Commercial Farmers' Union of Zimbabwe

Commercial Farmers' Union of Zimbabwe

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Solar and Biogas exploitation in Agriculture (Part I)

Solar and Biogas exploitation in Agriculture (Part I)

Tapuwa Justice Mashangwa Agriculture Column
IN today’s world characterised by ever rising costs in energy, new forms of alternative energy sources are not only relevant but greatly beneficial. Reliable and constant electricity supply is at present not available in Zimbabwe.

So, solar power and biogas plants are the solution to sustain and supply farm energy requirements efficiently and effectively. The amount of energy from the sun that reaches the earth each day is enormous.

All the energy stored in the earth’s reserves of coal, oil, and natural gas is equal to the energy in just 20 days of sunshine. Solar energy can be used in agriculture in a number of ways to save money, increasing self-reliance and reducing pollution.

It can also be used for heating purposes, crop and grain drying, greenhouse heating and electricity supply. One of the simplest ways to use solar energy is to design or renovate buildings and barns to use natural daylight instead of electric lights.

Dairy operations using “long day” lighting to increase production can save money with skylights and other sun-lighting options.

The sun’s heat can also be used to warm homes and livestock buildings.

In confinement operations, a steady supply of fresh air is critical to maintaining animal health. However, this can result in substantial heating bills.

“Active” solar heating systems, which use heat boxes and fans, can warm the air and thus saving on fuel.

“Passive” solar designs, where the building is designed to take advantage of the sun automatically are often the most cost-effective approach.

Solar water heaters can provide low to medium-temperature hot water for pen cleaning.

Dairy operations can use solar heated water to clean equipment and to warm and stimulate cows’ udders.

For homes or farms with electric or propane water heaters, solar collectors can save hundreds of dollars per year.

Using the sun to dry crops and grain is one of the oldest applications of solar energy.

Solar drying equipment can dry crops faster and more evenly than leaving them in the field after harvest with an added advantage of avoiding damage by birds, pests, and weather.

A typical solar dryer consists of an enclosure or shed, screened drying trays or racks, and a solar collector.

In a simple design, south-facing windows let sun into the shed. Other designs use a dark-coloured box with a glass cover to capture the heat.

Natural convection or a fan moves hot air through the crops to dry them.

While the cost of a solar collector can be high, using the collector to heat other buildings at other times of the year makes it more cost-effective.

Small or low-cost dryers are easy to make out of simple materials. If a farm has a crop dryer already in place, it may make sense to instal a low-cost solar heater to supplement a propane or oil heater.

The farmer would save on fuel costs while still being able to dry crops in cloudy weather.

Commercial greenhouses often rely on the sun for lighting, but on gas or oil heaters to maintain constant temperatures.

A solar greenhouse uses building materials to collect and store solar energy as heat.

Insulation retains the heat for use during the night and on cloudy days.

Sunlight can also generate electricity. Photovoltaic (PV) panels are often a cheaper option than new electric lines for providing power to remote locations.

And because they require no fuel and have no moving parts, they are more convenient to operate and maintain than diesel or gasoline generators.

In some areas, the distance from a power source at which PV becomes more economical than new transformers and electric lines is surprisingly short—often as little as 15 metres.

PV systems are a highly reliable and low-maintenance option for electric fences, lights, and water pumps.

Although current prices for solar panels make them too expensive for most crop irrigation systems, photovoltaic systems are economical for remote livestock water supply, pond aeration, and small irrigation systems.

In addition, the cost of PV is projected to decline significantly over time, which will make more applications cost-effective.

  • Eng. Tapuwa Justice Mashangwa, the writer is, a young entrepreneur based in Bulawayo, Founder and CEO of Emerald Agribusiness Consultancy. He can be contacted on +263 739 096 418 and email:

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