Unfavorable sites are defined as scattered, small, far away from the farm, bad soil conditions, wet, etc. sites.
· Currently, SRC in its standard form (2-5 year rotation length with willow and poplar) can not economically compete with crops on medium to good sites.
· On unfavorable sites, where there is less competition with other crops, SRC can be an opportunity to valorize unused lands.
· On unfavorable sites, where the profit margin is lower or zero, SRC can be an opportunity but it needs to be done in the right way/has therefore to be optimized:
1. It is recommended to establish producer – consumer pilot co-operations in order to improve the efficiency of SRC-value-chains and to overcome obstacles and constraints for implementation of any SRC-value-chains. A second possibility is to exploit the material on one’s own.
2. To define from the beginning the end use (energetic or non energetic) of the produced biomass, and the quality requirements by consumers.
3. To adapt the plantation design (density, rotation lengths, spacing, etc.) and management to the requirements and to the site conditions. Spacing has to make mechanical weed control possible. Moreover, denser plantations are likely to be more sensitive to drought episodes.
4. To use plant material using efficiently resources especially when they are limited. For instance, black locust has proved to be well suited for dry sites.
5. To valorize residual products where it is possible and allowed, to stimulate yields. If chemical fertilization is often inefficient and sludge spreading is sometimes constraining, the use of wastewater has shown its efficiency.
6. To choose mixture of species and clones rather than monocultures. It is important to avoid pathogen development. The use of species able to fix atmospheric nitrogen such as alder or black locust, in mixture or not with other species, can be interesting to enrich the nitrogen status of the plantation.
7. To plan harvest and logistic operations well in advance and in a professional way. This includes setting the timing for the harvest. For example, woodchips that are to be used in the same harvesting season should be harvested when the demand for them is high, such as in November and December. Material that is to be used in the next winter season should be harvested in February or early March to avoid biomass and wood quality loss during the preceding winter months. The machines to be used should be chosen well in advance, and cooperation with other producers should be sought for to reduce the machine transport costs. Special attention should be given to the biomass transport units used during the harvest. For example, the time required for one transportation cycle should be determined and the number of required transport units should be calculated well in advance. As a helpful tool, the KUP-Ernteplaner can be used.
8. To decide which kind of conditioning method is advisable according to the planned end use. Different kinds of conversion technologies have certain material requirements e.g., on water content and particle size. Whilst bigger burners have a higher range of tolerance for both mentioned values, smaller burners need specifically adjusted wood fuels. Therefore a natural storage process for SRC material is necessary, as active drying is not economically reasonable in many cases. Under material quality perspective, a rougher chip size with breathable coverage or even whole shoot storage is indicated, allowing a higher rate of inner heap air exchange with substantial reduction rates of water content. In consideration of an overall energy balance, a direct material use after harvest shows the highest energy efficiency and, but definitely a quite low material quality in terms of water content and net calorific value. In this case harvest should be done in November to January, in order to provide the material in the midterm of the heating season. As prices for dry chip assortments are higher and dry chips can be used for multiple energetic purposes and subsequent storage after harvest can be more valuable. In these cases, harvest in March is sufficient. Martial can be stored between six to eight month. After that the material can be used in the subsequent heating season.
· There are some other arguments than profit for the establishment of SRC on medium to good sites, such as environmental considerations (biodiversity, bioenergy production, carbon balance, etc.), extensive culture as compared with crops.
· However, financial support is needed.
Fore more precise information, you can download the SRC guidelines in French. The guidelines also exist in English.