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• Substitution factors for forest products for the Canadian context were developed. • Substitution factors ranging from 0.51 to 0.91 tC/tC were found. • They will lead to more accurate assessments of the forest GHG mitigation potential. • These factors will help governments to manage forest and fight climate change. Evaluating the climate change mitigation potential of the forest sector requires a holistic approach based on forest carbon (C) sequestration, C storage in harvested wood products (HWP) and substitution on markets. High uncertainty is associated with substitution factors, that express avoided fossil greenhouse gas (GHG) emissions from the use of forest-based products in replacement of GHG-intensive materials and fossil fuels. Few studies have focused on the development of substitution factors in Canada, resulting in the use of unrepresentative generic data. Here, we provide a framework to reduce uncertainties related to substitution factors for primary wood products in a Canadian context. A life cycle assessment framework is used to quantify fossil GHG emissions for a baseline and a wood-intensive scenario. For solid product substitution, we focused on the construction sector and analyzed a range of innovative wood buildings with steel and reinforced concrete as alternative materials. We found non-weighted averages of 0.80 tC/tC for sawnwood and 0.81 tC/tC for panels. For energy substitution, we analyzed cases with different specifications on biomass product, facility type and alternative fossil fuel source in non-residential heat production and biofuel transportation sectors. We found a non-weighted average of 0.80 tC/tC for non-residential heat production and 0.51 tC/tC for biofuel transportation, that can be interpreted as 0.91 tC/tC for heavy fuel oil, 0.69 tC/tC for light fuel oil and 0.68 tC/tC for natural gas substitution. These results provide a benchmark for substitution factors in Canada, to help guide forest management strategies for climate change mitigation. [ABSTRACT FROM AUTHOR]

Bioenergy with carbon capture and storage (BECCS) is regarded as a crucial negative emission technology (NET) in many prospective climate change mitigation scenarios that limit global warming below 2 °C. However, there is still insufficient understanding of the overall life cycle environmental performance of different BECCS configurations. Despite the fact that BECCS entails many technological combinations, the technology is still regarded as a single "black box" technology in most climate scenarios. This study presents a critical review of life cycle assessment (LCA) on a wide range of BECCS options: biomass direct-fired power generation, biomass gasification power generation, bio-hydrogen production, biomass application in industry sectors and other biomass conversion processes, such as pyrolysis and fermentation. It is evident from the review that the biomass direct-fired and gasification power plant with a 100% biomass firing ratio and the gasification-based bio-hydrogen processes have a strong potential to achieve negative emissions. However, the net negative life cycle emissions range widely among studies for each configuration due to variations in technology, LCA methodology and assumptions. Additionally, there is an insufficient assessment of comprehensive environmental impacts for BECCS systems other than GWP, making it still unclear about the trade-offs between the benefit from climate change mitigation and potential negative impacts. Main recommendations for improving LCA on BECCS include developing a generalized guideline and standardization for BECCS LCA, conducting LCAs with comprehensive impact categories, focusing on BECCS configurations being overlooked, considering the impact of land use change and the global warming potential of biomass, and extending LCA in both temporal and spatial dimension. [Display omitted] • Systematically review of life cycle assessment on BECCS systems. • Detailed review on various biomass conversion technologies. • Net negative life cycle emissions range widely among studies. • Insufficient studies of some biomass conversion pathways. • Insufficient studies on multi-environmental environment impact categories. [ABSTRACT FROM AUTHOR]

The Intergovernmental panel on climate change raised awareness on the urgent need for action to limit climate change. Answers include bioenergy with carbon capture and storage (BECCS), which could theoretically generate negative emissions. The life cycle assessment (LCA) method needs to be applied to BECCS systems to assess their negative emission potential and prevent transfers from one environmental impact category to another. To allow for informed decision-making, the quality of LCA results should be evaluated. The quality of results is related to the quality of the data used. The purpose of this article is thus to review the life cycle inventory data that are used for BECCS LCA. To this end, 35 recent BECCS LCA were selected and the inventory data they used was collected. Synthesis inventory tables were then compiled, including the observed range of variability for each data item. These tables cover biomass harvesting, pre-treatment, combustion, gasification, and carbon dioxide capture with a monoethanolamine (MEA) based solvent. Data quality is also reviewed, through the representativeness, reproducibility and completeness of the life cycle inventories highlighted in the selected articles. Only a third of the articles (13/35) provide life cycle inventory tables. Only half of the articles assess the impact on climate change leading to inventory cut-offs. BECCS systems including combustion followed by MEA-based capture have been most referenced (12/35 articles). More transparency on data quality is recommended. Certain promising BECCS systems should also be further studied. This applies, for instance, to BECCS systems that involve second-generation solvents. • A review of the data quality used in life cycle assessment (LCA) of BECCS is assessed. • Only a third of the studied articles provide their life cycle inventory tables. • Inventory data currently used in LCA of BECCS is compiled into synthesis tables. • BECCS systems including MEA-based capture are most frequently referenced. • BECCS systems that should be further assessed with LCA are identified. [ABSTRACT FROM AUTHOR]

