This is an energy efficient alternative to proof of stake blockchains developed by a team led by Bram Cohen, the creator of BitTorrent. The consensus mechanism

This is an energy efficient alternative to proof of stake blockchains developed by a team led by Bram Cohen, the creator of BitTorrent. The consensus mechanism is similar to proof of work, except that it basically recycles the computational work by storing an indexed cache of intermediate calculations so they can be reused each block until they manage to solve a block puzzle. While the initial "plotting" takes some computational power, once the plots are finished, doing the lookups on these cached intermediary computations is many orders of magnitude more efficient than recomputing then every block. It can be done on a raspberry pi over many terabytes of cached computations.