Study: It's Possible to Power All of California With Clean Energy, But...

A new study claims that California could power itself entirely with wind, water, solar, and geothermal energy by 2050, but it would require devoting more than 4,800 square miles of the state's land and waters to wind turbines and utility-scale solar power plants.

According to the study by Stanford engineer Mark Z. Jacobson and 27 colleagues, published in late July in the journal Energy, the state should theoretically be able to supply 95 percent of its projected demand for power with wind turbines and solar power plants, with the remaining 5 percent coming from geothermal.

The catch is that according to the study, California would need to build miles utility-scale solar power plants and wind turbines covering 3,426 square miles of the state -- more than seven times the size of the city of Los Angeles -- with offshore wind installations covering an additional 1,406 square miles of the Pacific Ocean.

The authors assume that California will be able to reduce its per capita energy consumption by between five and ten percent by 2050. They also project a huge increase in rooftop solar on homes, businesses, and government buildings, with more than 15 million new units generating 14 percent of the state's total energy consumption. The new panels would provide about 390 square miles of rooftop PV in the state, a figure not included in the 3,426 square miles of new utility-scale solar and wind facilities.

3,426 square miles seems like a lot, but it's hard to get a handle on just how much land we're talking about here. For perspective, consider that only 15 of California's 58 counties encompass more than 3,426 square miles. Or think of it as three times the size of Yosemite National Park -- the whole thing that takes a week to hike across, not just the valley.

In addition, the study counts that 1,406 square miles of offshore wind turbine fields incorporating 7,809 turbines, none of which currently exist off the California coast. The authors suggest the state amend its Renewable Portfolio Standard (RPS) law to set a goal of 5,000 megawatts of new offshore wind by 2030 -- about 1,000 new turbines in the next 16 years.

Jacobson et al have other policy suggestions, including expanding the RPS past 2020, when it requires California to derive 33 percent of its electrical power from renewable sources. The authors of the study suggest a ramping-up of three percent per year after 2020, so that the state would stand at 63 percent renewables by 2030.

The authors also recommend a raft of common-sense policy shifts such as making it easier to get solar permits, implementing greatly expanded urban solar incentive programs, and promoting mass transit.

The intermittent nature of wind and solar is a bugbear for renewable energy advocates: when the wind stops blowing and the sun goes down, we'd have to turn to another source of power, and that means coal or -- more commonly in California -- natural gas.

But according to Jacobson and his colleagues, the massive buildout of both wind and solar, plus development of energy storage capacity, would address the intermittency problem -- and the study assumes that new utility-scale concentrating solar facilities would include three hours worth of thermal storage.

Where would those new concentrating solar facilities (948 square miles of them, a total area more than twice the size of Los Angeles) and an additional 525 square miles of new utility-scale photovoltaic plants go? Jacobson et al pay heed to Californians' mounting concerns about replacing ecological habitat with industrial renewable energy facilities:

But they then go on to caution that our concern for wildlife shouldn't slow down development of those 1,473 square miles of industrial solar:

In theory, there are a lot of places in the state where large-scale solar projects should work. But a footnote in one of the study's tables shows what Jacobson et al have in mind. In a discussion of the numbers used to determine those big solar plants' real-world output, known in the trade as the plants' "capacity factor," the footnote reads:

So look for close to 2,900 square miles of California's deserts and offshore waters to be changed drastically, if this study gains admirers in Sacramento.