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Agriculture

Published on August 9th, 2019 | by Tina Casey

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From 1% To 30% Solar Power Without Losing Farmland — How Is That Possible?

August 9th, 2019 by  


Solar power only accounts for about 1% of US electricity production now, but it could shoot up to 30% by 2030 if the deep decarbonizationers have their way. The big question is where to put all the solar panels. Researchers at Oregon State University are hot on the trail of a solution that could also provide some relief to farmers in the US, who are struggling with the triple burdens of climate change, trade wars, and yes, feral hogs. The research team also discovered something that turns the conventional wisdom about solar power on its head.

solar power farms agrivoltaics

Sheep coexist with solar power at Oregon State University – Mark Floyd, Oregon State University.

Solar Power At Working Farms: What A Concept!

Optimal conditions for solar power typically involve the warm, sunny climate of the US southwest, but researchers are discovering that localized microclimates can exert a strong influence on solar cell efficiency.

In an online paper published at Scientific Reports, the OSU researchers describe four parameters that influence solar cell efficiency: insolation, air temperature, wind speed, and relative humidity.

Insolation refers to the amount of solar radiation hitting a particular area. Temperature is important because solar cells are less efficient when conditions are too hot.

A slight breeze is more optimal for solar power than stagnant air. Rounding out the four factors is relative humidity, which refers to the amount of water vapor the air is holding at a given time, compared to what it is capable of holding. Lower relative humidity is also more optimal than higher humidity.

In a nutshell, the researchers found that their research site — a 1.5 megawatt solar power installation on an active sheep grazing field — exhibited improved efficiency associated with those four elements.

Applying their findings to different types of land, the research found that croplands, grasslands, and wetlands would provide more potential for optimizing solar power than barren land.

That’s topsy-turvy from the conventional consensus on solar power, which focuses on barren, desert-like conditions, if not actual deserts.

Translating their findings onto 17 different types of land identified by NASA’s Moderate Resolution Imaging Spectrometer, the research team found that croplands provided the maximum optimization, followed closely by grasslands and permanent wetlands.

Interestingly, mixed forests also scored in the top five (mixed forests include both deciduous and evergreen trees), coming in at number four.

Barren land came in fifth, so there’s that.

Farmland Plus Solar Power

OSU’s solar power research site is located at the school’s Corvallis campus in the western part of the state, a little less than 50 miles from the Pacific coast.

The 1.5 megawatt solar array was built by SolarCity (that’s where the Tesla angle comes in) in 2014 at no direct cost to the school (though taxpayers subsidized the project). It goes by the name of 35th Street Solar Array, but don’t be fooled by the urban-sounding name. The site is an actual grazing area with actual sheep on it.

According to our friends at Grist.org, there is quite an interesting story behind the construction of the 35th Street Solar Array, but regardless of how the panels got there, they provided the researchers with data including temperature, humidity, wind speed, wind direction, soil moisture and incoming solar energy.

The data, collected every 15 minutes, enabled the team to develop a model for solar cell efficiency based on air temperature, wind speed, and relative humidity.

As for the idea that solar panels can coexist with active, commercially viable farm use, the evidence is beginning to pile up. It turns out that by raising solar panels a bit higher, you can get shade and moisture retention benefits for some uses.

The US Department of Energy has a handy farm-to-solar web page that outlines how farmers can benefit, including:

Reduced electricity costs

Diversification of the revenue stream

Increased ability to install high-value, shade-resistant crops for new markets

Marketing opportunity to sustainability-mindful audience

Ability to maintain crop production during solar generation

Allow for nutrient and land recharge of degraded lands.

There is even a new word — agrivoltaics — to describe the emerging trend. CleanTechnica is reaching out to USDA to see what they think, so stay tuned for more on that.

What About Floating Solar Panels?

Yes, what about them? Floating solar panels on bodies of water is another trend that takes land use into account.

Water does not fare so well in OSU’s methodology, coming in at number 10 between urban locations and woody savannah.

Nevertheless, the floating solar power trend is also taking off, and indications are that solar panels will soon pepper bodies of water in various parts of the globe.

The Energy Department, for one, is actively promoting floating solar panels in consideration of the vast amount of available human-made water bodies in the US — including ponds and reservoirs located on farmland.

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Photo: Sheep graze under the 35th Street Solar Array at Oregon State University, by Mark Floyd, Oregon State University (Usage Restrictions: None).

 
 





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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



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