Grass from municipal roadside verges is a potential yet largely unused resource for bioenergy recovery, which is mainly due to its unknown elemental composition. Therefore, we measured the concentration of 16 elements (Ca, K, Mg, N, Na, P, S, Al, Cd, Cl, Cr, Cu, Mn, Pb, Si and Zn) in a material from the city of Kassel harvested in different management intensities. The element concentrations were mainly close to reference values of agricultural or nature conservation grassland and usually within the range of literature data. Concentrations of most elements, including heavy metals, were below limiting values. Only N and Cl concentrations in the raw material exceeded the limiting values for combustion, but washing and dewatering of the biomass with the "integrated generation of solid fuel and biogas from biomass" technique resulted in concentrations in the press cake well below the limiting values. Considering the element concentrations of grass from urban roadside verges, utilisation for energy recovery may be possible, provided an appropriate technology is applied.

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Poplar clones were studied for their phytoextraction capacity in the second growth cycle (6-year growth) on a site in the Belgian Campine region, which is contaminated with Cd and Zn via historic atmospheric deposition of nearby zinc smelter activities. The field trial revealed regrowth problems for some clones that could not be predicted in the first growth cycle. Four allometric relations were assessed for their capacity to predict biomass yield in the second growth cycle. A power function based on the shoot diameter best estimates the biomass production of poplar with R values between 0.94 and 0.98. The woody biomass yield ranged from 2.1 to 4.8 ton woody Dry Mass (DM) ha y. The primary goal was to reduce soil concentrations of metals caused by phytoextraction. Nevertheless, increased metal concentrations were determined in the topsoil. This increase can partially be explained by the input of metals from deeper soil layers in the top soil through litterfall. The phytoextraction option with poplar short rotation coppice in this setup did not lead to the intended soil remediation in a reasonable time span. Therefore, harvest of the leaf biomass is put forward as a crucial part of the strategy for soil remediation through Cd/Zn phytoextraction.