This paper provides pathways of the carbon content of electricity extracted from the Intergovernmental Panel on Climate Change’s fifth Assessment Report scenarios database. It demonstrates three policy-relevant aspects of the carbon content of electricity that are implicit in most integrated assessment model results but under-discussed in academia and the policy debate. First, climate stabilization at any level from 1.5 °C to 3 °C requires the carbon content of electricity to decrease quickly and become almost carbon-free before the end of the century. As such, the question for policy makers is not whether to decarbonize electricity but when and how to do so. Second, decarbonization of electricity is still possible and required if some of the key zero-carbon technologies—such as nuclear power or carbon capture and storage—turn out to be unavailable. Third, progressive decarbonization of electricity is part of every country’s cost-effective means of contributing to climate stabilization. The pathways of the carbon content of electricity reported here can be used to benchmark existing decarbonization targets, such as those set by the European Energy Roadmap or inform new policies in other countries. They can also be used to assess the desirable uptake rates of electric and plug-in hybrid vehicles, electric stoves and heat pumps, industrial electric furnaces, or other electrification technologies. [ABSTRACT FROM AUTHOR]

Wood and other bio-based building materials are often perceived as a good choice from a climate mitigation perspective. This article compares the life cycle assessment of the same multi-residential building from the perspective of 16 countries participating in the international project Annex 72 of the International Energy Agency to determine the effects of different datasets and methods of accounting for biogenic carbon in wood construction. Three assessment methods are herein considered: two recognized in the standards (the so-called 0/0 method and −1/+1 method) and a variation of the latter (−1/+1* method) used in Australia, Canada, France, and New Zealand. The 0/0 method considers neither fixation in the production stage nor releases of biogenic carbon at the end of a wood product's life. In contrast, the −1/+1 method accounts for the fixation of biogenic carbon in the production stage and its release in the end-of-life stage, irrespective of the disposal scenario (recycling, incineration or landfill). The −1/+1 method assumes that landfills offer only a temporary sequestration of carbon. In the −1/+1* variation, landfills and recycling are considered a partly permanent sequestration of biogenic carbon and thus fewer emissions are accounted for in the end-of-life stage. We examine the variability of the calculated life cycle-based greenhouse gas emissions calculated for a case study building by each participating country, within the same assessment method and across the methods. The results vary substantially. The main reasons for deviations are whether or not landfills and recycling are considered a partly permanent sequestration of biogenic carbon and a mismatch in the biogenic carbon balance. Our findings support the need for further research and to develop practical guidelines to harmonize life cycle assessment methods of buildings with bio-based materials. [Display omitted] • Life cycle assessments of the same multi-residential building were carried out by experts from 16 countries. • Effects of methods and datasets of biogenic carbon accounting in wood construction were identified. • Different end-of-life scenarios (incineration, landfill, recycling) cause variations in the results. • Different interpretations of the permanence of storing biogenic carbon in landfills also cause variations in the results. • The input and output flows of biogenic carbon must be balanced to correctly assess its climate change impacts. [ABSTRACT FROM AUTHOR]

