Agroecological aspects of bioenergy

Le résumé fourni par la source

Bioenergy occupies a prominent place in debates on the global energy transition, yet its role requires critical reappraisal. Despite the intuitive appeal of biomass as a renewable carbon source, current energy yields per unit area and energy return on investment (EROI) indicate that bioenergy cannot serve as a system-forming foundation for the energy sector; rather, it should be regarded as a supplementary instrument, useful in certain applications but unable to deliver the scale and efficiency of fossil fuels or of other renewables, notably solar and wind. An analysis of greenhouse-gas emissions in the pre-industrial and industrial eras from AFOLU (Agriculture, Forestry and Other Land Use) and from fossil-fuel use indicates that the climate neutrality of bioenergy is not an inherent property but is shaped by ecological context and management practices. Within these constraints, particular avenues merit attention. Microalgae exhibit exceptionally high biomass productivity per unit area, yet their low technological readiness and unfavorable energy balances currently limit their broad deployment as a carbon feedstock for energy and chemical industries. Lignocellulosic resources remain the most realistic option for large-scale integration, provided conversion processes are optimized and land use is managed sustainably. Additional promising directions include coupling bioenergy with phytoremediation, where plants both accumulate contaminants and produce biomass that can be valorized for energy. Bioengineering approaches to develop plants that combine hyperaccumulation capacity, enhanced contaminant tolerance, deep and branched rooting systems, and high biomass yields are emphasized. The cultivation of perennial herbaceous energy crops and short-rotation woody coppice on marginal lands can contribute to soil carbon sequestration and improved soil quality. Energy recovery from biowaste is a further application area, but it requires a careful balance between energy extraction and the return of nutrients to soils. In conclusion, bioenergy should not be considered a universal substitute for fossil fuels; rather, it is a context-dependent, auxiliary tool that can generate synergies with ecosystem services such as soil restoration and the utilization of biowaste.

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