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Flow-volumes for the Stikine and Little Qualicum Rivers. Like other streams in central and northern BC, the Stikine has low flow throughout the winter and spring, and then high flow during the summer melt and early fall storms. In contrast, the Little Qualicum River, like other streams in the south coastal area, has its highest flows during winter storms and lowest flows during the summer. |
| Image © Steven Earle using data from Environment Canada. http://www.wsc.ec.gc.ca/hydat/H2O |
The key advantages of a run of river project over a typical hydro project are environmental; there is no reservoir, almost no land is flooded and the flow characteristics of the river are not significantly altered.
The key disadvantage is that there is no potential for storage of water, and hence almost no control over how much electricity can be generated at any specific time.
Because run-of-river cannot be relied on when river flows are low, the potential capacity of a run-of-river project should be rated at about 50% of its actual capacity. In other words a 10 MW project should be able to generate electricity at an average rate of about 5 MW.
In cold areas of Canada (including central and northern British Columbia) stream flows tend to be lowest during the winter, so the production of electricity is lowest when the province's demand for electricity is highest. On the southern coast and on Vancouver Island, stream flows are highest during the winter, so the match between electricity supply and demand is good.