Science

This Maine Farm is Harvesting the Sun’s Power While it Picks the Blueberries


Carey: I’m standing on a hillside. All around me are short shrubs with purple stems and waxy leaves. A brisk December wind moves through the lowbush blueberry bushes. But among the plants sits an odd sight… row after row of solar panels. 

You’ve heard of solar farms. And you’ve heard of blueberry farms. But a solar-blueberry farm? Probably not–this is the first farm to combine the two sun harvesters. And that combo could be vital as the Earth’s climate changes. 

Reporting from the coast of Maine, I’m Teresa Carey, and this is Scientific American’s 60-Second Science. 

[Walking sounds]

Sweetland: In this area we’ve got the solar panels in among the blueberry plants. And up here, it’s more open. We still have stone walls there and some rock piles, but most of the land is just opened for the blueberry production.

Carey: When it comes to raising blueberries, Paul Sweetland has seen it all. 

Sweetland: I’ve been doing blueberries basically my whole life. It’s been amazing to see how we’ve changed our cultural practices over time. 

Carey: Sweetland farms Maine’s lowbush blueberries – the tiny wild berries the state is famous for. In fact, Maine is the only state in the country where wild blueberries are commercially harvested. You can buy them in grocery stores from Hawaii, to Texas, to Alaska. They’re about half the size of conventional blueberries, but with twice the antioxidants and even more flavor. 

Sweetland: Way back, probably 30 years ago, the pruning method was burning. So we used to come in and burn the whole field. Originally, we all used hand rakes. Now there are not so many hand rakes and because we won’t be able to use some in here we have the tractor harvesters. There’s still a lot of blueberries ready to rake by the hand but there’s fewer people willing to work that hard.

Carey: Sweetland has tried every farming technique. He knows what works best. But for the 2022 harvest, things are going to be different. Last summer, David Dickey, the farm’s owner, partnered with BlueWave Solar to build an array of nearly 11,000 solar panels directly over top of his farm. They cover 12 of the 30 total acres. 

Sweetland: It’s just an interesting new challenge. Now that construction’s done, now we can come in and do what needs to be done for the blueberries. Basically, what we’re going to do is work between the rows. 

Carey: This unique farm is just one example of a burgeoning industry known as agrivoltaics — placing solar panels on productive agricultural land. Pilot farms like this are springing up all over the country, hoping to show how collecting sunlight on farms might improve agriculture and offer farmers a second source of income. But, it is still too early to know how well it will work. 

Calderwood: We’re trying to figure out exactly what it would take to shift from growing in a field landscape where there’s no obstruction, it’s just a big field of blueberries. 

Carey: Lily Calderwood is the University of Maine Extension’s expert in wild blueberries. 

Calderwood: And then in this situation, there are rows of solar panels. So it’s really shifting from a field crop to a row crop, which is a big shift to make.

Carey: Shading the plants and conserving water may potentially improve crop productivity. But no one knows for sure because it’s never been done before. Calderwood is determined to find out. 

She is heading a four-year research project, funded for the first year by Blue Wave Solar, to see if blueberries can thrive in the shade of a solar array. 

Calderwood: This past year was the prune year, so no crop was harvested. And then next year, there will be a crop harvested. And the following year will be another prune year, then the fourth year would be another crop year. So ideally, we would have two crop seasons of data to collect, and a total of four years.

Carey: Calderwood is monitoring soil quality, moisture, and crop productivity at the farm. She hopes to create a new set of farming rules for power + produce marriage. 

Alan Knapp, an ecologist at Colorado State University, has already seen successful agrivoltaics projects — in Colorado grasslands used for cattle grazing. 

Knapp: The first barrier to overcome is can it be done biologically? Can it be done physically? Can it be done? And then the next barrier would be adoption? How do you convince people who own the lands to be willing to change the way they’ve done things in the past, and integrate, for example, energy generation?

Carey: Luckily for Sweetland, since blueberries aren’t grazing animals, bushes can’t bump up against and break solar panels. 

And recently climatic unpredictability is already a motivating factor. In 2020, Maine blueberry yields dropped by 50% because of frosts in May and June, followed by a statewide drought. For this farm, a second, reliable income stream could really come in handy. 

But not everyone is on board. 

Calderwood: Some people feel that farmland should remain farmland. And why would we not put the solar panels on a building over a parking lot space that’s already industrial?

Carey: But solar panels require   a lot of area to generate power and effectively replace fossil fuels. There must be many panels, tightly packed together to maximize energy output. They also require unrestricted access to the sun, which is not always possible in a populated area.

Calderwood: Where rare we going to put all this energy? There’s a lot of interest and motivation behind finding ways to have clean energy in Maine. So farmers and blueberry farmers have a place in that space. We’re just trying to figure out where that might be.

Carey: Alan Knapp in Colorado would like to see more farmers give this approach a try. He says that if it works, it could be an important strategy to help the U.S. meet renewable energy goals.

Knapp: You can use the scorched earth approach, where you just put the solar panels in as dense as you can to optimize energy generation and usage. The ecosystem underneath is not going to be valuable. Or you can try   and integrate the two to maintain aspects of both. And I really think that’s the future. We have the ability to co-locate energy generation and natural ecosystem services.

[Walking sounds]

Carey: Over the winter, Sweetland will check on the blueberry bushes from time to time, but the real work will begin this spring when he harvests the first crop grown under solar panels. When asked if he thinks the blueberries will thrive or even survive with the solar panels, Sweetland says…

Sweetland: I’m not sure where I stand. Time will tell. (laughs)

Thanks for listening. For Scientific American’s 60-Second Science, I’m Teresa Carey.


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