3.2. The biogas plant in the agricultural farm and household system

3.2.1. The target groups

When biogas dissemination began, the opinion was that biogas plants should be built wherever they were ecologically necessary and feasible (thus e.g. also in the Sahel). Today, after about 15 years of experience with biogas programmes, it is now known that biogas plants can only be disseminated where, as agricultural technology, they can become an integral element in the living and working world on the farm. This central condition for a biogas dissemination programme requires "biogas favourable" farm and household systems to have definite structural features. A typical and ideal location for a biogas plant could be described as a farm on which animals are permanently kept indoors and where, as far as possible, mixed farming is practised. The farmer is the owner of the farm and has the power of disposal over his land so that he is able to profit from the investment in a biogas plant over the long term. The cattle are kept indoors every day and are put to pasture for a few hours at the most. The amount of dung occurring on the farm amounts to over 30 kg fresh weight daily. The quantity of water necessary for filling the plant and corresponding approximately to the amount of dung, can be constantly obtained without any unreasonable amount of work, also by women and children; water is not in short supply. Stabling with a concrete floor from which excrement and urine can be directly pushed into the inlet tank of the biogas plant would be ideal. The floor of the stabling is high enough for the overflow of the compensation chamber to lie above the terrain so that the slurry can flow down a slope into the neighbouring fields where, as far as possible, fodder grass is grown. (The floor of the stabling has to be at least 35 cm higher than the overflow of the biogas plant). The toilet could also be connected to the biogas plant; there is no prejudice against a toilet being connected. The gas is used as regularly as possible and completely in the direct vicinity of the plant. Experience in the use of organic fertiliser would be of advantage for optimum utilisation of the slurry. It would be favourable for regular filling of the plant if the people using the gas and those operating the plant were identical. Although in recent years the technical concept has been more and more successfully modified to the needs of the users, e.g. increasing operator friendliness, the integration into the farm and household routines remains a central criterion for the selection of a location. Where and which compromises on the ideal "biogas farm" described above are possible depends on very many factors which have to be examined in each individual case. (Colleagues with experience in biogas dissemination programmes should always be consulted in cases of doubt.) For example, the requirement of a short distance to the point of gas consumption could be deviated from. Long pipelines are only a cost factor and the function of the plant is retained even at distances of over 100 m (too great a loss of pressure can be counteracted by larger diameter of pipes). Also the connection to stabling favoured within German development cooperation is e.g. in India and Nepal, not a standard. Also toilets should only be connected to the biogas plants according to the express wishes of the customer.

Family structures could also be stated here as central criteria in the success of a dissemination programme. Division of labour and allocation of tasks in the household and on the farm according to sex, i.e. particularly the position of the women have to be carefully observed. In polygamous households where each woman has her own kitchen, the integration of biogas plants is hardly possible in the living and working world of the woman.

It is far less of a problem when the women take it in turns to cook in one kitchen. In this case it would be particularly important to investigate how the operation of the plant would be organised, or if coordination between the women is probable. If the women take it in turns to gather fuel, then operation of the biogas plant in turn could be organised. Despite this, it would have to be investigated who would be in absolute charge and whether, e.g. the first wife had the priority to supervise operation of the plant.

In Africa, the man is normally in charge of lighting in the household. In these cases, there could be a conflict of interests between the man and the woman concerning the use of gas for lighting and for the stove. The man who (normally) pays for the plant, naturally wants to save on his budget for lamp oil. The woman, who under some circumstances fills the plant and is in charge of firewood, wants primarily to use the gas for cooking. If there is no reconciliation of interests, the ruins of a biogas plant could appear on the farm in due course. It can be assumed that the woman who is responsible for cleaning the stabling, will neglect the plant if the husband insists on using "his" biogas plant for "his" light.

3.2.2. The demand for biogas plants

Although theoretically, all farms with the a.m. structural features may be considered for biogas, the actual dissemination is defined mainly by how willing the farmers are to invest in this technology. For the farmers, the biogas plant is a capital good binding a high amount of funds which will improve the energy, agricultural and hygienic situation of his farm and of his household. The attraction of a biogas plant for the farmers initially stems from the use of the gas. In view of this, dissemination concepts focussing on the utilisation of slurry have hardly been able to move the farmers to an investment unless some kind of simultaneous energy benefit, which was in a ratio to the amount of the investment, existed. Favourable regions for biogas dissemination have proved to be where farms have a bad supply of energy sources, but where a healthy economic substance exists. In these regions, the factor "comfort" plays a considerable role in the development of the demand - in particular on farms with a high to medium farm or family income. The biogas lamp as a source of light cannot compete with an electric light bulb. A connection to the electricity supply however does not have to be a reason for excluding a possible biogas programme. A low-cost biogas plant can turn out to be an interesting investment especially in regions where the fossil sources of energy are traded at high prices.

It is difficult to reach small farms with a low capital background with dissemination programmes although these farms, in comparison to the economically stronger ones, often suffer from a bad supply of energy. Their insufficient solvency and their weak capital background make the purchase of a biogas plant costing several hundred US dollars a hurdle which is often too high to take. The poorer classes of smaller farmers could only become members of the target group in India where subsidy programmes could be implemented on a long-term basis and in countries where the prices for plants are very low. To link the introduction of a new technology directly to the social question has proven to be a demand which could rarely be fulfilled in reality in past projects.

In the initial phase of a dissemination programme at least, orientation to economically more healthy farms seems advisable. They can be the forerunners which' when the technology has been established and no longer constitutes an investment risk, the weaker farms could possibly follow.

3.2.3. The potential

The development of demand is, on the whole, part of a long-term process during the course of which biogas technology grows into a generally accepted part of agricultural technology. Experience in India has shown how approx. seven years pass between the introduction of the technology to one region and the appearance of a dynamic demand. A dynamic demand develops where high potential exists. The potential increases with unfavourable energy supply conditions and with the number of farms (families) with sufficient livestock and a high and secure income from their farms. Important in estimating the potential is not only the expected number but also the possible density of biogas plants. If a high density of potential ''biogas customers" exists, the positive demonstration effects of the plants within the rural region influence the development of demand more rapidly. Apart from this, the potential density of plants and the potential number are important basic values when calculating the infrastructural demand of the dissemination programme. If the farms of potential biogas customers are scattered throughout the region, a greater demand can be expected on customer acquisition, advisory services and servicing. If ultimately only a few plants could be built the infrastructural expenditure for biogas dissemination would be in an unfavourable ratio with the macroeconomic benefit expected. Critical orientation values pro or contra a dissemination programme could be if less than 10% of all farms in the region were "biogas capable" or if less than 3 farms per km² could be considered for a biogas plant.