Solar irrigation from sustainability perspective

In Bangladesh, fuel-based irrigation is still popular with the farming community. According to the World Bank, Bangladesh spends $900 million every year for one million tons of diesel to run its irrigation system. However, over the years, there has been a noticeable shift to solar-based irrigation in different parts of the country. This innovative irrigation system is being adopted not only to reduce costs, especially in purchasing diesel fuel, but it is a realistic choice in the context of sustainable agricultural practices. The global demands for increasing the use of renewable energy technology, protecting environment and reducing consumption of inadequate earth resources have motivated many countries to go for solar energy applications as the best choice available.  
During the peak season of irrigation, about 20 per cent of our total electricity is used by the farmers. As a result, there is a shortfall in supplying electricity. If we consider for our long-term benefits in respect of the demand and supply of electricity, opting for solar-based power pumps can immensely help us access more electricity without interrupting the main supply chain. This, on the other hand, will reduce the burden of government spending in meeting staggering oil import bills.
Our irrigation system is using ground water resources extensively to irrigate the crop land. Different reports show that ground water quality is mostly better than the surface water (e.g. river, lake, pond etc) and good for crop health as well, but ground water resources are limited, even for our drinking and any production purpose. Because of extensive use of ground water in the irrigation system, the ground water aquifer is filling up its storage capacity by discharging saline water from the sea. As a long term impact, salinity intrusion has started to be channelled from the southern part of the country. Already, this situation has been an alarming signal with adverse impacts on agriculture. The solution might be to use conjunctive sources of surface and groundwater, because use of surface water is not possible in many areas as the sources of surface water are far away from the cultivable land, or not cost effective to collect, or are polluted. Assuming the mixed sources of water use, we should carefully examine the sustainability aspects before selecting the different options of conjunctive use of both the water sources. Therefore, solar-based irrigation needs to be planned with feasibility studies conducted to assess the aquifer storage availability, and comparative environmental and economic benefits of the possible water sources.
A recent report on the progress of solar based irrigation pumps shows that the present cost of irrigation is half the cost of the diesel operated irrigation system. In addition, solar pumps require fewer amounts of land and water. In the system, no drain is required to irrigate the land.
However, it cannot be denied that introduction of solar technology is cost-intensive to start with, though with appropriate planning it can eventually be worth the spending. It is here that the government has a lot to do, especially in mitigating the initial hiccups.
The writer is with BRAC. [email protected]