Use of Heavy Metals Contaminated Industrial Hemp (Cannabis Sativa L.) for Bioenergy Production

Worldwide human-related activities have caused the heavy metals contamination of large areas. Nowadays, different soil remediation activities are undertaken to ameliorate contaminated soils. Among the various soil reclamation technologies, phytoremediation is considered one of the most cost-effective and eco-friendly practices, where the use of industrial hemp (Cannabis sativa L.) has shown promising remediation potential. However, the proper management, disposal or valorization of the contaminated biomass represents a key point for the sustainability of the entire remediation process. This study aims to assess and evaluate the energy and environmental burdens of using heavy metals contaminated industrial hemp for bioenergy production. Specifically, the cumulative energy demand and climate change impact categories were selected from the life cycle assessment methodology. The data sample comes from real heavy metals contaminated sites, located in Sardinia (Italy), which have been subjected to soil reclamation by growing industrial hemp. The energy and environmental impacts of using the contaminated biomass as an energy resource were then modeled from a “field to wire” approach. The designed scenario analyzed the processes associated with field level, transportation, combustion of the contaminated biomass in a power plant and ash disposal. The results obtained underlined that the field level represents the main impacting process, while the electricity produced from the contaminated biomass allowed to save about 32 GJ ha−1 of primary energy while avoiding emissions of 642 kg CO2e per phytoremediated hectare. The study highlights that the use of heavy metals contaminated biomass for bioenergy production, improved the sustainability of soil reclamation activities turning unproductive lands into productive areas.