Let's Talk: Solar-Powered Drip Irrigation

(Source: freshome) 

Following on from my previous post, this week we will be exploring another form of irrigation, solar-powered drip irrigation, and its potential for small-holder farmers in sub-saharan Africa (SSA).

Solar-powered drip (SPD) irrigation has been on the rise recently in SSA and is recognised for being an extremely efficient method of irrigation. This is particularly useful for small-holder farmers in SSA where only around 6% of arable land is currently irrigated.  SPD irrigation saves around 40-80% of water and is proven to boost crop yields by up to 100% (Danso et al., 2018).

SPD irrigation is a simple process, as seen in figure 1. The system works by using solar panels to collect solar energy, which is then converted into electricity to supply power to the pump. The pump then extracts the water which can be stored in a water storage tank. Water can then be used for drip irrigation (or for other purposes). Drip emitters are placed close to the roots of the crops to ensure water uptake and efficiency (Wazed et al., 2017).  Solar radiation is key to this process and many countries in Africa have the potential to collect over 2000 kWh of global solar radiation annually, which is more than countries who are already using solar energy. Figure 2 shows the variation in solar radiation in Africa, with countries in Northern and South-Western Africa receiving the most annually. SPD irrigation has the highest potential to succeed in these regions.

Figure 1: Solar-powered drip irrigation process

(Source: Meyer et al., 2018)

Figure 2: Irradiation in Africa

(Source: hotspotenergy.com)

SPD irrigation comes with plenty of benefits, the biggest one being the absence of a diesel motor pump (unlike groundwater irrigation). As it does not rely on diesel to run, long gone are small-holder farmers’ worries about rising fuel costs. This is favourable particularly during times of drought as farmers will have a little extra cash on hand to use for other purposes. In a study by Lovejoy, it was found that the cost efficiency of using solar power would far outweigh diesel power (Lovejoy, 1985). The installation of the system does not require any specialised equipment either, so it is favourable for small-holder farmers in rural areas. It also allows small-holder farmers using SPD irrigation in the Sudano-Sahel region to keep 18% of their yield for their own consumption (Burney, 2010). With yields increasing up to 100%, small-holder farmers are able to increase their earnings, leading to increased economic activity. The extra income can be spent on staples such as protein and pulses during the dry season.

Furthermore, SPD irrigation allows farmers to use fertilisers efficiently and carefully without having to worry about fertiliser runoff affecting local surface water sources. Evapotranspiration is minimised as only a small amount of water is released at one time, allowing for efficiency gains. As water can be stored in a tank, this will be of much help during dry seasons when rainfall is infrequent.

Unfortunately, SPD irrigation does have its drawbacks. The upfront cost of the system itself is quite expensive for small-holder farmers and can be recognised as a major turn off. However, SPD irrigation requires very minimal maintenance and the cost is falling to make it more economically viable for small-holder farmers. In addition to this, there are NGO projects, government programs and private investors who are trying to make SPD irrigation more affordable (Burney, 2010).

Even if it is only a small amount of extra land that is being irrigated, vegetable yields will increase significantly. SPD irrigation is efficient and seeks to bring less harm to the environment. With falling costs of installing the SPD irrigation system, the potential for SPD irrigation to change the attitudes to irrigation in Africa is huge and could be the turning point in farming in Africa.