Climate change impacts of bioenergy technologies: A comparative consequential LCA of sustainable fuels production with CCUS.

The use of sustainable biomass can be a cost-effective way of reducing the greenhouse gas emissions in the maritime and aviation sectors. Biomass, however, is a limited resource, and therefore, it is important to use the biomass where it creates the highest value, not only economically, but also in terms of GHG reductions. This study comprehensively evaluates the GHG reduction potential of utilising forestry residue in different bioenergy technologies using a consequential LCA approach. Unlike previous studies that assess GHG impacts per unit of fuel produced, this research takes a feedstock-centric approach which enables comparisons across systems that yield diverse products and by-products. Three technologies-combined heat and power plant with carbon capture, hydrothermal liquefaction, and gasification-are assessed, while considering both carbon capture and storage (CCS) or carbon capture and utilisation (CCU). Through scenario analysis, the study addresses uncertainty, and assumptions in the LCA modelling. It explores the impact of energy systems, fuel substitution efficiency, renewable energy expansion, and the up/down stream supply chain. All technology pathways showed a potential for net emissions savings when including avoided emissions from substitution of products, with results varying from -111 to -1742 kgCO2eq per tonne residue. When combining the bioenergy technologies with CCU the dependency on the energy system in which they are operated was a significantly higher compared to CCS. The breakpoint was found to be 44 kg CO2eq/kWh electricity meaning that the marginal electricity mix has to be below this point for CCU to obtain lower GHG emissions. Furthermore, it is evident that the environmental performance of CCU technologies is highly sensitive to how it will affect the ongoing expansion of renewable electricity capacity.

Plastic futures and their CO2 emissions.

Plastics show the strongest production growth of all bulk materials and are already responsible for 4.5% of global greenhouse gas emissions1,2. If no new policies are implemented, we project a doubling of global plastic demand by 2050 and more than a tripling by 2100, with an almost equivalent increase in CO2 emissions. Here we analyse three alternative CO2 emission-mitigation pathways for the global plastics sector until 2100, covering the entire life cycle from production to waste management. Our results show that, through bio-based carbon sequestration in plastic products, a combination of biomass use and landfilling can achieve negative emissions in the long term; however, this involves continued reliance on primary feedstock. A circular economy approach without an additional bioeconomy push reduces resource consumption by 30% and achieves 10% greater emission reductions before 2050 while reducing the potential of negative emissions in the long term. A circular bioeconomy approach combining recycling with higher biomass use could ultimately turn the sector into a net carbon sink, while at the same time phasing out landfilling and reducing resource consumption. Our work improves the representation of material flows and the circular economy in global energy and emission models, and provides insight into long-term dynamics in the plastics sector.

The plastics integrated assessment model (PLAIA): Assessing emission mitigation pathways and circular economy strategies for the plastics sector.

Integrated assessment models (IAM) study the interlinkages between human and natural systems and play a key role in assessing global strategies to reduce global warming. However, they largely neglect the role of materials and the circular economy. With the Plastics Integrated Assessment model (PLAIA), we included plastic production, use, and end-of-life in the IAM IMAGE. PLAIA models the global plastics sector and its impacts up to 2100 for 26 world regions, providing a long-term, dynamic perspective of the sector and its interactions with other socioeconomic and natural systems. This article summarizes the model structure, mathematical formulation, assumptions, and data sources. The model links the upstream chemical production with the downstream production of plastics, their use in different sectors, and their end of life. Therefore, PLAIA can assess material use and emission mitigation strategies throughout the whole life cycle in an IAM, including the impacts of the circular economy on mitigating climate change. PLAIA projects plastics demand, production pathways and specifies the annual plastic waste generation, collection, and the impact of waste management strategies. It shows the fossil and bio-based energy and carbon flows in product stocks, landfills, and the emissions in production and at the end of life.•We included plastics production, use, and waste management into an Integrated Assessment Model (IAM).•Our model PLAIA provides a long-term, dynamic perspective of the global plastics sector until 2100 and its interactions with other sectors and the environment.•PLAIA can assess the impact of material use and emission mitigation strategies throughout the whole life cycle of plastics.

Attributional and consequential LCAs of a novel bio-jet fuel from Dutch potato by-products.

