Comparing energy crops for biogas production e Yields, energy input and costs in cultivation using digestate and mineral fertilisation Charlott Gisse ´n a , Thomas Prade a , Emma Kreuger b , Ivo Achu Nges b , Ha ˚ kan Rosenqvist c , Sven-Erik Svensson a , Mikael Lantz d , Jan Erik Mattsson a , Pa ˚l Bo ¨rjesson d , Lovisa Bjo ¨rnsson b,d, * a Department of Biosystems and Technology, Swedish University of Agricultural Sciences, PO Box 103, SE-23053 Alnarp, Sweden b Department of Biotechnology, Lund University, PO Box 124, SE-221 00 Lund, Sweden c Pra ¨stva ¨gen 5, SE-268 73 Billeberga, Sweden d Environmental and Energy Systems Studies, Lund University, PO Box 118, SE-221 00 Lund, Sweden article info Article history: Received 2 October 2012 Received in revised form 24 March 2014 Accepted 25 March 2014 Available online 17 April 2014 Keywords: Methane yield Biogas feedstock costs Primary energy input Digestate Energy crop yield abstract Analyses of six crops grown in southern Sweden for biogas production (hemp, sugar beet, maize, triticale, grass/clover ley, winter wheat) showed varying performance regarding methane yield per hectare and energy input and costs in the production and supply of crops as biogas feedstock. The highest biomass and biogas yield was observed for sugar beet. Crops with lower risk of negative environmental impact in cultivation, such as ley and hemp, produced less than half the methane energy yield per hectare. Triticale, also having less risk of negative environmental impact, gave an energy yield similar to that of winter wheat grain and maize. Replacing most of the mineral fertiliser with biogas digestate did not, with the excep- tion for hemp, influence crop yields per hectare, but energy input in cultivation decreased by on average 34% for the six crops tested. For hemp and sugar beet the biogas feedstock costs for the freshly harvested crop per GJ methane were close to that of the economic reference crop, winter wheat grain. For maize, beet tops and first and second year ley, the feedstock costs were lower, and for triticale much lower. When ensiled crops were used for biogas the feedstock costs increased and only those of triticale silage remained slightly lower than the cost of dried wheat grain. However, all feedstock costs were so high that profitable biogas production based solely on ensiled crops would be difficult to achieve at present Swedish biogas sales prices. ª 2014 Elsevier Ltd. All rights reserved. * Corresponding author. Environmental and Energy Systems Studies, Lund University, PO Box 118, SE-221 00 Lund, Sweden. Tel.: þ46 46 222 8324; fax: þ46 46 222 8644. E-mail addresses: charlott.gissen@slu.se (C. Gisse ´ n), thomas.prade@slu.se (T. Prade), emma.kreuger@biotek.lu.se (E. Kreuger), nges. ivo_achu@biotek.lu.se (I.A. Nges), hak.rosenqvist@telia.com (H. Rosenqvist), sven-erik.svensson@slu.se (S.-E. Svensson), mikael.lantz@ miljo.lth.se (M. Lantz), jan.erik.mattsson@slu.se (J.E. Mattsson), pal.borjesson@miljo.lth.se (P. Bo ¨ rjesson), lovisa.bjornsson@miljo.lth.se (L. Bjo ¨ rnsson). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy 64 (2014) 199 e210 http://dx.doi.org/10.1016/j.biombioe.2014.03.061 0961-9534/ª 2014 Elsevier Ltd. All rights reserved.