Last week, a new analysis was released that explored the technical, environmental, and economic implications of raising California’s Renewables Portfolio Standard (RPS) from 33 percent by 2020 to 50 percent by 2030. I’m excited to report that although the study illuminates the challenges of installing unprecedented amounts of renewables on the grid, it is technically possible. Moreover, California has tools in hand today to scale up renewables, and is developing programs and policies that will continue to lower the cost and technical challenges of doing so.
The study was led by a private consulting firm — Energy and Environmental Economics, Inc. (E3) — and commissioned by the state’s five largest electric utilities. E3 modeled a 33 percent by 2030 RPS and compared those results to a 40 percent RPS and several 50 percent RPS cases that varied primarily by the amount and size of photovoltaic (PV) investments.
The most pervasive reliability challenge was “over-generation” on the system, which happens when renewables are going gangbusters but we don’t have the electricity demand or export capability to put all those green electrons to use. Not surprisingly, these situations were much more acute in the 50 percent RPS scenarios compared to the 40 percent case.
Choosing to prevent this “extra” renewable energy from entering the grid is a technique that grid operators can use today, so E3 handled over-generation in its model by simply curtailing renewables when the system had too much. But curtailment is a blunt tool, and it might not be the most cost-effective way to deal with these issues in the long run. The study authors acknowledge this point, and identify additional strategies that California is already working on to address renewable integration:
- Enhance regional coordination: California and other western states can and should work closer together to expand electricity import/export capabilities and share resources. The California Independent System Operator (CAISO), PacifiCorp, and NV Energy have taken an important step forward by joining forces for an energy imbalance market, a first step towards greater western grid coordination.
- Diversify the renewable energy portfolio: California’s RPS is technology-neutral, but in the future we must take special care to invest in a diverse supply of renewables to take advantage of generation patterns happening at different times of the day and in different locations. This way, we can smooth out the aggregate supply curve and avoid boom/bust cycles of generation.
- Invest in energy storage: California’s recent energy storage procurement mandate has already positioned the state as a leader in energy storage development. Investing in cost-effective ways to store clean electricity and use it when the grid needs it the most is key to addressing grid challenges like over-generation.
- Use electricity demand as a tool: Demand response programs that shift electricity use towards times in the day when renewable generation is most robust and away from times when it’s less likely to show up is another key tactic. California has lagged behind Texas and the Mid-Atlantic states in this department, but the CAISO released a demand response roadmap in December and the California Public Utilities Commission is continuing to explore whether different electricity rate structures can be used to shift electricity usage in ways that are better for the system as a whole.
E3 took a high-level look at what would happen to over-generation if the strategies mentioned above were deployed. The impacts of deploying these techniques by themselves are displayed in the table below.
It’s pretty obvious that taking action to increase coordination between western grid operators and invest in programs that help us shift electricity supply and demand make a big difference. Take note that E3 did not look into the added benefit of combining these strategies.
As I’ve pointed out, California is already moving forward with many of these options and the big challenge is going to be identifying the most realistic and cost effective combinations of renewables, storage, demand response, energy efficiency, and other decarbonizing strategies that will help us achieve a cost-effective, reliable, and low-carbon electricity grid at the end of the day.
No one thought we’d snap our fingers and magically get a clean electricity grid, but this study shows that with a little elbow grease we can actually get there.
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