The CoP of a heat pump is greatly dependent on the difference in temperature potential of the source and sink. If it's extremely cold outside, it's very hard to pump heat from colder air into a house. When the temperature potential between the two reservoirs is equal, sure the CoP beats out electric heating but when it's high (When your house is warm and the outside is below freezing) its extremely poor.
http://alliedthermaldesigns.com/wp-content/uploads/2012/10/T...
This government study of an air source heat pump maintained a real world COP of ~3 in Connecticut:
https://www.nrel.gov/docs/fy13osti/56393.pdf
It would be pretty bad to design a heat pump that dropped much below 1, better to just install a big resistive element.
https://computing.qarnot.com https://www.qarnot.com/faq/
Disclosure: I work there :)
Small error in the FAQ though: "kW/h" ;-)
Obviously heat pumps are more efficient - that's kinda beside the point though.
The main point here is you can take anywhere you had a resistive heating element and replace it with a mining chip, and you're now doing something useful with that energy you were turning into heat anyway.
Yes heat pumps are more efficient but there are plenty of places in your house you have plain old heat elements that aren't going away (water heater).
Only obvious if you know what a heat pump is!
Plenty of people will hear "Electrical heating is 100% efficient" and interpret that to mean it's the ideal solution, when in a lot of cases it's just about the worst.
But yes, if you have electrical heating, you could throw in some CPUs or ASICs instead and they'll work just as well. The return on investment for cryptocurrency may drop off a cliff when the next silicon process comes out and mines more for the same energy, it's hard to see people wanting to keep upgrading their baseboard heaters on the same cycle that computers get replaced.
Whether it's money positive vs resistive heating will depend on A) price of your electronics relative to a cheap electric heater, B) how it stacks up vs future electronics if the payoff doesn't happen while it's new, and C) how insane the cryptocurrency markets get.
Strictly speaking, isn't it just a special case of resistive heating?
Remember, few things need constant heat output 24/7 365, otherwise your going to want to generate some or all of your heat from other sources.
Aka, you can uses them to cook with. Also, while you can use electricity to heat water it's vastly more efficient to burn natural gas to make heat than burn natural gas to make electricity to make it, ditto solar power etc.
They cost more money, but Consumer Reports says "payback time is short" (see https://www.consumerreports.org/cro/water-heaters/buying-gui... ).
They probably don't make as much sense in cold climates, but where I live, air conditioning in the summer (and spring and fall) dwarfs the energy usage from heating in the winter. So a device that makes it colder on average indoors would be a net win even if it didn't have the function of heating your water.
Has anyone had 7+ years experience with these, and if so, can you please share your ownership experience and the model & brand you used?
Is it useful? My (limited) understanding is that most of the work is just arbitrarily difficult number guessing for the sole purpose of being throttled...
Most heat pumps are no good below 20f.
There are other reasons electrical heating isn't great, heat pumps aside. An average coal plant (in the US in 2015, I'm using EIA numbers) was about 34% efficient in turning the energy in coal into electricity. Then you lose about 5% of that in transmission, so from the heat released by burning coal you're only getting 32% of that as electricity at your house. Converting 100% of that into heat is pretty unimpressive in the big picture, you'd get 3x more heat by buying some coal and setting it on fire.
Obviously you can't do that, but a high efficiency gas-fired furnace will get 90%-98% of the combustion heat into your ducts, with the much smaller remainder going up the chimney. Unless you're on solar power (or some other renewable), burning fossil fuels on-site does better than resistive electric heating.
Of course that may also not apply to Siberia. If the ground is frozen all the time it's harder to run gas lines compared to putting in an electric grid. Mostly I'm trying to dissuade anyone in most of the US from stocking up on mining machines thinking it'll be a great heating system.
Actually, you can. I know a few people in Pennsylvania, West Virginia, and upstate New York who use coal stoves to heat their homes.
