ABSTRACT
Pioneering work in the study of agricultural sector energy consumption by Leach,1 Leach and Slesser,2 Steinhart and Steinhart,3 and Gifford and Millington,4 was based largely on whole-sector methods of analysis, and depended on the analyst’s ability to identify and separate direct fuel and material inputs (with their aggregate energy inputs in turn) to specific ‘segments’ of the industry. This was often done by interpreting ‘money values’ back into “energy equivalents”. Identification of major energy inputs to intensive fodder crop production such as ammoniacal fertilisers, pesticides and herbicides, tractor fuel, has been made by Green5 in a review of the subject, and illustrates again the ‘holistic’ nature of the data employed. For a sector with one unique output (e.g. ‘hay’ or ‘oats’) this approach yields fairly convincing evidence about the relatively small absolute quantities of energy deployed in UK agriculture, compared with all other major sectors, and possibly provides a shred of comfort for planners at the National level who should be interested in the balance between, and the absolute totals of, energy usages in the economy as a whole (but see page 69). The problem becomes more involved when, for example, attempts are made to look at the energy requirements of mixed arable/livestock farms with a range of possible multiproduct outcomes. Thus, the farm manager wishing to achieve some ‘optimum’ balance between the inputs and recycled ‘wastes’ (manures, skimmed milk for pigs, etc.) will certainly be aware of the cost of direct energy (tractor fuels) to his system, but may not have an adequately detailed picture of the multiplicity of energy transactions within the sub-systems of arable, dairy herd, beef cattle, sheep and pigs, which form one important set of components of his operations. Blaxter6 (1975) has addressed certain aspects of this problem-emphasising again, however, the ‘aggregated’ nature of the data available to the decision maker, and hinting at the role which a more detailed pre-farm gate analysis could play in relation to local and national efforts to obtain a ‘balanced mix’ of food outputs for minimum energy cost. Since 1976, more detailed methods have been used to investigate energy inputs in ex-farm gate operations. Thus, Jacques,7 Jacques and Blaxter8 (1978) have discussed support-energy in meat processing, and Beech9 (1979) has recently completed a detailed study of energy in bread baking. These two studies exemplify attempts to isolate individual inputs to factory food processing, both by allocating fuel energy to clearly defined processing stages and, in an alternative breakdown of the data, to identifiable units of raw material processed or end product produced. In principal, these more detailed approaches are attempting a full input/output matrix approach to plant energy analysis, although it has to be admitted that a number of the required co-efficients are based on broad statistical assessments and not on specific one-plant measurements. It is also interesting that both of these studies have attempted to compare the energetics of large scale (factory) and small scale (butcher’s shop and domestic oven) food preparation and that both report significant (and surprising) variations. These differences may well interest the planner at large company or National level of decision making, but what is
far more significant is the way in which these detailed studies have shown to process management inconsistencies within their previous assumptions about plant behaviour. Whilst this is not the place for the minutae of the food processing industries, it is necessary to witness to the value of the detailed studies to line management; three ‘simple’ examples will suffice:
1) In integrated slaughter-house and butchering operations, boiler fuels required to supply steam and hot water for ‘hose down’ and hygiene control accounts for more than one third of all direct energy inputs and-
2) A further large energy requirement is associated with effluent disposal techniques-which could well lead (as in case (1)) to early changes in technology and daily practice associated with these operations.
