Solar in California's urban areas could provide 5 times the power the state needs

Photovoltaic panels deployed in urban areas could produce 15,000 terawatt-hours per year.

sun star solar

The Solar Star facility near Rosamond, Calif. will be the world's largest solar power plant, with 579MW of power capacity.

Credit: SunPower Corp.

The amount of energy that could be produced through solar equipment constructed on or around existing infrastructure in California would easily exceed the state's demands, according to a new study.

Currently, solar energy deployments are complicated by the need to find space for equipment without significantly altering the surrounding area.

The study, from the Carnegie Institution for Science, found that the amount of energy that could be generated from solar installations on and around existing infrastructure in California would exceed the state's demand three to five times over.

ivanpah mingasson 100571034 orig BrightSource Power

The Ivanpah Solar Power Facility in California's Mojave Desert is a concentrating solar power plant that uses huge curved mirrors to heat water, transforming it into steam to turn a turnbine. There are more than 300,000 software-controlled mirrors that track the sun in two dimensions and reflect the sunlight to boilers that sit atop three 459-ft tall towers. Together, three plants produce 392MW of power.

The research showed that by using areas around existing infrastructure and brownfields, California could substantially how much energy it gets from solar, without converting natural habitat and causing harm -- and without moving the installations to remote locations. The researchers found that using small- and utility-scale solar power in and around developed areas could generate up to 15,000 terawatt-hours (trillion watt hours) of energy a year using photovoltaic technology, and 6,000 terrawatt-hours of energy a year using concentrating solar power technology.

Published today in the scientific journal Nature, the study claims that about 8% of California's terrestrial surfaces have been developed, ranging from cities and buildings to park spaces. Residential and commercial rooftops, it found, present plenty of opportunity for power generation through small- and utility-scale solar power installations. Other urban spaces, such as parks, also offer untapped areas for  installations.

The research was performed by post-doctoral environmental earth scientist Rebecca Hernandez (now at the University of California, Berkley), along with researchers Madison Hoffacker, and Chris Field.

Overall, the team of three researchers found that California has about 6.7 million acres of land that is compatible for photovoltaic solar construction and about 1.6 million acres compatible for concentrating solar power. There is an additional 13.8 million acres that is potentially compatible for photovoltaic solar energy development with minimal environmental impact and 6.7 million acres that would be compatible for concentrating solar power development.

"Integrating solar facilities into the urban and suburban environment causes the least amount of land-cover change and the lowest environmental impact," Hernandez said in a statement.

 Rooftop solar

A view of solar panels recently installed on the roof of the Space and Naval Warfare Systems Command Headquarters in San Diego. The rooftop photovoltaic installation supports the Department of Defense's goal of increasing renewable energy sources to 25% of all energy consumed by the year 2025

Additionally, there is opportunity for solar energy deployments in undeveloped sites that are not ecologically sensitive or federally protected, such as degraded lands like  salt-saturated areas near roads and land around existing transmission lines.

This study involved the use of two kinds of solar tech: photovoltaics, which use semiconductor technology on solar panels, and concentrating solar power, which uses curved mirrors to focus the sun's rays to generate steam to power an electrical turbine.

A mix of both options would be possible, the study states, depending on the particular areas of installation, whether on a rooftop, in a park, on degraded lands or anywhere else deemed compatible or potentially compatible.

"As California works to meet requirements that 33% of retail electricity be provided by renewable sources by 2020 and that greenhouse-gas emissions be 80% below 1990 levels by 2050, our research can help policymakers, developers, and energy stakeholders make informed decisions," said Field, director of Carnegie's Department of Global Ecology. "Furthermore, our findings have implications for other states and countries with similarly precious environmental resources and infrastructural constraints."

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