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Solar-powered irrigation systems are potent weapons in the fught against hunger and poverty in arid sub-Saharan Africa, according to a Stanford University study published in the Proceedings of the National Academy of Sciences.
The study found that solar-powered pumps installed in remote villages in Benin, West Africa, were a cost-effective way of delivering irrigation water, particularly during the long dry season.
"Significant fractions of sub-Saharan Africa's population are food insecure," wrote lead author Jennifer Burney, of the Program on Food Security and the Environment and the Department of Environmental Earth System Science at Stanford.
"These food-insecure populations are predominantly rural, they frequently survive on less than $1 per person per day, and whereas most are engaged in agricultural production as their main livelihood, they still spend 50 to 80 percent of their income on food."
Only 4 percent of cropland in sub-Saharan Africa is irrigated, and most rural, food-insecure communities rely on rain-fed agriculture, which, in places like Benin, is limited to a three- to six-month rainy season.
"On top of potential annual food shortages, households face two seasonal challenges: they must stretch their stores of staples to the next harvest (or purchase additional food, often at higher prices), and access to micronutrients via home production or purchase diminishes or disappears during the dry season," the authors wrote.
Promotion of irrigation is therefore frequently cited as a strategy for poverty reduction, climate adaptation and better food security, they said.
Harnessing the sun in Benin
To address the lack of data, Burney and her colleagues monitored three solar-powered drip irrigation systems in northern Benin. The systems, which use photovoltaic pumps to deliver groundwater, were financed by the Solar Electric Light Fund (SELF), a nongovernmental organization.
"Water pumps save labour in rural areas where water hauling is traditionally done by hand by women and young girls," the authors said.
"Though photovoltaic systems are often dismissed due to high up-front costs, they have long lifetimes, and in the medium-term cost less than liquid-fuel-based pumps."
Striking results
The three solar-powered systems supplied 1.9 metric tons of produce per month, including tomatoes, okra, peppers, eggplants, carrots and other greens, the authors found.
Women who used solar-powered irrigation became strong net vegetable producers with extra income earned from sales, significantly increasing their purchases of staples and protein during the dry season, and oil during the rainy season.
During the first year of operation, the women farmers kept an average of 8.8 kilograms per month of the produce grown for home consumption and sold the rest in local markets.
Meeting the RDA
Villages irrigated with solar-powered systems had the greatest increase in vegetable intake – 500 to 750 grams per person per day, equivalent to 3 to 5 servings of vegetables per day – the same as the U.S. Department of Agriculture's Recommended Daily Allowance for vegetables.
"Photovoltaic drip irrigation systems have an additional advantage over liquid-fuel-based systems in that they provide emissions-free pumping power," they added.
"With the proper support, successful widespread adoption of photovoltaic drip irrigation systems could be an important source of poverty alleviation and food security in the marginal environments common to sub-Saharan Africa."
- SAPA, January 2010
