Environmental impacts of future bioenergy pathways: the case of electricity from wheat straw bales and pellets

This study presents the life cycle assessment of electricity generation from straw bales and pellets. Straw is the most abundant biomass residue in Europe and its use for energy purposes is promoted on the premise of high greenhouse gas savings. This assumption has delayed the study of sustainability of straw‐fired systems on a broader sense and the literature on the topic is almost absent. This study uses data from specific literature and emissions inventories to model a number of straw pathways. The plant modeled is a medium‐scale straw‐fired power plant of 50 MWth capacity. The results show that electricity from straw‐fired power plants can indeed realize high greenhouse gas savings compared both with existing coal plants and with the European electricity mix. The savings are in the range 70–94%. The influence of the geographical origin of straw is analyzed by using datasets for the cultivation of wheat in five different European countries. The highest emissions are recorded for the case of straw from Spain due to the small yields, whereas cultivation processes in United Kingdom and the Netherlands show high environmental impacts due to the high level of fertilization. Other environmental impacts are evaluated, such as acidification potential, eutrophication, particulate matter emissions, and photochemical ozone formation. The bioenergy system scores worse than the current European electricity mix for all the categories. However, it is important to notice that in Spain and United Kingdom the straw system shows lower impacts compared with the local average coal electricity. Finally, the study investigates the ‘break‐even’ distance at which the higher emissions from the pellets production are paid off by the saved emissions in their transport compared with the bales. The results show that no reasonable break‐even distance exists for road transport, whereas advantages for pellets are evident in any configuration for transoceanic transport.

[1]  Benoit Gabrielle,et al.  Life-cycle assessment of straw use in bio-ethanol production: a case study based on biophysical modelling. , 2008 .

[2]  Peter C. Flynn,et al.  Processing of Straw/Corn Stover: Comparison of Life Cycle Emissions , 2008 .

[3]  Gerald Rebitzer,et al.  IMPACT 2002+: A new life cycle impact assessment methodology , 2003 .

[4]  Philip Peck,et al.  Organisational frameworks for straw-based energy systems in Sweden and Denmark , 2012 .

[5]  N. Scarlat,et al.  Assessment of the availability of agricultural crop residues in the European Union: potential and limitations for bioenergy use. , 2010, Waste management.

[6]  S. Vassilev,et al.  An overview of the chemical composition of biomass , 2010 .

[7]  M. Hupa,et al.  Combustion Characteristics of Biomass Residues and Biowastes: Fate of Fuel Nitrogen , 2010 .

[8]  Francesco Cherubini,et al.  Crop residues as raw materials for biorefinery systems - A LCA case study , 2010 .

[9]  Denis Cormier,et al.  Life cycle emissions and cost of producing electricity from coal, natural gas, and wood pellets in Ontario, Canada. , 2010, Environmental science & technology.

[10]  J. Guinée.  Handbook on life cycle assessment — operational guide to the ISO standards , 2001 .

[11]  Sudhagar Mani,et al.  A systems analysis of biomass densification process , 2005 .

[12]  Staffan Melin,et al.  An environmental impact assessment of exported wood pellets from Canada to Europe. , 2009 .

[13]  Jacopo Giuntoli,et al.  Quantitative and Kinetic Thermogravimetric Fourier Transform Infrared (TG-FTIR) Study of Pyrolysis of Agricultural Residues: Influence of Different Pretreatments , 2009 .

[14]  Other,et al.  Global guidance principles for Life Cycle Assessment (LCA) databases: a basis for greener processes and products , 2011 .

[15]  Brian Grant,et al.  Crop residue removal and fertilizer N: Effects on soil organic carbon in a long-term crop rotation experiment on a Udic Boroll , 2010 .

[16]  Kuratorium fur Technik und Bauwesen in der Landwirtschaft Darmstadt.  Cooperation in livestock farming. A discussion from the KTBL. , 1980 .

[17]  Øyvind Skreiberg,et al.  Experimental investigation on NOx reduction by primary measures in biomass combustion: straw, peat, sewage sludge, forest residues and wood pellets , 2012 .

[18]  Changsui Zhao,et al.  NO formation during agricultural straw combustion. , 2011, Bioresource technology.

[19]  F. M. Brouwer,et al.  The Use of Plant Protection Products in the European Union: The Economics of Farming , 1996 .

[20]  Amit Kumar,et al.  Development of energy and emission parameters for densified form of lignocellulosic biomass , 2011 .

[21]  Freek Kapteijn,et al.  Agglomeration in fluidized beds at high temperatures: Mechanisms, detection and prevention , 2008 .

[22]  Emmanuel G. Koukios,et al.  Physicochemical upgrading of agroresidues as feedstocks for energy production via thermochemical conversion methods , 2002 .

[23]  Roberto Dones,et al.  Life Cycle Inventories of Energy Systems: Results for Current Systems in Switzerland and other UCTE Countries , 2007 .

[24]  Rural Affairs,et al.  Defra , UK - Department for Environment Food and Rural Affairs , 2002 .

[25]  V. K. Verma,et al.  Agro-pellets for domestic heating boilers: Standard laboratory and real life performance , 2012 .

[26]  X. Bi,et al.  Environmental footprints of British Columbia wood pellets from a simplified life cycle analysis , 2012, The International Journal of Life Cycle Assessment.

[27]  M. Stumborg,et al.  Quantifying Straw Removal through Baling and Measuring the Long-Term Impact on Soil Quality and Wheat Production , 2009 .

[28]  Ingwald Obernberger,et al.  The Pellet Handbook: The Production and Thermal Utilization of Biomass Pellets , 2010 .

[29]  Martin Junginger,et al.  The international logistics of wood pellets for heating and power production in Europe: Costs, energy‐input and greenhouse gas balances of pellet consumption in Italy, Sweden and the Netherlands , 2010 .

[30]  J. Werther,et al.  Combustion of agricultural residues , 2000 .

[31]  Anders Hammer Strømman,et al.  Life cycle assessment of bioenergy systems: state of the art and future challenges. , 2011, Bioresource technology.