Austin Kay, Swansea University
As the world races to meet net-zero targets, emissions from all industrial sectors must be reduced more urgently than ever. Agriculture is an important area of focus as it contributes up to 22% of global greenhouse gas emissions – almost as much as the energy sector.
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One approach to decarbonising the agricultural sector is agrivoltaics. It involves integrating solar panels – or photovoltaics (PVs) – into fields of crops, greenhouses and livestock areas, which can help farmers reduce their carbon footprint while continuing to produce food.
Agrivoltaics can also mitigate one of the main criticisms often made of solar power – that solar farms “waste” vast tracts of agricultural land that could otherwise be used for food production. In reality, solar farms currently occupy only 0.15% of the UK’s total land – not much compared to its 70% agricultural land.
The simplest example of an agrivoltaic system would be conventional, crystalline silicon PVs (the market-leading type of solar panels), installed in fields alongside livestock. This method of farm diversification has become increasingly popular in recent years for three main reasons.
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First, it enhances biodiversity as the fields are not seeing a regular crop rotation, being monocultured, or being harvested for silage. Second, it increases production as livestock benefit from the shade and the healthier pasture growth.
Finally, the solar farm has reduced maintenance costs because livestock can keep the grass short. All this is achieved while the solar panels provide locally-generated, clean energy.
But if they’re not set up properly, agrivoltaics may cause problems. One of the most important challenges is balancing the need for sunlight between crops and solar panels. Crops need light to grow, and if solar panels block too much sunlight, they can negatively impact crop yields.
This issue varies from place to place. In countries with fewer sunny days like the UK, the panels need to let more sunlight through. But in places like Spain or Italy, some shade can actually help crops by reducing the stress of intense heat during summer months. Finding the right balance is tricky, as it depends on local conditions, the type of crop, and even the needs of pollinators like bees.
The complexity deepens when we consider the type of PV material used. Traditional solar panels aren’t always suitable because they often block the wavelengths (colours) of light needed by plants.
This is where newer materials, like organic semiconductors and perovskites, are ideal as they can be customised to let crops get the light they need while still generating energy. Unlike traditional inorganic semiconductors, which are essentially crystals of metal and metalloid atoms, organic semiconductors are molecules mainly made of carbon and hydrogen. Perovskites, meanwhile, are like a hybrid of the two.
But there are thousands of combinations of these materials to choose from, with scientific literature containing a plethora of options. Figuring out which one works best can be a daunting task.
This is where computational tools can make a big difference. Instead of testing each material in real-world conditions – which would take years and be incredibly expensive – researchers can use simulations to predict their performance. These models can help identify the best materials for specific crops and climates, saving both time and resources.
The tool
We have developed an open-source tool that helps compare various PV materials, making it easier to identify the best options for agrivoltaics. Our tool uses geographical data and realistic simulations of how different PV materials perform.
It considers how light travels through these materials and reflects off them, as well as other important performance measures like voltage and power output. The tool can also take lab-based measurements of PV materials and apply them to real-world scenarios.
Using this tool, we simulated how much power different PV materials could generate per square metre over the course of a year, across various regions. And we calculated how much light passed through these materials to ensure it was enough for crops to thrive.
By running these simulations for multiple materials, we could identify the most suitable options for specific crops and climates.
Tools like ours could play a critical role in decarbonising the agricultural sector by guiding the design of agrivoltaic systems. Future research could combine these simulations with economic and environmental impact analyses. This would help us understand how much energy we can expect from a solar panel over its lifetime compared to the resources and costs involved in producing it.
Ultimately, our tool could help researchers and policymakers in selecting the most efficient, cost-effective and eco-friendly ways to decarbonise agriculture and move us closer to achieving global net-zero emissions.
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Austin Kay, Researcher in Sustainable Advanced Materials, Centre for Integrative Semiconductor Materials, Swansea University
This article is republished from The Conversation under a Creative Commons license. Read the original article.