What is Run-of-River?
Run-of-River hydroelectric (ROR hydro) projects generate electricity by channelling natural stream flows and utilizing natural elevation differences in mountainous regions like British Columbia.
A portion of the mountain stream is diverted by an intake structure into a buried pipe (called “penstock”) where it is channeled downstream into turbines. The flowing water causes the turbines to spin. A generator is directly attached to the turbines and creates electricity. The water from the turbines is released unaffected back into the stream.
Run-of-River is a readily available source of renewable electricity in carefully selected watersheds.
It plays a prominent role in sustainably meeting British Columbia’s growing energy needs and reaching greenhouse gas emissions reduction targets. ROR hydro projects directly distribute economic benefits to a larger number of communities and municipalities compared to Large Hydro projects. ROR projects are also situated closer to points of electricity demand thus reducing transmission losses. The scattered distribution of ROR Hydro projects lowers the overall power system risk versus large electricity sources in a single location.
Run-of-River vs Conventional Storage Hydro
In conventional storage hydro, a dam is placed across a river to create a reservoir with most of the water impounded behind the dam and the flow downstream regulated, which changes the natural variation of flow for the entire downstream river.
Run-of-River hydro projects have a much smaller environmental footprint compared to traditional reservoir storage hydro because they typically have very little water storage capacity thus less land is flooded, reducing potential footprint. With ROR hydro, only a portion of the stream flow is affected, and only a short length of the river experiences reduced flows. The volume of water a ROR project may divert through penstocks to run turbines depends significantly on stream morphology and environmental characteristics, but a typical plant utilizes less than two-thirds of a river’s annual flow. Immediately below ROR Hydro powerhouses, all flows diverted to produce power are returned to the stream and the natural downstream flow patterns are preserved.
Without storage, however, ROR hydro supplies electricity only as natural flow allows. Flow conditions conducive to ROR power generation do not always correspond to times when electricity demand is high. Accordingly, both technologies have advantages and disadvantages and should be viewed as complementary resources.
Run-of-River in BC
Run-of-River hydro projects have been used historically throughout British Columbia to power mines, mills, and towns. As of 2021, there are 68 independent ROR projects supplying electricity to BC Hydro.
In striving to meet environmental assessment standards in BC, the developers, consultants, and suppliers in the ROR hydro industry have become some of the most knowledgeable in the world on minimizing the impacts of hydro power. Some examples include turbine designs and operation measures to ramp up and down in a safe manner to ensure minimal impact on fish and fish habitat as well as energy dissipation chambers to ensure an environmentally sustainable development of local resources.
Although there are countless rivers and streams in the province, not all are suitable for ROR hydro projects. Potential sites must have the right balance between water flow and steepness of terrain; cost-effective transmission access and construction and the ability to operate with minimal impacts on aquatic and terrestrial life. While the potential for ROR hydro in BC is very high, only a small percentage of this potential will be developed because not all sites fulfill these requirements.
Environmental & Regulatory Considerations
- All ROR hydro projects undergo comprehensive environmental assessment. This process typically requires three or more years of field study followed by extensive review by provincial and federal government agencies.
- It takes 5-6 years to bring a typical ROR hydro project to construction, and it requires around two years to build. Many projects take more than 10 years from idea to operation.
- Each ROR hydro project requires over 50 permits, licenses, approvals, and reviews from over a dozen government agencies, involving extensive public and First Nations consultation.
- Projects that achieve approval must adhere to strict operational parameters. As a result of the environmental assessment and permitting process, every project must comply with dozens of operational conditions, which are monitored by independent, third-party engineers and compliance officers to ensure a high standard of environmental protection and mitigation.
- Water licenses for power generation issued by the provincial government typically run for a 40-year term. Over this period, the operator pays an annual water rental levy and land lease payments to the provincial government.
- When licenses expire, the developer may apply for renewals. If they are not granted, the right to use the land and water revert to the provincial government.
- In BC, a typical 10 MW ROR power plant producing 40,000 MWh of green energy annually displaces approximately 13,700 tons of carbon dioxide (the equivalent of taking about 3,000 cars off the road).
The socio-economic benefits of run-of-river hydro projects include:
Environmentally sustainable development of local resources
- Diversification of economic activity in remote areas
- Training and employment opportunities for First Nations and communities
- Continuous source of clean, green renewable energy with minimal environmental impact