The God Species_ How the Planet Can Survive the Age of Humans - Mark Lynas [81]
The Aral Sea could still be substantially restored if the political will were mobilized to make this happen. Given an ambitious effort to restore the original flows of the two rivers, experts have estimated that the entire Aral Basin could be refilled in less than forty years.28 The effort would require the large-scale abandonment of thirsty cotton crops and free markets to allow farmers to choose what they want to plant—instead of being dictated to by the Uzbek government. As well as a reduction in irrigated land overall by more than half, major investments need to be made to increase the efficiency of water infrastructure so that less of it is wasted via leaching and evaporation from canals. Farmers need to be provided with alternative livelihoods so that they are not even further disadvantaged as the focus moves away from agriculture in what is after all a very arid area. Given that what happened to the Aral represents the worst regional environmental disaster in the world, it is in the interests of the entire international community to restore as much of the damage as possible—and to pay for the necessary process of social transition that this implies.
Much of the Aral Sea’s vanished river inflow is captured for upstream hydroelectricity, demonstrating the trade-offs inherent in meeting the water planetary boundary. One of these is with the climate change boundary, for hydroelectric dams produce by far the largest fraction of the world’s renewable electricity—currently about 16 percent of the global total.29 China’s controversial Three Gorges Dam displaced 1.3 million people30 (submerging an astonishing 13 cities, 140 towns, and 1,350 villages) and further disrupted the ecology of the already highly impacted Yangtze Basin, but produces as much power as 20 big coal plants, avoiding the emission of perhaps 100 million tonnes of carbon dioxide every year. Fifty more dams are planned on the Yangtze by the Chinese government, which wants to double hydropower’s contribution to the country’s electricity supply by 2020 to a hefty 300 gigawatts. Given that China is already going flat-out for nuclear and wind—both better options than hydro in terms of overall ecological impacts—this is a serious conundrum, and one that is repeated globally in many rapidly growing developing countries like India. As always a balance will have to be found, based not just on economics but also on the environmental costs of competing forms of power generation—and in each case all the planetary boundaries must be considered.
One type of hydroelectric generation that certainly needs expanding is pumped storage. In a pumped storage plant, water is pumped uphill into a higher reservoir when electricity is cheap and plentiful on the grid (such as at night) and then released during periods of high demand. In many countries pumped storage systems are an important way to balance loads on the electrical grid, as they can respond very quickly to additional demands for massive amounts of power. The largest system in Europe, at Dinorwig in Wales, can go from 0 to 1.3 gigawatts of generation in 12 seconds (and maintain this rate for several hours), and the turbines are reversible as pumps to return the water to the higher reservoir once the peak of demand has passed.31 Pumped storage systems have minimal ecological impacts if they are closed-loop, off-river systems, where the water is used over and over again. Because these systems essentially act like enormous batteries, they represent the only existing grid-scale option for storing power and are likely to be an essential part of the energy mix as renewable and