Technology for the Anthropocene…
How agrivoltaics model permaculture
Photo source: I don’t know where these photos originally came from. A reverse image search on Firefox reveals multiple sources. My use is media comment for purposes of review and education in compliance the Australian Copyright Act.
A product of the rise in renewable energy adoption, the bulk of which has occurred over the past 30 years as the world began its shift away from fossil fuels towards renewables, the first iteration of agrivoltaics were the large wind turbines amid farm fields. Large scale photovoltaic systems on agricultural land followed.
The photos can be interpreted in terms of the design principles of the permaculture design system. Although it is unlikely these were deliberately applied, nonetheless they show how the principles could be applied within a permaculture design context combining renewable energy and farming.
Agrivoltaics is not technofantasy. It exists. Agrivoltaic installations are now becoming widespread. They represent the type of thinking our civilisation needs to cope with emerging climatic , environmental and social challenges we will encounter in the Anthropocene, the time now unfolding when the works of humanity dominated the Earth system and become something akin to a force of nature in their impact.
The principles of permaculture design were devised as guidance by the permaculture design system’s founders, Bill Mollison and David Holmgren. In 2002, David published a new exploration of them in his book, Permaculture: Principles and Pathways Beyond Sustainability.
Permaculture practitioners accept David’s principles although they sometimes modify them. David’s are the dominant set of principles today. They replicate and are compatible with the earlier, more-pithily-stated set commonly known as ‘Bill Mollison’s principles’.
The principles of permaculture serve as thinking tools when we come to design something. Not all principles are applicable in all circumstances. The notion is that in making use of them and increasing the beneficial connections between design components we can design and build systems and installations that are productive and resilient. In agrivoltaics, the beneficial connection is between food and energy production on the same land unit.
Principles are selected as relevant to what we design. The non-selective element in permaculture is its ethics of meeting the needs of the Earth’s biogeographic systems needed for its continuity, and the needs of the people who inhabit the planet through the distributionist ethic of sharing what is spare after meeting our own needs. These are catchily-summarised as Earthcare, Peoplecare and Fairshare.
Interpreting agrivoltaics in the language of permaculture
Although not the work of permaculture designers or technologists, the installation demonstrates a number of permaculture design principles. Let’s take a look at them.
Design From Patterns to Details
The first principle we see is about designing within the climatic, ecological, economic and social context within which our project exists. The design becomes a subset of this bigger picture and in doing so increases the potential to make more of the productive links with those contexts and increasing its resilience.
David calls this principle Design From Patterns to Details. In the photo, the pattern is a climate with enough year-round sunshine to generate electrical energy and grow a crop, and a geographical location suited to harnessing solar energy. The invisible pattern is the increasing use of renewable energy in the economy which makes agrivoltaics viable. That’s an economic, social and political pattern.
Harvest and store renewable resources where they occur
The principle is applicable in-part. The electrical energy generated by the solar array might be used directly as it is distributed through the grid or moved to a battery storage facility some distance away if some of it is not used on site — a grid-interactive system. The same goes for the food the farm produces. Most of that would go to more-distant processors and retailers.
Work with nature rather than against
An early principle of permaculture, both the crop and the photovoltaic array work by converting nature’s solar energy into other forms of energy. This demonstrates not another principle, but a law of physics — the First law of Thermodynamics, the law of the conservation of energy:
…energy can be changed from one form to another, but it cannot be created or destroyed.
As the Law says, the solar array does not create energy. It converts solar energy in the form of photons produced in the thermonuclear reaction of the sun into electrical energy. The crop converts solar energy and nutrients from the soil into the chemical energy of food.
The underestimated value of photons
The solar array works at the atomic scale of the ‘photoelectric effect’ described by Nineteenth Century French scientist, Edmund Bequerel, and early Twentieth Century physicist, Albert Einstein. The effect describes the property of some materials, silicon is commonly used in solar panels, to release electrons when electromagnetic energy in the form of light falls on them, causing the outer electrons to break free of their atomic bonds and move in one direction to create a flow of electrical current. This becomes available to do work, as electricity.
The crop makes use of photochemical arrays to harvest incoming solar energy, photons, in the chloroplasts in plant cells containing the photosynthetic pigment, chlorophyll. This produces a flow of electrons used to produce the carbohydrate, glucose, from carbon dioxide and water and produce oxygen release to the atmosphere.
Obtain a yield
If we get something from a crop we plant or a technology we install, we obtain a yield from it. In other words it does work or creates a product useful to people. The yield of a crop is food. The yield of a solar energy array is electricity. The yield of hiring out your skill is financial income. The yield of setting up a food swap is the biological energy obtained by someone eating your excess produce rather than letting it rot, although you could harvest less energy from the discarded food by composting, another chemical conversion process. You get less energy thanks to the Second Law of Thermodynamics which points out that energy is lost to systems as it is transformed.
Over time, the energy produced by the photovoltaic array, its yield, will be greater than the energy costs of manufacturing, installing and maintaining it. The chemical energy yield of successive crops will be greater than that embodied in maintaining them. This is the basis of regenerative systems.
Use and value renewable resources and services
The agrivoltaic system in the photo combines horticulture and technology, biology and physics, to obtain a mixed yield by using the renewable resources of sunlight, soil and human knowledge.
The idea of ‘valuing’ a renewable resource as stated in the principle is vague. Value it psychologically and morally by knowing that our making use of it is a good thing? Value it economically for its potential to yield income or reduce expenditure? Value it scientifically for obtaining a yield via applying scientific knowledge of physics and agriculture? Maybe all of these.
Design for multifunction
In the photos, the combination of food production and energy production on the same unit of land constitiutes the multifunction because it derives two yields from the same land unit. It applies Bill Mollison’s principle: each element performs many functions.
Permaculture is information and imagination-intensive
Another of Bill’s aphorisms, information gained through observation, measurement and scientific research is applied to cropping and energy production technology on the photos. The agrivoltaic system synthesises two branches of science: agricultural science and physics. Both of these are the results of generations of scientists and farmers applying curiosity and imagination.
How do agrivoltaics fit with Future Scenarios?
The agrivoltaic system exemplified in one of the photos shows a grapes-below-panels installation. It is not the only one. Other have planted vegetables or introduced grazing-below-panels and around wind turbines.
Referring to David Holmgren’s work, agrivoltaic systems fit well the Green Tech future he envisions in his 2009 book, Future scenarios: how communities can adapt to peak oil and climate change.
They would also fit his Earth Steward model because in the ruralised population distribution David envisions there would be a need for distributed energy production, although for less of it thanks to reduced demand due to household and institutional behavioural change and more-efficient technologies and design.
Agrivoltaic systems could contribute to regional energy internets where smaller renewable, distributed energy production systems feed into large-scale batteries and are linked into a regional grid for sharing, with the energy surplus to regional needs sent to the national grid. Such a system could contribute to the creation of regional economies based on regional energy markets, preferably structured as not-for-profit social enterprise or energy co-operatives.
Agrivoltaics is part of a new technology of the Anthropocene, a solution providing two basic human needs.
Combining Solar Panels With Agriculture Makes Land More Productive
Solar farms, land use and the rise of solar sharing
What is agrivoltaics?
Permaculture: Principles and Pathways Beyond Sustainability; 2002, David Holmgren; Holmgren Design Services, Australia. ISBN 9780994392848.
Future scenarios: how communities can adapt to peak oil and climate change
2009, David Holmgren; Chelsea Green UK. ISBN-10: 1900322501.