Pi achieves this by using a different type of consensus algorithm in its blockchain, rather than the widely known Proof of Work (POW) algorithm that consumes a lot of energy. Pi’s consensus algorithm is adapted from the Stellar Consensus Protocol (SCP) and an algorithm called Federated Byzantine Agreement (FBA), which do not require energy consumption to reach consensus in order to secure a ledger. This type of consensus algorithm requires the nodes to form quorums and exchange messages with each other based on a trust graph composed of individual quorum slices to come to a “consensus” on what the next block should be.
Mining is making contributions to the consensus algorithm to secure the ledger in blockchain for rewards. While POW mining requires nodes to “work” to solve mathematical puzzles to help the algorithm reach consensus and incidentally consume a lot of energy, Pi mining requires a distributed trust graph. The security circles of each individual mobile miners will aggregate into a global trust graph that will feed the consensus algorithm of the Pi blockchain. Therefore, each mobile miner is mining Pi by contributing to the intersectionality, security and feasibility of the consensus algorithm of the Pi blockchain in order to secure the Pi ledger.
While POW miners’ contribution to those blockchains is the energy, Pi mobile miners’ contribution to Pi Blockchain is their trust relationships and the active confirming of such relationships. The heavy lifting of running the consensus algorithm based on the trust graph that the mobile phones are creating is still falling into computer nodes. In fact, the Pi Testnet already has more than 10K such computer nodes that will be soon migrated to the Pi Mainnet, placing Pi into a good path into creating a very decentralized blockchain network.