To mitigate the climate change impact of aviation, jet fuels from bio-based by-products are considered a promising alternative to conventional jet fuels. Life cycle assessment (LCA) is a commonly applied tool to determine the environmental impacts of bio-jet fuels. This article presents both attributional and consequential LCA models to assess an innovative bio-jet fuel produced from potato by-products in the Netherlands. The two models led to opposite conclusions regarding the overall environmental performance of this bio-jet fuel. The attributional LCA showed that this bio-jet fuel could offer about a 60% GHG emissions reduction compared to conventional jet fuel. In comparison, the consequential LCA estimated either a much lower climate change benefit (5-40%) if the potato by-products taken from the animal feed market are replaced with European animal feed or a 70% increase in GHG emissions if also imported soybean meals are used to replace the feed. Contrasting conclusions were also obtained for photochemical ozone formation. Conversely, the attributional and consequential LCAs agree on acidification, terrestrial eutrophication and depletion of fossil fuels. Although the consequential LCA was affected by higher uncertainties related to the determination of the actual product displaced, it allowed understanding the consequence of additional animal feed production. This process was not included in the system boundaries of the attributional LCA.

Kraft lignin as a bio-based ingredient for Dutch asphalts: An attributional LCA.

In the last decade, lignin has received much attention as a feedstock to produce bio-based products. This study investigates the potential benefits of using lignin to mitigate the environmental impact of the road construction sector. An environmental life cycle assessment (LCA) of various top-layer bio-based asphalts using kraft lignin was conducted. From a cradle-to-grave perspective, lignin-based asphalts were compared with conventional asphalts. The results of the LCA revealed that the climate change impact of lignin-based asphalts could be 30-75% lower than conventional asphalts. For the other ten impact categories, trade-offs were observed. Overall, two key factors to make the environmental impact of lignin-based asphalts lower than conventional asphalts are 1) increasing the amount of bitumen-substituted and 2) using low-grade biomass fuels for process steam in the pulp mill. The substitution of weak filler with lignin was beneficial only for climate change and could lead to a worse overall environmental performance than conventional asphalts. Similarly, higher environmental impacts for lignin-based asphalts could be obtained if the pulp mill consumed natural gas to complete the energy balance to replace the part of the black liquor from which lignin is extracted. This study also includes an in-depth discussion on methodological choices such as the allocation methods for lignin, functional units, and asphalt layers considered. We believe that such a methodological discussion could be helpful to support future Product Category Rules for asphalt mixtures.

Paludiculture as paludifuture on Dutch peatlands: An environmental and economic analysis of Typha cultivation and insulation production.

Paludiculture, the cultivation of crops on rewetted peatlands, is often proposed as a viable climate change mitigation option that reduces greenhouse gas emissions (GHGe), while simultaneously providing novel agricultural business options. In West Europe, experiments are ongoing in using the paludicrop cattail (Typha spp.) as feedstock for insulation panel material. Here, we use a Dutch case study to investigate the environmental potential and economic viability of shifting the use of peat soils from grassland (for dairy production) to Typha paludiculture (for cultivation and insulation panel production). Using a life cycle assessment and cost-benefit analysis, we compared the global warming potential (GWP), yearly revenues and calculated Net Present Value (NPV) of 1 ha Dutch peat soil used either for dairy production or for Typha paludiculture. We estimated that changing to Typha paludiculture leads to a GWP reduction of ~32% (16.4 t CO2-eq ha-1), mainly because of lower emissions from peat decomposition as a result of land-use management (-21.6 t CO2-eq ha-1). If biogenic carbon storage is excluded, the avoided impact of conventional insulation material is insufficient to compensate the impact of cultivating and processing Typha (9.7 t CO2-eq ha-1); however, this changes if biogenic carbon storage is included (following PAS2050 guidelines). Typha paludiculture is currently not competitive with dairy production, mainly due to high cultivation costs and low revenues, which are both uncertain, and will likely improve as the system develops. Its NPV is negative, mainly due to high investment costs. This can be improved by introducing carbon credits, with carbon prices for Typha paludiculture (30 years) comparable to EU-ETS prices. In conclusion, Dutch Typha paludiculture has a significant climate change mitigation potential by reducing emissions from deep drained peatlands. Nevertheless, attention is needed to increase its economic viability as this is a key aspect of the system change.

Comparative cradle-to-grave life cycle assessment of bio-based and petrochemical PET bottles.

This article presents a life cycle assessment of bio-based polyethylene terephthalate (PET) bottles with a cradle to grave scope and provides a comparison with petrochemical PET bottles for 13 environmental impact categories. Besides the baseline bio-based PET bottles, which are produced from Brazilian sugarcane reflecting status-quo, two alternative hypothetical bio-based product systems were considered: European wheat straw and European crops market mix composed of maize, wheat and sugar beet. The land-use change (LUC) impacts were assessed based on a deterministic model. The end-of-life impact was assessed using the EASETECH model. Baseline bio-based PET bottles performed overall worse than conventional petrochemical PET bottles, offering only better performance (about 10%) in abiotic depletion (fossil fuels). Comparable performance is observed for climate change (2% difference without the LUC, and 7% with LUC impacts). Using European crops for ethanol production (alternative 1) instead of Brazilian sugarcane resulted in a worse environmental performance, due to lower yields attained compared to Brazilian sugarcane. When wheat straw was considered as biomass feedstock for ethanol production (alternative 2), similar environmental performance with petrochemical PET bottles was seen.

