what eventually destroys them (at least that was true of electronics 30 years ago, not sure if it's still true today.)

[+] keithnz|2 years ago|reply
Generally you only want heat for half a year, the other half you want it cool (roughly). In the half where you want it cool you then have extra load by the miner generating extra heat... or you turn it off, which seems like a massive waste of compute power.
[+] gpuhacker|2 years ago|reply
There was a company in the Netherlands, can't seem to find the name right now, that rented out GPU clusters as central heaters, while using the GPUs to mine crypto. I believe they went backrupt during the whole crypto crash and energy crisis.
[+] spiffytech|2 years ago|reply
"Space Heater Offers 50% Cash Back On Heating By Training AI In Your Home"

https://www.forbes.com/sites/johnkoetsier/2023/12/09/space-h...

[+] RogerL|2 years ago|reply
That device&company seems like a joke. Costs around $1000, multiyear payback (~3years) if you use it every day, you only get 400w from the computer(the rest just from a regular heater also built in), and the payback is "up to" $28, which I would assume would be the payback for 24/7 use.

At my rate of using space heaters, I'd expect probably a 10-20 year payback period (pay schedule is not clear, so it is a guess, and generous). Drop $1000 on a computer I don't use, hoping that the company stays in business for decades? No thanks. I'll run a pihole or a server or something and at least get my own compute out of it if I want heat from compute.

But a great answer to the question. Computers are around $1000 for anything approaching heavy compute, you are probably running around a 400 to 750 watt power supply, so you get a few hundred watts of heat out it (depending on load, obviously). Vs the $10 or so you'd pay for that much space heater (you get 1500 for ~20-30). Loooonnnng payback period.

[+] l0b0|2 years ago|reply
> A Bitcoin miner is more expensive to produce and maintain, yes, but over its lifetime shouldn't it pay for itself?

IIUC based on other news on HN, Bitcoin mining is already at the point where you need specialised hardware for it to pay for itself at all. 10 years ago, yes, it would've paid for itself, but it would've been a gamble.

[+] macilacilove|2 years ago|reply
Yep, heat is heat. If you manage to swap in your hardware for grandma's electric heater, you have free electricity for whatever you do.

But you need to make sure that the hardware is operated for sufficient time to pay for itself. Without end users harvesting your hw, data.

I think there can be a business to be made here, but it is not trivial at all.

[+] andy99|2 years ago|reply
Disclaimer: I consider this a scam

There is a company I saw (and I found it again by googling but I think it's the same) that sells you a heater that pays you some portion of the cryptocurrency it mines:

https://heatbit.com/

[+] rattlesnakedave|2 years ago|reply
I have heated portions of my home with S9s for a while. I know a guy who heats his pool with ASIC miners. It's not hard, but it is more expensive than conventional methods (additional cost not totally offset by proceeds). You should do it if you're interested.
[+] radicalbyte|2 years ago|reply
For electric heating: modern heat pumps have a 1:4 to 1:5 energy input to energy output ratio. They spend energy to move heat. Which also means that they can be used in reverse.