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Waste Not: Curtailment of Renewables Means Lost Energy

Waste Not: Curtailment of Renewables Means Lost Energy


CIRES' Spheres
March 2014

In the world of electricity, generators must provide the exact amount of energy, second by second, that users demand. But some conventional power plants, fueled by coal or nuclear, cannot be turned on and off like a light switch. So when demand drops very low, instead of reducing nuclear or coal production, which can’t easily drop below a certain base load, the power grid reduces production of renewable energy—below the amount these sources potentially could provide.Such reductions, called curtailment, allow energy production to equal energy demand, but also permit potential energy to drift away in the wind. Xi Wang, a CIRES graduate student with the Center for Science and Technology Policy Research, and her colleagues at the National Renewable Energy Laboratory, recently reported on curtailment practices worldwide.

They found that countries interested in bolstering the re-newables industry are attempting to mitigate curtailment, because high curtailment levels discourage investors: No one wants to produce energy they can’t sell.

Mitigation strategies vary from changes in energy markets to government incentives. “In many areas, for example, renewable energy generators now can offer bids into a wholesale electric-ity market,” Wang says. “If their bid is accepted, their energy is dispatched. When renewables can bid into the market like other generation sources, they know they’re competing based on market demands.” In other regions, especially Europe, energy providers compensate renewable-energy producers for curtailed energy. Curtailment takes another form too: Construction of transmission lines is expensive and can lag behind construction of wind and solar farms, so at times, not all the energy from a wind or solar farm can be transported to cities. So, completing transmission projects would also help maximize renewables’ potential. “We hope other regions encountering increasing curtailment can better plan by incorporating some of these successful mitigation strategies,” Wang says. Read more ...