On 100 out of the 144 days since 8 March, California’s electricity demand was 100% supplied by renewable energy for at least part of the day. For these 100 days, solar, wind, and hydroelectric power supplied the grid for durations ranging from a few minutes to ten hours. This milestone highlights the reliability of renewables, especially for regions where the pressure on the grid is high. However, further efforts are necessary to ensure consistent electricity production, even when weather conditions are not optimal. 

For 30 days within a 38-day period in March and April, California met 100% of its energy demand with renewable sources for durations ranging from 15 minutes to six hours each day. This achievement was highlighted by Mark Jacobson, a professor at Stanford University, who has been tracking the state’s progress in renewable energy. 

Environment California announced that California is the first state to achieve 100% clean energy, inspiring 12 other states to pledge similar goals. Hawaii, Washington, and New Mexico aim for 2045, while Connecticut, New York, Minnesota, Oregon, and Michigan target 2040. 

How Is this Possible? 

A combination of favorable weather and lower demand makes this possible. Springtime in California is ideal for renewable energy production, with longer days boosting solar energy and mild temperatures keeping electricity demand low. Additionally, wind power and hydropower from dams are performing well. 

Another key factor is the dramatic expansion of solar farms. Since 2005, renewable energy capacity, including rooftop solar panels, has more than tripled. In 2019, 63% of California's power came from carbon-free sources such as renewables, hydropower, and nuclear energy. 

Fossil Fuels Remain Essential 

Despite the progress in renewable energy, fossil fuels are still necessary to ensure reliable backup power during periods of high demand or limited renewable electricity supply. This was evident during two weeks in July when heatwaves required continuous operation of fossil fuel plants to power the grid. 

The challenge arises at sunset when solar farms stop producing energy. California must swiftly and seamlessly replace this lost power with other sources, such as hydropower and natural gas, to maintain a stable electricity supply. 

Storage for a Greener Future 

To progressively reduce reliance on fossil fuels, developing new technologies to store energy produced during the day for nighttime use is essential. California is rapidly constructing large battery projects to store daytime power for use at sunset. Over the past two and a half years, energy storage capacity in California has increased twentyfold, with other states like Texas following suit.  

To fully eliminate fossil fuels, energy storage projects must evolve to store power for days, not just hours, to ensure a stable supply during extended periods of cloudy weather or calm winds. Expanding the role of wind power is also crucial, as it generates electricity more reliably in the evenings. This combination of advanced energy storage and increased wind power utilization will be key in achieving a sustainable and fossil-free energy future.