SPIS Lecture - Benjamin Batinge.pptx

INTRODUCTION TO SOLAR-
POWERED IRRIGATION
Benjamin Batinge (PhD)
Thursday, April 27, 2023
University of Oldenburg

KNOWLEDGE INTEGRITY IMPACT
Background
 Water is an essential component for the growth of crops, enhancement of yield, and improvement in
overall food production. Thus, water is vital for food security globally.
 The role of water in food production is more pronounced in Africa, where extreme climatic conditions are
becoming more common.
 Seasonal farming is a common practice across the continent, as most farmers are dependent on rainfall.
There are, therefore, limited cases of all-year-round farming.
 The rising population has induced high demand for food, making rainfed agriculture a less reliable
approach for meeting food security in the future.
 Contemporary innovative irrigation systems are important for boosting food production.

Crop water sources
TARGET
There are two main ways that farmers and ranchers use agricultural water to cultivate crops:
 Rain-fed farming - the natural application of water to the soil through direct rainfall.
 Irrigation - the artificial application of water to the soil through various systems of tubes, pumps, and sprays.
Irrigation is usually used in areas where rainfall is irregular or dry times or drought is expected.

Irrigation types
TARGET
 Manual irrigation
Water is distributed across land through manual labour and watering cans. This system is
 Surface irrigation
Water is distributed over and across the land by gravity, with no mechanical pump involved.

Irrigation types
TARGET
 Sprinkler irrigation - water is piped to one or more central locations within the field and distributed by
overhead high-pressure sprinklers or guns.
 Localized/drip irrigation - water is applied to each plant or adjacent to it. Drip irrigation can achieve
90-95% efficiency by reducing evaporation and deep percolation (Baker, et al, 1993).

Mobility for Sub-Sahara Africa
– Sustainability thought through the Lifecycle
 These conventional pumps, however, have challenges, including the need for a regular supply of fuel and
physical attendance for operation and the high cost of maintenance.
 Solar photovoltaic pumps, are much less prone to the challenges of conventional pumping systems, with the
right knowledge on operation and maintenance.
Energy for pumping/transporting water for irrigation
TARGET

Ground Water:
 Open Wells
 Aquifers
Sources of water for irrigation
TARGET
Surface Water:
 Dams
 Rivers
 Ponds
 Storage tanks
Submersible Pump Surface Mounted Pump

Open reservoirs are inexpensive and relatively easy to construct,
 they have high evaporation losses of water
 there is an easy accumulation of debris and sediments as well as algae growth.
Open reservoirs
TARGET

A classic configuration of a Solar Powered Irrigation System. The pumped water is stored in an elevated water
tank, and irrigation functions by gravity.
Storage tanks (elevated)
TARGET
 the elevated tank serves as a battery where energy is stored in the form of water.
 the irrigation system pressure depends on the height of the water level in the storage tank.
 It also allows for pre-sunrise irrigation.

Most water pumps utilised for irrigation purposes worldwide are powered by engines running on fossil fuels:
• Diesel
• Petrol
• Gas
• Fossil fuel-based grid-supplied
Energy for pumping/transporting water for irrigation
TARGET
As traditional pumping technologies, such as manual or animal-powered pumps, reach their technical limits,
fossil fuels became the customary means of pumping irrigation water.

Water manually drawn and carried to the field
TARGET
Community Building Group, Ltd. Inc., 2020

Manually-operated Pumps
TARGET
Amina Day Ojijo, 2019
Community Building Group, Ltd. Inc., 2020

Manually-operated Pumps
TARGET
David Graham/iDE, 2017
Treadle pump
Hand-piston pump

TARGET
Petrol-operated Pumps
Nana Kofi Acquah/IWMI
IWMI, 2012
Internal combustion pumps

TARGET
Source: Bimala Colavito/iDE, 2017
Solar PV-operated Pumps
World Bank, 2019
Solar pumps

Solar Powered Irrigation Systems
TARGET
A form of irrigation that utilises solar energy to pump water for irrigation.
The system consists of;
 one or more solar panels (also known as solar modules or solar plates),
 a pump (mostly a centrifugal pump),
 electronic controls or a controller device to operate the pump,
 and other hardware such as inverters, batteries, etc.

 The solar panels produce electricity by using the photovoltaic effect.
 The solar panels absorb the photons from the sun and convert them into energy.
 An array of panels may be installed to meet the energy needs for a desired quantity of water.
Solar Photovoltaic System
TARGET

Solar Powered Irrigation Systems
TARGET
 It is a reliable, clean-energy solution for agricultural water management, especially in areas with high levels of
solar radiation.
 It enables farmers to practice yearlong farming, improve yields, and promote better agricultural outcomes.
 It provides local farmers with better planning and increased stocks to market in a highly cost-effective and
consistent manner.

Components of solar-power irrigation system
TARGET

 The water pump is a vital component. It is the piece of equipment that draws water from the source for
different applications.
 It can draw water from a well, pond, or other sources for irrigation and other essential purposes.
Water Pumps
TARGET

Inverters are used to convert direct current (DC) output into alternating current (AC), which can be used to
power electrical grids and off-grid electrical networks.
Inverter
TARGET
 conversion is necessary for many electrical devices, including water pumps, making inverters an important
part of the solar pump system.
 an inverter can help to keep a water pump running through cloudy or low-light days

The controller is the link between the solar generator and the motor pump and is essential for system reliability.
It adjusts the fluctuation in the output frequency of the solar generator resulting from varying irradiation levels.
Controller
TARGET
 It can be used to essentially control the water pump.
 it can help the water pump run more efficiently.
 it can be used to set a pumping schedule, turn the pump on or off, and help maximize the life of the pump.

The part of the irrigation system where the water quantity, quality and pressure are managed.
indispensable in irrigation systems that operate under pressure, such as sprinkler and drip irrigation.
The irrigation head typically contains:
 valves - to control the quantity of water flowing to the different sections of an irrigation system; filters - to remove
particles that could block drip emitters or sprinkler nozzles;
 fertigation system - to mix soluble fertilizer in the irrigation water;
 pressure regulators – to adjust pressure levels.
Irrigation head
TARGET

The amount of water you need depends on many factors, including:
 The size of the farm
 The crops you are growing
 The irrigation system you use (drip irrigation is most efficient)
 The soil type
 The climate
Quantity of water needed for irrigation
TARGET

Configurations of Solar Powered Irrigation Systems
TARGET
Source: Reinhold Schmidt, 2015

A layout of Solar-powered Irrigation Systems
TARGET
Source: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), 2020

A layout of Solar Powered Irrigation Systems
TARGET

A layout of Solar Powered Irrigation Systems

Comparison of different irrigation methods
TARGET

Main differences with fuel pumps:
TARGET
 Variable flow during the day, therefore time-consuming
 No fuel costs (no petrol)
 Higher investment
 Solar submersibles available – so they can extract water from below 8m
 Much higher investment
 Labour input is no longer a restriction therefore, larger irrigation plot.

Why solar-power irrigation is the way to go:
TARGET
 Reducing out-of-pocket costs for farmers
 Submersible pumps can access deeper groundwater
 Solar panels and most solar pumps have a longer lifespan
 Economic option for reduction of CO2 emissions
 Big interest from donors and investors, availability of green funds for subsidies

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