There is no quick fix for energy savings. Energy efficiency requires buy-in from everyone on the farm, a mindshift in management approach, and constant monitoring to ensure that whatever system you have in place, stays in place.
As always with energy management, start with the basics. A simple SOS (switch off something) programme is a good way to save, and will help to foster an awareness of energy saving and efficiency on the farm. A kilowatt hour not consumed is a kilowatt hour saved.
Maintenance of energy-hungry systems is as important for energy efficiency as it is for ensuring system reliability. Too many farmers are reactive when it comes to maintenance. “Don’t fix it if it ain’t broke,” they say.
However, maintenance should aim at ensuring that your systems always runs at peak efficiency. This requires careful planning and forward thinking, and costs associated with maintenance should be considered part of production costs, not overhead costs.
Reactive maintenance is the most expensive way to maintain large, energy-hungry systems. According to Murphy’s law, if anything can go wrong, it will – and on a Friday afternoon. You then face after-hours labour costs, potential loss of produce and production, and a stressful weekend.
When you add to this the fact that the system was running inefficiently for at least half the time, it soon becomes clear why regular maintenance is crucial to a profitable farm.
Cold rooms are large users of energy. The efficiencies of such systems are largely dependent on the ambient temperatures and simple maintenance. In plain English, the heat is removed from the cold room by the blower coil inside the cold room, and ejected to the atmosphere by the condenser coil. If either coil becomes dirty, the efficiency of the system is reduced – more energy is required to produce cooling.
A blower coil icing up inside may indicate restricted airflow.
Maintaining a refrigeration system
Ensure adequate ventilation around the condenser coil. Poor ventilation will cause high temperatures around the condenser, reducing efficiency and possibly leading to eventual equipment failure. For this reason, compressors and condensers should never be installed in a roof void.
Refrigeration systems are designed for a specific ambient temperature. Anything above this will result in reduced efficiency. This can be alleviated by spraying water onto the condenser coil.
- Make sure that the temperature probe is clean.
- Check that all insulation around the refrigerant piping is in good condition.
- Ensure that the gasket around the door seals properly.
- Always close the door.
The efficiency of your refrigeration can be reduced by up to 10% if these simple maintenance items are ignored.
If a pump system is not maintained properly, up to 30% of the energy used for pumping can be wasted. The head loss in a dirty strainer can increase by as much as 30%. Cleaning the filters and strainers regularly is therefore a simple, highly effective way to save a significant amount of energy.
Energy-saving tips for pump systems
Fix leaks: A leaking pipe is not only a waste of water, but a waste of energy.
Don’t kink pipes: Avoid the temptation to kink a pipe to temporarily stop water. This restriction will cause inefficiencies and hence energy wastage down the line.
Match pump to flow: Pumps are often oversized, and a valve is used to restrict the water flow. This valve is essentially ridding the system of excess energy. Ask your supplier to skim the impeller to match the required flow, or use two smaller pumps in parallel instead.
Pumps are designed with a specified minimum suction pressure. If the pump is installed in such a way that the suction pressure is less than the specified minimum, pumping efficiency is reduced significantly.
A holistic approach
No measure on its own will result in major savings. However, neglecting them can lead to major unnecessary energy and other costs. Energy management is a bit like rugby: add each bit of ground gained and you’re almost at the try line.
Nicol du Toit is a mechanical engineer and energy manager based in Johannesburg.