La biomasse, activité alternative au développement des zones rurales

b) Biomass 

According to the definition of Quid, the biomass is the result of a chemical reaction : «collected solar energy into moderate zone (0,5 to 1%) transforms itself into bituminous materials, sources of thermal or food calories »^20(*). For moderated zones, the annual average output is ten tons dry matter per hectare, with the maximum ones of twenty tons per hectares, that is to say a rough resource of surroundings 3,6 to 7,2 tons oil equivalent per hectare.

One can exploit the energy contained by the biomass in various ways in which most obvious consists in using heat coming from its combustion, that is to say directly by manufacturing vapor in order to generate electricity. The biomass can thus produce energy in a unit of cogeneration of heat and electricity, heat « residual » being able to be reinjected in a network of district heating or an industrial process. One can also obtain energy starting from the biomass by gasification and production of liquid fuels.

The biomass usable includes/understands : chips of wood (sylviculture, sawmills, buildings, industries), the wood of the gasolines with fast growths (willows, poplars), waste agricultural (straw, liquid manure), waste of the sugar cultures (beets, sugar canes), cereal (corn, corn), oleaginous ( solid colzas, sunflower), urban waste, household refuse and industrial effluents (of the agroalimentary sector in particular).

The biomass is a widespread and general-purpose resource which can be used as well at ends of heating of electricity. The sources of provisioning of bioénergie include/understand the agricultural, forest residues and the new energy cultures. The enormous potential of the forest residues and agricultural remained up to now almost unexploited. We will see further how the power station from the Mould in Guadeloupe uses the residues of cane with sugar.

One gathers under the term of biomass the whole of the energy sources coming from the organic matter. They account for 14% of the world energy balance^21(*) and approximately 3% of those of the European Union. This sector is broken up into three distinct dies :

· wood-energy : the European wood resource is considerable and is evaluated to 350 million cubic meter per annum. To develop wood-energy does not mean to in no case to return to the chimney, nor with the wood stove to be reloaded without stop in logs. Boilers drink optimized are used as systems of central heating. They are modern equipment of great capacity, automatically supplied. They are particularly adapted to the uses in collective heatings, networks of heat or with the industrial needs. Boilers powerful and adapted to the needs for the private individuals also start to appear on the market. The productions of heat and electricity added up 466.040 GWh in 1999 and France, strong of a remarkable potential places itself in first position with 108.925 GWH (Appendix 6).

· Biogas : the natural process of degradation of the organic matter leads to the emission of a mixture of methane and CO2. This gas can be used for traditional boiler or the unit power supply of cogeneration^22(*). The discharges of household refuse constitute an important biogas layer, currently, this gas escapes towards the atmosphere and takes part in the effect of greenhouse. The data available do not make it possible to distinguish the production from heat of that of electricity. All in all, one estimates at 22.205 GWh the energy production starting from biogas in 1999. Spain is the European country which most largely engaged in the exploitation of this resource with 13900 GWh. (Appendix 7)

· Biocarburants : they are obtained starting from biomass rich in sugar or starch as the cane with sugar, the Jerusalem artichokes, the sorghum or the beet. With the yeast intervention, one obtains a fermentation of sugars. It is then necessary to have recourse to distillation to collect Diester or of Buthanol. These procedures being only used little, they remain rather expensive, it is necessary to count on average ten francs for one liter of product. The current production of 2 million ton in 2001 should be 4,8 million tons in 2003 (Appendix 8). The expiries would then be respected, which will make it possible to achieve a second goal, namely that in 2005, 2% of the European market of the fuels would be of renewable origin. In spite of their cost of important cost, it is necessary to ensure the perenniality of these biocarburants like their growth on the market of fuels.

In the most voluntarist scenarios of use on a large scale of the long-term biomass for the energy needs, the such scenario of the Conference of the United Nations of Rio for the environment and the development presented in 1992 for the horizon 2050, the objective of the energy contribution of the biomass is of 4,9 giga ton oil equivalent, is less than 7% of the annual production of European biomass^23(*).

The European Union places the biomass at one of the whole foregrounds as regards future developments. The table in appendix 9 described the ambitions of the European Commission for 2003 and 2010 following various applications. However, concerning wood-energy and biogas, it is impossible to today locate the efforts of the European countries taking into consideration future expiry. « The multiple applications of these dies prove their fickleness but complex work of projections »^24(*). One can however advance that the principal countries currently developing these energies have in project of the programs in the short and medium term which will make progress the penetration of the biomass. In fact in particular the case of Sweden which wishes to stress biogas or Austria ambitionne to double the number of its boiler installations drink in the years to come.

* ²⁰ document Internet, http://www.quidfrance.com, consulted on March 6, 2001

* ²¹ document Internet, http://www.greenpeace.fr/campagnes/energie/biomasse2.htm, consulted on March 6, 2001

* ²² The cogeneration  : it is the simultaneous production of electricity and heat. The cogeneration can be carried out starting from any fuel. The gases coming from combustion are used to actuate a turbine and thus to produce electricity. The total outputs often exceed 80%.

* ²³ these figures are extracted from an article of Encyclopedia Universalis on the biomass  : http://sfp.in2p3.fr/debat/debat_energie/intro/node13.html, consulted on March 6, 2001

* ²⁴ EurObserv' ER, the barometer of renewable energies, Solar system N° 137- 2000, p58