Alternative energy systems for farmers
South Africa's farmers' dependence on electricity is precariously balanced on the national grid with its increasing costs and decreasing reliability. On the market side, agri-exporters feel increased pressure from export markets and consumers who demand low-carbon products and a reduction in carbon emissions. This brings an added motivation to include environmentally friendly options and reduce a farm's power costs.
How does one decide on including renewable energy technologies (RET) in an agri-business and which product will be suitable?
"The most suitable alternative energy source is any commercially proven technology that is economical for a specific farm's set-up" advises Neil Parker, energy manager from Cape Town. This might be a vague answer to very real and practical problems, but it means to show that aspects such as farming scale, cost and application need to be considered.
For example, one could use wave energy to desalinate and green the entire West Coast but time and money are constraints, Extensive environmental impact assessments and governmental legislation changes are hurdles to a wave energy option which can take many years.
Similarly, South African farmers may be able to manufacture fuel from crops such as soybeans and sunflower seeds (biodiesel) or sorghum and sugar cane (ethanol). However, the cost of chemical inputs required to grow these crops should be added into the environmental and economic equations to determine the advantage of reducing a fuel bill.
What practical options of RETs are available to farmers and agri-businesses?
Solar is the most practical and widely used RET used in South Africa. Solar hot water finds application in farm cottages, cleaning cattle pens and so forth while photovoltaics (solar electric panels) power remote water pumps, lights and electric fences.
Photovoltaic (PV) panels can be used in greenhouses to regulate humidity and temperature, it is employed in feed processors and daytime cold storage facilities.
These PV panels can be structure-based (installed on top buildings or on top of land) or can be floating, usually in locations where land is too valuable and a water body is present as an alternative. Floating PV mounting systems are about 30% more expensive than systems on land. Combining solar PV with battery energy storage systems (BESS), in South Africa's unstable electricity environment, is in most instances the most cost effective option. This allows the end-user to make use of other energy dispatch strategies such as 'demand charge management', (also called 'peak-shaving' which is the use of BESS's to smooth the demand curve of the loads), 'energy arbitrage' (charging batteries with off-peak tariffs or/and solar and dispatching the energy during peak tariff time slots) and Load Shifting.
BESS system's are also a viable alternative to diesel generators for a backup power supply and could make up the cost diesel generators after about 850 hours of load-shedding. South Africa experienced 1130 hours of load-shedding in 2021 and 2022 is expected to bring more load-shedding.
Wind energy is more feasible at a large or utility-scale. These large-scale applications justify the operational and maintenance inputs compared to small wind turbines where typically these inputs are not economical.
Gas is an excellent alternative for electric geysers for hot water in food processing factories and farm accommodation.
Biodigesters have applications in clean cooking where methane gas is one of the system's byproducts. An anaerobic biodigester breaks down organic materials such as food scraps, oil, and animal manure to release methane. The concept is simple, but its practicality depends on the type of feedstock (high energy vs low energy), water availability, power requirement etc.
Alternative energy solutions can easily and cost-effectively supplement or, in some cases, replace conventional power sources. Coupled with cost-saving measures such as optimising existing power sources and machinery it reduces dependency on the fossil-fuel-powered 'grid' and increases healthier environmental choices.
Talk to your Agrisell agent should you be interested in connecting you with a reputable firm for a quotation on your farm.
Author Marinda Louw Coetzee, Agri journalist