The global energy challenge: second-generation feedstocks on marginal lands for a sustainable biofuel production.

As the global population continues to grow, so does the demand for energy resources. As a consequence, using renewable energy sources as an alternative to fossil fuels has become mandatory to reduce the environmental footprint of the energy sector. Biofuels represent a renewable source of energy, but their production has raised concerns regarding their possible impacts on food security. Indeed, the current biofuel production primarily relies on food crops and arable lands. That is in conflict with the need to produce more food for an increasing world population. To overcome this incongruence, it is proposed to cultivate second-generation biofuel crops on marginal lands, since this option could bring benefits in terms of food security and sustainability. Based on the scientific literature, we addressed the following critical points: (i) whether marginal land worldwide can be considered a reasonable alternative to arable lands for biofuel production; (ii) evaluate the sustainability of biofuel production with respect to unintended negative consequences of crop cultivation such as indirect land use change, social insecurity and loss of biodiversity. It was concluded that the amount of land for growing plants can possibly sustain both food and biofuel production if marginal land are included. In this context, it becomes a priority to select biofuel crops with high productivity on marginal lands and pronounced resilience and adaptability traits. Underutilized crops such as Carthamus tinctorius, Ricinus communis, Brassica carinata, Camelina sativa etc. may fit the purpose and may represent a valuable alternative to first-generation feedstock because they require minimal agronomical input. Using underutilized crops on marginal lands can also provide important ecological services, including improving soil fertility and water regulation, increasing biodiversity and reducing soil erosion. To fully exploit this option, it will be critical to calibrate plant growth models to estimate the potential biofuel production on marginal land from second-generation feedstock and to create tools for a more rational management of this land. [ABSTRACT FROM AUTHOR]