Review of life cycle assessments of lignin and derived products: Lessons learned.

In the last decade, the use of lignin as a bio-based alternative for fossil-based products has attracted significant attention, and the first LCAs of lignin and derived products have been conducted. Assessing side-stream products like lignin and potential benefits compared to their fossil counterparts presents complex methodological issues. This article provides a critical review of forty-two peer-reviewed LCAs regarding lignin and derived products. Methodological issues and their influence on the LCA results include the choice of the modeling approach and system boundaries, functional unit definition, impact categories considered, type of data used, handling multifunctionality and biogenic carbon modeling. The review focused on climate change impacts, as this is also the main impact category considered in most studies. Other impact categories in the comparison between lignin-based products and counterparts were also discussed with examples from the studies. Based on ten lessons learned, recommendations were provided for LCA practitioners to increase future consistency of environmental claims made about lignin and lignin-based products. The finding suggest that the environmental performance of lignin-based products is significantly affected by both 1) LCA methodological problems such as allocation practices and biogenic carbon modeling and 2) technical aspects such as the percentage of lignin in the composition of products and the selection of the fuel to replace lignin in internal energy uses. Beyond this, the reviewed LCAs showed that often lignin-based products offer better environmental performances than fossil-based products, especially for climate change.

A Perspective on Biofuels Use and CCS for GHG Mitigation in the Marine Sector.

The greenhouse gas (GHG) emissions of the marine sector were around 2.6% of world GHG emissions in 2015 and are expected to increase 50%-250% to 2050 under a "business as usual" scenario, making the decarbonization of this fossil fuel-intensive sector an urgent priority. Biofuels, which come in various forms, are one of the most promising options to replace existing marine fuels for accomplishing this in the short to medium term. Some unique challenges, however, impede biofuels penetration in the shipping sector, including the low cost of the existing fuels, the extensive present-day refueling infrastructure, and the exclusion of the sector from the Paris climate agreement. To address this, it is necessary to first identify those biofuels best suited for deployment as marine fuel. In this work, the long list of possible biofuel candidates has been narrowed down to four high-potential options-bio-methanol, bio-dimethyl ether, bio-liquefied natural gas, and bio-oil. These options are further evaluated based on six criteria-cost, potential availability, present technology status, GHG mitigation potential, infrastructure compatibility, and carbon capture and storage (CCS) compatibility-via both an extensive literature review and stakeholder discussions. These four candidates turn out to be relatively evenly matched overall, but each possesses certain strengths and shortcomings that could favor that fuel under specific circumstances, such as if compatibility with existing shipping infrastructure or with CCS deployment become pivotal requirements. Furthermore, we pay particular attention to the possibility of integrating deployment of these biofuels with CCS to further reduce marine sector emissions. It is shown that this aspect is presently not on the radar of the industry stakeholders but is likely to grow in importance as CCS acceptability increases in the broader green energy sector.

Influence of livelihood assets, experienced shocks and perceived risks on smallholder coffee farming practices in Peru.

Smallholder farmers might adopt different farming practices to cope with multiple stressors depending on their livelihood assets, and with varying environmental and economic outcomes. Ongoing global change is triggering stronger and different stressors that threaten conventional farming practices; however, this could be resolved if livelihood assets that drive decision making are actionable and thus can be modified. This study assessed the influence of farmers' livelihood assets, risk perception, and shocks on the choice of non-conventional farming practices for smallholder coffee farmers in San Martín, Peru. Using household survey data, we collected data on 162 coffee plantations along an elevation gradient. We operationalized the sustainable livelihoods framework for the adoption of shade and input coffee farming strategies and explored farmers' motives to change them. Despite associated high risks with pest and disease pressure, coffee price volatility and climate change, these risks did not explain the current shade and input farming strategies. While in the past five years, farmers adapted shade and input management in response to pest and disease and climate change pressures, these occurred in diverging directions: we found higher human and social assets associated with higher shade levels, and a trend for higher physical and financial assets associated with higher input use. These findings illustrate that two main factors affect decisions on farming practices related to shade and input management and they relate to different livelihood capitals. This suggests a potential for conflicting decision-making, push-and-pulling decisions in different directions. Further the disconnect between livelihood assets and perceptions suggests that perception of risk and shocks might not be sufficient to motivate decision making under changing conditions. Such insights in decision-making typologies and drivers can inform the development of farming practices that enhance resilience and sustainability of smallholder coffee production in Peru and elsewhere in the tropics.

Life-cycle analysis of greenhouse gas emissions from renewable jet fuel production.

