So I have this silly idea/longterm project of wanting to run a server on renewables on my farm. And I would like to reuse the heat generated by the server, for example to heat a grow room, or simply my house. How much heat does a server produce, and where would you consider it best applied? Has anyone built such a thing?
A server produces an amount of heat equivalent to it's wattage.
A 500W server rack will produce 1/3rd the amount of heat as a 1500W space heater. If your rack draws 100W at idle, than that's how much heat it produces. So if it's cold outside you could spin up folding at home or some other thing to burn excess CPU cycles
As long as your server is inside your house it is offsetting the amount of heat your HVAC system needs to produce - granted it is also greatly increasing the amount of work your AC needs to do in the summer
There is a cricket farm in Quebec that heats it's enclosures with Bitcoin mining rigs.
Servers are 100% efficient at heating, but heat pumps are 300% efficient. Get the most energy efficient devices you can, and heat your house with a proper heat pump.
You can even dump the cold air from the heat pumps into the server room and pull the hot air back into the heat pump again to gain even better efficiency
Well, that was my plan when I set things up with an air-to-hot-water heatpump in the same room as my homelab. But the reality is that when it is hot outside, I don't need to run the heatpump (mainly because the solar-thermal water heater is so much more effective). And otherwise the there is no need for cooling in that room.
You can always dump the hot water in an outside radiator if you HAVE to cool the server room to keep the temps down. A simple fan duckt would probably doo fine too. However with the heat pump you can also heat a little hot tub to use outside in summer