A comparison of isoprene and monoterpene emission rates from the perennial bioenergy crops short-rotation coppice willow and Miscanthus and the annual arable crops wheat and oilseed rape

Biogenic volatile organic compounds (BVOC) emissions from bioenergy crops may differ from those of conventional crops. We compared emission rates of isoprene and a number of monoterpenes from the lignocellulosic bioenergy crops short-rotation coppice (SRC) willow and Miscanthus, with the conventional crops wheat and oilseed rape. BVOC emission rates were measured via dynamic vegetation enclosure and GC-MS analysis approximately monthly between April 2010 and August 2012 at a location in England and from SRC willow at two locations in Scotland. The largest BVOC emission rates were measured from willow in England and varied between years. Isoprene emission rates varied between <lod and 1960 lg g 1 h . Of the monoterpenes detected from willow, a-pinene emission rates were highest (<lod to 803 lg g 1 h ), followed by <lod to 268 lg g 1 h 1 for d-3-carene, <lod to 125 lg g 1 h 1 for b-pinene and <lod to 80.4 lg g 1 h 1 for limonene. BVOC emission rates measured in Scotland were much lower. Low emission rates of isoprene and a-pinene were measured from Miscanthus in 2010 (<lod to 6.42 lg g 1 h 1 and <lod to 20.8 lg g 1 h , respectively) but were not detected in subsequent years. Emission rates from wheat of isoprene were negligible but relatively high for monoterpenes (<lod to 422 lg g 1 h 1 and <lod to 104 lg g 1 h 1 for a-pinene and limonene, respectively). No significant emission rates of BVOCs were measured from oilseed rape. The measured emission rates followed a clear seasonal trend. Crude extrapolations based solely on data gathered here indicate that isoprene emissions from willow could correspond to 0.004–0.03% (UK) and 0.76–5.5% (Europe) of current global isoprene if 50% of all land potentially available for bioenergy crops is planted with willow.