Category: Food Insecurity

Agrivoltaics

Agrivoltaics & PV Restoration: Innovations at the nexus of Food – Energy – Water sciences.

[The Barron-Gafford research group is a collection of broadly-trained biogeographers, ecosystem ecologists, and plant ecophysiologists tackling a wide range of environmental topics.]

What is agrivoltaics?

agrivoltaics = agriculture + photovoltaics
(photovoltaics = renewable energy production from solar panels)

We are investigating the potential for reintroducing vegetation into the typical PV power plant installation in drylands.  Why??  We think that this novel approach may lead to increased renewable energy production, increased food production, and reduced water use!

Why might this benefit agricultural plants?
Plants need sunlight.  The truth is, though, that plants don’t continue to do increasingly well as you add more sunlight.  At some point, their potential to use the sunlight for photosynthesis plateaus out, and if they experience too much light, they can actually become less productive. Think about it – plants in drylands have adapted to deal with the excessive amount of energy in lots of cool ways.  Unfortunately, many of our agricultural plants are not desert adapted; we make up for this lack of adaptation by giving them plenty of water through irrigation. 

What if we mimicked nature?  One desert adaptation is to grow the shade of another plant. How might the shade of a solar panel array overhead lead to cooler temperatures and less excessive sunlight for agricultural plants? Our preliminary work suggests that there are measurable benefits for some species!

Why might this benefit renewable energy production?
Larger solar installations create a heat island effect, and that is bad for the PV panels because as they get too hot, they become less efficient. Basically, there two ways for the excess sun energy that is not converted into electricity to leave the area: sensible heat (the energy you can feel) and latent heat loss (the energy used to convert liquid water to water vapor).

In a natural ecosystem, this latent heat loss happens when plants transpire during the process of photosynthesis. The problem is that most PV installations don’t have plants in them any longer, which means they don’t have a way for sun energy to leave through latent heat loss.  This means that excess energy can only leave through sensible heat loss (which is why these areas become hotter). 

We are trying to increase the latent heat loss from plants so that there is less sensible heat loss.  Such a simple concept that can potentially have a big impact?  Yeah, we had our doubts too until we tried some preliminary experiments!

Why might this benefit water resources?
Water evaporates away more slowly in the shade, no? If we reduce the direct sunlight hitting the soil, we believe that water from each irrigation event will remain in the soil longer to do the work we put it there to do – sustain plants!

Why might this benefit people?
In addition to potentially producing equal or greater amounts of food and renewable energy with reduced water use, we anticipate our agrivoltaics approach to help humans in 2 key ways:

1. Drylands are often really hot environments, making our farm worker population prone to heat stroke and heat-related death.  Our preliminary data suggests that skin temperatures can be up to 20°F cooler when working under the PV array!  That makes for significantly more comfortable working conditions! 

2. We have partnered with the UofA Community & School Garden Program to help educate our next generation about all aspects of STEM (Science, Technology, Engineering, & Math), while integrating art and ecology.  See more about our Agrivoltaics Learning Labs below. 

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Solar Panels Pair Surprisingly Well with Tomatoes, Peppers and Pollinators

Solar panels pair surprisingly well with tomatoes, peppers and pollinators.

In ‘agrivoltaics,’ crops and solar panels not only share land and sunlight, but also help each other function more efficiently.

The world already needs more solar power. It’s clean, renewable energy, and it’s quickly outpacing the job creation and affordability of fossil fuels. But on top of that, a growing field of research suggests it can improve agriculture, too, helping us grow more food and pollinator habitat while also conserving land and water.

Big, utility-scale “solar farms” are one important source of solar power, helping complement smaller, less centralized sources like solar panels on the roofs of buildings. Solar farms take up a lot of space, though — and they thrive in places with many of the same qualities favored by food crops. As one recent study found, the areas with the greatest potential for solar power tend to already be in use as croplands, which makes sense, given the importance of sunlight for both.

“It turns out that 8,000 years ago, farmers found the best places to harvest solar energy on Earth,” said Chad Higgins, study co-author and professor of agricultural sciences at Oregon State University, in a statement.

Since crops already occupy many of those places, this might seem to cast solar farms and food farms as rivals for real estate. Yet while it’s smart to balance food and energy production, a growing field of research suggests it can also be smart to combine them. Unlike fossil fuels, one of the great things about solar power is that it’s clean enough to still use the land for food production, without needing to worry about contamination. And not only can crops and solar panels co-exist on the same land, but when combined in the right ways at the right locations, researchers say each can help the other function more efficiently than it would alone.

