Consequential Life Cycle Assessment Research Articles

A comparative prospective life cycle assessment of coal-fired power plants in the US with MEA/MOF-based carbon capture

The adoption of carbon capture technology in coal-fired power plants is expected to play a pivotal role in the energy transition. This study conducted consequential life cycle assessments (CLCAs) of coal-fired power generation in the United States using policy-level accounting. Monoethanolamine (MEA)-based and Mg-MOF-74-based carbon capture have been introduced, with a comparative analysis conducted on the emissions reduction potential of these two materials through their respective mechanisms of absorption and adsorption. The results indicate that carbon capture based on MEA or Mg-MOF-74 can significantly reduce emissions from coal-fired power generation, decreasing from 779.5 Mt CO2e to 50.1 Mt CO2e and 61.1 Mt CO2e in 2050, respectively. The introduction of ultra-supercritical power plants and carbon capture reduced direct emissions from 92% to 51%. MEA outperforms Mg-MOF-74 slightly, with lower emissions due to solvents and cleaning processes. Deviations in Mg-MOF-74's adsorption capacity and degradation rate could lead to 4%–6% model outcome variations. It is also concluded that the stability of MEA's marginal emissions depends on a steady expansion of existing production capacity, while the marginal emissions of Mg-MOF-74 are anticipated to remain unchanged. This study emphasizes carbon capture's potential but stresses the need for prompt implementation and comprehensive assessments before deployment decisions.

Mitigating environmental impacts of food consumption in the European Union: Is the power truly on our plates?

In the context of the sustainable use of our planet's resources, there is a pressing need for environmentally friendly diets. Moreover, health issues linked to inadequate nutrition are rising, further emphasising the need for more balanced diets. The aim of the planetary health diet developed by the EAT-Lancet commission is to sustainably feed 10 billion people in 2050 while not exceeding planetary limits. According to these guidelines, the EU should reduce red meat intake by 80 % and multiply legume intake by 15. This significant shift from animal to plant-based proteins could modify trade partnerships and EU dependency on plant-based proteins for animal feed, currently discussed within the EU protein strategy. This study evaluates land use changes and environmental consequences of this change in dietary patterns by applying a consequential life cycle assessment approach combined with an agri-economic model, additionally assessing if this diet shift could help to achieve EU Green Deal targets. For this simulation, the partial equilibrium model CAPRI was used, which is a global agricultural market model focusing on Europe, including bilateral trade worldwide. We found that the diet shift results in gaps between domestic demand and supply which are compensated by increased imports of legumes and additional exports of red meat from the EU due to an increased demand for red meat in non-EU countries, as a consequence of decreased red meat prices. Land use changes within NUTS-2 regions indicate broad disparities depending on regional specialisation and profitability. The results from our life cycle assessment show limited benefits for most environmental impact categories within the EU given the considerable change in diets. GHG emissions from the agricultural sector would be reduced by 9 %, representing 4 % of the change needed to achieve overall EU GHG emission targets i.e., a reduction of 55 % by 2030 compared to 1990 levels. Yet, the mitigation potential allocated to EU production of shifting diets could be greater if international trade were not offsetting expected local environmental benefits. Indeed, if EU red meat and animal feed production were reduced proportionally to the demand shift, domestic legume production could hypothetically be extended in the available agricultural areas coming along with improvements in all environmental impact categories. Scientific contribution and media regularly point out the significant influence of individual consumer behaviour as an impulse for change: “the power is on our plates”, while the results of our simulations show that this holds only to a limited extent. To minimise environmental pollution, strong supply-side policies are needed to complement the power on the consumers' plates.

Consequential LCA of NPK fertilizers from microbial, animal, plant, and mineral origin highlights resource constraints and environmental impacts

The production and use of mineral fertilizers lead to severe environmental impacts, therefore initiatives such as the European Green Deal promote organic farming and nutrient circularity. However, many organic fertilizers (those containing organic carbon and nutrients of exclusively biological origin) face constraints due to resource availability, and it is paramount to understand their environmental impacts to prevent unforeseen effects. This study employed a consequential life cycle assessment (LCA) to compare the environmental impact of mineral fertilizer to three types of organic fertilizers: animal-, plant-, and innovative microbe-based, considering market constraints and marginal suppliers. Organic fertilizers were complemented with mineral products to yield NPK compound fertilizers containing 1 t of nitrogen, 0.44 t of phosphorus, and 0.83 t of potassium (multi-substance functional unit). The findings reveal that 9 out of the 17 studied organic fertilizers are constained products, and that their demand is met through the supply of mineral fertilizers, soybean meal, and maize or barley grain. Consequently, for the transition to a circular and organic agrifood system, the focus should shift toward untapped resources like microbial fertilizers sourced from food and beverage industry wastewater, and sewage sludge. Constrained markets vary with time and geographical location, emphasizing the importance of context-specific decision-making. The impact of mineral fertilizers is relatively low across impact categories, but the gap between them and energy-intensive organic fertilizers narrows in an industrial symbiosis scenario where waste heat is available. An additional assessment of soil organic carbon estimated the contribution of organic fertilizers to the “4 per 1000" initiative's goal for soil carbon storage. Organic fertilizer application alone only achieves this goal in one scenario (rapeseed meal), but combining it with other management practices like crop rotation offers a promising strategy. The scenario that included fertilizer transport showed the potential for reduced environmental impacts by applying locally available by-products as organic fertilizer instead of imported mineral fertilizers. Overall, the results call for caution when transitioning from mineral to organic fertilizers as their availability and environmental impact are not self-evident.

