There are a growing number of blockchain applications in energy systems, but surprisingly little is known about their direct energy demand outside of cryptocurrency applications. Addressing this knowledge gap should be a key policy priority so that the energy use of blockchain systems can be better understood and managed as applications proliferate. To help policy makers and energy analysts achieve this goal, this article makes three contributions. First, we present a brief review of blockchain system components, energy demand drivers, and emerging applications to provide a common conceptual foundation. Second, we propose best practices for energy analysis of blockchain systems and identify best practice lapses in previous literature that presently cloud our understanding of energy use. Finally, we propose priority research areas to address identified lapses and knowledge gaps, which would ensure future research produces data and estimates that are maximally relevant to energy policy decisions.