This idea — known in the U.S. as “agrivoltaics,” a mashup of agriculture and photovoltaics — isn’t new, but new research is shedding light on how beneficial it can be. Beyond the benefits of harvesting food and clean energy from the same land, studies suggest solar panels also boost crops’ performance — potentially raising yield and reducing water needs — while crops help the panels work more efficiently. This could increase global land productivity by 73%, while generating more food from less water, since some crops under solar panels are up to 328% more water-efficient.

Agrivoltaics won’t necessarily work the same for every location or every crop, but we don’t need it to. According to Higgins’ research, if even less than 1% of existing cropland was converted to an agrivoltaic system, solar power could fulfill global demand for electricity. That still wouldn’t be as simple as it sounds, but amid the growing urgency of climate change, energy demand and food insecurity, it’s an idea that seems more than ready for its moment in the sun.

Types of agrivoltaic systems

illustration of three different agrivoltaics systems

Three different types of agrivoltaic systems: (a) using the space between solar panels for crops, (b) a photovoltaic greenhouse, and (c) a stilt-mounted system. (Illustration: Sekiyama et al. [CC BY 4.0]/Environments)

The basic idea of agrivoltaics dates back at least to 1981, when two German scientists proposed a new kind of photovoltaic power plant “which allows for additional agricultural use of the land involved.” It has evolved in the decades since, leading to new twists on the concept that have found success in several countries, including Japan — which has emerged as a global leader in “solar sharing,” as the practice is known there — as well as France, Italy and Austria, among others.

There are three general categories of agrivoltaic systems. The original idea placed crops between rows of solar panels, capitalizing on spaces that are otherwise mostly unused (see example “a” in the illustration above). A different tactic, developed in 2004 by Japanese engineer Akira Nagashima, involves solar panels raised on stilts about 3 meters (10 feet) off the ground, creating a pergola-like structure with space below for crops (example “c” above). A third category resembles the stilted method, but places the solar panels on top of a greenhouse (example “b”).

It’s one thing to plant crops in sunny gaps between solar panels, but sowing them underneath the panels means sunlight is blocked for at least a few hours every day. If the goal is to maximize the efficiency of both the crops and the solar panels, why let one block any sunlight from the other?

Made in the shade

agrivoltaic or solar-sharing system at rice farm in Japan

Solar panels stand above a rice paddy at a solar-sharing farm in Japan. (Photo: Σ64 [CC BY 3.0]/Wikimedia Commons)

Plants obviously need sunlight, but even they have limits. Once a plant maxes out its ability to use sunlight for photosynthesis, more sunlight can actually impede its productivity. Plants native to dry climates have evolved various ways to deal with excessive solar energy, but as researchers at the University of Arizona point out, many of our agricultural crops are not desert-adapted. To successfully grow them in deserts, we make up for their lack of adaptation with intensive irrigation.

Instead of using all that water, though, we could also mimic some of the natural adaptations used by dry-climate plants. Some deal with their harsh habitats by growing in the shade of other plants, for example, and that’s what agrivoltaics advocates are trying imitate by growing crops in the shadows of solar panels.

And that payoff can be substantial, depending on the crops and conditions. According to a September 2019 study published in the journal Nature Sustainability, agrivoltaics systems can improve three important variables that affect plant growth and reproduction: air temperatures, direct sunlight and atmospheric demand for water.

The study’s authors created an agrivoltaics research site at Biosphere 2 in Arizona, where they grew chiltepin peppers, jalapeños and cherry tomatoes under a photovoltaic (PV) array. Throughout the summer growing season, they continuously monitored sunlight levels, air temperature and relative humidity using sensors mounted above the soil surface, as well as soil temperature and moisture at a depth of 5 centimeters (2 inches). As a control, they also set up a traditional planting area near the agrivoltaics site, both of which received equal irrigation rates and were tested under two irrigation schedules, either daily or every other day.

agrivoltaic system at Biosphere 2 in Arizona

A view of the agrivoltaic system at Biosphere 2 in southern Arizona. (Photo: Patrick Murphy/University of Arizona)

Shade from the panels led to cooler daytime temperatures and warmer nighttime temperatures for plants growing below, as well as more moisture available in the air. This affected each crop differently, but all three saw significant benefits.

“We found that many of our food crops do better in the shade of solar panels because they are spared from the direct sun,” said lead author Greg Barron-Gafford, a professor of geography and development at the University of Arizona, in a statement. “In fact, total chiltepin fruit production was three times greater under the PV panels in an agrivoltaic system, and tomato production was twice as great!”

