Title:
Thermochemical Potential of Low ILUC Risk Grasses: the Case Study of Giant Reed Cultivated in Heavy Metal Contaminated Soils
Author(s):
Gomes, L., Costa, J., Moreira, J., Mendes, B., Santos, F., Fernando, A.L.
Document(s):
Paper
Abstract:
Dedicated crops represent an important feedstock to decarbonise the energy sector and to meet the no net emissions of greenhouse gases by 2050, as set by the European Green Deal. Indeed, dedicated crops are renewable and sustainable feedstocks for energy and materials, associated with energy supply diversification, greenhouse gas savings and mitigation of problems related with materials biodegradability. However, the greenhouse gas performance of biomass to energy can be negatively impacted by Indirect land use change (ILUC) effects. In fact, the increasing demand for biomass, associated with the technological development and the mandatory renewable energy targets, increases the competition for land, threatening food security. Consequently, cultivation of industrial crops on contaminated land is repeatedly suggested as an approach to minimize land use competition with food crops and land use change controversies. Most industrial crops are considered tolerant to contaminated soils and together with the production of bioenergy or biomaterials, the produced biomass may even have a soil decontamination action. But, the contamination of the soils may hinder the technological performance of the bioenergy production chain. Despite the potential amount of energy content, yields are reduced, and biomass characteristics may change, affecting processes and equipment’s chosen. Therefore, this work aimed to study the effects of soils contaminated with heavy metals (namely Zn, Pb and Cu contaminated soils) on the thermochemical potential of giant reed (Arundo donax), considering this crop versatility, bioenergy and phytoremediation potential. Results indicate that all contaminants, reduced significantly the yields by 25-45%. Zinc was the metal that reduced yields the least. Yet, regarding the energetic potential of the biomass, results indicate that the contamination did not interfere with the HHV of Arundo donax. Nonetheless, when considering the estimated energy potential per ha, results indicate that Zn soils present a similar potential to control soils, followed by copper soils. Lead contaminated soils showed the lowest energy potential production per area, once the yields reduced by 45%, compared with control soils. Considering biomass quality, results indicate that the ash content was similar for all the biomasses from control and contaminated soils, although showing a trend to an increment due to the contamination of the soils. In terms of nitrogen content, lead and copper soils, induced a higher nitrogen content of the biomass. The contamination with Zn did not affect the nitrogen content of the biomass. Considering the biomass quality and the HHV content, pros and cons of the exploitation of this grass via different thermochemical processes was investigated. The accumulation of metals in the aerial biomass and its potential damage to pipes and furnaces was addressed also. A preliminary analysis suggests that techniques such as fixed bed combustion heat (combustion), circulating fluidized bed for syngas production (gasification), and pyrolysis plus boiler for heat and steam; are good options to produce energy from giant reed cultivated in heavy metals contaminated soils. This choice reflects, their less restrictive usage requirements and higher maximum ash/nitrogen concentration allowable. An in depth analysis is being performed to certify these preliminary findings.
Keywords:
energy crops, heavy metals, Arundo donax L., phytoremediation, marginal soils, low ILUC crops
Topic:
Biomass Conversion for Bioenergy
Subtopic:
Biomass pretreatment for solid fuels and production of intermediates
Event:
30th European Biomass Conference and Exhibition
Session:
4CO.9.3
Pages:
600 - 603
ISBN:
978-88-89407-22-6
Paper DOI:
10.5071/30thEUBCE2022-4CO.9.3
Price:
FREE
