Blockchain is a technology that supports distributed trading?such as the cryptocurrency Bitcoin?which is threatening to disrupt a number of industries. Its name describes what blockchain software does: transactions are stored in virtual blocks, which are connected together in a chain, creating a complete history of all transactions that have ever occurred within a particular network. Potential use cases for blockchain are being developed in many different industries, particularly where it is desirable to accelerate transaction times, remove centralized market control, reduce the cost of performing transactions, and ensure trust between different market participants. While many use cases have been proposed for the energy industry, the one gaining the most traction at present is peer-to-peer (P2P) power trading, where owners of small-scale generation can sell excess generation direct to other consumers. Today, centralized control of distributed energy resources (DER) restricts to whom and when DER owners can sell their energy back to the grid. A blockchain-enabled P2P model allows much greater flexibility and could be a powerful enabler for truly customer-centric transactive energy. The earliest adopters of blockchain will likely not be utilities, but other stakeholders. Currently, those leading the research into blockchain are the owners of DER and startups seeking to sell directly to them. This Navigant Research report discusses the many specific requirements of an energy blockchain and provides several practical recommendations to the industry. The study offers an analysis of the drivers for P2P trading and discusses why blockchain is an attractive option to support transactive energy. It also includes discussion of case studies, opportunities, and implementation challenges associated with blockchain technology.