Glossary of Hydropower Terms

Type of facility

Conventional Hydro consists of a dam or diversion that diverts water to a powerhouse either at the base of the dam or further downstream via tunnels, conduits, and/or canals.

Pumped Storage is a method of generating power by moving water between an upper reservoir and lower reservoir using lower price non-peak power to pump the water to the upper reservoir then generating higher price power during times of high demand. Pumped storage hydro (PSH) projects are either open-loop (connected to a naturally flowing water feature) or closed-loop (not continuously connected to a naturally flowing water feature).


Mode of hydropower operation

Canal/Conduit generation is smaller-scale generation that is often added to existing irrigation and water supply canals. Even more limited is adding small microturbines to water and wastewater lines.

Peaking (Load Following) generation follows demand to maximize revenue from the project. This form of generation requires a storage capacity in order to save water during times of low power demand to generate later when the demand (price) is higher. This type of operation can result in erratic and rapid flow fluctuations downstream of the powerhouse as well as rapid fluctuations of reservoir levels.

Reregulating is the process of using a storage reservoir to capture erratic upstream flows created by peaking generation and then generating in a baseload fashion where the flows change gradually.

Run-of-river generation occurs where a project lacks storage capacity and needs to generate in real time using whatever inflow the project is receiving from upriver. This type of generation may be considered baseload generation as it occurs 24/7 and the quantity of generation is controlled by natural climate and weather cycles.

Run-of-river/Peaking generation is a hybrid of peaking and run-of-river when a project has limited storage capacity and is mostly operated in a run-of-river mode with the addition of limited peaking generation.

Run-of-river/Upstream Peaking generation is a project without storage capacity and its inflow and outflow is controlled by upstream power generation.

Learn more about modes of hydropower operation here.