Simulations in agri-voltaics suggest Canadian farms could one day double as giant solar batteries

There's a potential gold rush for Canadian farmers in the near-future as governments make a push to phase out fossil fuels in favour of renewable energy.

Joshua Pearce has been studying the potential of agri-voltaics, a term that blends the words agriculture and voltaic cells and would see farms lined with silicon and steel solar panels interspersed by crops growing in their shade. 

Pearce is an engineering professor at Western University who studies the potential of photo volatic cells being used in agriculture. He's also the John M. Thompson Chair in Information Technology and Innovation at the school. 

He spoke with guest host Colin Butler on CBC Radio One's Afternoon Drive on Wednesday to talk about unlocking potential of Canada's farms by turning them into giant solar batteries. 

Q: How does agri-voltaic farming work?

Joshua Pearce (JP): What you're doing is, instead of just building a solar farm where you're trying to maximize the amount of electricity you can squeeze out of an acre, you're trying to set up the solar panels in a way that will benefit the crops that grow either next to them or underneath and there's many different types of agri-volatics depending on whether you're growing something like corn, where the systems would be either elevated far above the crops themselves or held in vertical rows next to them like a fence, or even tracking units that would move out of the WAY. 

Q: What kind of crops grow better in the shade?

JP: Almost everything you can think of. So yes, it's completely non-intuitive that you would actually get higher agricultural yields when you shade something, but it turns out there's an optimal amount of sunlight that a plant needs and oftentimes they're getting too much. So particularly in any kind of area where you're starved for water, agri-voltaics is a massive benefit.

So for example, there's been a study done in the US where the pepper crop increased by 250 per cent, mostly because you're getting this kind of nice microclimate underneath the panels that's a little cooler. It retains water and so the crops grow better, but they've shown agricultural increase yields on obvious things like lettuce and spinach where they kind of, you know, you're getting more growth in the leaves to try to capture more sunlight.

Stuff like potatoes or pasture, grass or spinach, tomatoes, wheat, corn, Peppers, broccoli, basil, like many, many of the crops that we grow here in Canada have already been studied somewhere at least throughout the world, whether that's in Europe or Japan or in China.

Q: What other differences do these solar panels make on a farm?

JP: From a farmer's perspective, they represent a massive potential increase in revenue. The amount of electricity, the value of that electricity per acre is much larger than the crop that you're tending to grow on it.

Even if the farmer you know wasn't independently wealthy and able to finance the whole thing and him or herself, they're able to generate revenue by sort of leasing part of the land and then they personally get also the increase in the crop yield and not all of these crop yields are giant.

Some of the weak ones were only three or four per cent, but that's still three or four per cent more money than you'd get with not having a solar panel there to protect the crops.

So they, you know, they protect them from too much sun, but also things like hail or too much wind that can prevent erosion and one of the most interesting studies

I've seen is in China, they're trying to reverse desertification where they're putting solar panels out over the desert, kind of creating these little shaded microenvironments and starting to see things like grass grow there. 

Q: You said that they could increase their revenue, the farmers. How much revenue?

JP: It can be one to two orders of magnitude more than what they're getting per acre depending on what their crop is. But that does mean they have to put in the capital like if they want all the money, they also put in all the capital to do the investment. And putting on solar farm, solar to put out a solar farm is much more expensive than say, 'I need a bunch of potatoes.' So it's a long-term, you know, 20-year investment at minimum. The solar panels have warranties of 20 years. 

Q: Is that the catch, the investment?

JP: I think there's two catches. So for Canadians, there's isn't a huge amount of literature looking at what can be done here. I've done some simulation models and it looks very, very promising. But the US, Europe and Asia are all substantially ahead of Canada right now in terms of doing actual experiments.

At Western University, we're setting up experiments to do this, so to hopefully reduce some of the risk for our farmers and to try to find the optimal designs for the types of crops that we grow here.

Q: Is there a chance this could drive up the cost if energy companies, for instance, are willing to pay big bucks to rent land instead of, say, a small-scale farmer?

JP: Well, that certainly could happen, but the way I'm seeing this more likely to go is that you already have farmers are already farming, they will continue to farm and then in the solar industry we need to find a way to work with them at around the way that they're doing their current harvesting and farming practices.

What is likely to happen in the near future is that any farmer that's been able to invest or have someone else invest in agri-voltaics on their farm will be producing more food and that food should have a lower total cost. And the farmer will have sort of an insurance policy against, say, a bad growth year because they'll have some other source of revenue from the sale of the electricity from the solar array.

In most cases, the current ownership of the land and the way that the land is farmed will remain almost identical, and it's just that we and the kind of solar technical community need to find ways to do acrobatic arrays that match with the way that we're currently.

Q: How much does it reduce those two things for the average farm according to the models you've run?

JP: So if your goal is just to eliminate greenhouse gas emissions from the farm, that's dead easy. It takes a tiny little fraction of the farmland. In fact, you could probably just build a solar fence around your current farm and that would more than enough to power, you know, the farmhouse and the processing and the transportation, the tractors and that kind of thing.

What I'm talking about here is actually turning the farm itself into a giant energy source and to put some of these numbers in perspective, if we only converted even one per cent of agricultural land to agri-voltaics in Canada.

That would eliminate all fossil fuel burning for use of electricity and if we're slightly more aggressive than that, say that we want to install heat pumps in our homes to eliminate the need to burn natural gas to heat them, and that we had to add another percent or two.

If we wanted to eliminate all fossil fuels from transportation, again, it's around one per cent. So roughly four per cent of agricultural land converted to agri-voltaics would provide all of our energy needs and completely eliminate the need for burning fossil fuel.

So there's giant potential, I mean Canada truly is an agricultural powerhouse and only converting a fraction will free up a huge amount of energy. In most cases, farmers would be exporting giant amounts, like potentially millions of dollars of electricity from their farms.