4 ms·

There is a flaw in your reasoning: By definition if a plant needs to be throttled then it's surplus power generation has negative (or zero) utility/value and th

There is a flaw in your reasoning: By definition if a plant needs to be throttled then it's surplus power generation has negative (or zero) utility/value and therefore does not contribute to it's profitability whether it's running or not. Throttling the plant doesn't reduce it's profitability, since the power it would product at that point has no value - that's why you need to throttle it.

hwillis 8y ago
I'm not making an argument from semantics- whether or not you approve of the above explanations, they are the reason nuclear power is commonly said to be incapable of load-following. If you want a detailed and reputable investigation, the OECD has one[1]. The inability to load-follow is not a design flaw; any reactor built in the last ~40 years can ramp an order of magnitude faster than coal or gas-steam, and will run very happily at anywhere from 50-100% power, ramping up and down multiple times per day. Many can ramp at hundreds of megawatts per minutes. In fact all of them can ramp from 100%-10% output in about a minute, since that's legally required for reactor SCRAM. That's as fast as an average gas turbine[2] and at the high end it's faster than the fastest gas turbine. Nuclear plants are the most agile nonrenewable plants on the grid but the fact is that a nuclear plant operating <80% output does not generate a return. > Throttling the plant doesn't reduce it's profitability, since the power it would product at that point has no value - that's why you need to throttle it. I get what you're saying, but it's wrong. The grid is not a free market and excess generation is not legal. Electricity markets are based around contracts and producing too much is just as heavily penalized as producing too little. If you generate so much excess that you bring grid frequency or voltage out of spec, people start going to jail. To rephrase: If a nuclear plant throttles, its costs are constant and its revenue is lower. If it doesn't throttle, its costs are higher and its revenue is lower. Nuclear sees rising revenue/kWh by throttling, but not enough. Because of all that nuclear is not profitable in short term contracts. Generally they aren't used for ancillary services either, but that's more due to conventions- for instance they are used for frequency control in France. [1]: https://www.oecd-nea.org/ndd/reports/2011/load-following-npp.pdf https://www.oecd-nea.org/ndd/reports/2011/load-following-npp... [2]: https://www.wartsila.com/energy/learning-center/technical-comparisons/combustion-engine-vs-gas-turbine-ramp-rate https://www.wartsila.com/energy/learning-center/technical-co...

hwillis 8y ago

I'm not making an argument from semantics- whether or not you approve of the above explanations, they are the reason nuclear power is commonly said to be incapable of load-following. If you want a detailed and reputable investigation, the OECD has one[1]. The inability to load-follow is not a design flaw; any reactor built in the last ~40 years can ramp an order of magnitude faster than coal or gas-steam, and will run very happily at anywhere from 50-100% power, ramping up and down multiple times per day. Many can ramp at hundreds of megawatts per minutes. In fact all of them can ramp from 100%-10% output in about a minute, since that's legally required for reactor SCRAM. That's as fast as an average gas turbine[2] and at the high end it's faster than the fastest gas turbine. Nuclear plants are the most agile nonrenewable plants on the grid but the fact is that a nuclear plant operating <80% output does not generate a return. > Throttling the plant doesn't reduce it's profitability, since the power it would product at that point has no value - that's why you need to throttle it. I get what you're saying, but it's wrong. The grid is not a free market and excess generation is not legal. Electricity markets are based around contracts and producing too much is just as heavily penalized as producing too little. If you generate so much excess that you bring grid frequency or voltage out of spec, people start going to jail. To rephrase: If a nuclear plant throttles, its costs are constant and its revenue is lower. If it doesn't throttle, its costs are higher and its revenue is lower. Nuclear sees rising revenue/kWh by throttling, but not enough. Because of all that nuclear is not profitable in short term contracts. Generally they aren't used for ancillary services either, but that's more due to conventions- for instance they are used for frequency control in France. [1]: https://www.oecd-nea.org/ndd/reports/2011/load-following-npp.pdf https://www.oecd-nea.org/ndd/reports/2011/load-following-npp... [2]: https://www.wartsila.com/energy/learning-center/technical-comparisons/combustion-engine-vs-gas-turbine-ramp-rate https://www.wartsila.com/energy/learning-center/technical-co...