Coupling sorghum biomass and wheat straw to minimise the environmental impact of bioenergy production. (15th June 2017)

• Record Type: Journal Article
• Authors: Serra, P.; Giuntoli, J.; Agostini, A.; Colauzzi, M.; Amaducci, S.
• Is Part Of: Journal of cleaner production. Volume 154(2017)
• Page Start: 242
• Page End: 254
• Publication Date: 2017-06-15
• Subjects: Sorghum bicolor -- GHG emissions -- Environmental impact -- Life cycle assessment -- EROEI -- Indirect land use change; AP Acidification Potential -- EROEI Energy Return On Energy Investment -- EU European Union -- FFC Fossil Fuel Comparator -- FWE Freshwater Eutrophication -- GHG Greenhouse Gases -- GWP Global Warming Potential -- (I)LUC (Indirect) Land Use Change -- LCA Life Cycle Assessment -- LCI Life Cycle Inventory -- ME Marine Eutrophication -- NMVOC Non Methanic Volatile Organic Carbon -- NG Natural Gas -- PM Particle Matter -- POFP Photochemical Ozone Formation Potential -- RED Renewable Energy Directive -- SM Supplementary Material -- SNCR Selective Non-Catalytic Reduction -- SOC Soil Organic Carbon -- SSF Storage Satellite Facility -- JRC Joint Research Centre; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2017.03.208
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: The reform of the European sugar market in 2006 paved the way for the development of new agricultural value chains in the Po Valley (Italy). A value chain based on the use of biomass sorghum ( Sorghum bicolor (L.) Moench) to produce electricity in a medium-scale power plant was investigated. A Life Cycle Assessment was carried out to explore the environmental impact and energy performance of power generation from three biomass sorghum genotypes characterized by different earliness (early, medium-late and late) in the Po Valley (Italy). To fully cover the plant needs, sorghum was complemented by winter wheat straw. Productivity and losses of sorghum for the past 39 years as simulated inSerra et al. (2017) were used to produce a probability distribution of environmental impacts. Soil organic carbon change relative to the straw removal and sorghum incorporation in soil as well as indirect land use change CO2 emissions for the substitution of sugar crops with energy crops were also accounted for. To test the influence of the assumptions an extensive sensitivity analysis over several parameters was performed. The lowest average GHG emissions (68.9 g CO2eq. MJ −1 ) were achieved with the late genotype while medium-late and early genotypes emitted 73.5 g CO2eq. MJ −1 and 76.8 g CO2eq. MJ −1, respectively. Despite the conservative assumptions, the bioenergy system contributed on average 47.7% less GHG than a natural gas power plant. In the lowest productivity years the sorghum based energy system emitted 52% less GHG than the Italian electricity mix. Overall, when harvesting and bailing failed due to unfavourable weather conditions, the lowest GHG emissions were found, thanks to the increased replacement of sorghum with straw. In fact, soil incorporation of sorghum biomass resulted in more nutrients added to the soil than with incorporation of wheat straw. Considering that GHG emissions decreased linearly when sorghum biomass yield increased, the highest reductions of GHG were found with late genotypes, that produced the highest yields. The lowest GHG emissions were found when harvesting failed, as the fertilizer debit of straw is lower than the fertilizer credit of sorghum. However, since carbon and nutrients storage in the soil is not rewarded monetarily, this option will not correspond to an optimal profit as the risk of failures are highest with late genotype. All other environmental impacts assessed were higher for the sorghum based system than for the fossil alternatives. It was found that the presence of DeNOx SNCR (Selective Non-Catalytic Reduction) technology achieved the expected mitigation of acidification potential and photochemical oxidant formation but at the expenses of an increased climate change impact, due to additional N2 O emissions. Highlights: Sorghum electricity on average emits 47.7% less GHG than natural gas. Non-GHG impacts of bioenergy systems are always higher than fossil alternatives. The late genotype showed on average the lowest GHG emissions. Haymaking failures mitigate global warming potential by increasing soil nutrients. DeNOx SNCR causes a trade-off between decreased NOx and increased N2 O and NH3 emissions.