Bridging the gap between phytoremediation solutions on growing energy crops on contaminated lands and clean biofuel production

Project Information

GOLD

Grant agreement ID: 101006873

DOI

10.3030/101006873

Project closed

EC signature date 16 April 2021

Start date 1 May 2021

End date 30 April 2025

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost

€ 3 710 950,00

EU contribution

€ 2 999 950,00

Coordinated by

CENTRE FOR RENEWABLE ENERGY SOURCES AND SAVING FONDATION
Greece

Periodic Reporting for period 3 - GOLD (Bridging the gap between phytoremediation solutions on growing energy crops on contaminated lands and clean biofuel production)

Reporting period: 2024-05-01 to 2025-04-30

Summary of the context and overall objectives of the project

The GOLD project developed an integrated approach to transform contaminated land into a resource for both soil remediation and advanced biofuel production. Across Europe and China, field trials tested sorghum, miscanthus, hemp and switchgrass for phytoremediation of heavy metal–contaminated soils. Sorghum emerged as the most effective crop, combining high biomass yields with strong uptake of cadmium, lead and zinc, particularly when supported by humic/fulvic acids and mycorrhizal fungi.
Two thermochemical conversion routes were validated: high-temperature gasification with syngas fermentation, and autothermal pyrolysis with catalytic upgrading and Fischer–Tropsch synthesis. In both cases, heavy metals were successfully concentrated in solid residues (slag or biochar), ensuring clean liquid biofuel production. Integrated environmental, economic and social assessments identified sorghum-based value chains as the most promising, demonstrating greenhouse gas savings and soil restoration potential. While further cost optimisation and policy support are needed, GOLD confirms the feasibility of coupling phytoremediation with sustainable bioenergy production in line with European Green Deal objectives.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the 1st reporting period the following activities had been accomplished per project pillar.
The first step was to compare different management practices for improved phytoremediation. In total 7 contaminated sites had been selected and characterized. Soil from each contaminated site was collected and used for pot trials to select best performing practices per crop and contaminated site. Then the best phytoremediation practices per partner had been applied on pilot field trials (around 0.3 ha in each site). In each site field trials included three lignocellulosic crops had been established. Due to the delayed arrival of switchgrass seeds, all partner apart the coordinator carried out field trials with miscanthus, sorghum and hemp. By the end of the 1st reporting period the majority of the field trials had been harvested, characterized and analysed. It was planned how the distribution of the harvested biomass will be done to the partners running the conversion trials to clean liquid biofuels.
Clean biofuels will be produced using the contaminated feedstock produced in pilot trials of pillar 1.The 1st conversion starts with biomass pre-treatment, where three options will be tested: Torwash (TNO), torrefaction (TNO) and slow pyrolysis (RE-CORD). The pre-treated solids will feed the entrained flow gasifier (at temperatures of 1300-1500°C), where the metal(loid)s will be collected in a concentrated form as slag or ash and the produced syngas after its cleaning will be used for a fermentation step to produce clean liquid biofuels (alcohols). The humic acids derived from the Torwash will be sent to pillar 1 in order to be tested as biostimulants in the 2nd half of the project. The 2nd conversion route is being based on an autothermal pyrolysis and FT synthesis to fuels, led by the Canadian partners (UdeS). Here, the pollutant recovery will take place via the pyrolysis char. Synergies between the two routes have been scheduled. The first route had been organished by the European partners and the second by the Canadian one.
The third pillar organise the bridging the gap between phytoremediation and clean liquid biofuels production using the contaminated feedstock from the contaminated sites of the project. The first action was to set the boundaries and definitions for the sustainability assessment of the GOLD value chains. In parallel the contaminated sites of the project had been mapped. At the last phase of the project decontaminated projections will be done (a tool will be developed). Before the end of the 1st reporting period the setting of the value chains had been started having as milestone to be selected and modelled up to 16 value chains.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The expected results per project pillar are listed below:
To stimulate the selected high-yielding energy crops and to increase their phytoremediation capacity using two parallel ways: a) to increase their biomass production and/or b) to increase their inorganic bioaccumulation capacity and/or to increase their biodegradation ability of organic pollutants. Apart from these, a number of environmental services will be stimulated by cultivating energy crops on polluted sites resulting in mitigation of the environmental and health risks arising from these soils via (a) preventing erosion through vegetation cover, (b) reducing leaching, and (c) immobilizing the contaminants. In addition, soil carbon sequestration and organic matter will increase, soil biodiversity will be promoted and soil structure will be protected. Last but not least, the exposure root of humans to pollutants will be reduced with beneficial effects on their health and well-being. By producing feedstock from unexploited contaminated lands will also increase the income for local farmers and population, will create new jobs, new knowledge and new skills for young people and women and will stimulate the development of innovative entrepreneurship.
To produce clean liquid biofuels by following two conversion routes: The first conversion route aims to investigate the removal of certain metal(loid)s in the pretreatment technologies and to study the performance of the less-contaminated fuels in the EFG at laboratory- and pilot-scale with a focus on the fate of metal(loid)s in slag or fly ash. The aim is to reduce easily evaporated metal(loid)s, such as Pb and Cd, in the pretreatment and the remainder primary such as Cu and Ni during the gasification process through incorporation into slag. The produced syngas will be provided for the downstream fermentation process in bottled form. The ambition of GOLD is to investigate the syngas fermentation in a lab-scale bioreactor system. Biofuels like ethanol, 1-butanol, 2,3-butandiol and 1-hexanol (products are specific for individual acetogens) are produced and the metabolisms examined for contaminations. A (continuous) lab-scale gas fermentation process at well-defined reaction conditions is established for efficient production of biofuels.
To develop and model optimized value-chains where selected energy crops will be grown on selected contaminated sites for the dual purpose of biofuel production and land decontamination, thus achieving a win-win solution. It will fill research gaps in the value chains, from the cultivation phase till the clean biofuel production. In addition, it will apply existing spatially explicit models that will assess the long term changes in contaminant levels in soil, as well as provide estimates of the regional production capacity of biomass to be used for biofuel production.

Poster presenting the key GOLD actions