Jalapeños produced a similar amount of fruit in both the agrivoltaic and traditional scenarios, but did so with 65% less transpirational water loss in the agrivoltaic setup.

“At the same time, we found that each irrigation event can support crop growth for days, not just hours, as in current agriculture practices,” Barron-Gafford said. “This finding suggests we could reduce our water use but still maintain levels of food production.” Soil moisture remained about 15% higher in the agrivoltaics system than in the control plot when irrigating every other day.

This echoes other recent research, including a 2018 study published in the journal PLOS One, which tested the environmental effects of solar panels on an unirrigated pasture that often experiences water stress. It found that areas under PV panels were 328% more water-efficient, and also showed a “significant increase in late-season biomass,” with 90% more biomass under solar panels than in other areas.

agrivoltaic system at UMass in South Deerfield, Massachusetts

Machinery can still operate among panels in an agrivoltaic setup, researchers say. (Photo: NREL [CC BY-NC-ND 2.0]/Flickr)

The presence of solar panels might seem like a headache when it’s time to harvest crops, but as Barron-Gafford recently told the Ecological Society of America (ESA), the panels can be arranged in a way that lets farmers continue using much of the same equipment. “We raised the panels so that they were about 3 meters (10 feet) off the ground on the low end so that typical tractors could access the site. This is was the first thing that farmers in the area said would have to be in place for them to consider any kind of adoption of an agrivoltaic system.”

Of course, the details of agrivoltaics vary widely depending on the crops, the local climate and the specific setup of solar panels. It won’t work in every situation, but researchers are busy trying to identify where and how it can work.

A ‘win-win-win’

agrivoltaic system at UMass in South Deerfield, Massachusetts

NREL researcher Jordan Macknick and University of Massachusetts professor Stephen Herbert survey an agrivoltaic test plot at the UMass Crop Animal Research and Education Center. (Photo: NREL [CC BY-NC-ND 2.0]/Flickr)

The potential perks for crops alone might make agrivoltaics worthwhile, not to mention the reduced competition for land and demand for water. But there’s more. For one thing, research has found that an agrivoltaic system can also increase the efficiency of energy production from the solar panels.

Solar panels are inherently sensitive to temperature, becoming less efficient as they warm up. As Barron-Gafford and his colleagues found in their recent study, cultivating crops reduced the temperature of panels overhead.

“Those overheating solar panels are actually cooled down by the fact that the crops underneath are emitting water through their natural process of transpiration — just like misters on the patio of your favorite restaurant,” Barron-Gafford said. “All told, that is a win-win-win in terms of bettering how we grow our food, utilize our precious water resources and produce renewable energy.”

Or maybe it’s a win-win-win-win? While solar panels and crops cool each other off, they might do the same for people working in the fields. Preliminary data suggest human skin temperature can be about 18 degrees Fahrenheit cooler in an agrivoltaics area than in traditional agriculture, according to research from the University of Arizona. “Climate change is already disrupting food production and farm worker health in Arizona,” says agroecologist Gary Nabhan, a co-author of the Nature Sustainability study. “The Southwestern U.S. sees a lot of heat stroke and heat-related death among our farm laborers; this could have a direct impact there, too.”

Generating buzz

solar panels and wildflowers (Tithonia rotundifolia)

The space around solar panels can provide valuable habitat for pollinators, hosting wildflowers like these Mexican sunflowers. (Photo: Michael G. McKinne/Shutterstock)

Aside from all the aforementioned benefits of agrivoltaics — for crops, solar panels, land availability, water supplies and workers — this kind of combination could turn out to be a big deal for bees, too, along with other pollinators.

Insects are responsible for pollinating nearly 75% of all crops grown by humans, and about 80% of all flowering plants, yet they’re now fading from habitats worldwide. The plight of honeybees tends to get more attention, but pollinators of all kinds have been declining for years, largely due to a mix of habitat loss, pesticide exposure, invasive species and disease, among other threats. That includes bumblebees and other native bees — some of which are better at pollinating food crops than domesticated honeybees are — as well as beetles, butterflies, moths and wasps.

Lots of valuable crops depend heavily on insect pollination, including most fruits, nuts, berries and other fresh produce. Foods like almonds, chocolate, coffee and vanilla wouldn’t be available without insect pollinators, according to the Xerces Society for Invertebrate Conservation, and many dairy products would be limited, too, given the large number of cows that feed on pollinator-dependent plants like alfalfa or clover. Even many crops that don’t need insect pollinators — like soy or strawberries, for example — produce higher yields if they’re pollinated by insects.

