Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.

Lightning Bitcoin is a cryptocurrency protocol with a DPoS consensus mechanism. It is a hard fork of Bitcoin that was created with the goal of improving transaction speeds and scalabilty. Lightning Bitcoin's on-chain governance system enables LBTC holders to vote for the blockchain improvement proposals and the delegates who maintain the network as Lightning Nodes. Lightning Bitcoin is not related to the Lighting Network, which is an off-chain protocol built on the Bitcoin blockchain.

Energi Coin is a Proof-of-Stake (PoS) cryptocurrency that combines smart contracts, decentralized governance, and a self-funding treasury. Energi was founded by Tommy World Power, with the goal of creating a more sustainable cryptocurrency that had the potential for mass adoption. Energi Coin's funding model is a built-in to the protocol and fuels the growth of the project. Aa portion of freshly-mined coins is assigned to the Treasury. The treasury allows the project to fund not only development, but also support, operations, and marketing. The founder, Tommy World Power personally funded the initial development of the project. Energi is currently shifting to a Solidity-based smart contract platform that will combine all of Ethereum’s existing capabilities with Energi’s unique governance and treasury model.