Look What’s Cropping Up — Agrivoltaics. But Will They Work in Cities?
There’s a new symbiotic relationship growing between farming and renewable energy.
It’s a very simple diagram that is being fuelled by climate change: food supply is at risk and we need more arable land, but we also need more land for renewable energy installations. If we overlay solar photovoltaics on farming land we get Agrivoltaics, and it could be the city adaptation we desperately need.
We’ll often hear from the sceptics that climate change will help plants grow more because there’s more CO2 in the atmosphere. The fact is that even if this does help some plant types, their food productivity still decreases and the nutritional value of the produce falls. Of more concern is the fact that many crops are at risk of failure once it gets too hot.
Climate change will pose significant risks to global food supply.
“… If climate changes reduce crop yields, international food prices and the number of food-insecure people are expected to increase globally… there are large numbers of households that would be especially vulnerable to a loss of food access if food prices were to increase” (Mbow 2019)
It might seem counterintuitive, but too much sunlight for food-growing plants is also not a good thing — a little shade during the hottest parts of the day can help, even more so under a heating climate.
The situation hasn’t been lost on some researchers, and we’re now finally beginning to see some valuable data emerging around the benefits of Agrivoltaics — the combination of solar photovoltaics (PV) and agriculture. Says Chad Higgins, associate professor in Oregon State’s College of Agricultural Sciences,
“Agrivoltaics provide a rare chance for true synergy: more food, more energy, lower water demand, lower carbon emissions, and more prosperous rural communities,”
Agrivoltaics are an emerging industry, but some countries are already leading the charge. Japan is at the forefront with some 230MW of solar installed over 330 hectares of land as at 2017, followed by an array of variations on the theme in the US, Germany, UK, Austria and the Netherlands.
Australia has had its own bespoke version emerging where farmers and graziers are installing solar panels in their fields for extra income and using their sheep to keep the grass down (around 30% cheaper than mechanical mowing). There’s a great primer on this approach here by Nick Armentrout of Agrivoltaic Solutions in the US, presented recently at the Sustainable Futures Conference (10 minute presentation).
It’s almost a symbiotic relationship in that the cooler ground beneath the PV panels helps improve their energy output — panels that get too hot start to lose efficiency. A new study from Australia has shown that solar panels over a green roof are on average 3.63% more efficient, which is significant. If you want to dive into the detailed Agrivoltaic science then I’d highly recommend this new paper published by MPDI, which assesses the rapidly growing array (like that one?) of Agrivoltaic systems and approaches.
As a side note, I’m really looking out for some examples of Agrivoltaic farming using regenerative agriculture principles — now that would be exciting!
What I’m really curious about though is this;
“Could we overlay Agrivoltaics onto our urban roofscapes as a city adaptation to climate change, not only creating renewable energy and food, but also providing green open space for people?”
We’re already seeing amazing growth in the rooftop greenhouse space (more on that another time), but I’m yet to find a good example of Agrivoltaics finding their way onto urban roofscapes. There would be a raft of benefits.
- The PVs and gardens shade the building, helping reduce climate-driven heat risk and reducing energy consumption for cooling
- Food production, whether that be for larger scale commercial growing or smaller scale community-focused growing
- Provides green and shaded open space in our cities and is adaptable to suit the building use, whether that be educational purposes for a school or university, community space for apartment dwellers, social space for office workers, or fresh food and clean energy for a hospital
- Protected from animals — mostly. An elevated garden will in many cases be better protected from nocturnal critters
- Can create jobs, maintaining the solar array, tending the gardens or farms, picking, packing, selling etc. (watch this space for start-ups!)
- Can also be configured to harvest rainwater and control flooding risk
- Could be suited to the use of timber structures rather than steel. I have a little concern with the perverse outcome of this system driving further emissions through the use of ‘non-green’ steel, although the net carbon benefit is yet to be studied
- And of course the renewable energy generation. The output wouldn’t be as high compared to a complete PV array without any other uses, but if we look at the latest data from the agricultural sector we can still see a payback.
This certainly hits the sweet spot in combining adaptation, carbon mitigation and community resilience. This is a new field in the sustainability narrative and I’m absolutely excited about where this might go in adapting our cities for a hotter climate. Watch this space.
