Study urges optimization of solar energy development

Solar energy's land-use impact
A typical solar generating installation. Credit: Rebecca Hernandez

With mounting vigor for combating global climate change, increasing the use of renewable energy resources such as solar, without compromising natural habitats, is a challenge to the traditional model of utility-scale solar energy installations. Such facilities use vast swaths of land for solar gathering and generating equipment. Until now, studies quantifying the effects on land-cover change and analyses of impacts on protected areas near solar facilities have been limited.

New work from Carnegie's Rebecca R. Hernandez (now at UC-Berkley and Lawrence Berkeley National Lab), Madison K. Hoffacker (now at UC-Riverside's Center for Conservation Biology), and colleagues, published in the Proceedings of the National Academy of Sciences, assessed the siting impacts of 161 existing, under construction, and planned utility-scale solar energy facilities in California. Utility-scale solar energy facilities generate at least 1 megawatt, which is enough to power approximately 165 homes. The researchers found that a majority of sites are located in natural California shrub- and scrublands covering about 145 square miles (375 km2); 28% are in croplands and pastures; less than 15% are in developed areas; and some 19% are in areas far from existing transmission infrastructure, which has adverse economic, energetic, and environmental consequences.

This study included two kinds of solar technologies, photovoltaics (PV), which use semiconductors, and concentrating solar power (CSP), which use mirrors to focus the sun's rays for generating steam. Previous work by Hernandez and colleagues, published in Nature Climate Change, found that these solar technologies in built-up areas could meet California's energy demands three to five times over.

"California, as an early adopter of solar energy, is a model system for understanding the complex siting decisions made by all parties—from developers, to governmental agencies, to stakeholders and communities—involved in utility-scale solar energy development," remarked Hernandez. "Solar energy in developed areas, or for example on contaminated lands, would have great environmental co-benefits, but this is not what is being emphasized. Instead, we see that 'big solar' is competing for space with natural areas. Knowing this is vital for understanding and creating predictions of a rapidly changing global energy landscape."

In analyzing impacts on protected areas, the researchers calculated the proximity of solar installations to them. The fact that nearly 20% of solar facilities were far (greater than 6 miles, or 10 kilometers) from transmission infrastructure means that the energy must travel farther and therefore have greater energy losses; they cost more to build; and new transmission corridors degrade the natural environment. Michael Allen of UC-Riverside, a co-author on the study stated, "As a goal of reducing the human carbon footprint, and protecting the environment including California's incredible biodiversity, careful planning of siting of facilities and selection of appropriate technologies should become standard."

Almost 30% of all installations were in croplands and pastures. "We were struck by this finding too," Hernandez stated. "We are seeing landowners, particularly in the Central Valley, shift from harvesting crops and forage to harvesting the sun." It is possible that the mounting pressure from drought has made this shift to solar energy an easier decision for farmers, a novel interaction that Hoffacker is currently studying in greater depth.

After evaluating land-cover change from solar facilities, the researchers used the Carnegie Energy and Environmental Compatibility computer model to develop a compatibility index to identify areas of potential and direct conflict with respect to environmental resources California-wide. Compatible areas are areas that are already developed. For photovoltaic technology, they identified some 8,500 square miles (22,028 km2) of these compatible areas (11.2% of total PV installations) and 30,000 square miles (77,761 km2) of potential compatible areas (71.7% of PV installations). Potentially compatible areas are the next best thing. They are not protected, they would not require heavy site preparation, such as grading steep slopes, and they are within 6 miles (10km) of transmission lines and roads. There are many locally unique considerations that come into this category, for instance view disruption for local residents. Incompatible areas are natural and protected areas. The scientists found that some 55.5% of CSP installations were in either compatible or potentially compatible areas.

Hernandez explained, "If our country wants to reduce greenhouse emissions by 80% of 1990 emissions by 2050, some 27,500 square miles (71,428 km2) of land could be required for solar installations, which is about the area of South Carolina. We can increase the land-use efficiency in ways such as decreasing spaces between rows of photovoltaic modules or concentrating solar power mirrors. Better yet, is to locate installations in areas already affected by humans, such as on land fills, over parking lots, and on rooftops and nearest to where the energy is being consumed."

Kara Moore, an applied ecologist at the Center for Population Biology at UC-Davis, who has conducted landmark experimental studies on effectiveness of rare species mitigation within a utility-scale facility stated, "This study gives policy-makers clear guidance on the great potential we have to site utility-scale renewable energy more sustainably by building it into our existing human-affected landscapes. By doing so we benefit by simultaneously increasing the efficiency of renewable energy systems and by avoiding unnecessary impacts to our precious remaining natural areas."

