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Hydraulic Dependent On Weather/Climate/Climate Change - First of a Series

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James Kirby's picture
Retired Senior Manager At Ontario Power Generation, Retired

Areas Of Expertise- Toxic contaminants, New Technology assessments, Computer Modeling, Interconnections - Reliability Assessments, Purchase and sales Forecasting, Reserve value of...

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  • Oct 4, 2021

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With weather and/or climate change affecting both load and intermittent generation how many days of storage will we need without Nuclear?

Matt Chester's picture
Matt Chester on Oct 4, 2021

Such an important question-- and then what level of reliability do you plan for? The common engineering challenge of designing for the 100 year storm, for example, only for disaster to strike when the 200 year storm hits and the people question why we weren't prepared for that!

James Kirby's picture
James Kirby on Oct 4, 2021

Planning is a dynamic process. The planner's old job was to look ahead and position the system to be able to respond to the future as it unfolds. In a competitive environment, no one carries the responsibility for that. The decisions are left to the companies involved. The current design of the spot market is a trap, one which negates most investment unless it is subsidized. The current design of the market is leading us into a situation where the reliability and the resiliency of the system is, to say the least, in question. To continue with the idea of an open and competitive the rules for it must change to set the price signals that will encourage the market to function in ways that will not lead us into situations like this without measures in place, stopgap or otherwise, to maintain reliability and resiliency. 

Instead of this, the California governor is recklessly gambling with the reliability of the California system by closing the Diablo Canyon nuclear plant in the middle of a capacity shortage that is only going to get worse. If his gamble fails, the governor will lose his job over this in my opinion.


Stopgap measures will be implemented to ration drinking water supply and to overcome the limits on getting the remaining water in Lake Mead over the Hoover Dam. If the drought is permanent 20 million people are about to become climate refugees, but because of those stopgap measures will not be aware of it for a while. The impending load cuts in California will receive the attention, and ironically enough intermittent renewable energy designed to mitigate the global warming will be blamed.

Carbon capture and storage is likely to proved to be a myth. Certainly, over the longer term because there is not enough aquifer capacity to take more than a relatively small fraction of the CO2 emitted. Putting a complex chemical plant at the front of a combined cycle or coal-fired plant will not prove to be viable. In my opinion, demand management (efficiency), Long term (days to weeks) energy storage and nuclear in the mix are necessary, and we have to make them viable. 

James Kirby's picture
James Kirby on Oct 4, 2021

I would like to have another go at answering that question.


How do we know what the 100-year storm will look like in the face of climate change? Experience doesn't tell us too much about the future we may be entering, and the reality is that we have to classify that as a known unknown. Nonetheless, we still have to make judgments and these will be neither pleasant nor easy.

Planning is a dynamic process, and ideally, we should position ourselves so that we can react to new information as it becomes apparent. Accomplishing this in a competitive market will require careful attention to the market design, a regulator can send pricing signals to accomplish whatever it is they believe they need to. That could be asking for bids to start the planning process for new generation that may never be built. 


You plan to the widest range that you expect to see. Planning is cheap. That means positioning the system to be able to respond in a timely manner to limit the damage if things are worse than your criteria requires. So, the question becomes what do you commit to?

The answer to that question becomes one of economics and safety. If the consequences of something are severe enough you might well plan for that worst in 200 year storm, if you can figure a what it is. 

The reality of life is that if you wanted there when you need it, you have to have it there when you don't. People are going to ask you why you have too much unless it turns out you have too little. The unfortunate individuals charged with this task will never keep anybody happy. Acceptance of that fact is a job requirement.

James Kirby's picture
James Kirby on Oct 6, 2021

"What level of reliability do you plan for?" 

Much of the utility industry plans to a one day in 10 year criteria applied on a probabilistic basis. Ontario Hydro used an unserved energy criteria when I was there. I have forgoeten what the criteria was, but it took into account the frequency the duration and the magnitude of the outages. At least that was the idea. Ontario Hydro's criteria was derived based upon economic assessments taking into account and assume value of a megawatt hour unserved. Based upon the spot market reactions to shortages this value is quite high. The unserved energy was calculated assuming a load forecast uncertainty of about 6%, assumed to be normally distributed, atf the five-year lead time. Leadtime enters into it because it is a planning criteria. It takes into account the forecasting errors that exist at the time you are making the decision.

The philosophy of the approach is what I am trying to get across and not the numbers. They criteria is economic and as such there are always a variety of measures that can be taken to reduce the unserved energy or the loss load probability. Because it is economic because there are a variety of measures with different lead times the answer to your question is that you plan for anything that is economic to plan for taking into account the consequences and the probabilities of the various contingencies. Because the value of unserved energy or loss of load is very high this criterion leads to reserve margins that mean few if any load interruptions due to generation for shortfalls occur. This of course is intuitive because the cost of an interruption is high so you don't want very many interruptions. 

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Thank James for the Post!
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