  With the rapid growth of renewable energy resources, the energy trading began
to shift from centralized to distributed manner. Blockchain, as a distributed
public ledger technology, has been widely adopted to design new energy trading
schemes. However, there are many challenging issues for blockchain-based energy
trading, i.e., low efficiency, high transaction cost, security & privacy
issues. To tackle with the above challenges, many solutions have been proposed.
In this survey, the blockchain-based energy trading in electrical power system
is thoroughly investigated. Firstly, the challenges in blockchain-based energy
trading are identified. Then, the existing energy trading schemes are studied
and classified into three categories based on their main focus: energy
transaction, consensus mechanism, and system optimization. And each category is
presented in detail. Although existing schemes can meet the specific energy
trading requirements, there are still many unsolved problems. Finally, the
discussion and future directions are given.
