What is Proof of Capacity?
Proof of Capacity (PoC) is a blockchain consensus mechanism that enables miners to earn the right to validate transactions and add new blocks by using their available hard drive space. Unlike Proof of Work (PoW), which demands constant computational effort, or Proof of Stake (PoS), which requires locking up digital assets, PoC leverages precomputed cryptographic data stored on disk. The more storage a participant dedicates, the greater their chance of successfully mining a block.
PoC was developed as a response to the high energy usage of PoW systems and the centralization risks of PoS. By shifting the mining process to storage-based participation, PoC reduces energy consumption while lowering the barrier to entry—making it more accessible to individuals using standard hardware.
How Proof of Capacity Works
Understanding how Proof of Capacity operates helps you see why it's considered a greener alternative to traditional mining methods.
Plotting Phase: Miners create plots by hashing data such as their account info. Each plot includes many nonces, with each nonce holding 8,192 hashes. Hashes are paired into "scoops"—e.g., hash 0 and 1 form scoop 0, hash 2 and 3 form scoop 1.
Mining Phase: When mining starts, a random scoop number is generated. The miner reads that scoop from each nonce and calculates a "deadline"—how long they must wait before they're eligible to forge a new block.
Block Forging: The miner with the shortest deadline waits that amount of time. If no one else forges a block during it, they can add the new block and earn the reward.
Energy Efficiency: Since the heavy lifting is done during plotting, mining only requires reading from disk—making it much more energy-efficient than PoW.
This four-step process—plotting, mining, deadline selection, and block forging—enables fairer and greener mining, while encouraging miners to refresh their plots periodically to stay competitive.
Benefits of Proof of Capacity
Energy-Efficient: Lowers environmental impact compared to energy-heavy PoW systems.
Accessible Hardware: Utilizes standard hard drives, allowing broader participation.
Longer Equipment Lifespan: Causes less wear and tear on hardware compared to GPU or ASIC mining.
Drawbacks of Proof of Capacity
High Storage Demand: Requires significant disk space, which could become a barrier for some participants.
