Integrated Crop Management (CPA Book)

Energy Management


Introduction

Energy costs money, but it is an invisible resource and therefore easy to waste. Furthermore without meticulous records, it is difficult to assign the quarterly fuel bill to different parts of the business. Most energy is generated from fossil fuels which are themselves a finite resource and which increases the burden of atmospheric carbon dioxide when they are burnt. So on both economic and environmental grounds, it makes sense to make the best use of energy on the farm. This means increasing the  efficiency of energy use, and eliminating waste.

The three most commonly used fuels on the farm are fossil fuels, gas and electricity to meet energy requirements in the form of heat, light and power. However, it should not be forgotten that fertilisers (especially nitrogen) and to a lesser extent, pesticides represent significant but essential inputs of energy in addition to the one major natural source - sunlight. Fertilisers and pesticides are discussed in other chapters. Here we are concerned with the use of fossil fuels.

The main energy consuming functions on any farm are:

  • Powering farm vehicles and field machinery such as combine harvesters, balers, sugar beet harvesters;
  • Powering static machinery such as driers, ventilators, grain elevators, milking equipment, pumps;
  • Lighting the farm buildings, livestock houses, glasshouses, offices and any domestic premises;
  • Heating (or cooling) in livestock houses, cold stores, refrigeration units, offices and domestic premises.

Practical steps to reduce consumption

Most people are conscious of the need to turn off lights and shut doors in the home to conserve energy. Similarly, driving a car well within its performance capability without undue use of accelerator and brake is a technique likely to improve fuel economy and prolong the life of the vehicle. Integrated Crop Management requires that the same principles are applied to the whole farm business in a more structured and formalised manner.

Part of this process might be, for example, the substitution of one type of machinery for another. A good example is the handling and treatment of liquid animal waste, which can be a big problem on the farm. Electric pumps are easily installed, can be remotely controlled and can utilise cheaper night rate electricity. In this way tractor power can be released for other work. In the field, careful management of fertiliser and pesticides use, the use of flotation tyres and tracks, and careful adjustment of tyre pressures are all energy-saving measures.

Sensible judgements about managing energy can only be made with a detailed analysis of current practice. A farm energy audit which sets down all costs and energy consumption is the only way to start. Even if the audit reveals that some important records are not kept, it will have served a valuable purpose! After that, the various activities can be studies in more detail and a farm energy plan formulated.

...vehicles and machinery

Economy starts at the time of purchase; fuel consumption should be a major consideration. the tractors on the farm should be a capable of meeting predicted needs. This requires careful assessment of the overall demand for power so that horsepower can be matched to need. All farm vehicles and machinery should be regularly serviced and this should include fuel consumption and emission measurements, as well as adjustments of tyre pressures for maximum efficiency of operation.

Paradoxically, having obtained the equipment, the aim should be to minimise its use. An obvious but often overlooked, waste is vehicle idling. Clearly a balance has to be struck between frequent restarting and leaving machines running, but extended idling is not good for the machine itself. Field operations, such as cultivations and drilling, or drilling and rolling, should be combined wherever possible so that the number of passes over the land are minimised. This has to be balanced against power that might be needed and the consequent extra damage to soil structure.

Haulage distances and general vehicle movements can often by reduced by spending some time planning ahead. This can be helped by measures such as providing an in-field water supply when spraying, and the use of radio or telephone to improve communications between staff on the farm.

Careful record keeping is the only way to manage fuel consumption. Consumption figures should be kept for each vehicle and machine so that the overall cost can be correctly apportioned. This will then give an indication of comparative performance and efficiency which will become a guideline at the time of the next purchase.

Static machinery

Many of the same considerations are relevant, but the principle of 'out of site, out of mind' can easily apply to a machine like a pump or a drier that is left to run, perhaps for 24 hours a day. So long as it sounds alright the temptation is to assume that it is alright. Static machines need to be maintained on a regular basis and their fuel consumption and emissions monitored. The possibility of updating and modernising equipment should be constantly reviewed in the context of improved efficiency.

Other steps to consider are the installation of remote or automatic control equipment such as time switches and thermostats. In the case of electrical equipment, control equipment to take advantage of low cost tariffs is another possibility.

...grain storage

Grain needs to be stored on the farm whether for the purpose of orderly marketing or for keeping for livestock feed. The process requires control of the moisture content and temperature so that organisms that cause deterioration cannot develop. Where the incoming grain is at too high a moisture content, it must be dried at the beginning of the storage period. The process is expensive in terms of energy consumption, especially where continuous flow or other high temperature driers are used to evaporate the surplus moisture rapidly. However, on most farms the major component in drying costs is the overhead cost of the equipment itself. Any cost-saving plan should address this aspect first before considering energy consumption. However, if the grain is to be kept on the farm after drying, energy costs can be reduced by combining the functions of drying and storage. Of course, major savings can be made by timely harvesting of a clean crop which requires no drying prior to storage.

...vegetable storage

Conditioning and storage of fresh vegetable produce to meet a market demand that is far wider than the normal harvest 'window' is a precision task. In most cases it is necessary to create a gradual steady temperature drop in the store from the 'field' temperature to the optimum storage temperature. Often this is close to 0 C, but it is also necessary to prevent any frost damage if temperatures fall lower than this. Although manual control of ventilation can be used, it entails a considerable degree of management and supervision. This can be replaced by the use of a differential electrical thermostat with probes in the produce and in the outside atmosphere. Almost certainly this will represent a more efficient use of electrical energy as well as significantly reducing the risk of storage losses.

Lighting and heating

Any requirements for lighting for safety or security should not be compromised. However, the use of time switches, movement sensing switches and energy efficient bulbs (e.g. fluorescent tubes) are all worth considering. Heating equipment, especially oil-fired boilers, can become inefficient with age, even with regular servicing. At the time of updating or modernising, simultaneous consideration can be given to switching fuel, from oil to gas for example.

The term 'environmental control'  in agriculture refers to the balancing of  temperature by ventilation and heating. It is mainly used in controlling the climate in livestock housing, but it can also refer to controlling the equipment in crop and produce stores. in the latter case it may also include adjustment of carbon dioxide, oxygen and nitrogen levels. The extent of energy input required will nearly always be determined by the insulation in the fabric of the building.

Most householders know that the biggest single reason for loss of heat from the home is poor insulation in the roof, the walls and the windows. The same applies to farm buildings. Improving the insulation of existing buildings can be difficult if they are very old but energy conservation should have high priority in the planning of any new building.

Alternatives

As technology advances , the possibility of using alternative sources of energy should be continually reviewed. Solar energy and wind can be harnessed, although often at some environmental cost. Some crop residues, for example straw, prunings and forestry waste are sources of energy, albeit limited. growing willow or poplar biomass or bio-diesel from rape oil are all future possible alternatives to the use of fossil fuels.

The recently published National Biomass Strategy from the UK Government outlines a five-year plan for encouraging the development of renewable energy production from crops such as short rotational coppice and agricultural by-products such has straw, poultry litter and slurry.

Conclusion

As with everything else in ICM, energy consumption and utilisation can only be managed if measured. Investment of one or two hours on a farm energy audit together with regular monitoring and meticulous record-keeping are the ways forward.   Existing practices can be assessed and future improvements planned. The audit provides the baseline against which progress can be measured.

Inefficient use of non-renewable fossil energy is costly and wasteful in any business. To be compatible with the principles of ICM, energy consumption needs to be monitored and optimised.

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© University of Hertfordshire, 2011