Imagine a future where families can go to the roof to collect food for dinner. A daydream.
The main obstacle to achieving this dream is, essentially, economic. What if we could have economic systems where food crops thrive on most green roofs, while also harvesting energy from the sun?
Agrivoltaico mon amour
Green roof farming is a promising area of research involving the co-location of both food and energy production. A solution that is fully part of the concept of "agrivoltaic", the study of crops grown near or under solar installations. I also talked about it in this article.
As mentioned, it is an expensive solution today: but with the growing attention to food security and the vulnerability of food supply chains (the pandemic has opened a glimpse into the future) the price may be worth it.
Adding resilience to the urban space can be an option. Especially when you have two systems (food and energy), with valuable and renewable products on the same space, which was previously unused.
Mutual assistance of green roofs
Both systems and solar panels benefit greatly from being placed together on green roofs. A interesting research by Legambiente last October showed that plants under and around solar panels thrive more than those found in fully exposed areas. The reason? Temperature variability is less near solar panels in both summer and winter. Plant stressors such as wind and bright sunlight are also reduced. In environments such as green roofs, reducing these stressors helps to conserve more water and thus feed plants and vegetables more consistently.
The performance of solar panels, on the other hand, increases because green roof systems provide evaporative cooling and improve the efficiency of the panels' energy production, even in an environment that can reach high temperatures such as those of a roof.
In summary: a sector that needs more research and funding, to get out of the narrow bed of a few enthusiasts and university campuses, which have already shown a more than interesting perspective for the future of this solution. More green roofs are good for everything: the environment, energy and nutrition.