We started mining Bitcoin in 2022 as a pilot project to test out on a small scale, heating a couple of pools. This solution would be scalable to anybody needing hot water, whether that was for heating pools, domestic hot water or building heating applications such as radiant flooring. However, it’s an ideal solution for use cases that have a very consistent base load, such as pools or heated hammams.
Before getting into the details, let’s have a refresher on the Law of Conservation of Energy:
“The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside. The only way to use energy is to transform energy from one form to another.”
We purchase off-the-shelf ASICs (Application Specific Integrated Circuit), which are computers designed specifically for Bitcoin mining. We remove the fans and convert them for immersion cooling because they typically come designed to run air-cooled. Then, the ASICs are immersed in a tank filled with dielectric fluid with an integral pump and a heat exchanger on the tank. There are lots of different kinds of heat exchangers, here is a simple diagram of how they work:
Instead of using electricity for an electric pool heater, we use electricity to run the miners. The electricity used for the computing power is converted into heat as a byproduct by the ASICs. The heat (energy) is captured in the dielectric fluid in the tank that the miners are sitting in. Going back to the Law of Conservation of Energy, energy cannot be created or destroyed. So ALL of the electrical energy used by the miners is converted into heat energy.
The heat exchanger on the tank has four ports: hot oil in, cold oil out, cold water in, and hot water out. The water from the “hot water out” port runs in a loop from the heat exchangers on the mining tanks to the heat exchangers in our pool plumbing, recycling the energy used by the miners to heat the water in the pools. If we have a little excess heat left over we use it in our domestic hot water system, which we accomplished by utilizing an indirect hot water heater. The loop then returns the now-cooled water back to the “cold water in” port on the mining tank’s integral heat exchanger and the system runs in perpetuity.
The net result is that this system is energy-neutral because we are powering the miners with energy we already needed to purchase in order to heat our pools. (Remember, energy can’t be created or destroyed – only converted). Therefore, we are able to use the energy from this electricity "twice" in a certain sense. Once, to mine Bitcoin, and a second time to heat our pools. The miners were a direct one-for-one replacement of our electric pool heaters in terms of total watts, so the total energy input remained the same. We are able to recover some of our energy costs with earned Bitcoin while supporting the Bitcoin network and nerding out on a fun engineering project.
Here is a diagram of the complete set up:
- ASIC: https://www.bitmain.com/
- Law of Conservation of Energy: https://www.feynmanlectures.caltech.edu/I_04.html
- Indirect hot water heater: https://www.energy.gov/energysaver/tankless-coil-and-indirect-water-heaters
- Dielectric fluid: https://shop.engineeredfluids.com/collections/bitcool
- Heat Exchanger: https://www.iqsdirectory.com/articles/heat-exchanger.html
- Tank: https://cryptocooling.eu/scale-out/#tab-1693575287283-7