Agro-Forestry and Agri-Pv Technologies using Bamboo, Sunflowerand Indian Mustard to Regenerate Nature in Post-Mining Areasassociated with Aspen Plus Simulation of Hydrogen Production

Abstract

The management of soil contaminated with heavy metals, especially that ofabandoned mining sites, represents a major challenge for environmentalprotection. Among the possible solutions, phytoremediation offers promisingprospects for post-mining restoration. However, this option is limited by the needfor long-term monitoring and the considerable potential of inedible biomass. Thisstudy aimed to combine agroforestry and Agri-PV systems to regeneratedegraded land while producing green hydrogen from solar energy andbiohydrogen from harvested biomass. To achieve this, a one-hectare copper mining site in Zambia was divided into twoplots: one for agroforestry and the other for Agri-PV. Moreover, three plants,sunflower, Indian mustard and bamboo, were theoretically evaluated for theirphytoextraction and phytostabilisation efficiency. Thereby, Aspen Plus was usedto simulate the production of green hydrogen by alkaline water electrolysis fromsurplus electricity from the Agri-PV system, after meeting irrigation needs. Inaddition, biohydrogen production was modelled with the same software frombiomass harvested at the contaminated site, using downflow gasification withenhanced tar and char cracking. The results revealed that sunflower is the most suitable for phytoextraction,thanks to its high translocation of metals to the aerial parts (TF > 1). On theother hand, mustard and bamboo showed better phytostabilisation capacity, withgreater accumulation in the roots. Bamboo stood out for its high efficiency inabsorbing and removing heavy metals. After one season, all metals were reducedto acceptable levels, except for copper and cobalt, which would require anadditional two and nine years, respectively, to be completely remediated. Energysimulations yielded 7,923.3 kg of green H2/year and 284.3 kg of bio H2/year, for atotal of 8,207.5 kg of H2/year for the two systems combined. The theoretical model designed for the restoration of abandoned mining sitesshows particular promise for the ecological rehabilitation of soils contaminatedwith heavy metals. However, experimental validation remains an essential stepin confirming its effectiveness and demonstrating its practical relevance, pavingthe way for its actual application in the field.