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Agroenergie, what they are. The use ofbiomassfor the production of renewable energy. The environmental impact of agro-energy understood as biomass and biofuel.
Agroenergie, what they are
When it comes toagroenergyone only thinks ofbiomass. In fact, with the termagroenergyanyenergy potential derived from agricultural activity.
In its current state, theagroenergymore established are thebiofuels(biodiesel and bioethanol) and energy from biomass (biogas, electricity, thermal energy).
Agroenergy and environment:the impact of biomass and biofuel
Theagroenergythey are undoubtedly energy resourcesrenewablebut not necessarilyclean or ecofriendly. Both when it comes tobiomass, both when it comes to the production ofbiofuelsdebates are not lacking.
In the case ofbiofuelsthe heated debate focuses on the fact that this source of agricultural energy is radically changing the scenario of modern agriculture, especially when it comes toland grabbingand exploitation of agricultural land.
Many Third World countries committed agricultural land for the production of foodstuffs. With the production ofbiofuels, many fertile lands previously used for food, have been destined for the cultivation of vegetables for energy use. The consequences have been many and even catastrophic: on the one hand, in some developed locations around the globe, there has been a rise in food prices and on the other, strong imbalances have been triggered in non-developed countries.
The debates on the sustainability of this agroenergyseem to have calmed down with the introduction ofsecond and third generation biofuel. Forbiofuelsnew generation refers to those agroenergy produced with other techniques and other more accessible raw materials. Among the raw materials that can be exploited for the production of new generation biofuelswe point out biomass (wood and cellulose), algae or miscanthus, a shrub belonging to the grass family that can be grown in residual soils.
There is also controversy on theenvironmental sustainabilityenergy from biomass, first of all biogas. Thebiogas is obtained from the decomposition of the organic substance in an anaerobic environment, the decomposition is "catalyzed" by microorganisms capable ofdigestorganic waste and release biogas as a product of anerobic digestion. Once the biogas is obtained, it must be refined. Raw biogas consists ofmethaneat 55 - 65%, the remaining percentage composition is given by other gases and among these a good part ofCO2.Carbon dioxide does not represent a problem for the environment as it is eliminated from the raw biogas with a PSA process, pressure swing absorption, which uses absorbent matrices, alternatively it can be eliminated with a water scrubbers.
As is clear, the production of biogas from plant biomass does not have a negative environmental impact. Much more controversial is the question of the derivation of raw materials: where does the plant biomass used to produce biogas come from?
The production of biogas is sustainable only when it has a short supply chain, that is when the raw material is self-produced by the same farm that deals with the production of biomethane; alternatively, the biomass should be of local origin otherwise, the energy spent on the transport of biomass should also be considered in the energy balance.
Just as seen for the biofuel, also for the production of biogas, the use of raw materials collected from dedicated crops is very controversial, above all because too often the corn crops (from which the biomass for the production of biomethane is obtained) are very far from the plant of production.
In the ideal, theagroenergyshould exploitbiomassdestined for landfill (to the organic fraction). In this case we could talk about energy from organic waste, very convenient both economically and from an environmental point of view. For further information, please read the page:energy from waste.
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