Introduction
According to World Food Programme (2023), over 345 million in 82 countries face the risk of food insecurity, tossing people into steep global hunger partly due to the climate crisis and the post-impact COVID-19 pandemic. There is an urgent need to meet food demand to avert this catastrophic hunger. Additionally, using renewable energy can help prevent the effects of climate change as it is generated from clean, non-polluting sources. Renewable energy technologies like wind, solar, hydro, biomass, and geothermal are some of the technologies deployed for power generation in place of fossil fuels. Solar Photovoltaic (PV) generation is a predominantly adopted renewable energy technology in Nigeria as it is easy to maintain and cost-effective. Based on application, it can be mounted on the roof, poles, or ground. The ground-mounted PV modules take up a large area of land space. It limits the possibilities of other economic opportunities that could be derived in such land space, particularly in areas where there is competition between solar PV and agriculture. However, this leaves us questioning whether crop and solar panel farms can be juxtaposed.
Concept
Agrophotovoltaics or Agrivoltaics describes the complementarity of agricultural practices and solar PV energy generation. This concept was pioneered in 1981 by a scientist from Freiburg, Armin Zastrow, and German Physicist Adolf Goetzberger from German Institute Fraunhofer ISE as a solution for farmers to install energy clean energy without limiting land use. However, the first research pilot project was carried out in 2004 by Akira Nagashima in Japan. This system has been adopted in some other countries, including Switzerland, China, Belgium, Japan, France, Kenya, and Austria. In February 2022, a collaboration between the African Centre for Technology Studies, the Centre for Research in Energy and Energy Conservation, the Stockholm Environment Institute, the University of Sheffield, York, the University of Teesside, UK, and World Agroforestry, opened the first Agrivoltaics system in East Africa located Insinya, Kenya to foster the development of the technology and experiment how users experience can foster the roll-out of the systems across East Africa. Since then, Agrivoltaics has been evolving. Research and experimentation efforts on designs that ensure effective and efficient energy generation and crop yield in implementation are ongoing, particularly considering the placement of solar modules as shades. Sunlight is vital for photosynthesis and necessary for plant growth. However, exposure that exceeds the light saturation point can adversely affect the plant. Therefore, Agrivoltaics systems reduce the lighting available for the crops by acting as shades. Based on research, the impact of shading on crop production output varies based on weather conditions and is not easy to predict. Some crops that thrive in shade conditions include but are not limited to; berries, herbs, soybeans, groundnuts, potatoes, tomatoes, and lettuce.
According to Shiva Gorjian and other authors in their study on “Progress and Challenges of Crop Production and Electricity Generation in Agrivoltaics Systems Using Semi-transparent Photovoltaic Technology”, Agrivoltaics systems are categorized using a variety of metrics. Some of these metrics are (A). Based on the type of application (arable farming, pastoral farming, aquaculture, and horticulture). (B). Based on the movement of modules (fixed, one-axis, or two-axis tracking) (C). Based on the type of system (closed or open). (D) Based on the type of structure (Interspaced PV or overhead PV).
Based on structure type, the interspaced PV structure provides sufficient spacing between rows of PV array to support agricultural production. It is suitable for arable and pastoral farming. In this structure, the use of machinery is limited to the row spaces, and there is low land use efficiency. The vertical PV structure is a form of the interspaced PV structure using bifacial modules. The row height often determines the available row space for agricultural productivity. On the other hand, the overhead PV structure places PV modules 2 to 6 meters above the ground, allowing for plant cultivation beneath and the use of machinery without obstructions. It has a higher land use efficiency compared to interspaced PV structures. It opens up the possibility of incorporating irrigation management and rainwater harvesting. However, due to the complexity of the mounting structure, it is more expensive. Overhead PV is suitable for horticulture, arable farming, and greenhouse structures.
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Benefits and Drawbacks
According to research on “Sustainable Farm Agrivoltaics” by Oregon State University, Agrivoltaics is a win-win-win relationship between the three most foundational elements of modern life: food, water, and energy. Agrivoltaics presents a promising pathway for sustainable agriculture and renewable energy symbiotic coexistence. It caters to the maximum productivity of the land area. It also mitigates the impact of climate change by generating energy from the sun using solar PV technology, which is one way to reduce greenhouse emissions. The shading from the modules, especially in arid regions, reduces the soil’s water evaporation rate, reducing demand for irrigation and reducing the rate of soil degradation by creating a conducive microclimate. Shading protects certain crops from heat stress and improves overall crop output. Also, to overcome the adverse effects of shadow, plants respond by increasing their leaf area in shade conditions making Agrivoltaics a desirable option for vegetable cultivars like lettuces because the leaves are the primary farm produce. In dry regions, this technology offers crops opportunities to grow, thereby contributing as carbon sinks to atmospheric carbon reductions. Deploying Agrivoltaics in rural and agrarian communities could foster collaboration, create employment opportunities and generate a thriving economic value chain from electricity credit and agricultural produce sales. This phenomenon allows for the cheap generation of energy.
Also, using land for dual purposes increases the productive use of land. It can be deployed to power greenhouses around the country. The electricity generated can power farm activities like pumping water for farm needs, lighting, and powering farm machinery like incubators. Surplus energy can be stored in battery banks and used to meet energy demands at night.
One of the major drawbacks of this system is its capital-intensive nature. The considerations of the length and durability of the overhead structures on which the panels are mounted account for the extra cost of the system, making overhead PV system mounting more expensive than the conventional roof or ground mount structures. Also, this system incurs additional operational costs in maintenance and monitoring. Soil and air humidity changes can adversely impact certain plants’ growth.
Conclusion
Agrivoltaics is a remarkable techno-ecological synergy as food and energy security are essential for socio-economic development. It plays a vital role in energy transition and the decarbonization of the economy. It holds good prospects in Nigeria and can be explored based on locational needs in areas with competing land space. Agrivoltaics can be viewed as a solar carport with agricultural production underneath. It is a tool to increase profitability while maximizing space. This system does not favour all crops; experiments are ongoing to determine favourable crops. Tomatoes and leafy vegetables can be experimented with within Nigeria. Also, support from the government and development funders will be essential to support early experimentation and adaptation of this technology as it is very capital-intensive. Also, efforts should be made within the country to encourage the exploration of Agrivoltaics beyond crop production.
