Abstract
Hydropower plays a key role in the evolving energy grid. In the United States, thousands of non-powered dams (NPDs) represent untapped opportunities for new energy production. This paper reviews past NPD resource assessments, with a particular focus on those in the United States, and evaluates where there is room for improving methods, data, and assumptions for estimating development potential. Through this review, we catalog the types of information that are available to stakeholders involved in NPD development. Past assessments have generally focused on interests of project developers (i.e. how much hydropower development potential is available); however, needs of other stakeholders are not adequately addressed in literature. We thus suggest specific actions for improving methods and data used in assessing development potential: establishing consistency among datasets, accounting for uncertainties, representing technology in a more robust way, and accounting for a broader suite of factors that affect potential. To support development at NPDs, future research should consider emerging technologies, explore co-development strategies, and incorporate socio-economic incentives and constraints. Additionally, we survey recent NPD retrofit projects in the United States and identify patterns at successful projects (restrictions on additional flow alterations and water quality/ecological requirements are common) and unsuccessful projects (surrendered licenses often cite lack of economic feasibility). A comparison between retrofits and the remaining population of NPDs highlights that certain characteristics are disproportionately observed in successful retrofits (i.e. concrete dams with the primary purpose of navigation). Understanding the current state of the literature and recent patterns in NPD development will help improve future analyses of potential and support broader development-related interests.
