If the United States stops burning coal, shuts down one-quarter of existing nuclear reactors and trims its use of natural gas by 2050, the resulting increased reliance on wind, solar and other renewables will not result in a less reliable electricity grid.


This scenario is according to a new report by Synapse Energy Economics Inc., conducted for the nonprofit Civil Society Institute (CSI). The study found that, in an envisioned 2050 with a heavy reliance on renewables, regional electricity generation supply could meet or exceed demand in 99.4 percent of hours, with the load being met without imports from other regions and without turning to storage. In addition, surplus power would be available to export in 8.6 percent of all hours, providing an ample safety net where needed from one region of the country to another.


Grant Smith, senior energy analyst at the CSI, said: “This study shows that the U.S. electricity grid could integrate and balance many times the current level of renewables with no additional reliability issues. Recent improvements in both renewable technologies themselves and in the technologies that are used to control and balance the grid have been proceeding at a rapid pace, and the incentives and rewards for success in this area continue to drive substantial progress. In contrast, the alternative of continuing to rely on increasing combustion of fossil fuels to generate electricity and producing ever-increasing levels of greenhouse gases is far less feasible and presents much more daunting technical, economic and social challenges to human and environmental welfare. In comparison, the challenge of integrating increasing levels of solar and wind power on U.S. power grids requires only incremental improvements in technology and operational practices.”


Report co-author Thomas Vitolo, an analyst at Synapse, added: “Put simply, the message is this—it is a myth to say that the United States cannot rely on renewables for the bulk of its electricity generation. This study finds that the projected mixes, based entirely on existing technology and operational practices, are capable of balancing the projected load in 2030 and 2050 for each region, in nearly every hour of every season of the year.”


In 2011, Synapse prepared a study for the CSI that introduced a “transition scenario” in which the United States retires all of its coal plants and a quarter of its nuclear plants by 2050, moving instead toward a power system based on energy efficiency and renewable energy. The study showed that this transition scenario, in addition to achieving significant reductions in emissions of carbon dioxide and other pollutants, ultimately costs society less than a “business as usual” status quo strategy, even without considering the cost of carbon. The 2011 study also projected that, over 40 years, the transition scenario would result in savings of $83 billion (present value) compared to the status quo strategy.


To achieve these lower cost and low-emissions results, the transition scenario included large amounts of renewable-energy resources with “variable output,” such as wind and solar. While the need for variable-output resources is well-defined, questions have been raised about the impact of large-scale wind and solar integration on electric system reliability. To address this, Synapse paid careful attention to the amount of wind and solar in each region when designing the transition scenario for the 2011 report, taking steps to ensure that the projected regional resource mixes could respond to all load conditions.