Biomass is an attractive natural energy resource for mitigating climate change. However, the loss of carbon sequestration as an ecosystem service due to biomass harvest has not been considered in previous studies. To assess the impact of biomass harvest on carbon sequestration, carbon dynamics in the forests and the atmosphere were integrated. The impact of forest biomass harvests on carbon sequestration was assessed based on the difference between carbon sequestration after harvest and carbon sequestration without harvest. A Chapman-Richards function and the forest vegetation simulator (FVS) were used to simulate the growth of a forest stand. The carbon dynamics in the atmosphere were simulated by the Bern2.5CC carbon cycle model. Characterization factors of the impact were calculated in three time horizons: 20-, 100- and 500-year. According to the simulations, postponement of harvest and low harvest intensity could prolong the compensation period. The annual impact on carbon sequestration was mostly negative over a short time and became positive in the end of compensation period. The highest characteristic factors of the impact on carbon sequestration were found in rotation length of 100 years with the time horizon of 500-year in the Chapman-Richards simulation and in the lowest harvest intensity with the time horizon of 500-year in the FVS simulation. Based on the results, increasing growth rate, postponing harvest, reducing harvest intensity and increasing length of time horizon could reduce the impact of forest harvest on carbon sequestration. The method proposed in this study is more proper to assess the impact on carbon sequestration, and it has much wider applications in forest management practice. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biofuels are necessary to mitigate the climate impacts in the EU maritime transport. • Impacts of biofuels are heavily dependent on countries' electricity mixes. • Without carbon capture, synthetic natural gas has the highest mitigation potential. • Among carbon-free biofuels, bio-ammonia has the highest mitigation potential. • By 2050, bio-hydrogen can provide the lowest emissions per unit of energy. Alternative fuels are crucial to decarbonize the European maritime transport, but their net climate benefits vary with the type of fuel and production country. In this study, we assess the energy potential and climate change mitigation benefits of using agricultural and forest residues in different European countries for drop-in (Fast Pyrolysis, Hydrothermal Liquefaction, and Gasification to Fischer-Tropsch fuels or Bio-Synthetic Natural Gas) and hydrogen-based biofuels (hydrogen, ammonia, and methanol) with or without carbon capture and storage (CCS). Our results show the combinations of countries and biofuel options that successfully achieve the decarbonization targets set by the FuelEU Maritime initiative for the next years, including a prospective analysis that include technological changes projected for the biofuel supply chains until 2050. With the current technologies, the largest greenhouse gas (GHG) mitigation potential per year at a European scale is obtained with bio-synthetic natural gas and hydrothermal liquefaction. Among carbon-free biofuels, ammonia currently has higher mitigation, but hydrogen can achieve a lower GHG intensity per unit of energy with the projected decarbonization of the electricity mixes until 2050. The full deployment of CCS can further accelerate the decarbonization of the maritime sector. Choosing the most suitable renewable fuels requires a regional perspective and a transition roadmap where countries coordinate actions to meet ambitious climate targets. [ABSTRACT FROM AUTHOR]

The global methanol industry provides a unique supply chain to a plethora of chemicals and processes while also contributing to high quotas of greenhouse gas (GHG) emissions. Hence, as the world focuses on climate change mitigation, green technologies are emerging, allowing for low carbon operations. However, the timeliness and scalability of these technologies limit the sustainable transition of the current methanol industry. Thus, to promote low carbon operations within business-as-usual methanol production, innovative technologies need to be investigated-boasting high resource and energy efficiencies. Here, we examine the effectiveness of novel gas-heated reforming (GHR) over autothermal (ATR) and steam reforming (SMR)- coupled with carbon capture and storage platforms (CCS), in promoting sustainable methanol operations. Our results highlight the GHR as the most efficient flowsheet- with 11 % overall higher energy efficiency and 17 % increase in resource efficiency over ATR and SMR processes. Furthermore, through coupled CCS and electrification, energy and resource efficiencies were improved with GHR systems- achieving 14–41 % reduced GHG emissions compared to ATR and SMR flowsheets. Lastly, considering process economics, GHR flowsheets outperform- producing minimum selling prices up to 24 % lower than the current market. Ultimately, as the world seeks to promote a sustainable transition through the deployment of low carbon energy sources, GHR systems emerge as the preferred technologies- providing both economic and environmental benefits for future low carbon methanol operations. [Display omitted] • Methanol production through Gas-Heated Reforming (GHR) was investigated. • GHR gives 8 % higher energy efficiency over ATR and SMR systems. • Low-carbon electrification sources reduced GHG emissions by 71 %. • CCS integration further lowers GHG emissions by 44 %. • Overall sustainable operations favours GHR and GHR+CCS systems. [ABSTRACT FROM AUTHOR]

