Science Wednesday: Better Together: Wind and Solar Power in California

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

About the author: Matthias Fripp is a doctoral student in the Energy and Resources Group at the University of California, Berkeley. His work is funded by an EPA Science to Achieve Results (STAR) Graduate Research Fellowship.

Before I started my studies, I thought that graduate students were free to study any topic they liked. That’s true in principle, but in practice we need to find funding for our research. Fortunately, I was granted an EPA STAR fellowship in 2006, allowing me to pursue a question I consider particularly important: how much wind and solar power should we use in the electricity system in upcoming decades?

Over the last couple of years, I’ve gathered data on the amount of power that could be produced every hour at potential wind farm sites and solar power facilities all over California. I’ve also collected information on existing power plants and transmission lines, and forecasted the cost of building new wind, solar or conventional power plants or transmission lines in the future.

Next, I built a computer model that determines which combination of new and existing power plants and transmission lines will give the least expensive electricity between 2010 and 2025, while also ensuring that the state has enough power every hour. I also use this model to see how much our power bills might change if we work seriously on reducing greenhouse gas emissions.

wind farm turbines on hillThe results of this research are exciting. I found that wind and solar power are available at complementary times in California, so we can use them together to make a more reliable (and cheaper) power system than we could if we just used wind or solar alone. I also found that even if we didn’t care about greenhouse gas emissions, we should still plan to use a lot of wind power, because it is beginning to be less expensive than power from natural gas plants. Finally, I found that there is no sharp limit to the amount of renewable power we could use in California: power bills rise slowly as we build more and more renewables, but emissions could be reduced substantially with little or no extra cost.

The EPA STAR fellowship has made a huge difference, freeing me to focus all my efforts on this work, and providing the resources to do it right.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.