by Donald Jones, P.Eng.
Ontario’s Integrated Power System Plan (IPSP) was put out for comment by the Ontario Power Authority (OPA) in 2005 and submitted to the Ontario Energy Board (OEB) in 2007 August. In 2008 September the then Minister of Energy and Infrastructure, George Smitherman, pulled the IPSP back from the OEB and requested that the OPA take another look at it to increase the amount of renewable energy and conservation, amongst other things. It has not surfaced since so one can only wonder if the OPA is concerned about the economic and technical aspects of the request from the energy minister or indeed is having second thoughts on the economic and technical aspects of the rest of the plan which would shut down all coal generation and replace it with natural gas, and wind when it is available. The OPA may be taking encouragement from its former CEO, Jan Carr, a power system expert, who has said that the government’s promotion of wind power, as a feel good approach to climate change, is being done at the expense of securing a stable and economic energy future for the province and will jeopardize its prosperity. In the meantime there is no plan.
Closing all the province’s coal-fired power plants by 2014 will result in a transition to natural gas-fired generation. The coal plants have served Ontario well providing baseload, intermediate load, peaking load, operating reserve, and high ramping capability for load following as well as frequency control and voltage control. Coal is much more flexible than gas. It has a much lower minimum load and a shorter minimum run time than the gas-fired combined cycle gas turbine units with their large complex heat recovery steam generators. Coal has over twice the dispatch flexibility range, between minimum loading and full power, which means either twice as many gas units would be needed to provide the same dispatch flexibility range as similar sized coal units or the gas units would have to have twice the capacity of the coal units. Ontario already has more gas generation capacity than coal generation capacity. Dispatching combined cycle plants is much more complex than dispatching coal-fired plants since the steam turbine is a slave to the combustion turbines and various combinations of the multiple combustion turbines with and without the steam turbine are possible, with warm-up of the steam generators and steam turbine to be considered. The dispatchable load following capability of the gas and coal-fired units, and of the stored water hydro units when conditions allow, enable the nuclear plants and run-of-the-river hydro units to operate at constant full power and compensates for the intermittency of the wind turbines, so at the present time the fossil units are critical in balancing the supply and demand on the grid as well as providing some baseload. Thus the continued availability of gas, at a reasonable price, will be crucial.
Wind will also be a part of the government’s power supply mix. Earlier in the year the Ontario government announced a renewable energy deal with a consortium led by Samsung and Korea Electric Power Corporation for 2,500 MW of wind and solar and signed off on 184 solar, wind and hydro projects for nearly 2,500 MW. A lot of this new supply will be from wind, around 3,500 MW nameplate capacity. If we add this to the present 1,000 MW or so of wind on the grid we are looking at 4,500 MW on the grid in a few years with more to come, if the government has its way, for maybe a total of around 8,000 MW as transmission links become available. With an installed grid capacity of around 35,000 MW and maximum demand on a hot summer day that could be about 25,000 MW the addition of 4,500 MW of nameplate capacity wind may not seem to be a problem. However the present demand has gone down due to the poor economy. During the spring and fall months and at night and weekends when the demand can drop to 11,000 to 12,000 MW wind becomes significant since effectively it is added to the baseload supply from the nuclear and large hydro units that have a combined capacity of around 14,000 MW. This exacerbates Surplus Baseload Generation (SBG), when the demand is less than a baseload supply that cannot readily be reduced due to technical or contractual reasons.
SBG is happening right now, even without wind input, and such periods will increase in frequency and depth for some time until an improving economy and growing population increases demand. Under SBG conditions coal generation would be shutdown, baseload hydro minimized, exports maximized but enough gas would still need to be operating to compensate for any powered down nuclear, to handle load following dispatches and as insurance against the wind dropping. At present nuclear plants that provide relatively low cost emission free electricity have to power down or shutdown so that wind generators that provide high cost electricity can stay on line. Depending on the amount of the surplus enough nuclear would have to shutdown to reduce the supply and to allow gas-fired units to operate in their dispatchable load following range of around 70 to 100 percent full power. Coal has a dispatchable range of 20 to 100 percent full power, which means more nuclear would be shutdown by using gas than by using coal and would lead to an increase in carbon dioxide emissions even though carbon dioxide emissions from a combined cycle gas-fired plant are just over half the amount from a coal-fired plant for the same output. Using gas in place of coal in SBG periods when nuclear has to be shut down is not very good economically and it increases greenhouse gas emissions. Coal, with back-end clean up, might be a better partner for wind than natural gas.
