Solar irrigation

Mar 16, 2024

Wasi Ahmed

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As the global thrust on agricultural productivity is gaining high prominence, efforts to render cultivation hassle-free and affordable are also made by most governments to get their priority right. Replacing costly fuel oil with solar technology for irrigation is one such method that has proved to be a great success. For the less wealthy, developing countries like Bangladesh solar-propelled irrigation can be a real game changer, according to experts.

It is a fact that a major problem farmers all over Bangladesh find critically linked to cultivation, and also to their misery, is the scarcity of power or the high cost of oil-propelled power for irrigation. Absence of a viable alternative to diesel to reduce the cost of irrigation in the country has seen unaffordable rise in the cost of cultivation. Solar-powered irrigation, in this regard, is a reliable alternative for farmers as it helps reduce costs, protect the environment, and lower import of expensive diesel.

In Bangladesh, farmers need to irrigate their lands mostly for the Boro paddy cultivation. As regards the other major paddy crop Aman, they depend on monsoon rainfall. But it is not always the case, as scarce rainfall even in the monsoon season forces farmers to go for irrigation -- that too by means of costly oil propelled pumps. This has happened this year. In the month of June, rainfall in the country was 16 per cent less than normal, and in July it registered 50.8 per cent below normal. So, costly irrigation is sure to push up the overall cost of production. Since irrigation of the crop lands is a must, the lower the cost is the better. It is here that solar pumps prove to be an ideal substitute for oil propelled pumps.

There are, reportedly, around 13.4 lakh diesel-operated pumps, supplying water to 34 lakh hectares of land in the country. On the other hand, there are 2,659 solar irrigation pumps, with an installed capacity of around 50 Megawatt-peak (MWp), according to the Sustainable and Renewable Energy Development Authority. Clearly, the number of solar pumps needs to be raised to a reasonable level to cater to the requirements.

The main advantage of the solar water pump is that it uses sunlight at no cost. Just as solar pumps reduce dependence on electricity or diesel, once installed, these pumps require very little maintenance, according to reports.

The government signed a $10 million grant agreement with the World Bank, as part of a total commitment of $24.5 million, to introduce solar irrigation pumps for farmers. A project under the multi-donor financing is in place to enable installation of more than 1,300 solar powered irrigation pumps covering more than 65,000 bighas of land for paddy cultivation. Aimed at providing farmers with clean energy at considerably lower costs compared to diesel, this project is designed to replace diesel pumps with solar irrigation pumps in areas where grid electricity has not reached. It has been learnt that 1,300 solar irrigation pumps to be installed in phases under the project would save the country $3.2 millions in foreign currency annually due to replacement of diesel. Needless to say, large-scale use of solar powered irrigation pumps will substantially reduce the country's diesel imports. Bangladesh currently spends $900 million per year on diesel to power its irrigation systems. Besides, as a result of the use of clean and renewable energy, carbon emission is expected to be reduced by 10,000 tonnes every year.

Solar powered pumps are extensively used in the African continent. Once a very expensive technology, it has reportedly registered drop in prices in recent years because of widespread use and rebates provided by governments. Solar irrigation system is extensively used to pump water from wells or rivers for irrigation and domestic consumption. In the Indian states of Gujrat and Karnataka, solar pumps are mainly responsible for revolutionising cultivation because of uninterrupted supply of water for irrigation at affordable costs. The typical solar powered pumping system consists of an array of solar panels. These solar panels power an electric motor which provides power to the surface and bore pumps. The water is pumped from the ground or a nearby stream into a storage tank, which provides a gravity feed.

Pumping water using the PV (photovoltaic) technology, according to experts, is reliable, simple and requires minimum maintenance. PV pumping systems comprise a PV array, a bore pump and a motor. Solar water pumping arrays are fixed or mounted, or sometimes they are placed on passive trackers. This is done to increase the pumping volume and save time. AC and DC motors with displacement or centrifugal pumps are used for the same purpose. In farmlands where a creek runs through the property, using solar-powered water pumping solution means less tampering with the waterways and also less erosion of the water banks. This can also lead to better pasture management as livestock can access water via multiple water distribution points.

In Bangladesh, installation of solar pumps at the initial stage may be costly but according to experts, extensive use will cut cost to a level far below the diesel cost. There is thus the need to popularise the technology as well as attract investment in research and innovation to bring down the cost.

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