[LUM#19] Alice, age 12: “With the drought, will we still be able to generate electricity using dams?”
Alice, age 12, future headmistress of Hogwarts.
Not all the dams you see are built to generate electricity; some are used to support agriculture or regulate river flow. In France, dams thatgenerate electricity account for between 11 and 12 percent of the country’s total electricity production—less than nuclear power but more than wind and solar power. Globally, hydropower is the world’s leading source of carbon-free energy. It’s called that because it doesn’t emit CO₂, even though carbon is produced during the construction of the dam. These structures are primarily a means of storing electricity: we store water because we don’t yet know how to store electricity on a large scale in an economically viable way.
There are three main types of dams: run-of-river dams that continuously generate power from a river, reservoir dams that have a large water storage capacity and thus allow for inter-seasonal storage, and pumped-storage plants that consist of two dams, one upstream and the other downstream of a penstock. Water is pumped from downstream to upstream during off-peak hours, and electricity is generated during peak hours by turbining the water from the upstream dam. This allows for optimizing the timing of electricity generation.
There is still significant potential for hydroelectric power generation worldwide, but this potential remains limited in France. Global warming could indeed jeopardize the use of hydropower due to a lack of water in rivers, as well as reduced snowfall in the mountains, since snowmelt is a major contributor to river flow. Furthermore, competition between energy and agricultural water uses is likely to intensify if water becomes scarcer. River water is also used to cool nuclear power plants, which explains why new plants are more likely to be built along the coast. Dams sometimes have to release water to allow for irrigation, particularly in the summer. However, the released water is then no longer available in the winter, which reduces electricity production.
Jacques Percebois – Professor Emeritus at the University of Montpellier.
An article in partnership with The Conversation.
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