Description of the scientific and technological problem Biomass can be considered as a strategic resource because not only is it renewable, but it is

also available everywhere and can provide products of vital interest to sectors of strong external dependence (i.e. fuel for transportation, electricity, chemicals etc.), and also because it may raise benefits for the environment and for socio-economic development, (particularly in a rural areas).

Annually around 700 million tons of agriculture wastes are produced within the EU (European Topic Centre on Waste and Material Flows, 2001) which represent a high load for farmers that are forced to get rid of these wastes, taking into consideration not only environmental but also economic and social aspects in their proper management. So far, the majority of the manure and crop residues have been receiving the cheapest treatments although these are not the most adequate or efficient ones; direct use as soil conditioner and direct use as animal feed or feed supplement together with upgrading to compost, landfilling and incineration are mainly applied.

Landfilling is already forbidden in several European countries in others it will only be allowed for a very limited time (Council Directive 1999/31/EC of 26 April on the landfill of waste). Other treatments, more appropriate such as gasification or fluidised bed incineration results to be too expensive for the investment capacity of farmers. It is therefore necessary to find a sustainable alternative in order to overcome the drawbacks of the above-mentioned technologies. The upgrading of agriculture wastes to biogas

through anaerobic co-digestion represents a treatment alternative with a great potential as it provides a solution to prevent pollution but also allowing at the same time for energy, bio-fertiliser and nutrients recovery.

Thus, anaerobic digestion (AD) can convert a disposal problem into a source of income, specially provided the present situation of the agricultural sector, currently undergoing a process of adaptation to the latest Common Agricultural Policy (CAP) reform of 2003, which changed completely the way

in which the EU supports the sector; in the future, the vast majority of subsidies will be paid independently from the volume of production and will consider, among others, the total surface in production and the compliance with environmental standards. The development of AD for agricultural waste treatment will help farmers to adapt to the CAP reform since it will allow them to comply with the EU environmental standards while providing a source of income from the energy and biofertiliser produced through the co-digestion of the mentioned wastes along with other cosubstrates whose treatment can be subject to management fees (organic municipal solid waste or residues from agriculture related industries surrounding the farms).

In addition, those farmers who cultivate their fallow or surplus productive land with energy crops (maize, sunflower, grass, beets etc) will obtain an extra source of income from the EU subsidies, reducing agricultural surpluses of other products and improving co-digestion. Although AD started to be applied mainly to treat sewage sludge or animal manure 20 years ago, there are still many problems to be solved in order to make this technology effective to treat agriculture wastes (both green waste and liquid manure), optimising the co-digestion process with other residues and finally making it widely accessible to European farmers.

Among them the following topics are especially relevant:

- Low effectiveness of co-digestion biogas plants operated at present. Even in those countries where the AD technology is more developed, the performance of the biogas plants is far from satisfactory. Such is the case of Germany, where the majority of European farm AD plants are located. According to a German study, around 60% of the German biogas-farm plants analysed recognise to share similar problems during the operation processes such as instability and disturbance of the process due to inappropriate mixtures of co-substrates, difficulties to prevent possible inefficient quality and quantity

of the biogas produced, low availability of skilled people to run the plants.

- Uneven levels of know-how in the field among EU members. The current

distribution of biogas facilities and know-how presents a very unequal pattern in the EU (EurObserv’er, 2003), with some countries like Great Britain and Germany with high biogas production rates (1,151 and 685 thousand of toe respectively) and others, with a relative important agriculture sector, like Ireland, Greece, Portugal or Italy, having low biogas production rates (from 28 to 155 thousand of toe). This dispersion of the knowhow in the field implies that the accessibility of farmers to this technology is highly dependent on the location of their facilities.

- Lack of information available to the potential users of the technology. In most of the cases the farmers are not aware of the benefits that they can obtain from the revalorisation of their organic wastes through AD.

In order to solve these problems, the AGROBIOGAS project intents to gain sufficient R&D knowledge about the optimal and effective anaerobic co-digestion of agricultural waste and disseminate the results to both IAGs and their SMEs members.

With this purpose, the following activities will be carried out during the project:

- Detailed study of potential co-substrates in South and North Europe, optimal

mixtures ratios to both increase the biogas production and obtain a stable and marketable bio-fertiliser with the fermentation residue, given the conditions of each European region analysed. Special attention will be placed on sanitation issues related to the management of additional organic co-substrates avoiding any kind of toxicity that could further reduce the efficiency of the process, produce a polluted and useless AD sludge or even block it,

- Analysis of the different AD technologies currently in use to discern among them, the best available ones for each regional situation, farm size and economical possibilities of the farmers,

- Development of pilot-scale biogas trials to study in detail the process (best cosubstrates and co-digestion ratios, required pre-treatments, physic-chemical and biological optimisation of the process, biogas yield avoiding any unforeseen disturbances in the process and optimising it),

- Development of full-scale experiments based on the results of previous pilot-scale biogas trials in some of the existing digesters of the partners included within the consortium to check the best operational parameters finally chosen,

- Development of technical guidelines including best management and operation practices to help farmers who already have applied this technology to optimise their process and also, for those farmers who are planning a future development, the guidelines will include financial, legal and technical advise,

- Development of specific training and dissemination tools that, containing the results of the assessments, researches and trails under regional conditions, could serve as useful tools for farmers to guide them to plan in advance and also for developing and managing efficiently their AD plants.

All the material developed during the project will be continuously updated and theinformation will be shared between the involved IAGs in order to keep awareness of new developments on the field.