Wind is a take-when-available energy source and has priority to the grid during SBG periods ahead of nuclear, provided there are no technical or reliability concerns, 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 1,000 or so megawatts now on the grid from the earlier Renewable Energy Standard Offer Program). 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). This may reduce but not eliminate SBG. The IESO says that similar approaches would have to be applied to non-utility generators operating under contract and even to nuclear operators to encourage them to participate. Such participation seems unlikely unless the compensation is enough to cover the future maintenance caused by the wear and tear of nuclear manoeuvring or shutdown. The IESO cannot dispatch wind off for economic reasons, only for technical or reliability reasons, although it is trying to be allowed to do this.
Even if future wind production is sufficiently reduced during SBG periods to avoid shutting down nuclear some gas-fired units will always need to be operating in their load following range to provide dispatchable load following capability, since present nuclear was not designed for load following (although it was designed for load cycling, see “IESO – less dispatching of nuclear if you please”, Canadian Nuclear Society’s BULLETIN journal, 2010 April), and some could be at significant low power in case the wind dropped. Gas-fired generation cannot just be turned off when the wind blows. Without proven, reliable, flexible coal, less flexible gas will be providing operating reserve, peak load, intermediate load, and baseload making grid management more difficult.
Additional wind on the grid will result in more expensive electricity for little, if any, environmental benefit. In Ontario, as the wind picks up gas-fired generators (and coal, right now) power down to keep the grid in balance but enough must be kept operating, inefficiently, as insurance against the wind dropping and to to provide dispatchable load following capability since present nuclear was not designed for load following. As the wind picks up more, or demand on the grid decreases, it becomes necessary to minimize hydro generation and then curtail nuclear generation leading to an increase in gas-fired generation. Adding several thousand megawatts more of wind generation to the grid in the future will make the situation worse since it can result in expensive wind generation displacing a lot of low cost emission free nuclear generation but not displacing greenhouse gas emitting, and likely expensive, gas-fired generation. All this wind, when available, added to the baseload supply will make SBG periods deeper and more frequent resulting in questionable greenhouse gas savings and in more expensive electricity.
Despite all the green propaganda about wind, dispatchable coal is being replaced by dispatchable gas, not by intermittent wind. Natural gas will need to be burned in gas-fired power plants whether the demand on the grid is high or low and whether or not the wind is blowing. In 2009 wind supplied 1.6 percent of Ontario’s electricity while gas and coal supplied 10.3 and 6.6 percent respectively. Although they contribute little energy to the grid in times of need wind turbines make it more difficult to keep the grid in balance. Since greenhouse gas emissions from the transportation sector and the industrial sector in Ontario are much higher than those from electricity generation the money being spent on wind, for questionable green house gas reduction, should go towards electrification of the commuter rail system, building light rail systems, expanding the subway system, making industrial processes more efficient, and to making more use of natural gas in transportation rather than in electricity generation. It would also have health benefits since diesel engine exhaust, a mixture of gases and respirable sized soot particles, is likely a human carcinogen. Ontario is already one of the world leaders in generating greenhouse gas free and pollutant free electricity since it generates 80 percent of its electricity from nuclear and hydro.
