Struggling to stay calm?  So what generator is powering your aircon?

Struggling to stay calm? So what generator is powering your aircon?

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If you think you’ve had trouble staying cool during the Northern Hemisphere heatwave this summer, consider the fate of power generators.

Every time you turn on a fan or air conditioner, it adds some demand to the grid. When everyone does this at the same time, say when arriving home at the end of the day to a cluttered house, the effect can be huge. Making matters worse, this transition often occurs towards sunset, just as generation from the solar panels is winding down.

In California, conventional power plants would need to increase their output by about half in three hours to reach the evening peak. Delhi, where air conditioners and fans sometimes consume half of electricity, saw its peak grid demand last month amid a record-breaking heatwave.

All of this is an immensely water-intensive process. Thermal generators — those powered by heat from fossil fuels, organic matter or waste, or nuclear fission — work by piping fluids through a reactor, causing them to expand. This drives turbines and produces electricity, before the fluids are cooled in heat exchangers and returned for another trip through the reactor.

Thermal power plants were responsible for about 41% of water withdrawals in the United States in 2015, more than three times the total household sector use and more than all of the country’s irrigated agriculture combined. All these problems intensify as temperatures rise and rivers dry up.

For the simplest power plants that draw cooling water directly from rivers and oceans, heat waves can cause shutdowns. Temperatures around discharge stations are closely monitored to prevent wildlife die-offs, algal blooms and other problems, and when they get too high — either because the turbid river water itself warms, or because of drought it’s low — the discharge is turned off. , blacking out the generator.

More sophisticated systems use cooling towers — those huge, concave concrete structures associated with large nuclear and coal plants — as giant heat exchangers, making more efficient use of water. The problem is that they depend on low air temperatures to work most effectively. During heat waves, generators have difficulty cooling and must reduce their output to avoid overheating.

This is what we see happening right now. According to Len Clarke & Peacock LLP, the heat wave is already hurting the efficiency of Europe’s power plants, with gas and nuclear generators reducing their planned output, adding upward pressure on electricity prices. French nuclear plants are relying on waivers to release warmer-than-normal water into rivers.

These things are significant. According to a study last year, climate change has already increased the duration of thermal plant outages by 0.75 to 1 percentage point. With each additional degree Celsius of warming, the impact of such unplanned shutdowns alone would be enough to require an additional 40 to 60 power plants worldwide, assuming a typical 450-MW unit.

There are a few neat solutions to this problem. Cutting back on fossil-fueled energy would stave off the warming that exacerbates heat waves, but in the best-case scenario, the world faces decades of summer energy shortages. Renewable energy suffers less in the heat, but wind speeds often drop during extreme events, while the efficiency of solar panels and battery storage also decreases. Power systems that experience deeper peaks as a result of a 2022-style heat wave will find it difficult to give up the switch-on, switch-off dispatchable power that only fossil fuels can currently provide in substantial quantities. Hypothetical peaking generators based on burning green hydrogen would face the same cooling problems as current gas, coal and nuclear plants.

The worst problems will be faced by emerging economies such as China and India, which have spent billions over the past two decades building thermal power plants that will not be suitable to handle future summer peaks. In 2016 alone, Indian power plants lost nearly 14 terawatt-hours of production due to cooling water shortages in the midst of a drought, enough to power Sri Lanka for a year.

Fossil energy sells itself to such countries for its long-term impact on the global climate, in the short term it will be the only way to provide reliable electricity when it is needed most. This heat wave shows that promise won’t last either.

More from other Bloomberg Opinion writers:

• India’s heat wave is testing the limits of human survival: Fickling and Pollard

• Europe’s heat wave bad for energy prices, but drought worse: Javier Blas

• Feed the world? Chapati crisis at home in India: Andy Mukherjee

This column does not necessarily reflect the views of the editorial board or Bloomberg LP and its owners.

David Fickling is a Bloomberg opinion columnist covering energy and commodities. Previously, he worked for Bloomberg News, The Wall Street Journal and the Financial Times.

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