I'm not sure what the efficiency on those is today. Article from 1980 [1] mentions 74% for a good quality stove, it's possible they've improved, but I doubt there's been as much development work on coal burning stoves as there has for gas fired furnaces.
I can't wait to get rich and be warm this winter.
I was actually just being tongue-in-cheek from the get-go.
But I would never be cold for a whole year.
1-https://www.reddit.com/r/Bitcoin/comments/6cf1wn/i_mined_bit...
Assuming that the fossil fuel to electricity conversion is about 1/3 efficient and the heat pump CoP is 3, then on-site combustion heating is effectively as "efficient" as a heat pump.
I guess the main point is that "fossil fuel -> electricity -> grid -> heat pump" cycle seems crazily inefficient in terms of losses, especially when heating is a large portion of electricity consumption in many households.
I believe this isn't really an exception, this energy would also just be converted to heat?
So not 100% of that sound or light will be an exception, but some of it might.
Well, yes, but heat pumps can't mine Bitcoin :)
Heat pumps have better energy efficiency than electric heaters but whether that translates to cheaper costs is another thing. Heat pumps are expensive (about $3000 per pump) and they require regular maintenance (a few hundred bucks per pump every few years). They're also big, bulky and noisy and installation requires poking holes in exterior walls.
I have 3 heat pumps and 2 fire places in my house but I still do need a bunch of electric heaters when it gets properly cold. The weather around here is right about freezing this time of year and so far no electric heaters are needed.
But soon it's time to turn on the heat and it's a consideration of money, not energy efficiency.
A GTX1060 6GB can mine ETH at around 80 watts. And currently, earn you $25/month of ETH with electricity costing $10/month. Cost of card is $260.
https://www.cryptocompare.com/mining/calculator/eth?HashingP...
1: https://bitcoinnewsmagazine.com/bitmain-antminer-r4-home-bit...
https://books.google.com/books?id=A4DGiaOn3BwC&pg=PA167&dq=%...
I have to disagree. At its most general, the concept of efficiency means "desired output achieved per unit of scarce good expended" and can be applied in a variety of contexts: new users per dollar spent on marketing is a measure of your marketing efficiency, treasure value found per hour spent searching is a measure of your treasure-finding efficiency, etc.
Heat pumps are just a case where a) we use the same units for output and input even though they're different things, and b) in that unit system, the value for the output can be greater than the input. Since people can be unnecessarily suspicious of >100% efficiency, they use different terms for it.
If you expressed the efficiency as "2 joules of heat moved per joule of mains electricity consumed" you eliminate the canceling that would let you phrase the ratio as 200%.
But that's the performance. Efficiency is usually a measure of how good the performance is.
In this case there's a practical reason not to call it efficiency, because there is a well understood maximum performance which is the Carnot limit, so for practical purposes (to avoid confusion) PumpedHeat/Power is called "coefficient of performance"and CarnotLimit/PumpedHeat is called "efficiency", and it has the usual properties that it cannot exceed 100% and it measures how well your system works in a more or less absolute sense.
Electric heaters are 100% efficient at turning electrical energy into heat. All the energy they take in, that's where it goes.
Bitcoin mining (and computers in general) are basically in the same boat. There's some ancillary energy use for blowing air around or shining lights or making sound waves, but for the most part the electricity turns into heat and does some math along the way.
Sounds great! Perfectly efficient! But the important caveat is that heat pumps are (effectively) more than 100% efficient. They can take 100 watt of electricity to transfer 300 watts of heat from outside to inside.
It's not technically a measure of "efficiency", we call this the "coefficient of performance" instead. Or we call it the "seasonal energy efficiency ratio", which is the same thing except multiplied by some constant factor because somebody wanted a scale that went up to higher numbers. Or for heating, the heating season performance factor, which I forget the specifics of, but is geared toward how well it works pumping heat in from outdoors when your heat source (outdoors) is very cold.
In short, it's just as efficient as any other electric heater, but heat pumps are 3-4x better than that.