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from the you-mean-there's-good-climate-news dept.
According to a recent talk presented at the Ecological Society of America, solar panels and crops aren't always in competition.
In dry, hot areas, cooling by transpiration, not sunlight is the limiting factor of crop growth. Sometimes as much of 3/4 of sunlight is wasted in these places. An experiment by Greg Barron-Gafford hoped to take advantage of that.
"In an agrivoltaic system," Barron-Gafford says, "the environment under the panels is much cooler in the summer and stays warmer in the winters. This not only lessens rates of evaporation of irrigation waters in the summer, but it also means that plants don't get as stressed out." Crops that grow under lower drought stress require less water, and because they don't wilt as easily midday due to heat, they are able to photosynthesize longer and grow more efficiently.
Moreover, the passive cooling of the transpiration the plants are doing cools the solar cells and helps keep them closer to optimum operating temperatures.
The solar panels themselves also benefit from the co-location. In places where it is above 75 degrees Fahrenheit when sunny, solar panels begin under-performing because they become too hot. The evaporation of water from the crops creates localized cooling, which reduces heat stress on the panels overhead and boosts their performance. In short, it is a win-win-win at the food-water-energy nexus.
Saving water in drought-parched areas, producing renewable electricity without needing to develop new land, increasing crop yields, and better performing solar panels. What's not to like?
(Score: 1) by fustakrakich on Tuesday July 30 2019, @02:52AM (5 children)
You gotta drive your tractor underneath, and around all the support structure too.
La politica e i criminali sono la stessa cosa..
(Score: 4, Informative) by ikanreed on Tuesday July 30 2019, @03:13AM (2 children)
They covered that in the article. Their demo solar panels are indeed elevated to 4 meters above the ground, and they're exploring retractable solar panels.
(Score: 3, Informative) by JoeMerchant on Tuesday July 30 2019, @12:29PM (1 child)
It is work worth doing, for sure.
I will note: solar panels + water vapor = accelerated decrepitude. Not that you can't get a good useful lifetime out of a solar panel in a moist environment, just that - all else being equal - you can get a much longer one in a dry desert environment.
The payoff of increased crop yield and especially reduced water usage should greatly outweigh the reduced lifetime of the solar panels.
Like wind power, a big question I have here is: how useful is this food and power if it is being grown in a desert environment? Maybe surrounding cities like Phoenix, but out in the middle of nowhere the cost of getting the water to the farm, getting the workers to the farm, getting the food to market, and even getting the electricity to market all become uphill battles. Ask T. Boone Pickens how many customers he has for his wind power around Amarillo, he can sell it into the surrounding grids, but there is a significant cost involved in moving electricity 500 or 1000 miles from point of generation to point of use, so the price paid by grids oversupplied by local generation is justifiably lower than the price paid for generation capacity near need/load centers.
🌻🌻 [google.com]
(Score: 1) by khallow on Tuesday July 30 2019, @09:59PM
Not really. Solar cells will decay even in the driest environment due to UV damage. You just need the moisture sensitive parts to last a few decades (or be really cheap to replace).
(Score: 0) by Anonymous Coward on Tuesday July 30 2019, @03:22AM (1 child)
Next steps include working out the optimum coverage area -- maybe the plants really want 1/3 sun instead of 1/4?. Also, the panel size, spacing and height should be such that no spots stay shaded all day, the plants all probably like some direct sun??
(Score: 2) by Osamabobama on Tuesday July 30 2019, @09:33PM
They only need to get close on the sun coverage. Once the solar panels are installed, they will be there for 20 years. The crops can be adjusted via gene editing to optimally thrive in the (now standardized) environment.
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