Run-of-the-river hydroelectricity

Run-of-the-river, or ROR, hydroelectricity is considered ideal for streams or rivers that can sustain a minimum flow or those regulated by a lake or reservoir upstream.

[1][2] A small dam is usually built to create a headpond ensuring that there is enough water entering the penstock pipes that lead to the turbines, which are at a lower elevation.

Traditional hydroelectric dams store enormous quantities of water in reservoirs, sometimes flooding large tracts of land.

[7]Many of the larger run-of-the-river projects have been designed to a scale and generating capacity rivaling some traditional hydroelectric dams.

[10] The advantages and disadvantages of run-of-river dams depends on the type, the following sections generally refer to Dam-Toe unless otherwise stated.

[11] Diversion Weir has very little flow regulation, which is generally used to cover exclusively short-term peak times electricity demand.

[11] When developed with care to footprint size and location, run-of-the-river hydro projects can create sustainable energy minimizing impacts to the surrounding environment and nearby communities.

A dam may create a reservoir hundreds of kilometres long, but in run-of-the-river the head is usually delivered by a canal, pipe or tunnel constructed upstream of the power house.

In British Columbia, the mountainous terrain and wealth of big rivers have made it a global testing ground for 10–50 MW run-of-river technology.

As of March 2010, there were 628 applications pending for new water licences solely for power generation, representing more than 750 potential points of river diversion.

[18] In undeveloped areas, new access roads and transmission lines can cause habitat fragmentation, allowing the introduction of invasive species.

Short-term climate anomalies such as the El Niño Southern Oscillation (ENSO)[1] can significantly disrupt the flow and can have a profound impact on the operation of these projects.