Is solar irrigation set to take over Africa?

Jan 30, 2019

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Bruce Campbell (CCAFS), Frank Rijsberman (GGGI), Mark Smith (IWMI)

Against a backdrop of plummeting solar energy costs and expanding solar energy generation (see figure), the World Economic Forum hosted Keith Breen’s blog back in 2016: “Is solar set to take over the world?” We ask that question for African irrigation, and query whether Africa’s abundance of sunlight can help the continent leapfrog to a different food future. Recent scientific articles in the energy and agriculture literature suggest solar has a major role to play, but also point to challenges.

Globally, 20% of cropland is irrigated, but only 5% in Africa; and yet Africa has the greatest food insecurity, partly due to unreliable growing seasons. Growing seasons will become more unreliable with climate change, while expanding and urbanizing populations will be needing more and different foods as diets and demand change. Can irrigation be a strategy for both climate adaptation and helping smallholders enter expanded markets? 

Xie and colleagues have estimated that irrigated land area in the drylands of Sub-Saharan Africa (SSA)—home to about 425 million people—can be expanded by 6–14 million hectares, 84% of which is small-scale irrigation. Modelling estimates that food import dependency can be reduced from 54% under business-as-usual to 17–40%; and that hunger and under-nutrition can be reduced. Previously, it was estimated that across 13 African countries studied, groundwater could expand irrigated land area by 13.5 million hectares, but with strong differences in potential amongst countries. Thus, the potential for expanding irrigation in Africa is there.  

Shah and colleagues write that “South Asia’s groundwater economy stands at the threshold of a revolution in adoption of solar irrigation pumps”. In India, the Farmers Energy Security and Empowerment Program will install more than 2 million solar pumps through a USD 22 billion fund. Can solar be the cornerstone of Africa’s groundwater development? Wazed and colleagues in their recent prospectus for solar irrigation technologies for SSA are highly positive about the future of solar, noting that photovoltaic “powered water pumping technologies are well developed, easily accessible and require almost no maintenance over the course of the lifetime of the technology”. In addition, what is feasible today will be outstripped by multiple technological innovations soon

However, there are challenges, and here we briefly mention four. Firstly, inequality in irrigation schemes and water provision is widely reported from research, e.g. women having lower access than men to water, information and credit. Secondly, underperformance of irrigation schemes has been a challenge in many developing countries because of poor participation of smallholders in infrastructure maintenance. 

Thirdly, and perhaps one of the most significant challenges, is over-abstraction of groundwater, amounting to a “global groundwater crisis”. Searching “groundwater depletion” and “irrigation” on Google Scholar yields about 990 English language articles since 2018, indicating the scale of the problem. Solar pumping comes with almost no marginal costs; thus, pumps can keep running even when water is not really needed or is used for low-value or water-loving crops. So, if diesel and electric pumps have caused a crisis, solar has the potential to exacerbate it.

Shah and colleagues suggest that linking irrigators into electricity grids may be an answer. In a pilot scheme in India, when farmers were not connected to the grid, they used all of their solar-generated energy for irrigating their own and neighbours' fields; but when connected to the grid, they sold as much power as they could and used only 35% of what they generated for pumping. Solar power sales thus became an additional source of income for farmers, contributed to the national grid, and could reduce the current fossil fuel subsidies for irrigation. 

Fourthly, the high initial investment costs coupled with inconsistent energy policies (e.g. subsidies to fossil fuels, high import taxes on photovoltaics) and the economic issues faced by many developing countries (e.g. low foreign investment, high interest rates, limited agricultural credit) can be prohibitive. Given high up-front costs for solar irrigation, private investment needs to be fostered through, for example, farmers being connected to the grid while also tapping into high value agricultural markets (with good connections to input and output markets).

Blessed by sunlight, African countries can greatly benefit from solar energy to make use of groundwater resources, but there are implementation challenges that must be overcome. Capital costs must become more affordable and better water governance is needed to help reduce inequalities and improve water management. As in Asia, preventing groundwater over-use is critical, but is possible with incentives created by linking solar irrigation to development of national, or perhaps local, grids. Solar irrigation can be a win-win for climate change adaptation (less reliance on rainfall, increased and diversified incomes) and mitigation (renewable energy to grids, less reliance on diesel and electricity pumps). If we get it right, solar irrigation can create a win-win-win-win for food, water, energy and climate. 

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