Hacker News Reader

Hacker News

Comment by michaelleland | Hacker News Reader

Full thread

michaelleland

What about the electricity costs to run the machines?

View on HN

It's a cost-sharing agreement, so electricity costs are split between the data-furnace provider and the home-owner.

According to the efficiency of the device?

The heating efficiency has to be 100%, because the electricity isn't being converted into any other energy form.

(That's still worse than an electric heat pump though, though - those have > 100% heating efficiency in terms of electricity input).

Everything above 0K will emit photons, no?

Right, but at those temperature the photons have near infrared frequency, hence they won't escape your house and simply heat it

There will also be plenty of RF interference, although that's at a lower energy, and therefore will use less energy to produce.

> (That's still worse than an electric heat pump though, though - those have > 100% heating efficiency in terms of electricity input).

"Coefficient of Performance" being the over-100%-not-technically-efficiency measure for heat pumps. [0]

Or "Seasonal Energy Efficiency Ratio" if for god knows what reason you want to measure it in British thermal units per Watt hour. [1]

So a setup like this isn't actually competitive with a heat pump in most conditions, but if the electricity was going to be burned in a datacenter anyway you might as well use the heat for something productive.

https://en.wikipedia.org/wiki/Coefficient_of_performance

https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_rat...

If I understood it correctly, there is a server running inside that thing. So by definition, all the heat being generated is inefficiency. Therefore, if 1000 W are being disposed as heat to the environment, then the machine itself is consuming WAY more than that. Otherwise, they found a way to do computing without consuming any energy.

edit: Upon further googling, it looks like I was stupid here. So almost all energy consumed by a PC is dissipated as heat? Did not know that, sorry.

So almost all energy consumed by a PC is dissipated as heat?

Yes. The other forms of energy leaving your PC range from tiny to infintesimal: light from the keyboard/case LEDs, kinetic energy in the exhaust air molecules, radiated RF (both intentional like WiFi and unintentional), radiated sound (both intentional from inbuilt speakers or connected headphones and unintentional from vibrating components), earth leakage, and resistance losses in external wired network connections.

Most of these forms are then reabsorbed and converted to heat by other objects in the immediate surroundings as well.

Increases in the energy stored within the PC are entirely dominated by temperature increases (which will equalise with the surroundings over time). There would also be a truly infintesimal amount of energy stored in changed potential energy in magnetic domains on your hard disk or stored charges in your SSD.

Yes, I get it. Being a Mechanical Engineer and used to balancing energy in heat engines, I just (incorrectly) assumed that SOME kind of work was being done by the computer to perform its main function, which is obviously not the case (at least not to non-negligible amounts). Thanks for clarifying.

Ahh, as an ME you would appreciate then that the useful work a computer does is not thermodynamic work but a decrease in the disorder of some system it is a part of, and this necessarily requires increasing the entropy of its environment - typically by transferring heat to it!

Some energy (but not much!) goes out through the network.

Half the time it would be "off" (during summer), so that means I will pay for 100% of the actually used energy? In that case I'll stick with natural gas for my heating. Also this arrangement should not be called "free".

It's installed on an external wall so when you turn the heater 'off', the heat is redirected to outside. They will apparently also reimburse you for energy used.

That's what I mean, off means it's still "burning" but I get no benefit. And according to ihsw the bill is split leaving me with: In winter: Gaining 50% of the power in heat (don't know how that compares heat-wise to natural gas) and in summer, wasting 50% of my own paid-for electricity. I actually doubt if ihsw's comment is true.

The bill is not split -- it says they reimburse you for the measured power usage of the device. Nowhere does it say that this only applies when the heat is being directed into your house, that I could see.

I don't think that's right, their FAQ says

"Can I really heat my home for free using your heater?"

"Amazingly, yes! The Heater measures how much energy it uses to heat your home and you’ll get fully reimbursed for the cost of this energy. This means that with our Heater you’re heating your home for free!"

http://www.nerdalize.com/faq/

I can't find anything about a cost sharing agreement, the only cost I can see is the upfront purchase price in the BBC article (although nothing on the nerdalize site itself).

Reply on news.ycombinator.com