LCA of energetic biomass utilization: actual projects and new developments—April 23, 2012, Berne, Switzerland

Introduction: In the last years, the use of biomass for energy purposes has been seen as a promising option to reduce the use of nonrenewable energy sources and the emissions of fossil carbon. However, LCA studies have shown that the energetic use of biomass also causes impacts on climate change and, furthermore, that different environmental issues arise, such as land use and agricultural emissions. While biomass is renewable, it is not an unlimited resource. Its use, to whatever purpose, must therefore be well studied to promote the most efficient option with the least environmental impacts. The 47th LCA Discussion Forum gathered several national and international speakers who provided a broad and qualified view on the topic. Summary of the topics presented in DF 47: Several aspects of energetic biomass use from a range of projects financed by the Swiss Federal Office of Energy (SFOE) were presented in this Discussion Forum. The first session focused on important aspects of the agricultural biogas production like the use of high energy crops or catch crops as well as the influence of plant size on the environmental performance of biogas. In the second session, other possibilities of biomass treatment like direct combustion, composting, and incineration with municipal waste were presented. Topic of the first afternoon session was the update and harmonization of biomass inventories and the resulting new assessment of biofuels. The short presentations investigated some further aspects of the LCA of bioenergy like the assessment of spatial variation of greenhouse gas (GHG) emissions from bioenergy production in a country, the importance of indirect land use change emissions on the overall results, the assessment of alternative technologies to direct spreading of digestate or the updates of the car operation datasets in ecoinvent. Conclusions: One main outcome of this Discussion Forum is that bioenergy is not environmentally friendly per se. In many cases, energetic use of biomass allows a reduction of GHG and fossil energy use. However, there is often a tradeoff with other environmental impacts linked to agricultural production like eutrophication or ecotoxicity. Methodological challenges still exist, like the assessment of direct and indirect land use change emissions and their attribution to the bioenergy production, or the influence of heavy metal flows on the bioenergy assessment. Another challenge is the implementation of a life cycle approach in certification or legislation schemes, as shown by the example of the Renewable Energy Directive of the European Unio

Life Cycle Inventories for the Nuclear and Natural Gas Energy Systems, and Examples of Uncertainty Analysis (14 pp)

Goal, Scope and Background: The energy systems included in the ecoinvent database v1.1 describe the situation around year 2000 of Swiss and Western European power plants and boilers with the associated energy chains. The addressed nuclear systems concern Light Water Reactors (LWR) with mix of open and closed fuel cycles. The system model ‘Natural Gas' describes production, distribution, and combustion of natural gas. Methods: Comprehensive life cycle inventories of the energy systems were established and cumulative results calculated within the ecoinvent framework. Swiss conditions for the nuclear cycle were extrapolated to major nuclear countries. Long-term radon emissions from uranium mill tailings have been estimated with a simplified model. Average natural gas power plants were analysed for different countries considering specific import/export of the gas, with seven production regions separately assessed. Uncertainties have been estimated quantitatively. Results and Discussion: Different radioactive emission species and wastes are produced from different steps of the nuclear cycle. Emissions of greenhouse gases from the nuclear cycle are mostly from the upstream chain, and the total is small and decreasing with increasing share of centrifuge enrichment. The results for natural gas show the importance of transport and low pressure distribution network for the methane emissions, whereas energy is mostly invested for production and long-distance pipeline transportation. Because of significant differences in power plant efficiencies and gas supply, country specific averages differ greatly. Conclusion: The inventory describes average worldwide supply of nuclear fuel and average nuclear reactors in Western Europe. Although the model for nuclear waste management was extrapolated from Swiss conditions, the ranges obtained for cumulative results can represent the average in Europe. Emissions per kWh electricity are distributed very differently over the natural gas chain for different species. Modern combined cycle plants show better performance for several burdens like cumulative greenhouse gas emissions compared to average plants. Recommendation and Perspective: Comparison of country-specific LWRs or LWR types on the basis of these results is not recommended. Specific issues on different strategies for the nuclear fuel cycle or location-specific characteristics would require extension of analysis. Results of the gas chain should not be directly applied to areas other than those modelled because emission factors and energy requirements may differ significantly. A future update of inventory data should reconsider production and transport from Russia, as it is a major producer and exporter to Europe. The calculated ranges of uncertainty factors in ecoinvent provide useful information but they are more indications of uncertainties rather than strict 95% intervals, and should therefore be applied carefull

Taking into account water use impacts in the LCA of biofuels: an Argentinean case study

Purpose: The assessment of biofuels has until now mainly focused on energy demand and greenhouse gas emissions. Only little attention has been given to other impacts, although the general importance of water use for the life cycle assessment (LCA) of agricultural products has been recognized in recent publications. The aim of this work is to assess in detail the water consumption along a biofuel production chain taking into account irrigation efficiencies, levels of water scarcity, and type of feedstock, and to integrate those results in a full LCA. Furthermore, we compare the results for biofuels from various feedstocks and regions with conventional petrol. Methods: We calculate the water consumption and overall life cycle assessment results in a case study for the production of methyl ester from irrigated and non-irrigated rapeseed. The results are compared with other irrigated and non-irrigated biofuels based on different feedstocks. Results and discussion: Water consumption in biofuel production chains based on non-irrigated crops does not vary greatly and is in the same range as for fossil fuel. In contrast, as a consequence of irrigation, agricultural water consumption dominates the overall results of all irrigated crops. Consequently, the level of water scarcity plays a key role for the LCA results. In our case study, the environmental impacts of methyl ester from irrigated rapeseed in a water-scarce region, measured in aggregated Eco-Indicator 99 scores, are almost doubled by water consumption. Variations in irrigation efficiency, however, are of little influence on the results, as the assessment method used here is based on consumptive water, which depends mainly on the evapotranspiration of the crop. Conclusions: The focus on greenhouse gas emissions of the main regulatory schemes neglects other relevant environmental impacts and may provide the wrong incentives. Water consumption may thus become a major concern, offsetting the benefits of biofuel use with respect to climate chang