BACKGROUND: The introduction of renewable jet fuel (RJF) is considered an important emission mitigation measure for the aviation industry. This study compares the well-to-wake (WtWa) greenhouse gas (GHG) emission performance of multiple RJF conversion pathways and explores the impact of different co-product allocation methods. The insights obtained in this study are of particular importance if RJF is included as an emission mitigation instrument in the global Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). RESULTS: Fischer-Tropsch pathways yield the highest GHG emission reduction compared to fossil jet fuel (86-104%) of the pathways in scope, followed by Hydrothermal Liquefaction (77-80%) and sugarcane- (71-75%) and corn stover-based Alcohol-to-Jet (60-75%). Feedstock cultivation, hydrogen and conversion inputs were shown to be major contributors to the overall WtWa GHG emission performance. The choice of allocation method mainly affects pathways yielding high shares of co-products or producing co-products which effectively displace carbon intensive products (e.g., electricity). CONCLUSIONS: Renewable jet fuel can contribute to significant reduction of aviation-related GHG emissions, provided the right feedstock and conversion technology are used. The GHG emission performance of RJF may be further improved by using sustainable hydrogen sources or applying carbon capture and storage. Based on the character and impact of different co-product allocation methods, we recommend using energy and economic allocation (for non-energy co-products) at a global level, as it leverages the universal character of energy allocation while adequately valuing non-energy co-products.

Linking carbon stock change from land-use change to consumption of agricultural products: A review with Indonesian palm oil as a case study.

Numerous analyses have been performed to quantitatively link carbon stock change caused by land-use change (CSC-LUC) to consumption of agricultural products, but results differ significantly, even for studies focussing on the same region or product. This is due to the different focuses and interpretations of the links between direct drivers and underlying causes of CSC-LUC, which can be translated into differences in key functions, i.e. specific methods, algorithms and parameters embedded in the analysis. Using the example of Indonesian palm oil production (often associated with CSC-LUC), this paper carries out a meta-analysis of 12 existing studies, determines the different settings for the key functions embedded in consumption-based CSC-LUC studies and discussed their implications for policymaking. It identifies the underlying reasons of adopting different settings within the eight key functions and their advantages and trade-offs. Examples are the way of determining how deforestation is linked to oil palm, and the inclusion of non-agriculture and non-productive drivers in the accounting to weight their roles in CSC-LUC in comparison to palm oil consumption. Following that, the quantitative results from the selected studies were processed and harmonised in terms of unit, allocation mechanism, allocation key and amortisation period. This resulting in ranges of 0.1-3.8 and -0.1-15.7 tCO2/t crude palm oil for historical and projection studies, respectively. It was observed that CSC-LUC allocated to palm oil is typically lower when propagating effects and non-agricultural or non-productive drivers were accounted for. Values also greatly differ when marginal and average allocation mechanisms were employed. Conclusively, individual analyses only answer part of the question about CSC-LUC drivers and have their own strengths and weaknesses. Since the context can be very different, using quantitative results from a single study for accounting purposes in policymaking is not recommended. Instead, insights from different studies should be combined, e.g. the relative role of logging and oil palm or the contribution to CSC-LUC in regional and global perspectives.

Linking carbon stock change from land-use change to consumption of agricultural products: Alternative perspectives.

Agricultural expansion driven by growing demand has been a key driver for carbon stock change as a consequence of land-use change (CSC-LUC). However, its relative role compared to non-agricultural and non-productive drivers, as well as propagating effects were not clearly addressed. This study contributed to this subject by providing alternative perspectives in addressing these missing links. A method was developed to allocate historical CSC-LUC to agricultural expansions by land classes (products), trade, and end use. The analysis for 1995-2010 leads to three key trends: (i) agricultural land degradation and abandonment is found to be a major (albeit indirect) driver for CSC-LUC, (ii) CSC-LUC is spurred by the growth of cross-border trade, (iii) non-food use (excluding liquid biofuels) has emerged as a significant contributor of CSC-LUC in the 2000's. In addition, the study demonstrated that exact values of CSC-LUC at a single spatio-temporal point may change significantly with different methodological settings. For example, CSC-LUC allocated to 'permanent oil crops' changed from 0.53 Pg C (billion tonne C) of carbon stock gain to 0.11 Pg C of carbon stock loss when spatial boundaries were changed from global to regional. Instead of comparing exact values for accounting purpose, key messages for policymaking were drawn from the main trends. Firstly, climate change mitigation efforts pursued through a territorial perspective may ignore indirect effects elsewhere triggered through trade linkages. Policies targeting specific commodities or types of consumption are also unable to quantitatively address indirect CSC-LUC effects because the quantification changes with different arbitrary methodological settings. Instead, it is recommended that mobilising non-productive or under-utilised lands for productive use should be targeted as a key solution to avoid direct and indirect CSC-LUC.