gas (or any combustable heating source) can never be more than 100% efficient. Law of conservation of energy. 1 BTU of chemical energy in natural gas can at most produce 1 BTU of usable heat.
The very best modern furnaces are 92% to 97% efficient. Older cheaper furnaces are in the 80%. If you have a furnace more than 20 years old it is likely is sub 80% efficiency.
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Yeah, furances aren't that great. My landlord doesn't have central heating installed for my appartment (heat pump or otherwise) and the only heat we're allowed to use (per terms of the lease) is the electric heater installed in the wall. That has a 100% efficiency for confirting electricity to heat.
100% of electricity used by a computer comes out as heat. ANY electricity coming into a building and being used is ALWAYS converted 100% into heat... with only two main exceptions:
- If you have tons of light indoors and it is pouring out the windows, some of that energy escapes (even though glass is opaque to infra red)
- Amateur radio and you are broadcasting. You are actively sending RF out
- reverse exception being if you have a heat pump. Those things use magic though so they don't count.
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Now electrical resitance heating will always be 100% efficient (it simply can't be anything else). A good heat pump (as long as you outside air doesn't get below 20F or so) can be 200% to 300% efficient but that doesn't apply to mining.
At best a furnace* is going to be 97% efficient but most are in the 80% range. Still at $8.43 / $20.52 = 41% even a malfunctioning furnace operating at 50% efficiency is going to be cheaper. Nat gas is just crazy cheap in the US. We keep finding more and more of it. Hell they might start bringing back natural gas fired heat pumps again.
* Since there seems to be confusion by furnace I mean a device which burns combustible material (i.e. natural gas, propane, fuel oil, wood, garbage, human waste, etc). Electric heat would be either resistance (100% efficiency) or heat pump (COP of >1 = >100% "efficiency"). At least in the US using the term furnace to refer to electric heat would be uncommon.
Thanks DeathAndTaxes... but actually, the modern ones are even more efficient than you stated:
Prepare for your mind to be blown:Water-to-Air:
Closed Loop: >=17.1 EER; >=3.6 COP
Open Loop: >=21.1 EER; >=4.1 COP
Water-to-Water:
Closed Loop: >=16.1 EER; >=3.1 COP
Open Loop: >=20.1 EER; >=3.5 COP
Direct Geoexchange (DGX): >=16 EER; >= 3.6 COPMore heat than you put into it. It's basically an air conditioner running in reverse. Similar tech to the "heat pipe" system used in modern cooling where you can conduct heat better than solid copper or silver by using phase change internally. Or also look at air conditioner efficiency.
See also:
coefficient of performance
So in my case, if my computer is generating ANY bitcoin, it is effectively providing cheaper heat than turning on the crappy heater in the wall.
I just love discussions like this one