Taking into account water use impacts in the LCA of biofuels: An Argentinean case study

Purpose: The assessment of biofuels has until now mainly focused on energy demand and greenhouse gas emissions. Only little attention has been given to other impacts, although the general importance of water use for the life cycle assessment (LCA) of agricultural products has been recognized in recent publications. The aim of this work is to assess in detail the water consumption along a biofuel production chain taking into account irrigation efficiencies, levels of water scarcity, and type of feedstock, and to integrate those results in a full LCA. Furthermore, we compare the results for biofuels from various feedstocks and regions with conventional petrol. Methods: We calculate the water consumption and overall life cycle assessment results in a case study for the production of methyl ester from irrigated and non-irrigated rapeseed. The results are compared with other irrigated and non-irrigated biofuels based on different feedstocks. Results and discussion: Water consumption in biofuel production chains based on non-irrigated crops does not vary greatly and is in the same range as for fossil fuel. In contrast, as a consequence of irrigation, agricultural water consumption dominates the overall results of all irrigated crops. Consequently, the level of water scarcity plays a key role for the LCA results. In our case study, the environmental impacts of methyl ester from irrigated rapeseed in a water-scarce region, measured in aggregated Eco-Indicator 99 scores, are almost doubled by water consumption. Variations in irrigation efficiency, however, are of little influence on the results, as the assessment method used here is based on consumptive water, which depends mainly on the evapotranspiration of the crop. Conclusions: The focus on greenhouse gas emissions of the main regulatory schemes neglects other relevant environmental impacts and may provide the wrong incentives. Water consumption may thus become a major concern, offsetting the benefits of biofuel use with respect to climate change.Fil: Faist Emmenegger, Mireille. Technology and Society Lab.; SuizaFil: Pfister, Stephan. Institute of Environmental Engineering; SuizaFil: Koehler, Annette. Institute of Environmental Engineering; SuizaFil: De Giovanetti, Luca. Institute of Environmental Engineering; Suiza. Technology and Society Lab.; SuizaFil: Arena, Alejandro Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Zah, Rainer. Technology and Society Lab.; Suiz

Position-Specific Isotope Analysis of Propane by Mid-IR Laser Absorption Spectroscopy

Intramolecular or position-specific carbon isotope analysis of propane (13CH3–12CH2–12CH3 and 12CH3–13CH2–12CH3) provides unique insights into its formation mechanism and temperature history. The unambiguous detection of such carbon isotopic distributions with currently established methods is challenging due to the complexity of the technique and the tedious sample preparation. We present a direct and nondestructive analytical technique to quantify the two singly substituted, terminal (13Ct) and central (13Cc), propane isotopomers, based on quantum cascade laser absorption spectroscopy. The required spectral information on the propane isotopomers was first obtained using a high-resolution Fourier-transform infrared (FTIR) spectrometer and then used to select suitable mid-infrared regions with minimal spectral interference to obtain the optimum sensitivity and selectivity. We then measured high-resolution spectra around 1384 cm–1 of both singly substituted isotopomers by mid-IR quantum cascade laser absorption spectroscopy using a Stirling-cooled segmented circular multipass cell (SC-MPC). The spectra of the pure propane isotopomers were acquired at both 300 and 155 K and served as spectral templates to quantify samples with different levels of 13C at the central (c) and terminal (t) positions. A prerequisite for the precision using this reference template fitting method is a good match of amount fraction and pressure between the sample and templates. For samples at natural abundance, we achieved a precision of 0.33 ‰ for δ13Ct and 0.73 ‰ for δ13Cc values within 100 s integration time. This is the first demonstration of site-specific high-precision measurements of isotopically substituted non-methane hydrocarbons using laser absorption spectroscopy. The versatility of this analytical approach may open up new opportunities for the study of isotopic distribution of other organic compounds.ISSN:1520-6882ISSN:0003-270

Quantum cascade laser absorption spectrometer with a low temperature multipass cell for precision clumped CO2 measurement

We present a quantum cascade laser-based absorption spectrometer deploying a compact (145 mL volume) segmented circular multipass cell (SC-MPC) with 6 m optical path length. This SC-MPC is embedded into an effective cooling system to facilitate operation at cryogenic temperatures. For CO₂, the sample is cooled to 153 K, i.e. close to the sublimation point at 10 mbar. This enables efficient suppression of interfering hot-band transitions of the more abundant isotopic species and thereby enhances analytical precision. As a demonstration, the amount fractions of all three CO₂ isotopologues involved in the kinetic isotope exchange reaction of ¹²C¹⁶O₂ + ¹²C¹⁸O₂ ⇌ 2·¹²C¹⁶O¹⁸O are measured. The precision in the ratios [¹²C¹⁸O₂]/[¹²C¹⁶O₂] and [¹²C¹⁶O¹⁸O]/[¹²C¹⁶O₂] is 0.05 ‰ with 25 s integration time. In addition, we determine the variation of the equilibrium constant, K, of the above exchange reaction for carbon-dioxide samples equilibrated at 300 K and 1273 K, respectively.ISSN:1094-408