ENERGIES

Agrivoltaic systems: harvesting energy together with food

Agrivoltaic systems: harvesting energy together with food

Solar arrays located in agricultural fields can benefit both energy and crop production. These sets are called agrivoltaic systems.

In 2008, J. David Marley, an engineer who owned a construction company in Amherst, Massachusetts, had an idea. He had just finished building a large solar array on the roof of his downtown office building.

He had learned that the labor and effort to place it there was much more expensive than if he had built the solar array on the ground.

In heavily populated Massachusetts, farmland is relatively rare and only 10% of its food is homegrown. If you had placed your solar panels in a farm field, Marley wondered, what would they do with food production?

After more than a decade of experimentation, a study written last month by 11 scientists gave us an answer. In many cases, farmers and future food supplies will benefit from having solar panels in their fields, especially as climate change introduces more drought and scorching temperatures in agricultural areas.

The study found that the conventional way of installing solar panels tends to increase heat. Ensembles often sit on a bed of white gravel that smothers vegetation and reflects sunlight back to ensemble. That raises its temperature and can reduce electricity production by 1% to 3%.

The study noted that grazing animals and many vegetable crops can benefit from partial shade under solar panels. Additionally, the resulting flow of renewable electricity is equivalent to another crop, providing farmers with more income and reducing emissions from fossil fuel-based electricity.

The National Renewable Energy Laboratory (NREL), part of the Department of Energy, has supported multiple solar growing experiments. In a recent statement, he said that the co-location of solar panels "could deliver win-win results" in many agricultural sectors.

Last month, NREL helped publicize the study that appeared in Nature Sustainability under the heavy name "agrivoltaic systems." It is the concept of placing solar panels on active agricultural fields. He found that the changes "impacted every aspect of plant activity" with three different food crops, usually for the better. The study predicted that future savings from water used to irrigate Arizona's dry farmlands, where the study authors tested them against conventional crops, would be "substantial."

Jordan Macknick, an NREL researcher who has followed the agency's agrivoltaic studies since they began in 2010, said there are 25 experiments in remote locations across the US They include grazing animals in Colorado and growing tomatoes, potatoes. and melons without irrigation in Oregon. Others include raising bees around flowers protected by solar panels in Minnesota and placing solar panels over blueberry swamps in Massachusetts.

"We assume that by 2030 there will be about 3 million acres of land in the United States with solar panels on them" for combined agricultural and energy production purposes, Macknick explained.

There were experiments from the early 1980s in Germany, France, and Japan. They hinted at the beneficial marriage between solar panels and agriculture, but when he began his experiments in Amherst in 2008, Marley knew nothing about them.

But he was sure that conventional solar panels would have to be redesigned to present to farmers. Reflective gravel should be removed along with traditional concrete foundations and steel pipes. While conventional dies sat low above the ground, Marley wanted to raise them to a minimum of 7 feet. That would provide enough space for the animals to graze, while allowing tractors to work crops planted in the bare ground below.

Anne Marley once said this about her husband: He was a man with a plan and in a rush to do something about climate change. "He thought we were late," he said. "We are behind schedule, and instead of waiting for the government to do it, we have to make it happen."

FOOD VERSUS ENERGY

J. David Marley formed a company, Hyperion Systems LLC, and developed a partnership with the University of Massachusetts, Amherst, from which he graduated, to build a test site in 2009. He envisioned arrays that could be built into wooden pole structures that could be eliminated if farmers wanted to plant something else.

The arrangements reached up to 15 feet to make room for farming and let the rain and snow flow. Stephen Herbert, an agronomist at the university, helped determine the optimal spacing between panels for enough sunlight to reach the ground.

"This came out of nowhere," Herbert recalled. The favorable economics of combining solar panels with pasture for cattle and sheep grazing was, as he put it, "obvious". Pasture, farm animals and electricity production benefited.

Marley, who later patented the designs and won a $ 1.5 million grant from the Department of Education to teach technical school students new uses for solar photovoltaic systems, died in 2013. Herbert upholds the tradition in his agronomy classes, explaining how the experiments led to a variety of vegetables, including kale, chard, lettuce, beans, broccoli and bell peppers, and renewable electricity that is profitably grown on various plots of land in Massachusetts.

As Herbert explains, governments will have to get more involved and make decisions on how to use the new system, otherwise a warmer climate will force farmers to “take the land out of productivity while increasing the number of hungry people ”.

“I tell young people that it is their future, not so much mine. They will have to take politics seriously, ”he said.

Governments have certainly gotten more involved. Since 2017, the Massachusetts departments of Energy and Agricultural Resources have been struggling with a grant program that encourages farmers to try renewable energy. At the same time, the program tries to restrict companies that sell arrays and solar power from taking over too much farmland.

In 2017, Massachusetts set a goal of reaching 1,600 megawatts of solar power by 2020, but imposed a cap aimed at protecting farmland. Fifty percent of the land on a farm had to be exposed to sunlight. Now the state plans to add 800 MW, and is considering a proposal to give farmers a lower rate for their electricity if they continue to expand the area covered by the arrangements.

More farmers want to participate in the program, and some solar industry advocates are pushing for 4,800 MW. They want more access to farmland to bring a higher percentage of renewable energy to nearby communities. Herbert believes that the proportion of farmland without solar panels could drop slightly below 50% and still make economic sense for farmers. Beyond that, he thinks that existing farmland should be preserved for traditional crops and not for increasing electricity.

At this time, the program is waiting for the state to write new regulations; they are supposed to be released in February.

Meanwhile, interest in agrivoltaic agriculture continues to spread. The DOE program retained Marley's company, Hyperion, as a partner in 2015 and plans to establish a new experimental site in Puerto Rico. The land is being used to raise cattle and grow coffee.

An advisor on that project will be Jake Marley, David Marley's son and Hyperion's new manager. He said the DOE program, called InSPIRE for "innovative site preparation and environmental impact reductions," reflects his father's conservative approach to using farmland. "Their main objective was not to take the land out of production," said Jake Marley. "He believed in the production of food first, and energy second."

The original idea was the product of two scientists in Germany in 1981. They produced a paper called “Kartoffeln Unterm Kollektor” (“Potatoes under panels”) that showed for the first time how the economics of agriculture could work with solar panels.

The idea has spread around the world, and Macknick, the NREL researcher, said it will lead to more innovations, including some from companies in India planning to hang solar panels over irrigation canals to produce electricity and reduce evaporation of water from water. precious watering in the same time.

He says there is more innovation underway in the US, where companies are thinking of using translucent solar panels to let in more sunlight and build electric solar greenhouses to combine power and plant production. “Solar powered” tomatoes and honey are being sold at farmers markets.

The experimentation continues. "There will be a huge appetite for this in small countries or those that don't have a lot of farmland available," Macknick said. "You'll see a lot of conflicts between food and energy there, and there are ways you can help minimize them."

"But there are still many open questions about how to grow this right," he added.

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