In his 2015 inaugural address, California Governor Jerry Brown turned more than a few heads when he called on lawmakers to pass a 50% mandate for renewable power by 2030. The state already has one of the most aggressive mandates in the world, requiring its utilities to obtain a third of their power from a select group of renewable sources.
“The governor has presented a policy for California to be a leader in carbon reduction and this is the focus of his broad plan,” a spokesman for Southern California Edison told UtilityDrive in a recently published report.
If the response of one of the state’s largest utilities sounds less than enthusiastic about Brown’s proposal, that’s because ramping up renewables to half of California’s energy mix represents uncharted territory. Aside from Hawaii, which is an energy outlier in most important ways, no other U.S. state has a renewable mandate greater than 30%. California’s plan is ambitious, to say the least, but it also might push the envelope on what is technically possible for integrating renewables into the grid.
Of particular concern is the widespread use of solar rooftops owned by residential and commercial buildings to meet the mandate. Ironically, what troubles grid operators the most at such high levels of solar integration is not a failure of the solar panels to produce electricity, but over-generation. Because solar power cannot be dispatched at will by a central power provider, too much solar power can exceed customer demand and endanger the stability of the grid.
“Over-generation is pervasive at Renewable Portfolio Standard (RPS) levels above 33%, particularly when the renewable portfolio is dominated by solar resources,” says a study of a higher renewable mandate in California. (It is worth noting that the study is pro-mandate.)
Faced with over-generation, the only proven way for policy makers and grid operators to manage renewable supply is to curtail solar production. In a 50% renewable case, the study found, a tenth of the state’s solar supply would need to be curtailed. Those in the solar industry, and particularly those who invest in the solar industry, are understandably not excited about the prospect of being told to hit the off-switch on production. Industry insiders say curtailment disrupts the solar market and suppresses potential renewable investment. And with an expected boom in the solar market in 2015 and 2016 due to changes in federal subsidies for renewable generation, curtailing solar power as a grid solution is the last thing the industry wants to hear.
“Curtailment is one of the biggest challenges in making the economic case for more renewables,” says Union of Concerned Scientists Senior Energy Analyst Laura Wisland. “This is not a reliability problem. This is an economic problem.”
“This is about how solar can get the revenue streams it needs so that we don’t have what looks like an epic fail on our doorstep,” adds Bingham McCutchen Senior Counsel Arthur Haubenstock. “Severe curtailment could produce more emissions and the renewables would not survive economically.”
Any way you slice it, the large-scale integration of solar power due to a 50% mandate is easier said than done. It poses looming problems for the solar industry itself and will likely force the state’s utilities to “build a bunch of gas plants to balance the load,” as one industry observer notes. Ultimately, because of increased use of natural gas to stabilize the grid, some speculate the higher mandate might not result in any decrease in California’s greenhouse gas emissions. As an alternative, some believe a solution could be for California to install as much as 10 gigawatts of new wind power capacity. That’s a whole lot of turbines for a state that values its pristine beauty.
For now, not even California experts, armed with a wealth of experience integrating renewables, have the answers. Governor Brown and those who support the 50% mandate are simply optimistic that tools like energy storage will leap forward in the next fifteen years and provide a silver bullet for the Golden State’s renewable integration challenge. They could be right. Or, they could be terribly mistaken.
The rest of the world, for its part, will mostly watch with curiosity. Worldwide, the combination of solar, wind, and geothermal is expected to contribute just 4% of global electricity production by 2040. Most states and nations are taking a more cautious approach than California, which is understandable. Much is at stake for power customers. Let’s hope policy makers keep a close eye as California tries to navigate uncharted territory. Knowing the dangers and pitfalls is vital for everyone’s future.