And that’s the impetus behind a push for more pollinator habitat on solar farms, especially in agricultural areas where pollinators can play the biggest economic role. This is well-established in the U.K., where a solar company began letting beekeepers set up hives at some of its solar farms in 2010, according to CleanTechnica. The idea spread, and the U.K. now has a “long and well-documented success using pollinator habitat on solar sites,” as Minnesota nonprofit Fresh Energy describes it.

monarch butterfly on Mexican sunflower near solar panels

A monarch butterfly rests on a wildflower in front of a solar panel. (Photo: Michael G. McKinne/Shutterstock)

The pairing of pollinators and solar power is increasingly popular in the U.S., too, especially after Minnesota enacted the Pollinator Friendly Solar Act in 2016. That law was the first of its kind in the country, establishing science-based standards for how to incorporate pollinator habitat into solar farms. It has since been followed by similar laws in other states, including MarylandIllinois and Vermont.

Much like crops, wildflowers could help cool off solar panels overhead, while the panels’ shade could help wildflowers thrive in hot, dry places without taxing water supplies. But the main beneficiaries would be bees and other pollinators, who should then pass on their good fortune to nearby farmers.

For a 2018 study published in the journal Environmental Science & Technology, researchers at Argonne National Laboratory looked at 2,800 existing and planned utility-scale solar energy (USSE) facilities in the contiguous U.S., finding “the area around solar panels could provide an ideal location for the plants that attract pollinators.” These areas are often just filled with gravel or turf grass, they noted, which would be easy to replace with native plants like prairie grasses and wildflowers.

And aside from helping pollinators in general — which would likely be wise even if we couldn’t quantify the payoff for humans — the Argonne researchers also looked at how “solar-sited pollinator habitat” might in turn boost local agriculture. Having more pollinators around can increase the productivity of crops, potentially offering farmers a higher yield without using additional resources like water, fertilizer or pesticides.

The researchers found more than 3,500 square kilometers (1,351 square miles, or 865,000 acres) of farmland near existing and planned USSE facilities that could benefit from more pollinator habitat nearby. They looked at three example crops (soybeans, almonds and cranberries) that rely on insect pollinators for their annual crop yield, examining how more solar-sited pollinator habitat might affect them. If all existing and planned solar facilities near these crops included pollinator habitat, and if yields rose by just 1%, crop values could rise by $1.75 million, $4 million and $233,000 for soybeans, almonds and cranberries, respectively, they found.

Enlightening research

peppers and solar panels at agrivoltaic farm

Peppers grow under solar panels at the UMass agrivoltaic test plot. (Photo: NREL [CC BY-NC-ND 2.0]/Flickr)

Farming in the U.S. has become increasingly difficult lately, due to a mix of factors from droughts and floods to the U.S.-China trade war, which has reduced demand for many American crops. As the Wall Street Journal reports, this is leading some farmers to use their land for harvesting solar power instead of food, either by leasing the land to energy companies or by installing their own panels to cut electricity bills.

“There’s been very little profit at the end of the year,” says one Wisconsin corn and soybean farmer, who’s leasing 322 acres to a solar company for $700 per acre annually, according to the WSJ. “Solar becomes a good way to diversify your income.”

Agrivoltaics may not be a quick fix for farmers who are struggling now, but that could change as research reveals more insights, potentially informing government incentives that make it easier to adopt the practice. That’s what many researchers are focusing on now, including Barron-Gafford and his colleagues. They’re working with the U.S. Energy Department’s National Renewable Energy Lab to assess the viability of agrivoltaics beyond the U.S. Southwest, and to examine how regional policies might encourage more novel synergies between agriculture and clean energy.

Still, farmers and solar companies don’t necessarily need to wait for more research to capitalize on what we already know. To make money from agrivoltaics right away, Barron-Gafford tells the ESA, it’s mostly just a matter of elevating the masts that hold up the solar panels. “That is part of what makes this current work so exciting,” he says. “A small change in planning can yield a ton of great benefits!”

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Boston Hospital Rooftop Farm

Three years ago, the hospital launched a rooftop farm to grow fresh produce for the pantry. The farm has produced 6,000 pounds of food a year, with 3,500 pounds slated for the pantry. The rest of its produce goes to the hospital’s cafeteria, patients, a teaching kitchen and an in-house portable farmers market.

The hospital joined a handful of medical facilities across the country that have started growing food on their roofs. The initiative is the first hospital-based farm in Massachusetts and the largest rooftop farm in Boston. The facility’s 2,658-square-foot garden houses more than 25 crops, organically grown in a milk crate system.

“Food is medicine. That’s why we’re doing what we’re doing,” says David Maffeo, the hospital’s senior director of support services. “Most urban environments are food deserts. It’s hard to get locally grown food and I think it’s something that we owe to our patients and our community.”