Prospective Life Cycle Assessment (pLCA) is useful to evaluate the environmental performance of current and emerging technologies in the future. Yet, as energy systems and industries are rapidly shifting towards cleaner means of production, pLCA requires an inventory database that encapsulates the expected changes in technologies and the environment at a given point in time, following specific socio-techno-economic pathways. To this end, this study introduces premise , a tool to streamline the generation of prospective inventory databases for pLCA by integrating scenarios generated by Integrated Assessment Models (IAM). More precisely, premise applies a number of transformations on energy-intensive activities found in the inventory database ecoinvent according to projections provided by the IAM. Unsurprisingly, the study shows that, within a given socio-economic narrative, the climate change mitigation target chosen affects the performance of nearly all activities in the database. This is illustrated by focusing on the effects observed on a few activities, such as systems for direct air capture of CO 2 , lithium-ion batteries, electricity and clinker production as well as freight transport by road, in relation to the applied sector-based transformation and the chosen climate change mitigation target. This work also discusses the limitations and challenges faced when coupling IAM and LCA databases and what improvements are to be brought in to further facilitate the development of pLCA. [Display omitted] • Prospective LCA can benefit from projections of models such as IAM. • Premise streamlines the production of LCA databases based on prospective scenarios. • Emissions and energy efficiencies of major industries are aligned with IAM scenarios. • Stricter greenhouse gas targets result in larger transformations in the LCA database. • However, such targets result in increased LCA impacts other than global warming. [ABSTRACT FROM AUTHOR]

Abstract: This study uses a hybrid Life Cycle Assessment approach to evaluate the environmental impacts of large-scale deployment of Carbon dioxide Capture and Storage (CCS) in coal and natural gas based electricity generation, based on IEA scenarios. For the Baseline scenario, all impact categories would increase 2–3-fold in 2050 from 2005 levels. Green House Gas (GHG) emissions are found to decrease by ∼40% in ACTmap scenario and by ∼75% in more CCS-intensive BLUEmap scenario. These climate mitigation scenarios also show significantly reduced impacts of acidification, particulate matter formation and human toxicity, suggesting the existence of co-benefits. For eutrophication, all scenarios indicate substantial increases, but the increases are largest in the Baseline scenario. For photochemical oxidant formation, only the mitigation scenarios manage to stabilize this impact from fossil fuel based power production. This study does not assess the impact of alternative power generation or energy efficiency technology that replaces part of the fossil fuel power in the mitigation scenarios. [Copyright &y& Elsevier]

The urgent need for climate change mitigation and the potential threat of energy crisis have allowed the popularity of biomass for biofuels to increase. However, the approaches to assess the climate change impacts of biomass utilization are still questionable. To allow a more accurate assessment, we developed a new framework by integrating six impact components including (1) fossil fuel-derived greenhouse gas (GHG) emissions, (2) biogenic CO 2 emissions-loss, (3) biogenic CO 2 emissions-combustion, (4) emissions from land-use practice change, (5) regrowth for compensation, and (6) difference in carbon sequestration. To illustrate the performance of the framework, seven case studies, which covered the first-, second-, and third-generation biofuels, were conducted. The majority of the positive impacts were contributed to by the fossil fuel-derived emissions, biogenic CO 2 emissions, and regrowth for compensation. For the first-generation biofuels, the life cycle GHG emissions were much higher than those of energy-equivalent fossil fuels (144 and 218 kg CO 2 /GJ for Soybean-to-Biodiesel and Corn-to-Ethanol). The second- and third-generation biofuels had less accountable positive GHG emissions (−62 to 53 kg CO 2 /GJ) due to the offset of negative impacts from land-use practice change and difference in carbon sequestration. However, the negative effects are not determinist. High uncertainty from model-simulated carbon sequestration and decomposition is perceivable. High life cycle GHG emissions for the second- and third-generation biofuels are possible. Image 1 • A new framework was developed to estimate the GHG emissions from biomass utilization. • Different biomass feedstock and conversion technologies were studied as illustrations. • The GHG emissions from the first-generation biofuels can be higher than fossil fuels. • The second- and third-generation biofuels could have negative climate change impact. • High uncertainty is perceivable from model simulation for regrowth and decomposition. [ABSTRACT FROM AUTHOR]

