California looks towards pumped storage to meet zero carbon target

The US state of California, a leader in renewable energy has pledged to get all of its energy from renewable sources by 2045. A major hurdle to this ambitious target is energy storage. Renewable energy requires a storage system to smooth the inconsistencies associated with intermittent energy sources. An old method involving water may be the solution California is looking for.

The solution is “pumped storage”. This method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. During periods of high electrical demand, the stored water is released through turbines to produce electric power.

California has mandated 60% renewable energy sources for its power generation by 2030, and all zero-emission sources by 2045. The Lake Hodges facility near San Diego, a relatively small 40 megawatt generating station, is one of 40 pumped storage facilities around the United States and many more planned, and its operator says it is helping the state meet its ambitious goals.

How it works:

According to Gary Bousquet, deputy director of engineering at the San Diego County Water Authority, when you have excess energy during the day, you pump the water up a hill. At the end of the day when solar generation has stopped, you’re able to bring that generating unit online, and then supply that energy back into the grid. The water runs downhill and activates generators.

The efficiency of pumped storage is about 80% due to losses, Gary Bousquet said. The experts say, however, it’s the best solution now to store large amounts of energy for high-demand periods and regulate a clean power grid. Its main disadvantage is the specific landscape requirements; it must be in a hilly region with availability of water

Nigeria is blessed with hilly regions rivers and coincidentally, these areas are mainly found in the north with an overabundance of solar energy.  Solar pumped hydroelectric systems have not come into the Nigerian energy discourse but remains a viable means of harnessing the abundance of sunlight in the country for boosting energy supply across the national grid.

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