1. Energy crop production on metal contaminated land Sofie De Moor Prof. Erik Meers, Prof. Filip Tack Dr. Evi Michels

2.  Cultivated for energy production  For example:  Energy maize for anaerobic digestion to biogas  Energy maize for fermentation to ethanol  Rapeseed for extraction and transesterification to biodiesel  Short rotation coppice for combustion as wood chips Energy crops

4.  Ethics? Food versus energy

5.  Energy crops that are not subject to the food vs energy debate  How?  Food wastes  Agricultural wastes  Cover crops, winter crops  Grass from roadside verges or grassland management  Greenery cuttings  Unused or marginal lands  Contaminated lands Low-impact biomass

6.  Campine region: historical metal contamination  700 km² contaminated (BE + NL)  Test site Lommel: cadmium (Cd) and zinc (Zn)  Previous research: phytoremediation Campine region

7.  Metals? => phytoextraction  Different extraction capacity for different plants  Hyperaccumulators e.g. sunflower (Zn)  Excluders e.g. grass species  Advantages  Non-invasive  In-situ  Not expensive  Challenges  Slow soil remediation  What to do with the contaminated biomass Phytoextraction

8.  Focus = valorization  Longer-term effect = soil remediation  Valorization  Materials: chemicals, papermaking, fibers, hardboards…  Energy: combustion, gasification, anaerobic digestion, biodiesel, bio-ethanol, pyrolysis, torrefaction… Phytoattenuation

9.  Phytoattenuation with energy crops on metal contaminated land  Studied aspects:  Biomass yield, growth capacity + optimization  Metal extraction  Metal mobility in the soil  Energetic valorization: process choice, fate of the metals  End-product PhD research

10.  5 poplar clones, 8 willow clones  Lommel: Cd and Zn  Study in the second growth cycle  Outcome:  Modelling of biomass yield  Different biomass yields  Different metal uptake  Metal concentration in different plant parts  Leaf harvest = indispensable condition for soil remediation Clonal variation in short rotation coppice (SRC)

11.  Set-up: pot experiment with soil form Lommel  Fertilized with  Compost  Pig manure (crude)  Digestate (crude, thick and thin fraction)  Struvite (MgNH 4 PO 4 ·6H 2 O)  Acid scrubber water ((NH 4 ) 2 SO 4 )  Calcium carbonate (CaCO 3 )  Planted with rapeseed  Soil and plant analysis Influence of soil amendments/fertilizers on Cd and Zn mobility

12.  Influence of soil amendments/fertilizers on metal mobility  Influence on plant uptake  Influence on plant growth  Aim for phytoattenuation: improved biomass yield, no induced metal leaching Influence of soil amendments/fertilizers on Cd and Zn mobility

13.  No significant influences of the amendments on the biomass production could be found. However field experiments or longer experiments could confirm the trends: increased yield with the liquid fraction of digestate and struvite.  Stabilisation of the metals was observed when compost, crude manure, digestate, the thick fraction of digestate and calcium carbonate were used.  A decreased metal extraction rate was found for treatments with acid scrubber water and calcium carbonate. The main cause was a decreased biomass production for acid scrubber water, while calcium carbonate showed a decreased extraction rate due to the stabilisation of the metals.  Take home: soil amendments can have a significant effect on metal availability and extraction rate. Their use on contaminated fields should thus be carefully considered to avoid unwanted side-effects like metal leaching. Influence of soil amendments/fertilizers on Cd and Zn mobility

14.  Slow pyrolysis: heating without oxygen  Products: energetic gas (including condensable fraction) and biochar  Hydrothermal carbonization: hot water + pressure  Products: energetic gas and hydrochar  Research questions:  Fate of the metals?  Safe use/disposal of end-product? Energetic conversion

15.  Energy crops on metal contaminated land  Avoid food vs energy debate  Contributes to achieve 2020 goals of EU  Whole-chain approach  Soil  Biomass yield  Fate of the metals during valorization  Safe end-product use Take home

16. This work has been funded by the European Commission under the Interreg IVb Project “Accelerating Renewable Energies through valorization of Biogenic Organic Raw Material (Arbor)”. Thank you for your attention!