The rapid growth of the rate of cryptocurrencies makes more people engaged in mining. So, one of the members of the online community "Tesla Owner Worldwide" on Facebook offered to use electric power and built-in Tesla computer in electric vehicles for the cryptocurrency Mining. In particular, it was proposed to use a powerful computer responsible for the autopilot in the Tesla for the computing platform. However, this idea was not implemented because of security concerns.
Then for the farm one of the members of the community suggested using capacious batteries. His idea is to use energy from the network of charging stations Supercharger, which the owners of Model S and Model X in the US are free. It is unlikely that it will be used for Bitcoins mining, but for the extraction of some cryptocurrencies with small "stretches" will do.
What advantages this setup would have to offer over a regular in-home mining rig? It's not clear really.
The idea was suggested in order to use the free access to electricity with the Supercharger network. Technically, if someone is able to draw power from the Tesla to power those mining systems, which is what this owner is claiming though it's not clear how he is drawing the 2.8 kW of power required from battery, they could only use free energy if their Tesla falls under the unlimited free Supercharging program, which represents most Model S and Model X vehicles.
Of course, that presents its own issues. Ethically, it's not what the Supercharger network is meant to power and therefore, some might find issue with people using it to power mining rigs instead of long distance driving.
Also, it would require an increased use of the battery pack, which is not good for durability.
Finally, that rig would create a lot of heat inside the Model S. Aside for preheating your car while making a few bucks, it's not clear what use someone would have for that heat. Aside from the free power, which again has its own drawbacks, the setup doesn't really offer many advantages.