If you’ve ever spent time around a cryptocurrency mining computer, you know that they throw off a ton of heat.

That’s because mining crypto is an extremely power-intensive operation. According to the BBC, cryptocurrency mining worldwide uses more power than the country of Switzerland. And once a mining computer uses that power to perform a mining operation, it’s released into the environment as waste heat.

With crypto mining as a whole using 7 gigawatts (not 1.21, mind you) around the world at all times, that’s 61,230-gigawatt hours used per year.

What is that in the heat? A cool (pun definitely intended) 209,232,575,034,000 BTU/hrs, which means the same energy as 2,092,325,750 therms of natural gas. That’s enough to heat about 4.2 million homes for an entire year or run 139 million barbecue grills for all of the grilling season.

In short, it’s a lot of heat. And at the moment, most of that heat is being wasted — thrown away into the environment, or treated as something that needs to be disposed of rather than used.

What if instead, we could apply all that heat for some useful purpose? What if we could use it as a no-added-impact way to heat our homes? I decided to experiment with this and built a cryptocurrency heater of my own.

First Principles

Let’s start with firsts — the First Law of Thermodynamics, actually. The First Law says that energy cannot be created or destroyed. That means that all the energy entering your house cannot simply vanish once it’s done being used to cook your food, run your dishwasher, or power your mining computer. Instead, it has to turn into something else. And that something else is heat.

That might seem counter-intuitive at first. We tend to think of heat as something created by our furnace or stove. But actually, every watt of energy entering your house ultimately turns into heat. That goes for electricity coming from a wall outlet, natural gas used in your water heater, the power that runs through your computer — even the sunlight which streams in your window.

And it’s a perfect 1:1 ratio since heat can never be destroyed. So if your mining computer is drawing 500 watts of electrical power, it’s also creating 500 watts of heat. Many people pay good money for a 500-watt space heater — and here you’ve had one all along.

A few companies have picked up on this concept, and produce commercial crypto space heaters. But these are expensive conversation pieces — with a little DIY, you can build something much cheaper and better.

My Rig

I decided to test out the idea of heating my home with crypto. So I built myself a basic crypto mining rig.

My rig is a simple motherboard, with an EVGA Platinum power supply, Windows on an old hard drive, and an NVIDIA 1070 graphics card. The 1070 does the actual mining operations. I don’t bother with a monitor, and access it via Teamviewer from another computer.

To simplify things for this test, I used Nicehash for actual mining. It’s super simple — you install the software, set up some basics, press a button, and it starts using all your available hardware for mining different cryptocurrencies, depositing the proceeds into your Bitcoin wallet.

Obviously, to heat my home, I needed the rig in my actual home. So I placed it behind a TV in my living room, where it could blow hot air out into the room but wouldn’t get in the way. It’s quiet enough not to cause a disruption, too.

I used Afterburner to control power consumption. But really, for this test, I wanted to use a good amount of power, since my main goal was to generate heat. The more watts I burn, the more heat I make. A normal space heater is generating heat by wastefully running power through a resistive coil. Mine would generate heat through the much smarter process of looking for coins.

Results and Impact

I ran my rig for several months over the winter of late 2018 and into early 2019.

Mining at full throttle, it draws about 220 watts. That’s 716 BTUs of heat per hour or 17,184 BTUs per day. During my testing, it generated about $0.76 in mining profits each day.

My winter electric rate is $0.24 per KWH, so at 220 watts * 24 hours per day, that’s 5.28 KWH per day. That means my rig costs $1.26 per day to run. Subtract the $0.76 in crypto earnings, and that’s a net cost of $0.50 per day.

So how does this stack up against other forms of heating? Well, compared to a normal electric space heater, it’s immediately lower cost (not counting the cost of equipment).

Remember that a 220-watt space heater would draw 220 watts of power and produce 220 watts of heat. And you wouldn’t get any of that back in crypto earnings. So even if it only generated a penny each day, heating with crypto still saves money versus other forms of electric heat.

My house is mainly heated by natural gas, though. How does a crypto heater stack up against natural gas heat? Natural gas is measured in therms. A therm equals 100,000 BTU. Remember that my rig is making 17,184 BTUs per day of heat, so it’s essentially saving .17184 therms of natural gas per day.

