Driven by the mighty waters of Kootenay Lake’s West Arm and the Kootenay River, Nelson Hydro generates power for its 11,000 customers at the 16MW Bonnington Dam power plant and the city’s community solar array, then distributes power from the dam, solar array and FortisBC’s supply system, to a network of seven substations and 320 kms of transmission and distribution lines.
How Generation Works
Nelson Hydro owns and operates a run-of-the-river 16 MW hydroelectric generation facility that harnesses the power of moving water to generate renewable electricity located at Bonnington Falls on the Kootenay River 16 km southwest of Nelson. The current water license allows a year-round output of 9.1 MW, which represents about 50% of our annual energy requirements and generates the most electricity during freshet, or, the time between mid-May to mid-July when the headwaters of the Kootenay River are at their peak from melting snow from the surrounding mountains.
Watch the video below to learn how a run-of-the-river hydroelectric generating station works.
Steps to Generating Power
- Dam. There is potential energy stored in the water reservoir (forebay) impounded by the dam. It is converted to kinetic energy when the water starts flowing down the penstock from the dam and through the turbine.
- Generator: The falling water strikes a series of blades in the turbine that are attached to a shaft which converts kinetic energy to mechanical energy which rotates the turbine. The shaft is attached to a generator so that when the turbine turns, the generator turns. The generator converts the turbine's mechanical energy into electric energy.
- Step-up Transformer: Nelson Hydro generators produce electricity at 12kV. In order for the transmission lines to carry the electricity efficiently over long distances, it is increased to 63kV (transmission voltage) by a step-up transformer.
- Terminal Station: Terminal stations receive the flow of power from the Step-Up Transformer and then they reduce the voltage to 12kv-25kv (distribution voltage) levels.
- Transmission Lines: Transmission lines supply power from terminal stations to distribution substations.
- Distribution Substation: A distribution substation is a system of transformers, meters, and control and protective devices. At a distribution substation, the transmission voltage is reduced to distribution levels and supplied to individual feeder circuits.
- Distribution System: The distribution system is comprised of lines, poles, transformers and meters distributing the power from the distribution substation to individual homes. The distribution level voltages are transformed to customer level voltages by means of a distribution transformer on the utility poles for overhead power and also on pad-mount transformers for underground power.
What is not generated, the remainder is purchased. Approximately 50% of the annual energy requirements are obtained via wholesale power purchase from FortisBC. Nelson Hydro connects to the FortisBC electric system at three points; Fortis' Coffee Creek, Nelson Hydro's Generating Station, and Nelson Hydro's Granite Substation. These interconnections are required so that the 88,859,645 kWh (2021) of purchased energy can seamlessly integrate into the Nelson Hydro grid to supply the needs of our customers.