Powering Agriculture: Irrigation

Agriculture is the backbone of local economic development in the majority of developing and emerging countries. Therefore, access to reliable and affordable irrigation water is a crucial factor for the economic development.

Background

Manual lifting of irrigation water significantly reduces the scope of cultivation and the efficiency of irrigation – it does not, for example, allow for pressurized systems that are required for water saving drip or sprinkler irrigation techniques. In the absence of reliable electricity supply due to lack of grid connection or intermittent service, farmers in developing countries have hence to rely often on diesel-driven pumps for water abstraction and conveyance. These diesel-driven pumps create high operation costs and are prone to service gaps due to an insufficient fuel supply and technical defects. A reliable and cost-effective supply of irrigation water is therefore a core problem in many rural areas in developing and emerging countries.

The perspective of grid extension and the establishment of uninterrupted and affordable electricity supply into rural areas is a distant vision in many of these countries. Rural electrification in economically weak rural areas in Africa, Asia and Latin America will be largely based on investments into local off-grid solutions.

Types of Irrigation

There are various irrigation methods, each requiring an experienced farmer to determine the quantities of water to apply and the timing of the irrigation. The most commonly used modern irrigation methods are:

• Surface irrigation. Types:
  
• Basin irrigation (entire field is flooded)
  
• Furrows (water is fed into small channels)
  
• Borders (strips of land are irrigated)
  
• Sprinkler irrigation
  
• Drip irrigation
  

A number of factors determine the suitability of the various methods:

• Natural conditions: soil type, slope, climate, water availability, water quality
  
• Type of crop
  
• Type of technology
  
• Previous experience with irrigation
• Capital requirements and availability
  
• Costs and benefits
• Labour input
  

For further information on irrigation click here

Energy sources for irrigation water pumping

Motor-driven water abstraction and conveyance requires a reliable energy source – or a reliable combination of energy sources. The vast majority of water pumping for irrigation purposes is to date effected by diesel or petrol motors or electric motors fed from the grid or from diesel generators. The utilization of renewable energy sources is steadily increasing but still on the minority side.

the most commonly used energy sources for irrigation water pumping:

• Petrol engine
• Diesel engine
• Natural gas engine
• Electric engine: distinction has to be made according to the actual source of electricity
• Network/grid-supplied electricity
• Generator (diesel, petrol)-supplied electricity
• PV-generated electricity
• Electricity generated from other off-grid RE sources (biogas, biomass generators)
  
• Wind powered pumps
  

Solar-powered irrigation systems

In regions with high solar insolation levels, electricity from solar cells open up new options for lifting and distributing water in an efficient, reliable and economically viable and ecological-sound way. The technological option of solar-powered irrigation is rarely taken into consideration due to a lack of pertinent experience and the comparably high investment costs of the past. Nevertheless, as prices for solar modules have fallen substantially in recent years, governments, extension services and technical cooperation are reconsidering PV water pumps to be employed in agricultural production and beyond. Demand in this regard will have to be largely generated from the side of the rural farm households themselves.

Barriers

• Farmers and extension services are not aware of the variety of new technologies that may be appropriate for them
• CES (clean energy technologies) are relatively new, therefore farmers have limited access to distributors for installation, parts, and service
  
• Farmers often do not have the means to cover high capital costs associated with clean energy upgrades – and financing is seldom available
  

Case Studies

Solar-Powered Pumps for Improved Irrigation in Honduras, Nepal, Zambia: iDE’s Clean Irrigation Solution (CIS) can compete with fossil fuel pumps both in terms of cost and enhancing agricultural productivity. CIS’s universal piston pump can run on a variety of power sources (solar steam power, photovoltaic power, and grid-connected alternating current (AC) where available). The system accesses groundwater from deeper depths than conventional pumps, and maintains a slow, steady discharge rate. iDE will work with local businesses to sell and service the CIS. Recently, field testing of pumps has been started in Nepal: read more here.

Micro-Solar Utilities for Small-Scale Irrigation in Senegal: Earth Institute’s solution will enable a small group of farmers to use a central solar energy unit to power multiple AC pumps for irrigation. The proposed solution takes advantage of the benefits of solar without the high costs associated with DC-powered pumps and battery storage. This power will be accessed by farmers with prepaid electricity cards issued by a micro-utility, and sold through local vendors who will benefit from a small commission. Recognizing that a major obstacle to technology adoption is financing, a tariff-based financing model will allow customers to cover their appliance loans in small payments added into their micro-utility bills. Read more.

Solar Powered Irrigation Systems in Egypt and the initiative "RaSeed": The initiative aims to promote the use of Photovoltaic (PV) systems in drip irrigation farming in order to support cost-effective and sustainable agriculture. Therefore, the aim is to introduce high capacity solar operated water pumps - of up to a pump size of 100kW - to the Egyptian agricultural sector. Furthermore, soil in the “New Lands” is mostly sandy, and water used for irrigation is ground water. Hence, it is crucial to use water efficient irrigation systems. RaSeed targets farm specific optimization of drip irrigation systems that enable maximum fuel savings and water efficiency by taking into account soil compositions and environmental conditions. In order to further the initiative, a Private Public Partnership (PPP) was established with a solar energy firm that is supported by the multi-donor initiative ‘PoweringAgriculture - an Energy Grand Challenge for Development’. Together with its partners, RaSeed establishes a network, providing high quality solar energy technology and training in Egypt. Read more.

Further Case Studies:

• Advanced Solar Irrigation Scheduling for Sustainable Rural Development: A Case of India
  
• Potential for Solar PV Water Pumping for Irrigation in Bihar
  
• Micro-Solar Utilities for Small-Scale Irrigation in Senegal
  
• Techno-Economic Feasibility of PV Irrigation in Egypt
  
• Potential of Solar Irrigation Water Pumps in Pakistan
  

Further Information

• Solar Energy for Powering Agriculture
  
• Promotion of Solar-Powered Irrigation Systems (SPIS) - Workshop Documentation
  
• Photovoltaic (PV) Pumping Systems for Irrigation
  
• Article on Agriwaterpedia
  
• Entry in PoweringAg Technology Database: Appropriate Irrigation
  
• Entry in PoweringAg Technology Database: Smart Irrigation Controls
  
• Practical Action: Fact sheet on the advantages and disadvantages of solar photovoltaic water pumping, including real world application.
  
• Climate Tech Wiki: Solar Water Pumps