Explore further

Solar could meet California energy demand three to five times over

More information: Solar energy development impacts on land cover change and protected areas, Proceedings of the National Academy of Sciences,
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Oct 19, 2015
We may wind up needing all we can build. Utilities with nukes now find many of them are grossly uneconomical, and are closing them. That increases the gas we have to burn to make up for them, increasing our carbon output.

The power towers and big CSP units can be retrofitted with line-focus collectors on the same grounds, obviating the issue with burning birds.

We have a lot of options.

Oct 19, 2015
We have a lot of options.
a lot of options that require large land/offshore areas, causing more disturbance on the environment than nuclear per unit of energy generated.

Oct 20, 2015
If you've ever been on a flight and looked out the window you can see hundreds of HUGE warehouses right on the outskirts of cities. All that real estate is PRIME for solar panels.

The warehouses are paying top dollar to air condition their buildings when they could easily be shaded by solar panels. They're also wasting all that space on top of their buildings. That area is doing nothing for them.

I wouldn't go so far as suggesting that 'flat' roofs should be mandated to have solar panels installed, but companies should be strongly incentivized

Oct 20, 2015
I wouldn't go so far as suggesting that 'flat' roofs should be mandated to have solar panels installed, but companies should be strongly incentivized

Just cut the tax breaks they get for their electricity bills. That should be incentive enough. (The tax breaks are the reason why they don't use solar panels. Air condition is dirt cheap for companies).

Oct 20, 2015
The utilities missed a big opportunity, being sunk in their own corporate-think. Installing PV panels on the roofs of their customers, which would reduce their biggest expenses, was "out of the box" thinking, I guess.

Linear thinkers keep us in the box. Silicon Valley uses intuitive thinkers (the ones Big Business hates), for progress,and linear ones for production. It is easy to see the differences in those who attack other ideas, those who are frustrated with the ideas of others, the ideas they do not understand. If it is not in wiki it does not exist.

That is why they do not live or work in Silicon Valley, where the future is invented.

Oct 20, 2015
Didn't Paris just pass a law referencing living roofs and solar panels?

Oct 20, 2015
Antialias, what tax breaks? Can you document that?

You need to get your head around solar power. A solar power plant is only going to produce electricity fraction of the time. In Italy is 9% per annum. Can't build or maintain civilization on renewable power (wind and solar).

It is an economic dead end without vast improvement in storage.

Oct 20, 2015
No, it is not. Why would you assume ALL the power would come from them? Instead, the most expensive power, peaking power can be generated by them, and every kWh they produce offsets what we would have had to generate with polluting power.

I suggest you look into the western grid for how disparate sources are integrated.

Oct 20, 2015
Didn't Paris just pass a law referencing living roofs and solar panels?
I dont know did you forget how to look this sort of thing up? Why do you expect others here to do it for you?
I suggest you look into the western grid for how disparate sources are integrated

Your word is worthless here due to your compulsive lying and fact-forging.

Oct 24, 2015
Roderick should know that solar is already as cheap as coal, even without the coal scrubbers needed for us to keep breathing. If they can ever clean up coal, it will be as expensive as nuclear power, which is dying in the US.

Look up the relative costs for wholesale power from PV,wind, and Vogtle. How many nuke plants have closed in the last few years? How many more in planning stages of shutdown?

The secret to clean, efficacious and efficient power is integration. In the 1980's our PG&E system was fed by wind, hydro, nuclear, geothermal, pumped storage, landfill gas, gas peaking boilers, supercritical gas boilers, solar thermal, photovoltaic, fuel cells of all kinds, some sources I forgot, and even the emergency generators in the facilities of our customers dispatched directly by us.

You can learn the same thing.

Oct 24, 2015
solar is already as cheap as coal
Tell us about your solar-powered car that can run fast day/night, cloudy/sunny. Yabba dabba doo!

Oct 26, 2015
Solar cannot provide power most of the time. Even if it were the cheapest, it is irrelevant because solar power is poorly correlated with demand. In fact, solar is lousy as peak power - power demand peaks in the winter, not the summer. And solar is not the cheapest. Every cost calculation that claims solar power is cheaper ignores the cost of having other sources of energy during the 90% of the time that solar is not available.

Nuclear power is not expensive. France proves that. Sweden proves that. The reality is that those countries do not pay subsidies to nuclear power companies to artificially their rates.

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