By: Donald Jones, P.Eng.
Ontario exports large amounts of electricity to neighbouring jurisdictions day and night. Exports occur for technical and financial reasons. Ontario presently has an excess of baseload generation so it makes sense to export the surplus. In the immediate future there will be many thousands of megawatts of installed wind power on the grid and exporting will be the only way to maximize its accommodation on the grid while maintaining grid reliability. Since supply contracts with the non-utility gas generators apparently mean that consumers pay whether the generation is needed by Ontarians or not, it makes some sort of misguided sense to export at a subsidized price and get at least something for it.
At times of the year, usually the shoulder seasons of spring and fall, the province presently has a surplus of baseload generation. This Surplus Baseload Generation (SBG) occurs when baseload generation, from nuclear, must-run hydro, combined-heat-and- power, and wind, that cannot be reduced for technical or contractual reasons, exceeds demand. If an export market is available of sufficient capacity this will prevent powering down or shutting down nuclear units that could be offline for up to three days leaving gas and coal to take up the slack. In this case it makes sense to export even at negative prices if it prevents manoeuvring our present nuclear units.
Wind is a take-when-available energy source and has priority to the grid during SBG periods ahead of nuclear but the latest wind contracts with the Feed-In Tariffs, signed in early 2010, provide financial incentives for future wind generators to curtail production during SBG periods (although such incentives are not provided for the 1,400 or so megawatts that will be on the grid from the earlier Renewable Energy Standard Offer Program-RESOP). For example the feed-in-tariff of 13.5 cents/kWh for on-shore wind is reduced a cent for every cent/kWh the electricity price goes below zero but wind generators will get paid the full cost of forecast production if they voluntarily curtail production when requested to do so by the Independent Electricity System Operator (IESO). For wind generators installed under the old pre Feed-In-Tariff (FIT) program, RESOP, the wind has priority to the grid over nuclear unless there are technical or reliability reasons to prevent it. The IESO cannot dispatch wind off for economic reasons under either program, only for technical or reliability reasons, although it is trying to be allowed to do this.
The governments Long-Term Energy Plan calls for 12,000 MW of nuclear capacity to provide just 50 percent of total generation, since anything more than 50 percent causes concerns about nuclear turndown in low demand periods. For details see, “Ontario Needs More Than 2000 MW of New Nuclear” By 2018 there will be 10,700 MW of installed wind, solar and bioenergy – let us assume 8,500 MW of installed wind – and 9,000 MW of hydro, including run-of-the-river and storage. The gas-fired generation will be maintained at its current level of over 9,500 MW – say 10,000 MW – and there will be 1,000 MW of Combined Heat and Power added to the baseload supply.
If we assume the maximum available 10,000 MW of dispatchable gas generation is on line and that it is all combined cycle and that it can get down to, say, 50 percent, then it can integrate 5,000 MW of wind. The 50 percent is an average figure since some plants may be kept at the bottom of their dispatchable range while others may be down at say 20 percent with some turbines in a multi-gas turbine plant shutdown. The other 3,500 MW of wind would have to be integrated by reducing hydro generation by 3,500 MW. If hydro can be dispatched down to the must-run hydro minimum of around say 2,000 MW it means that there must be at least 5,500 MW of hydro on line to accommodate the remaining 3,500 MW of wind.
This shows that there could be potential concerns during a day when gas and hydro are operating at less than their maximum capacity (which is most of the time) and wind kicks in since all the installed wind generation would not be able to be accommodated on the grid. However if there were high levels of export much more of this wind could be accommodated. This also has technical advantages since the combined cycle gas turbine generators on the grid might not have to be powered down below their dispatchable range of around 70 to 100 percent of full power. When in their dispatchable range the units can respond appropriately to dispatches sent every five minutes by the IESO. When operating below their dispatchable range they might not be able to raise power quickly enough if the wind suddenly drops, putting the grid at risk. The safe and reliable operation of Ontario’s nuclear units depends to a certain extent on the reliability of the grid to which they are connected. In the future, without exports, there could be insufficient dispatchable gas and coal-fired generation available on the grid that could be powered back to accommodate the potential wind generation. Exports maximize the amount of wind that can be integrated into the grid and improves the grid reliability. This is explained in detail in, http://coldaircurrents.blogspot.com/2011/01/more-wind-means-more-risk-to-ontario.html
Minister Duguid recently said that ”exporting Ontario power at prices lower than those paid by the province’s consumers makes sense”. Exporting at prices that do not include the Global Adjustment (GA) charge that Ontario consumers pay does not make sense. In a properly run system this would not happen. The only possible rationale for this is that the gas-fired non-utility generators have been contracted by the Ontario Power Authority to supply a certain amount of megawatt hours per year, for many years, and they get paid even if their supply is not needed by Ontarians. Without this type of contract the generators would only produce what was needed and consumers would save on the GA charge and less fuel would be burned with less accompanying pollution. The financial saving is shown in the lowest plot on http://morecoldair.blogspot.com/2011/01/mcguinty-thinks-this-is-fun-it-hasnt.html Something is better than nothing in Minister Duguid’s case only because of the poor management of the electricity system.
This shows that rather than trying to minimize the output of gas and coal-fired generation technical and financial issues will increase the output, burning more gas and producing more Ontario pollution. With controversial unconventional shale gas becoming more of the mix, gas prices are surely to rise. With large amounts of installed wind coming on to the grid and without exports the grid reliability will be reduced.