Rather than constantly solving cryptographic puzzles in real time for every block as in Proof of Work, Proof of Capacity works by performing a 1-time hashing cycle called plotting before any actual mining begins. This certifies the identity and capacity of the drive being used by the miner and populates it with pre-calculated solutions to a large number of cryptographic puzzles. PoC mining uses Shabal-256, an encryption algorithm which is more suitable for disk storage than the regular SHA-256 used by Bitcoin. Each plot is unique and depends on system specifications, hard drive space, and the time of writing. This prevents collisions of block answers between network participants. Each drive is populated with billions of pre-calculated hashes that are the solutions to cryptographic puzzles that can potentially be set by the network. This is the only computationally intensive part of PoC mining.
During the mining process itself, the drive is searched for answers at every block time. If a solution is found within the block deadline, it’s efficiency, that is the speed with with which it computes the answer, is compared to other competing solutions and the block reward is assigned to the miner with the fastest solution. Some solutions are faster than others. The block reward goes to the miner who submits the fastest solution. More hard drive space equals more potential solutions thus increasing your probability of getting the block reward.
Mining with Proof of Capacity requires negligible electricity, making PoC currencies some of the very few cryptos that can be profitably mined on simple commodity hardware. The PoC mining process itself is not computationally intensive and requires negligible energy. This means that mining a currency like Burst has practically zero cost, just hard drive purchasing costs, making it the only consensus algorithm that can profitably be mined on personal computers or even phones. PoC mining is at the same point in its cycle as Bitcoin in its early days, you can mine it on almost anything. To start mining Bitcoin today, you’d need at least USD 1,100 for a single ASIC miner, or you could buy an external hard drive, start plotting and start mining a PoC coin like Burst. “It is a lot easier”. Furthermore, the plot files can be deleted and the hard drive repurposed for another currency or another use altogether. Bitcoin mining rigs, on the other hand, can only be used for Bitcoin mining.
The most successful PoC cryptocurrency to date is Burstcoin. Burst has been running reliably since 2014 and is increasingly gathering interest in the crypto community. We expect many more PoC coins to appear.