My utility, PGE, currently charges $1.42 per therm. So heating with crypto is saving another $0.24 per day by avoiding some natural gas costs. There are likely other costs, too. To heat with natural gas, my HVAC uses a heat pump and fans, which draw around 1000 watts when the system is running. That probably adds another 10 to 15 cents per day in electricity saved by the crypto heater vs. natural gas.

So to recap, my crypto heater costs $1.26 per day to run, in pure electric costs. It makes back $0.76 of that from crypto earnings, and another $0.35 or from reduced natural gas usage and reduced electric costs for my HVAC. So running it costs me about $0.15 per day.

That’s not bad–I’m not getting paid to heat my home, or quite breaking even, but offsetting heating costs with crypto profits does greatly reduce the amount I spend for those 220 watts of heating power.

If I lived in a state with lower electric costs, I could likely break even, or even make money heating my home with crypto. Or if crypto prices increased, I could likely close the gap and break even on heating costs, too.

Scaling Up

This is neat, but we’re only talking about 220 watts in this proof of concept test. What if I wanted to scale this up, and heat my whole home with crypto?

According to PGE, I use an average of 1.16 therms of natural gas per day. Some of this is for my stove, water heater, dryer, etc. So let’s assume it’s about 1 therm per day for heating.

That means I’d need six mining rigs to fully heat my home (1 / .1784). It would cost me a net amount of about $0.90 per day ($0.15 x 6). That’s not too bad, considering that heating with natural gas would cost $1.42 for the 1 therm per day.

And if I had electric heat, that same therm would require 29 KWH, at a cost of $6.96 per day. Electric heat is expensive!

You have to consider the cost of hardware too, though. My rig cost about $450 to build. That means six rigs would cost $2,700. That’s a lot to spend on hardware to save less than $1 per day in heating costs!

Crypto Heat in the Real World

Based on my proof of concept test, it wouldn’t make sense to heat my home using crypto here in California.

But with some slightly different conditions, it would make a lot of sense. If I lived in a place with lower electric prices, I could likely break even or even make money heating with crypto.

Where I grew up outside Philadelphia, for example, electricity costs about $0.065 per kWh. In that environment, my rig would still make $0.76 per day, but it cost only $0.34 per day to run. That means I’d make a profit of $0.42 per day from each mining/heating rig. With six rigs, you’d earn back the $2,700 in hardware costs in less than 3 years.

Likewise, if I heated my home with electricity here in CA, then it might make a lot of sense to use crypto heaters instead of normal electric heaters. Remember that heating my home with electric heat would cost $6.96 per day. Heating with crypto would have a net cost of $3 per day ($0.50 * 6). So I would save almost $4 per day. Payoff time on the mining hardware would be less than 2 years.

And finally, if crypto prices increased, heating with crypto could make sense too, even here in California and as an alternative to natural gas. My rig would earn more each day–potentially enough to offset the electric costs and operate at a profit.

A Greener Alternative

But here’s the coolest thing, and a reason to consider crypto heating right now. Burning a therm of natural gas releases 11.7 pounds of CO2. But because our electricity in the Bay Area is delivered by MCE and generated by 100% renewable energy, heating with electricity here releases no CO2 at all.

That alone might be reason enough to consider heating with crypto. It’s a much cheaper alternative to traditional electric heating since the costs of the power are offset by crypto profits.

And because electricity can be generated with no CO2 emissions, electric heat (with the right supplier) could be a much greener way to heat millions of homes than relying on fossil fuels like natural gas — or worse, oil heat, which is still used in much of the Northeast United States.

Will we all be heating our homes with crypto one day? Probably not. But I think what you will see are more and more crypto mining operations finding productive uses for their waste heat.

This could mean heating homes, businesses, or even agricultural spaces. A startup called Heatmine is already pursuing this in chilly Canada, using crypto waste heat to heat greenhouses for growing strawberries. I’m sure the cannabis industry is taking note, too.

Greenhouses can benefit from crypto heating. Credit: NYPL

Ultimately, we as a society can’t afford not to find ways to make crypto greener, given the amount of power it uses. Pairing crypto with solar or other renewables, and then using its waste heat for productive purposes, is the best way to start down a greener path for the industry as a whole.

So if you’re mining already, consider thinking about ways to use your waste heat more productively. You can channel it into your home, situate mining computers in cold places in your warehouse or business space, etc.

And hey, I hear that greenhouse-grown strawberries are delicious.