Failure to condemn wind may condemn Darlington B

Unless sense prevails, by 2015 the Ontario power grid is going have around 8,000 nameplate MW of wind, solar and bioenergy, mostly wind, and 10,700 MW by 2018. Even today with just over 1,700 MW of wind the grid is unmanageable during periods of surplus baseload generation (SBG) without exporting large amounts of electricity at ridiculously low prices, even negative (reference 1), or powering down or shutting down nuclear plants (reference 2). The Independent Electricity System Operator (IESO) has finally proposed new rules (its SE-91 on Renewable Integration) to integrate wind into the grid. Rather than power manoeuvre or shutdown nuclear and baseload hydroelectric units during SBG periods it wants to dispatch wind off the grid first. The present approach, at least for those wind generators with feed-in-tariff contracts, relies on market incentives, like negative pricing and payment for foregone energy, to reduce output during SBG periods.

The proposed new IESO rules will mean paying the wind generators for the foregone energy that did not get onto the grid, calculated using data from the proposed centralized forecasting system that consumers, not the wind generators, will be paying for. Dispatching wind every five minutes during SBG events (usually overnight or weekends) can give a better match of baseload supply to demand than the present coarse manoeuvring, or even shutdown, of Bruce B nuclear units that prefer to drop 300 MW rather than smaller, say 80 MW, increments (reference 3). Dispatching wind and hydro ahead of nuclear will reduce the amount of SBG that has to handled by Bruce B units using a steam bypass system that was not originally designed for the task.

The Ontario Society of Professional Engineers (OSPE) has issued a draft report (reference 4) on the integration of wind into the grid that makes a case for improving the robustness of the steam bypass systems on the nuclear units so that they can be powered down during SBG events without dispatching wind off. Since there is expected to be around 7,000 nameplate MW of wind on the grid by 2015, or earlier, it is doubtful if the steam bypass improvements could be done in time anyway even if they could be done during unit outages instead of during the refurbishments.

Unfortunately, rather than condemning wind both the IESO and OSPE assume that wind is here to stay and are prepared to support it and in the case of OSPE even going so far as manoeuvring nuclear units for its accommodation. With no change in the nuclear scene this means that natural-gas fired generation and some hydroelectric generation will continue to provide for the intermediate and peak loads with gas also providing flexible support for wind. In the short term even the lost generation from the closure of Pickering can be replaced by two or three large combined cycle gas turbine units which would provide flexible power to support more wind when the Ontario demand picks up, and remove the need for Darlington B.

The government’s rationale for wind was that it was replacing coal and would reduce greenhouse gas emissions whereas in fact it is gas that is replacing coal with wind now supposedly reducing the emissions from the gas-fired plants. Any reduction would be slight to non-existent (reference 5) and at high cost. Without wind the camouflage is removed and the substitution of gas for coal becomes obvious. However gas has no long term future (which means wind has no long term future) because of emissions and future cost concerns so inevitably the focus has to change from gas to flexible nuclear. Life cycle greenhouse gas emissions from shale gas are said to be comparable to coal.

By 2024, or thereabouts, all refurbishment work and any new Darlington B construction will have been completed and a skilled nuclear workforce will be looking for work. The refurbished nuclear units will be decommissioned around 2045/2050 and likely replaced by new nuclear because of the uncertainty of gas. However the nuclear workforce will have long gone. The solution is to put a continuous new build program into affect after 2024. This can only happen if the refurbished Bruce and Darlington units have improved load cycling/following capability such as a more robust steam bypass system so that they can be powered down during the overnight and weekend periods of SBG caused by the new build nuclear units. If any of the several thousands of proposed wind turbines are still operating by then they can be dispatched off to minimize the manoeuvring of the nuclear units. This would allow more new nuclear, potentially around 6,000 MW in addition to the 2,000 MW of Darlington B, to be added to the grid to replace an equal amount of expensive greenhouse gas emitting gas-fired generation (reference 6) that is used to support the wind. For all this to happen means the power manoeuvring capability of the present nuclear units has to be improved during the refurbishments (or normal outages if it can be done), using steam bypass with or without changes to the way the reactor is operated. There really is no time to waste.

Don Jones, P.Eng.
Retired nuclear industry engineer

1. “Why Ontario has to export electricity”, Don Jones,

2. “More wind means more risk to the Ontario electricity grid”, Don Jones,

3. “Ontario’s CANDUs can be more flexible than gas-fired generation and hydro generation”, Don Jones,

4. “Wind and the Electrical Grid”, Ontario Society of Professional Engineers, Draft, 2011 December 13,

5. “IESO—will Ontario’s wind turbine power plants reduce greenhouse gas emissions?”, Don Jones,

6. “An alternative Long-Term Energy Plan for Ontario—Greenhouse gas-free electricity by 2045”, Don Jones,

2 comments for “Failure to condemn wind may condemn Darlington B

  1. EL
    April 18, 2012 at 16:38

    Maybe meeting 50% of your energy needs with nuclear is the problem (and not wind paired with gas generation, or some other form of energy storage). If “surplus baseload generation” is the challenge here, how is adding more of it the solution? What this tells me is that the Ontario electricity grid is inherently inflexible, and that this inflexibility is proving very difficult to manage in a deregulated market and is driving up retail electricity rates. Wind should help to alleviate these concerns (especially when paired with energy storage or an expansive grid), rather than exacerbate them. And solar, matching the demand curve, is another great resource in this area.

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