Lindsay Allen, a farmer who has been managing the rooftop oasis since its inception, says her farm’s produce is being used for preventative care as well as in reactive care. She says 72 percent of the hospital’s patients are considered underserved, and likely don’t have access to healthy, local organic food.

What people put in their bodies has a direct link to their health she says, adding that hospitals have a responsibility to give their patients better food.

In addition to running the farm, Allen teaches a number of farming workshops to educate patients, employees and their families on how to grow their own food. The hospital’s teaching kitchen employs a number of food technicians and dieticians who offer their expertise to patients on how they can make meals with the local produce they’re given.

This is part of the medical center’s objective to not only give patients good food, but also provide them the tools to lead a healthy life.

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Joe Neguse Service Town Hall

U.S. Congressman Joe Neguse, Rep. Matt Gray, and Councilwoman Guyleen Castriotta had a service town hall, where residents worked with our elected officials to help stock items for Broomfield FISH. The second half of the gathering was a brief update from the federal, state, and local governments, followed by a Q&A. 

Broomfield FISH is a vital community resource, providing food and financial assistance to Broomfield County residents in need. Services include a thriving food pantry, transportation assistance, rent and utility assistance, and other services. Serving approximately 6,000 people each year.

Taskforce Denver Homeless Block Party

I had the privilege of taking pictures at the Taskforce Denver Homeless Back to School Block Party for individuals and families experiencing homelessness or near homelessness. The services that were provided included free veterinary care, haircuts, medical clinic, laundry services, community resources, school supplies, food, SNAP, employment services, and more. 

Human dignity is so easily taken away from us. So many of us, at one point or another struggle. As an affluent community, there is a social and moral responsibility to assist those in our community that are struggling. Small gestures of kindness and caring go a long way in momentary restoration of our human dignity. I found the experiences of the day to be profound, moving, and at moments emotionally overwhelming.

Broomfield has no homeless program. None. We use the resources of Boulder and Denver when people who are experiencing homelessness need shelter or temporary housing. We can change that.

#taskforcedenverhomeless
#dsedenver

Urban Rooftop Farm

Paris is opening the world’s largest urban rooftop farm.

Europe’s most densely populated city is growing. But we’re not talking about people here: it’s growing fruit and vegetables.

At the edge of the French capital, an urban farm is being built that will supply residents with a tonne of food a day. Currently being renovated, the Paris Expo Porte de Versailles is set to become home to the world’s largest urban rooftop farm next year.

The 14,000 m² of space – equivalent to about two football pitches – will be loaded with around 30 different types of plant. They’ll be grown in columns without soil and fed with nutrient-rich solutions and rainwater. This aeroponic method uses little water and means a large number of plants can be grown in a small area.

Visitors will be able to purchase produce as well as sample it in the rooftop restaurant. The farm will also host educational tours and various events. And citizens will also be able to rent space to grow their own crops.

Urban farming is a growing trend – in fact Agripolis, the company behind the farm, already runs other rooftop farms around France. Founder Pascal Hardy wants more urban spaces to take up the mantle: “Our vision is a city in which flat roofs and abandoned surfaces are covered with these new growing systems. Each will contribute directly to feeding urban residents who today represent the bulk of the world’s population,” he told The Guardian newspaper.

Since being elected in 2014, the city’s Mayor Anne Hidalgo has been on a mission to make Paris a greener city. The French government’s Parisculteurs initiative aims to cover 100 hectares of the city’s rooftops, walls and urban spaces with plants by 2020. One-third of this space will be dedicated to urban agriculture.

All images by Agripolis
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Stamp Out Hunger 2019

Broomfield FISH is a vital community resource, providing food and financial assistance to Broomfield County residents in need. Services include a thriving food pantry, transportation assistance, rent and utility assistance, and other services. Serving approximately 6,000 people each year.

Every second Saturday in May, letter carriers in more than 10,000 cities and towns across America collect the goodness and compassion of their postal customers, who participate in the NALC Stamp Out Hunger National Food Drive — the largest one-day food drive in the nation.

Led by letter carriers represented by the National Association of Letter Carriers (AFL-CIO), with help from rural letter carriers, other postal employees and other volunteers, the drive has delivered more than one billion pounds of food the past 25 years.

In Broomfield, 48% of the people FISH helps are children under the age of 18. The cost of living in Broomfield has skyrocketed to the point where FISH families are spending 80% of their total income just on housing.  Many seniors on a fixed income have to choose between purchasing needed medicines and food.