Cryptocurrencies have an energy problem. The entire Bitcoin network now uses more energy than all of Ireland, and a single Bitcoin transaction requires the same amount of energy your house uses in a week. Ethereum, the second most popular cryptocurrency, isn’t much better. This is bad news for the environment, but also for the miners who generate cryptocurrencies with massive amounts of computing power, which can rack up a huge electricity bill. So, it’s no surprise that miners have sought the cheapest forms of electricity to maximize their profits from mining cryptocurrencies. In China, where the largest Bitcoin mines are operated, miners use ultra-cheap hydro energy. In Europe, small scale miners are beginning to experiment with wind-powered mining rigs. Now at least one Tesla owner is getting a piece of the action by installing mining rigs in their trunk to take advantage of the free electricity provided to some Tesla owners—or so it seems.
The rig was initially reported on the blog Eco Motoring News, but as a cryptocurrency miner myself I was immediately skeptical. Let’s go down the rabbit hole together, shall we? A member of the Facebook group Tesla Owners Worldwide posted a photo of their Tesla mining rig to the group after another member jokingly suggested someone should try to use a Tesla to power a Bitcoin mining rig. Mining Bitcoin requires specialized computer chips (ASICs) that perform repetitive math problems millions of times per second to verify Bitcoin transactions on the network. Other cryptocurrencies are similar, but rather than using specialized computer hardware, these currencies can be mined with off-the-shelf GPUs, the same types of computer chips used by gamers. Based on the picture posted to the Facebook group, the Tesla isn’t being used to mine Bitcoin—there are no ASIC chips. Instead, there are four motherboards and four power supply units mounted to what looks like pieces of plywood. The blue cords are attached to powered risers, which are used to connect several GPUs to a single motherboard. In this case, each motherboard is outfitted to run 4 GPUs. The GPUs are not connected to the risers in the picture, so it’s uncertain whether the person who posted it ever actually mined anything with their Tesla, or was just trying to get a laugh. As someone who has built and run a crappy Ethereum mining rig of their own, I’m skeptical about the feasibility of their plan.
First of all, having this many GPUs running in your car would be unbearably hot, meaning that mining would really only be feasible while the car was parked at a recharging station and the driver is not in the vehicle. There’s also the fact that there’s really nowhere to safely mount GPUs in the vehicle, which means the driver will have a bunch of expensive computer equipment rattling around in their trunk while they’re driving.
But even if these practical difficulties were surmounted, would this really be a cleaner or cheaper way to mine cryptocurrencies? If we assume that each of the GPUs in this rig draws around 150 watts (pretty good for a GPU), then the 16 GPUs have a total power draw of 2.4 kilowatts per hour or 57.6 kilowatt hours per day if they ran for a full 24 hours. According to Green Car Reports, a Tesla Model S gets about 3 miles per kilowatt hour, meaning that running this mining rig for a full day is the equivalent of driving nearly 173 miles in the Tesla. According to the Federal Highway Administration, the average American drives around 260 miles a week. In other words, running this cryptocurrency mine out of the trunk of a Tesla for a day and a half would use as much energy as driving that Tesla for a full week, on average. Moreover, drivers who are not a part of Tesla’s unlimited free energy program (that is, anyone who bought a Tesla after last January) are limited to 400 kilowatt hours of free electricity per year, meaning they could only run their rig for a little over 7 days on free energy.
Okay, but how about the cost? Let’s assume that this person is mining Ethereum with their GPUs. Out of the box, an average GPU can do about 20 megahashes per second on the Ethereum network (that is, performing a math problem known as hashing 20 million times per second). This Tesla rig, then, would have a total hashrate of about 320 megahashes. According to the Cryptocompare profitability calculator, if the Tesla rig was used to mine Ethereum using free electricity, it would result in about .05 Ether per day—equivalent to nearly $23, going by current prices at the time of writing. In a month, this would result in $675 in profit, or about the monthly lease for a Tesla Model S.
So the Tesla would pay for itself, assuming the owner never drove it or used it for anything other than mining Ethereum, Ethereum doesn’t drop in value below $450, and the Tesla owner gets all of their energy for free. (This also doesn’t take into account the price of each of the mining rigs, which likely cost about $1,000 each, depending on the quality of the GPUs used.)
Mining cryptocurrency out of your electric, self-driving car is a pretty futuristic idea, but unfortunately it’s also quite a stupid one.