Agrivoltaics: A stabilizing solution for our food and energy needs

The Agrivoltaic energy system. Photo credit: Stacey Kihiu/ICRAF, Feb. 22, 2022

 

By Cecilia Bremner, Law and Policy Clerk

Agrivoltaics combines food production with energy production. The same land that is used to grow crops to produce food is used to hold solar panels which produce energy. With world population growth expected to reach almost 9.8 billion by 2050 and climate warming expected to exceed the 1.5 degrees Celsius threshold established by the IPCC in the 2030s, there is a real and immediate threat that both the global food and energy systems will collapse, and soon! These systems are already struggling with about 45 million people near starvation and 1.1 billion people without access to electricity. Agrivoltaics is a potential solution to both the food and the energy crisis.

Agriculture is highly resource intensive process relied on to feed the global population. About 38 percent of the world’s land surface, or five billion hectares, is used for agriculture. Irrigation of agriculture constitutes about 85 percent of global water consumption. Agriculture also contributes over a third of global greenhouse gas(GHG) emissions and accelerates biodiversity loss. National Geographic has proposed five steps to feed the growing population while accommodating the climate crisis—all five of which boil down to making agricultural practices more sustainable.

At the same time, electricity generation also needs to become more sustainable. This includes efficient use of land for renewables, like solar which requires a significant amount of land with similar characteristics to land that is also appropriate for agriculture.

Rather than competing for the limited resource of land, solar panels and crops can be placed together for more efficient land use. Currently, the major challenge to combining agriculture and solar is that the ground beneath solar panels is not usually suitable for agricultural purposes. Dual use is the only current exception whereby traditional solar parks are used for beekeeping and for grazing small livestock, such as sheep and chickens, which help to maintain the vegetation beneath the panels. Otherwise, panels are too close together for modern farming equipment to maneuver and they provide too much shade for effective crop yields.

These challenges have solutions. The three basic agrivoltaic setups are currently: 1) solar arrays spaced for crops, 2) solar arrays tilted above crops, and 3) greenhouse solar arrays. These setups increase distance between the panels and adjust the height of the panels to allow different machinery and potentially larger grazing livestock to pass through. Additionally, these setups adjust the transparency and angle of the panels to ensure an efficient amount of light passes through to the crops below the panels.

Studies suggest that combining crops and solar panels actually improves the conditions for both the crops and the panels. Regarding crops, too little light and their ability to photosynthesize and grow is limited. Too much light and the crops can no longer absorb energy and instead evaporate water to get rid of the excess energy; this threshold is called the light saturation point. Regarding solar panels, too high a temperature can decrease their efficiency. When crops and panels are used together, systems have shown a 30 percent improvement with the use of shade-tolerant crops. Additionally, summer crops seem to thrive in the favorable microclimate created with heat and water flow controls. The shade from the panels reduced crop evaporation overall such that they required less watering. The crops were also irrigated by the residual water from cleaning the panels ensuring this water served another purpose. Any evaporation from the crops created a cooling effect for the panels which increased their efficiency. The crops were also protected from the elements allowing them to be sold even after weather that might otherwise have rendered them unfit for the market. Thus, solar panels provide a shady and protective canopy for the crops while the crops help to keep the panels cool and efficient. The benefits of this canopy extend to the workers cultivating and maintaining the crops who are also kept cool and sheltered.

Despite these significant benefits, agrivoltaics do pose some challenges. Because of the shade created by the panels, really only shade-tolerant crops are suitable. The installation costs of panels higher off the ground, especially those with the ability to adjust the panel angle, are also likely to be higher than traditional solar installations. Crop yields may be marginally lower than if the land was purely dedicated to agriculture. The amount of energy generated will also probably be lower than a traditional solar farm as there are fewer panels for the same area. Additionally, farming machinery will need adaptations to protect the panels from damage.

These challenges can be overcome. A recent study by Oregon State University estimated that converting even just 1 percent of America’s existing farmland to agrivoltaics could have significant beneficial impacts such as meeting national renewable energy targets, saving water, and improving future food system reliability. While the upfront investment for such conversion will be significant, Oregon State University’s Vegetable Research Farm estimates that an investment of $1.12 trillion over 35 years will be paid back in just 17 years through the green electricity produced by these systems. Such a conversion to agrivoltaics could also create a much-needed revenue stream for farmers who increased their bankruptcy filings by 23 percent in the past year. Agrivoltaics allows everyone to win.

Agrivoltaics is a realistic option to help stabilize food supplies and decarbonize electricity grids. Both are imperative for our survival. So, let’s embrace agrivoltaics and take a positive step towards our climate resilient future.

