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How Agrivoltaics Technology, AI Are Pushing Limits of Efficiency

24 days ago

Farmers have long been seen as the original environmental conservationists who harness the energy of the sun — but instead of storing energy in batteries, they now store energy in silos.

The implementation of technology in concert with time-tested techniques (and with some good-old-fashioned elbow grease) has long been the recipe used to finagle a living from the land.

At the forefront of this movement are researchers, engineers and farmers collaborating to unlock the full potential of arable land. Their work is not just about maximizing yields or generating electricity — it’s about creating a harmonious ecosystem where crops are harvested along with energy.

Remember when you were a kid mowing your lawn and how the grass under that sun-bleached table was longer than the rest of the grass? That’s agrivoltaics.

Light Saturation Point

All crops have something called a light saturation point (LSP), where they don’t benefit in any measurable way from being exposed to additional sunlight. In fact, when crops reach their LSP, they dramatically increase their water consumption and actually sweat, a process called transpiration. Research has demonstrated that a plant will lose nearly 99% of its lifetime intake of water through transpiration.

The concept of agrivoltaics is elegantly simple, yet profound. As of March 2024, the National Renewable Energy Laboratory had identified nearly 500 agrivoltaic projects in the U.S., representing over 8.2GW of solar capacity. Most of these projects are grazing and pollinator habitats, with only about 30 of those focusing on crops.

Traditional solar farms often occupy vast expanses of land, limiting their compatibility with agriculture. However, agrivoltaics flips this paradigm by utilizing the space above and between crops for solar panels. This dual-use approach not only maximizes land efficiency but also eliminates the “either/or” choice between energy production and food cultivation.

The Tri Cities is an expansive and wind-swept region in Southwest Washington and serves as the breadbasket for the nation’s second-most dynamic agricultural economy, producing more than 300 different crops — trailing only California.

Feeding Billions With Clean Energy

Since the last ice age, humans have managed to clear one-third of the Earth’s forests and two-thirds of its wild grasslands, much of it for agriculture, yet arable land is at an all-time premium. As the world population is pushing past 8 billion — there’s ever-increasing pressure on farmland to produce more food while states continue to pinch them by mandating more clean-energy practices.

The state of Washington has some of the most aggressive clean energy policies in the nation, mandating that coal-generated electricity be eliminated from the state’s energy profile by next year. This robust food production combined with enthusiastic legislation has created competition for space as land-hungry solar arrays and towering wind farms gobble up land in the rolling hills of Southwest Washington. 

At the end of 2022, the state’s Energy Facility Site Evaluation Council approved plans to cover 1,700 acres of agricultural land with photovoltaic (PV) panels, while construction on what will be the state’s largest wind farm is supposed to start next year, fueling community concerns over the long-term impacts of losing priceless cropland. 

A recent study from the University of California, Davis, however, shows how farmers may soon be able to harvest crops and energy together. 

The particles that make up light, called photons, have different properties — blue ones have higher energy than their red counterparts, resulting in light with shorter wavelengths and a higher frequency. While that gives blue light the jolt needed to generate power, the extra pulsing also generates heat.

The different bands within the visible-light spectrum can be filtered and harnessed independently — blue lightwaves to generate solar power and red lightwaves to grow fruits and vegetables. 

“Why does [agriculture] have to be a zero-sum game if we can optimize the land for both?” Majdi Abou Najm, an associate professor in the Department of Land, Air and Water Resources at UC Davis and an Institute of the Environment fellow, said about the research he co-authored. 

Through computer modeling, lead author Matteo Camporese, an associate professor in the Department of Civil, Environmental and Architectural Engineering at the University of Padova, in Italy, found that applying red lightwaves to plants increases photosynthesis and carbon assimilation — the process by which they metabolize carbon dioxide into organic compounds — while lowering transpiration. In other words, under the cooler spectrum crops can get the same amount of CO2 using less water.

Field Study

The researchers also conducted a limited field study of photo-selective cropping at the UC Davis Agricultural Experiment Station. The team planted processing tomatoes — a common local crop — on small plots, one canopied with a photo-selective red filter, another with blue and a third was left uncovered as a control. 

After approximately 120 days, including a record heatwave in early September, the two filtered plots each yielded about a third less than the uncovered one. Yet, when sorted into “ripe,” “unripe” or “bad” — the control plot accounted for twice the amount of rotten tomatoes.

Add energy generation and the net-gain would more than compensate for the diminished harvest. By co-locating crops and solar generation, 100% becomes a low number when you can get 140% yields.

And for countries and regions facing a tight squeeze on farmland, that makes increased productivity even more valuable, especially given that generating clean energy requires 10 times more land per unit of power than fossil fuels.

Custom Sunlight

The genius of agrivoltaics is the customizing of sunlight for specific crops. For example, leafy greens thrive under blue-enriched light, while fruiting plants prefer a combination of red and far-red wavelengths. By optimizing the spectrum, these panels are also optimizing productivity.

The integration of advanced data analytics and artificial intelligence (AI) has further enhanced the capabilities of agrivoltaic systems. Smart sensors embedded in the soil and on solar panels continuously monitor environmental parameters, providing real-time feedback to farmers.

Imagine having a virtual agronomist guiding your decisions, AI algorithms analyzing data on soil moisture, temperature, light levels and crop health, all while offering actionable insights to optimize irrigation, shading and even energy production.

Abou Najim hopes his research will “motivate the industry” to create a new generation of solar panels and sees potential in organic solar cells, which, unlike the shiny, metallic, silicon-based surfaces, are derived from carbon-based compounds. Thin and translucent, the cells are applied like a film onto various surfaces, including glass. This technology could be used to develop photo-selective PV panels that filter blue light to generate power, while passing the red spectrum to crops planted directly under the solar panels.

By giving plants just the right amount of shade and sunlight, efficiency skyrockets.

Article written by Allen P. Roberts Jr. | Senior Writer


Farmers Hot Line is part of the Catalyst Communications Network publication family.