Blockchain – a really high-tech “spreadsheet” or ledger used to record transactions securely – offers exciting potential for clean energy. With the rapid rise of distributed energy technologies — such as rooftop solar, batteries, smart energy devices, and electric vehicles — some analysts believe the market for blockchain applications in the energy sector is many times larger than it is for cryptocurrency in the financial sector. Blockchain technology may hold great promise for a sustainable future, but we need to solve some important challenges first. Companies are already experimenting with peer-to-peer energy trading on a microgrid — a small network of electricity users (like an apartment building or campus) with a local electricity source (like solar panels and a battery) that is able to function independently — using blockchain. This would allow “customer A” to purchase solar power from “customer B” while they aren’t home (AirBnB for energy anyone?). Blockchain can, in real time, determine how much power is needed against how much power is available on the network, and execute a micro-transaction between customers that is automated, verified, and secure.