Most of the gas-fired generation comes from, and will come from, combined cycle gas turbine generators with a small amount from simple cycle gas turbine generators for peaking and some from baseload combined heat and power plants. If the four oil/gas-fired units of the Lennox Generating Station (conventional steam cycle units) are included gas generation presently comes to around 8,535 MW and could grow to around 12,000 MW over the next several years. The only way to avoid this reliance on gas in the future will be for the government to lift its arbitrarily imposed 14,000 megawatt limit on nuclear and build many more nuclear plants, with load following capability or have sufficient
suitable dispatchable loads on the grid including thermal storage and hydrogen production. Improving the load cycling capability of existing nuclear while adding more nuclear with deep daily and weekend load cycling capability with incremental powering up and powering down could be another approach when, not if, Ontario’s venture with gas fails. With this load cycling, nuclear (and some hydro) would provide the base and intermediate loads so that only a very small amount of coal (yes coal, with back-end clean up) or biomass-fired generation or hydro would be necessary to handle any load following dispatches that may be needed to trim the grid. As the demand on the grid increases new nuclear will be needed anyway to avoid having even more non-renewable and likely expensive gas supplying the baseload with attendant green house gas emissions.
When the venture with gas does fail the wind turbines will be useless since stored water hydro power, that depends on precipitation, is a valuable reserve and intermediate and peak load provider, and will not be wasted to support wind. In the mean time the reliability of the new combined cycle gas turbine generators, when subjected to the wear and tear from the varying demand of the grid and not helped by large amounts of intermittent wind, will be the keystone of the electricity supply. Wind is just a very expensive nuisance to the grid but gas will be vital. The price and availability of gas in Ontario will depend on conditions elsewhere on the continent. Demand for gas will increase as utilities across North America expand their gas-fired generation to meet new environmental requirements. In the United States coal presently provides 50 percent of the electricity. Utilities that have little or no nuclear will use gas for baseload generation instead of coal which will result in higher cost electricity and the waste of even more non-renewable natural gas. Utilities with older and smaller coal-fired units may find it cheaper to convert the boilers to burn gas instead of installing back-end clean up which means much more gas would be burned than in modern combined cycle gas turbine units due to the lower thermal efficiency of the converted coal units. Even electricity generated from coal will cost more since the kilowatt-hour cost is set by the highest cost generator on the grid, gas, and this would affect Ontario if it had to import electricity from gas and coal-fired generators in the United States.
Besides its unnecessary use in power generation gas is used in space heating, in industrial processes and as a feedstock in the petrochemical industries and will find more use in road transportation as oil prices climb and environmental concerns mount, particularly about the invisible ultrafine particulates in diesel exhaust. Lower lake levels caused by seasonal droughts and longer term climate change effects will result in less hydro-electric generation in Ontario and a need for more gas-fired generation. Conventional gas supplies in North America are dwindling and will have to be replaced by gas from unconventional sources, such as controversial shale gas and coal-bed methane and by imported liquid natural gas, so cost is sure to go up, more so when carbon is taxed, and security of supply will become an issue. The present low price of natural gas compared to past prices demonstrates the extreme price volatility of this energy source though even with today’s relatively low gas prices electricity rates in Ontario are increasing. Rate increases might even affect nuclear generation. For example the Energy Minister recently had to ask Ontario Power Generation (OPG) and Hydro One to take another look at their requests for a rate increase before submitting them to the Ontario Energy Board because of public grumbling. Any OPG rate cut back must not be at the expense of necessary maintenance work on the nuclear stations that could reduce their present excellent capacity factors and future grid reliability.
In summary. Since Ontario already generates over 80 percent of its electricity from non-greenhouse gas emitting sources, nuclear and hydro, the money being put into the transition from flexible coal to gas and wind could be better spent elsewhere where more significant greenhouse gas reductions could be obtained. Pollutants from coal can be cleaned up at the back-end and some plants could burn biomass. Demand for non-renewable gas is increasing across North America and supply cannot be assured for the long term so gas must not be wasted for electricity generation but restricted to applications where there are presently no easy substitutes. Nuclear provided 55 percent of the electricity generated in Ontario in 2009 but the government’s long term plan is for this to drop to 40 percent. France produces close to 80 percent of its electricity from nuclear and Ontario’s long term aim should be to do the same. The government is taking a big risk with the future prosperity of the province and it and it’s agencies, the OPA and the IESO, must take another look at this gas and wind thing.
Donald Jones, P.Eng.
Retired nuclear industry engineer.
by Donald Jones, P.Eng.