Production of energy crops in heavy metals contaminated land: opportunities and risks

An increasing global awareness that the supply and security of petroleum-based materials is diminishing, coupled with environmental concerns related to climate change, water availability, and soil degradation, has increased demand for more renewable, diversified, and sustainable systems, of which biomass resources are one of the pillars. Yet, the demand for biomasses may increase sharply, thus increasing the risk of conflicts on land use due to competition for food and feed. Hence, segregating the growth of dedicated biomass crops on contaminated land is considered a suitable option to overcome these conflicts. In fact, most of energy crops are considered tolerant to soil contamination, and the cultivation of those crops can be considered an approach to restore or attenuate and stabilize contaminated soils while bringing additional revenue to owners. But, is it sustainable to produce energy crops in contaminated land? Yields and biomass quality can be affected by the contamination, reducing the energy and the greenhouse savings and compromising its economic exploitation. Nonetheless the production of energy crops on contaminated land may contribute also to improve the quality of soil and the biological and landscape diversity. In this context, studies on the production of energy crops in heavy metals contaminated land are reviewed, taking into account environmental, economic and socio-economic aspects. In the end, a critical assessment of the literature is made and opportunities and risks are pointed out.