 

The blogs posted on Charged Debate reflect the writers' opinions in their individual capacities, and do not necessarily reflect the perspective of the Green Energy Institute, Lewis & Clark Law School, Lewis & Clark College, or the writers’ past, present or future employers or other associations. Any information in any blog on Charged Debate is meant purely for general educational purposes, does not constitute legal advice and should not be relied upon for any purpose. No representations or warranties, express or implied, are made with respect to any content in any blog posted on Charged Debate.

Solar Canals

By Casey Bage, Law and Policy Clerk

 Photograph by Triddle, 2005

Solar canals address multiple problems at once. The impacts of climate change are so far-reaching and so grave that any multifaceted solution able to combat two or three problems at once cannot be overlooked if we want to live in a world of abundance. The realization of plentiful clean drinking water, clean air, and clean reliable electricity requires big ideas and a willingness of siloed entities to look outside their own specified expertise. Water agencies across the west have just such an opportunity. An article written by Staff Writer Sammy Roth of the Los Angeles Times recently highlighted the option of covering open-air water canals with photovoltaic solar panels. The article was inspired by a 2021 study released by the Sierra Nevada Research Institute at University of California Merced in collaboration with the Environmental Studies Department at UC Santa Cruz that solar installs over aqueduct canals have a 20-50% higher net present value than ground mounted solar farms.

We do not have the amount of water we need and our crisis will only worsen if we do nothing. California is once again experiencing extreme drought, along with the rest of the entire Western United States.  Lake Mead, providing water for over 24 million people, is at its lowest levels ever. Placing solar panels over open-air canals combats future clean water shortages in multiple ways according to the UC Merced study and I tend to agree with their assessments. 

The first conclusion of the study is that covering open-air canals with a roof of solar panels reduces evaporation, saving massive amounts of water as it makes its journey to thirsty rural and urban communities alike. The projects could also reduce aquatic weed growth in canals and, most importantly, add additional renewable energy projects to aid us in the ultimate goal of combating climate change and reining in mega-droughts. That’s three separate benefits for increasing abundant clean water.

On top of water savings, the placement of solar over water creates multifaceted victories for solar energy as well. Solar panels work more efficiently in a cooler environment, like a water-cooled canal, leading to more kilowatts of electricity generated from each panel. On top of that, many states are finding push-back against solar farm development, including the desire to preserve natural spaces and arable farmland producing our food.  Placing panels on already developed land assuages those concerns as well. Interestingly, the study finds that solar installed over canals could have a 20% - 50% greater net present value than standard ground mounted solar farms, due to the multi-pronged list of water and energy benefits, including the opportunity for California farmers to utilize that solar power instead of polluting diesel generators to pump water to their farms.

Now for the rub. Development costs money. Complex stuff, right? California’s Department of Water Resources gets their electricity from hydro-electric dams at very cheap prices. But, since water levels continue to shrink, the dams will most likely have less water to churn out that cheap power. On top of that, the Department of Water Resources has a new goal of reducing its greenhouse gas emissions to 75% below 1990 levels by 2030 and 100% by 2040. Solar-panel-covered canals are a major opportunity for the department, considering it is the State’s single largest electricity user. Water experts in the agency have expressed challenges that need to be addressed in order for this concept to take flight, namely: the need for new transmission lines from the aqueducts, accessing the canals to conduct maintenance, and paying for the investment. While some might view this list of difficulties as a reason to kill this idea, I view it as the project already getting off the ground especially with Roth reporting that  department head Karla Nemeth is “‘all ears” and ‘glad this is getting another look.’” The marketing firm that inspired the UC Merced study is named Citizen Group and has now started the company called Solar AquaGrid LLC. They are interested in developing pilot projects with “smaller water agencies that operate their own canals.” 

Having been born and raised in California and made my adult home in Oregon, I would be remiss if I didn’t mention this as a great opportunity for Oregonians as well. Central Oregon could be a ripe testing ground for this concept. The Central Oregon Irrigation District alone has 700 miles of canals, much of which is open air including the two major canals (Central Oregon Canal and Pilot Butte Canal). Oregonians, including Deschutes County commissioners, are acknowledging that water conservation efforts are critically needed as extreme drought take hold.

The blogs posted on Charged Debate reflect the writers' opinions in their individual capacities, and do not necessarily reflect the perspective of the Green Energy Institute, Lewis & Clark Law School, Lewis & Clark College, or the writers’ past, present or future employers or other associations. Any information in any blog on Charged Debate is meant purely for general educational purposes, does not constitute legal advice and should not be relied upon for any purpose. No representations or warranties, express or implied, are made with respect to any content in any blog posted on Charged Debate.