More wind generation on Ontario electricity grid means more pollution

January 12, 2015

By: Donald Jones, P.Eng., retired nuclear industry engineer, 2015 January

It seems that the more wind there is on the Ontario electricity grid the more pollution there is. Case in point, a snapshot of the Independent Electricity System Operator’s (IESO) Generator Output and Capability Report for 2015 January 8 at 7 pm, which was a high wind high demand day. Wind was generating 2,631 MW, natgas or frackgas was generating 3,783 MW with the balance of the demand being met by nuclear and hydro. There were net exports of 3,500 MW. Now if there were no exports, natgas generation could have been reduced to 283 MW (assuming this low generation were achievable technically and under the must-run contracts) with a clean supply of nuclear, hydro and wind meeting the major part of the Ontario demand. Obviously 283 MW of natgas generation produces less greenhouse gases (GHGs) than 3,783 MW of natgas generation. So why did we need to export any gas generation in the first place since exports are highly subsidized by Ontario ratepayers to the benefit of the recipient jurisdiction?

This large amount of gas generation was likely exported because of the concern the IESO may have had with the risk of losing substantial wind generation under these circumstances (reference 1). Since most of the gas generation would be shutdown without exports the potential loss of 2,631 MW from wind would have had to be met from hydroelectric generation. With hydroelectric generation at this time already at a high 5,535 MW there may not have been enough extra MW and MWh available to cover the time period until the combined cycle gas turbine (CCGT) units could be fired up and dispatched to meet the wind shortfall. Ontario has only one quick start simple cycle gas turbine (SCGT) unit of 393 MW. Imports from other jurisdictions may not be available since wind failures affect large geographical areas and Quebec may have needed all its generation in house or had it already committed. The solution seems to have been to keep the CCGTs running at around their lowest dispatchable load so that they would always be available in case wind generation failed and the only way to do this was to feed an export market (reference 2). If sufficient extra MW and MWh of hydroelectric generation were available until the demand dropped there would be less or even no need to fire up the CCGTs. However, over the next five years or so several thousand MWs of additional wind will be coming onto the grid. With hydro generation limited the grid will see more use of the GHG emitting CCGTs (in MW and in MWh) and of exports (as in this snapshot) to maximize the use of the wind generation investment and minimize wind curtailment. The Ontario grid will depend even more on an export market and on reliable wind forecasting.
Read the rest of this entry »