Struggling to stay cool?  This is the generator that powers your air conditioner

Struggling to stay cool? This is the generator that powers your air conditioner


If you think you’re having trouble staying cool during the heat waves that have ravaged the northern hemisphere this summer, consider the fate of power generators.

Every time you turn on a fan or air conditioner, it adds a little bit of demand to the network. When everyone does it at the same time, for example when arriving home at the end of the day to a sweltering house, the effect can be enormous. To make matters worse, this shift often occurs as the sun sets, just as the generation from solar panels decreases.

In California, conventional power plants currently have to increase their production by about half in the three hours heading into the evening peak. Delhi, where air conditioners and fans sometimes account for half of its electricity consumption, saw the highest demand on the grid last month amid a record heat wave.

All this is a water-intensive process. Thermal generators—those powered by heat from burning fossil fuels, biomass, or waste, or from nuclear fission—operate by tubes of fluids through the furnace, causing them to expand. It powers turbines and produces electricity, before the fluids are cooled in heat exchangers and back on another journey through the furnace.

Thermal power plants accounted for about 41% of water withdrawals in the United States in 2015, more than three times what the entire domestic sector used and larger than all of the country’s irrigated agriculture. All of these problems are exacerbated by rising temperatures and drying up of rivers.

For the simplest power plants that draw cooling water directly from rivers and oceans, heat waves can cause a shutdown. Temperatures around the discharge stations are closely monitored to prevent wildlife deaths, algal blooms, and other problems, and when the temperature rises—either because the dilute river water itself is warmer, or lower due to drought—the discharges have to stop, darkening the generator in turn.

More advanced systems use cooling towers – those vast, concave concrete structures associated with large nuclear and coal power plants – as giant heat exchangers, making more efficient use of water. The problem is that they rely on lower air temperatures to function more effectively. During a heat wave, generators find it difficult to cool down and need to reduce their output to avoid overheating.

This is what we see happening now. The heat wave is already hurting the efficiency of power plants in Europe, with gas and nuclear generators reducing their planned production, according to Lane Clark & ​​Peacock LLP, adding upward pressure on electricity prices. French atomic stations rely on concessions to discharge hotter-than-normal water into rivers.

These issues are important. Climate change has already increased the amount of time thermal plants experience outages by 0.75 to 1 percentage point, according to a study last year. With each additional degree of warming, the effects of such an unplanned shutdown alone would be enough to require 40 to 60 additional power plants worldwide, assuming a typical unit of 450 MW.

There are a few exact solutions to these problems. Reducing energy from fossil fuels will eliminate the warming that intensifies heat waves, but in a best-case scenario, the world faces decades of summer energy crises ahead. Renewable energy is affected less by heat, but wind speeds often drop during extreme events, while the efficiency of solar panels and battery storage also declines. Energy systems experiencing deeper peaks as a result of 2022-style heat waves will find it difficult to give up the on and off energy that only fossil fuels can currently provide at a sufficient scale. Virtual peak generators based on burning green hydrogen will face the same cooling problems as existing gas, coal and nuclear plants.

The worst problems will be faced in emerging economies such as China and India, which have spent billions over the past two decades building thermal power plants that will not be well suited to managing summer peaks in the future. In 2016 alone, a lack of cooling water in the middle of a drought caused Indian power plants to lose about 14 TWh of generation, enough to power Sri Lanka for a year.

Fossil energy has sold itself to such countries on the understanding that despite its long-term effects on the global climate, in the short term it will be the only way to provide reliable electricity when it is most needed. This heat wave shows that even this promise will not hold.

More other writers at Bloomberg Opinion:

• Heat waves in India are testing the limits of human survival: Fickling and Pollard

Heat wave in Europe is bad for energy prices, but drought is worse: Javier Blas

• Feed the world? India suffers from home-brewing chapati crisis: Andy Mukherjee

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

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

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