In this study, field-specific data was collected from a 10-year experiment in central Spain in which vetch (Vicia sp. L.) and barley (Hordeum vulgare L.) were established as cover crops and compared to the traditional fall-winter fallow between two irrigated cash crops, maize (Zea mays L.) and sunflower (Helianthus annuus L.). The global warming potential (GWP) balance included direct and indirect (nitrous oxide (N 2 O) resulting from the deposition of ammonia (NH 3) or from leached nitrate (NO 3 −)) soil greenhouse gas (GHG) emissions, changes in soil organic carbon (SOC) and albedo, and carbon dioxide equivalent (CO 2 eq) emissions from inputs, irrigation and farm operations. Several scenarios involving i) changes in the termination method of the cover crops, ii) consideration of the application of a distinct nitrogen (N) source (urea, slurry or manure instead of ammonium nitrate) or nitrification inhibitors, iii) employing the same N rate for all treatments (i.e., conventional instead of integrated fertilization), iv) modelling SOC accumulation over a 100-year horizon, and v) using default emission factors, were also analysed. Under the conditions of our experiment, cover crops mitigated yield-scaled emissions by 77.4% (barley) and 91.9% (vetch). Synthetic N fertilization (particularly the industrial production of fertilizer) contributed 38% to the balance of the cover cropping treatments, followed by SOC (22.5%), irrigation (14.7%) and albedo (14.5%). All scenarios led to notable mitigation efficacies, ranging from 39% mitigation (in barley when considering default or non-specific emission factors) to a net CO 2 eq sink (i.e., >100% mitigation) in the scenario consisting of the replacement of ammonium nitrate by urea or organic fertilizers although with side effects on NH 3 volatilization and/or yields. Based on these results, the combined use of cover cropping and integrated soil fertility management could lead to the design of C-neutral irrigated cropping systems in semi-arid regions. Image 1 • Vetch and barley as cover crops abated net GWP by 90% and 75%, respectively, in comparison to fallow. • Synthetic N fertilization (particularly the industrial production) contributed 38% to GWP. • Soil organic C, albedo change and irrigation were also important GWP components. • All scenarios led to notable mitigation efficacies, ranging from 39% to a net CO 2 eq sink. • Improving N management enhanced the GWP mitigation potential of cover crops. [ABSTRACT FROM AUTHOR]

Environmental assessment of pig production systems using local breeds remains poorly documented in the literature. So far, studies did not account for specificities of outdoor rearing which is quite common in such systems. The present study aimed at evaluating the environmental impacts of pig production systems using local breeds in Europe, while accounting for emissions associated to consumption of grass and mitigation of impacts through soil-C sequestration. Environmental impacts were estimated for 48 farms using local pig breeds: 25 in France (Gascon breed), eight in Italy (Mora Romagnola breed) and 15 in Slovenia (Krškopolje breed). Assessment was performed with and without accounting for pasture-intake emissions and potential soil-C sequestration. The data were obtained from on-farm surveys. Systems with Gascon pigs had the lowest impacts per kg of live weight for global warming and cumulative energy demand, due to lower impacts of feeds. Acidification potential was higher for Krškopolje pigs due to high dietary crude protein content and high AP of feeds, while eutrophication potential was higher for Gascon pigs due to higher phosphorus content of feeds (28% higher than the mean of the other farms). When impacts were expressed per ha of land use, pig production in Gascon farms had the lowest impacts due to more available area per pig, except for eutrophication. Low contribution of soil-C sequestration to climate change mitigation was observed (4.7% on average). However, it may have a substantial contribution for the most extensive pig systems using large land surfaces. Emissions resulting from grazing had a rather low contribution to Global Warming Potential (4%) and Eutrophication (3%), but a substantial one to Acidification impact (9% on average). In the frame of our study, the contribution of emissions related to grazing is moderate because commercial feed supply for outdoor pigs was higher than in extensive systems studied in literature. This study highlighted that main hotspots include feed composition and supply and the origin of feed ingredients. It also suggests that future assessments of extensive pig systems relying on pig foraging on grasslands or rangelands should account for soil-C sequestration and emissions associated to grazing and foraging. • Grazing emissions and potential carbon sequestration were estimated. • Farms had great variability in environmental impacts. • Systems relying the most directly on natural resources had the lowest impacts. • Outdoor systems can reduce CO 2 emissions by sequestering carbon. • Feed composition, supply and feedstuffs origin are hotspots for improvement. [ABSTRACT FROM AUTHOR]