Modelling the transition from cost-based to bid-based pricing in a deregulated electricity-market

Alberta is a province in western Canada with a deregulated electricity-market. Market clearing prices for most hours reflect the cost of either coal-fired or gas-fired thermal generation. Whenever there is a chronic shortage of generation or even a temporary one due to an outage, prices can be bid much higher than fuel costs would suggest. The province of British Columbia borders Alberta to the west and its electric utility, BC Hydro, has a history of trade with the utilities in Alberta. BC Hydro has predominantly hydroelectric resources and large storage reservoirs. Prior to Alberta’s deregulation in 1996, BC Hydro was able to enter into mutually beneficial load-factoring contracts with the Alberta utilities. Now, as long as the transmission is available, BC Hydro can buy low priced off-peak coal-fired energy and sell into the high priced periods without having to share the benefits. BC Hydro uses a combination of econometric and Monte Carlo modelling to simulate hourly price-duration curves for Alberta that capture both cost-based and bid-based characteristics. This approach provides a good fit with the stochastic dynamic programming model that BC Hydro has developed for its mid-term hydro scheduling.