A green lung which needs revitalising
Such an undertaking could also contribute to the – very contemporary – problematic of energy savings and the reduction of CO2 emissions. Certainly burning wood releases carbon dioxide into the atmosphere, but the itself has enabled carbon to be stored for very long years. ‘In the case of the Sart Tilman site, the average calorific value per cubic metre ranges from 8,800 to 9,000 Mj/cubic metre,’ adds Jacques Rondeux. ‘We could thus produce annually on the area defined, at the strict minimum, the equivalent of 100,000 litres of fuel, whilst the figure of 200,000 is perfectly conceivable.’ Other scenarios are also possible: one could imagine that a small proportion of the wood gathered in the forest, instead of being used for fuelwood, is used for timber of the highest economic value, (joinery work, construction frameworks, etc.) and whose sales proceeds would enable investments in silvicultural operations:cleanings, plantations, thinnings, etc. One could also imagine short-rotation coppice plantation (SRC). The SRCs are trees of small size and/or rapid growth, such as willow and poplar, to be cut down every seven to eight years. They could be planted in the 7 hectares of weed zones included in the site, for example under overhead power transmission lines, or on terrains with no particular occupancy or which only need to be valorised. Whilst on the subject, let us point out that such a biomass heating system could allow the ULg’s buildings’ CO2 emissions to be reduced by 100 to 400 tons, depending on whether the heating is a fuel/wood mix or strictly fed by woody biomass. In other words from 0.13 to 0.49% of the total of the ULg’s building property.