Making Room for Renewables: Grid Integration Solutions for California's Clean Energy Future

I’ve blogged many times about the clean energy policies California has in place that have made it a leader. The state is well on its way to supplying 33 percent of its electricity from renewable sources by 2020 and now, in a visionary step to dramatically reduce global warming emissions, is considering ways to increase that amount to 50 percent by 2030.

Meeting half of California’s electricity needs with renewables will transform its electricity grid and pave the way for other states and countries to do the same. But with anything transformational, there are new challenges to overcome. Perhaps the most exciting part is that the solutions to integrating large quantities of renewable electricity are actually at hand. Renewable grid integration is not a technical challenge but an economic one; to maximize our future renewable investments, we must deploy technologies that provide grid reliability services while not causing us to waste significant amounts of clean energy. A quick summary of how to do this is explained below, but for additional detail, check out the fact sheet UCS just released.

Making room for renewables on the grid

The challenge grid operators face is to not waste energy created by renewables when the supply of electricity exceeds demand. “Overgeneration,”as energy geeks call it, is most likely to occur in the middle of the day when California’s world-class solar resources really start firing up. To avoid overgeneration, grid operators can curtail the output of renewable energy facilities to reestablish the supply/demand balance. But this option should not be overused. After all, once a renewable generation facility is built, the marginal cost of that generation is very low and we want to use that electricity, not dump it. To minimize curtailment, we need to determine whether it’s possible to turn down other forms of generation instead of renewables.

Investing in grid services that don’t crowd out renewables

The subset of grid services used to balance supply and demand in California are largely met by natural gas and hydropower plants today; unless grid operations change, incremental needs will be met by natural gas. For natural gas plants to provide most of these services in the timescale required, they must be online, which means they are generating global warming emissions and air pollution even when the electricity they generate is not needed to meet demand. All this means that when renewables are online and generating, natural gas used to provide grid services could significantly crowd out them out, causing that clean electricity to be wasted.

A conceptual day in the future with high levels of renewable energy penetration. Source: UCS

Grid integration solutions for California

Fortunately, many of the low-carbon generation and demand-shifting technologies that exist today are capable of offering these services; several are able to respond even faster than a natural gas plant. Some solutions, like expanding the regional electricity marketplace and investing in energy storage and demand response technologies were laid out in a recent Op-Ed authored by three of California’s most important energy leaders. But that article did not mention the future role of our gas fleet, or question our reliance on natural gas to provide grid reliability services. If we are going to make the most of our clean energy transition, we must focus on investing in non-fossil fast-acting grid services that will allow us to meaningfully reduce, and ultimately replace, much of the natural gas we depend upon today.