(Bloomberg) — China’s Three Gorges Dam is a formidable sight, a massive barrier across the Yangtze River that contains enough concrete to fill seven Wembley Stadiums and more steel than the Empire State Building. Its wind turbines can power the Philippines.
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But this summer, the world’s largest power plant was eerily quiet.
During a late August visit to the facility, the water on both sides of the dam was stagnant. There was no sign of the white spray that usually rises from the spillway or the splash of water from the turbines. Scorching temperatures and increasing droughts have depleted water reserves, greatly reducing the plant’s ability to generate electricity.
China’s famous Great Dam’s water problems are part of a global hydropower crisis exacerbated by global warming. From California to Germany, heat waves and drought have shrunk the rivers that feed dams. Hydroelectricity production fell by 75 terawatt hours in Europe this year to September – more than the annual consumption of Greece – and fell by 30% across China last month. In the US, generation is expected to fall to a six-year low in September and October.
It’s a cruel irony that forces utilities to reconsider the traditional role of hydropower as a reliable and fast source of green energy. Dams are the world’s largest source of clean energy, but bad weather makes them ineffective in the fight against climate change.
The cycle is “a warning sign about designing energy systems,” said Wenxuan Xie, a managing consultant with Wood Mackenzie Ltd. “You really have to think about the possibilities of extreme events, and maybe what you once thought was very dangerous. It happens more often.”
The problem is that there are few methods that can be updated as flexible or common. Globally, hydroelectricity produces more electricity than nuclear and more energy than wind and solar combined. In countries like Norway and Brazil, dams generate more than half of all electricity. What’s more, large dams have historically been more reliable, producing power on average about 42% of the time, compared to 25% for wind and 12% for solar, according to BloombergNEF data. And grid operators can use them as a dispatchable resource—one that can be switched quickly when needed, like coal or gas.
Except when there is no water.
“Deteriorating drought conditions as part of climate change will begin to reduce the availability and distribution of water resources and reduce capacity in areas such as Southwest China and the Western US,” said Xizhou Zhou, managing director of energy and renewables at S&P Global Commodity Insights. . . That will affect both the revenue generated by the dams and the reliability of the feeding grids, he said.
The worst drought in 1,200 years this year in the US West means that burned dams could produce half the power they normally supply in California, raising the risk of blackouts across the state. National hydro production fell to 17.06 terawatt hours in September and was expected to decline further in October, according to the Energy Information Administration, the lowest since September 2016.
In Europe, dry rivers reduced September hydro production to the lowest since at least 2015, according to climate think tank Ember. That is forcing utilities to rely more on coal and gas, using fuel stocks the continent is trying to conserve to avoid winter power cuts caused by supply disruptions from Russia.
In Brazil, which usually depends on hydro for more than 60% of its electricity, a drought last year brought the country to the limit of energy balance and forced it to rely on the sale of goods from neighbors Uruguay and Argentina, or to buy more expensive fuel. to make a mistake.
Reservoir users must balance competing demands for their water. Large reservoirs provide irrigation for crops, water supply for cities and navigation. The main purpose of the Three Gorges Dam, for example, was to control the Yangtze’s floods that occasionally destroyed towns and farms downstream. This summer, as drought has reduced the flow of water in the river, the dam has had to hold enough water to keep the road to Chongqing, China’s largest city about 2,000 kilometers from the sea.
Lake Mead, the reservoir behind Hoover Dam on the Colorado River in the Western US, provides 90% of the water supply for Las Vegas and major cities like Los Angeles and irrigates hundreds of thousands of acres of crops. The lake level dropped so much this summer that human remains were unearthed from the lake bed, prompting a police investigation.
No country has built more dams than China, where the worst drought in at least 60 years in Sichuan, a province the size of Germany, cut generation by 50% in August just as demand for air conditioning rose to cope with the heat. Officials had to shut down power to several domestic factories for nearly two weeks, disrupting supplies to major equipment manufacturers including Apple Inc. and Tesla Inc.
“When such an event occurs, it does two things – it reduces electricity and improves energy demand, so there is a double whammy,” said Li Shuo, a Greenpeace analyst.
Even after the Sichuan drought ended at the end of August, the effects remain. In neighboring Yunnan province, aluminum smelters are being forced to operate at reduced capacity to conserve energy and give reservoirs a chance to refill before the cold winter months, when electricity supplies can be tested again with high demand. To cope with energy shortages, China has had to rely more on polluting coal and natural gas, even as global fuel costs soar to record highs.
“An additional drought like we’ve seen this year could have a negative impact,” said David Fishman, a Shanghai-based analyst with the Lantau Group. “Reservoirs take a long time to refill and be ready to reproduce.”
Soon after returning to using more coal or gas, countries struggling with unreliable supply from hydro turbines may invest in nuclear power or in wind and solar battery storage. Another option is to build multiple power lines to distribute the load to multiple power sources in different regions.
Solar panels floating on water bodies can help too, generating power when it’s sunny and slowing evaporation, said Lei Xie, head of energy policy at the International Hydropower Association. “The combination of hydro and solar power works well,” he said, and the Chinese government has implemented a plan to increase the flexibility of hydro installations.
However, severe weather can affect all sources of clean energy. Wildfire smoke and dust storms dim solar panels, while low winter temperatures can freeze wind turbines. Europe’s drought halted production of nuclear reactors that rely on river water for cooling.
Concerns about the reliability of dams as the planet warms are fueling growing resistance to new hydroelectric projects in many countries. Dams are blamed for ecosystem disruption, loss of wetlands and extinction of aquatic life. Major projects are displacing local people to build dams – more than 1.3 million people in the case of the Three Gorges.
Those winds mean that electricity is unlikely to maintain its leading role in clean energy for long. BloombergNEF expects an 18% increase in global hydropower capacity between now and 2050, compared to an 8-fold increase in solar and a three-fold increase in wind power.
In fact, hydro development may be shifting to what used to be a niche role in the industry: pumped storage. In these, water is pushed back up the reservoir during periods of excess electricity generation and allowed to flow downstream through turbines when more electricity is needed. The technology can be combined with central wind and solar power to provide carbon-free electricity around the clock. Because pumping systems operate in a closed loop, they are less affected by drought, according to the power association.
China could develop 270 gigawatts of such projects by 2025, according to the state’s top dam builder, compared to national plans to add 60 gigawatts of traditional hydro during the same period.
Hydro’s struggles underscore the difficulty of building a robust renewable energy network to replace fossil fuels, especially in developing countries that must contend with rising electricity demand as per capita consumption grows. At the same time, the drought issues underscore the need to accelerate efforts to curb rising temperatures as the costs of making the energy transition rise, Greenpeace’s Li said.
“If we don’t address this issue which is the main cause of climate change and reduce emissions, we have to accept that there will be things that we cannot plan for or that are too expensive to plan for,” he said. “There will be catastrophic losses.”
–Courtesy of Mark Chediak.
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