To what extent do geopolitical conditions affect the environmental sustainability of the circular economy? A comparative LCA study of lactic acid production in Denmark and Iran

Transitioning to a circular economy is inevitable in well-developed and developing economies. Biowaste valorization into value-added products has shown a promising sustainable solution compared to its fossil-based counterparts. However, it has yet to be scientifically analyzed to what extent geopolitical conditions affect the environmental sustainability of the circular economy. To fill this gap, we conducted a consequential life cycle assessment of biorefining biowaste into lactic acid and bioenergy in Denmark and Iran as representative examples of developed and developing economies, respectively. Despite the notable environmental impacts associated with fossil-based energy consumption and infrastructural limitations, Iran could benefit more environmentally from the suggested biorefinery by 2030 than Denmark. This contrast arises from the fact that the existing dominant waste management solution in Iran consists of sanitized and unsanitized landfills, which appear likely to continue through 2030. Therefore, any alternative waste management scenario would help avoid the environmental impacts arising from landfills. In contrast, Denmark already has a well-established and sustainable waste management practice for biowaste, namely anaerobic digestion. Accordingly, the environmental impacts of the investigated scenarios in Denmark were, on average, 85 %, 855 %, 177 %, and 130 % higher than those in Iran regarding resource scarcity, ecosystem quality, human health, and climate change, respectively. In both countries, incineration, the culture medium, ion exchange, vacuum distillation, transportation, emissions from digestate applications on farmlands, and the inorganic waste landfilling process (only applied to IR scenarios) contributed most to the overall environmental impacts. Besides impacts arising from geopolitical conditions, our study revealed that abiotic augmentation and P. acidilactici bioaugmentation demonstrated superior environmental performance compared to other methods. The results also highlight the importance of international collaboration to implement circular economy approaches in developing countries and accelerating global environmental mitigation efforts. To comprehensively evaluate the environmental sustainability of circular bioeconomy, it is recommended to examine scenarios aligned with socio-economic pathways and various representative concentration pathways.

Environmental performance of eco‐design strategies applied to the building sector

AbstractThe application of eco‐design principles in the building sector is considered a promising way to mitigate its substantial environmental impacts. However, quantitative evidence for this mitigation potential is lacking. The objective of this study was to quantify the environmental performance of diverse eco‐design strategies when applied to the building sector. A macroscale model capable of simulating the future demand for housing and related material flows within the urban building stock was developed based on an existing building stock model. These material flows were used to build inventories for a consequential life cycle assessment and, in turn, to quantify the potential environmental consequences of introducing eco‐design strategies in the building sector, assessed across 16 impact categories. Model outputs have a high level of uncertainty but are still useful for decision‐making, given the model's simplicity and transparency. The main results show that impact reductions can be obtained from specific uses of wood and wooden products, for example, when used for the walls in high‐rise buildings, whereas using hempcrete for partition walls increases the impact. Although the use of adaptability or disassembly strategies can reduce impacts, this pay‐off can only be obtained after a long period of implementation. In summary, the present study provides new quantitative insights into the ability of eco‐design strategies to mitigate environmental impacts in the building sector.

Method for Calculating the Avoided Impact of Specific Information and Communication Technology Services

Particular Information and Communication Technology (ICT) services can help avoid environmental impact in larger contexts. However, there is no commonly agreed bottom-up methodology for calculation of the total net reduction effect of specific digital ICT services. Life Cycle Assessment (LCA) is a common denominator for most methodologies. The most common method is the Attributional LCA (ALCA), and recently the emerging handprint ALCA estimating so-called positive environmental impacts. Moreover, Consequential LCA (CLCA) can be used to capture market effects. The third conceptual approach is Input-Output LCA. The purpose is to propose and test a new method based on some of the existing ones. The existing concepts are compared and a synthesis is made to create a practical but still useful method. The new method is applied to two illustrative cases in the ICT domain; the introduction of a 5G enabled drone for pipe inspection and the 5G enabled health consultation. Compared to simplified ALCA, the difference between the absolute scores for the baseline system and the target system changes around 10% when the proposed simplified CLCA (SCLCA) method is used. The results show that SCLCA, when combined with analytical methods for expressing digital ICT services’ own impact, is a fruitful approach which is both practical and feasible. The new method includes formulae for calculating the total lifetime environmental impact of a specific ICT Equipment when reused or replaced.

Life cycle assessment of carbon emissions for bridge renewal decision and its application for Maogang Bridge in Shanghai

The renewal of old bridges is sometimes restricted to avoid the high carbon emissions caused by materials and construction, which however might not be conductive to climate change mitigation due to their insufficient functions. In order to facilitate the optimization of renewal timing and strategy from the perspective of reducing the comprehensive global warming impacts, we put forward the low-carbon bridge renewal decision method referring to the ideas of consequential life cycle assessment (LCA) and dynamic LCA. In the proposed method, a comparative system boundary matching the bridge renewal characteristics is constructed, where the carbon emission reduction owing to the traffic efficiency improvement by functional updating is incorporated as the low-carbon benefits of renewal, and three types of time-dependent factors, i.e., time-dependent characterization factor, trend factors and changes of traffic demands, are introduced to characterize the influence of renewal timing. The proposed method provided guidance for the renewal of Maogang Bridge, the first long-span cable-stayed bridge in Shanghai. Results illustrate that the global warming impacts of renewal construction activities and the low-carbon benefits from functional updating decrease with the renewal timing. For Maogang Bridge, the rapidly increasing traffic demands inevitably advocated renewal in advance, and the reduction of global warming impacts from emission reduction or carbon uptake could be manifested for renewal in advance. Adopting material recycling in the disposal of old bridge helped reconstructing a new bridge while deconstructing the old one in 2019 becoming the finally selected low-carbon renewal strategy, which is expected to reduce 15.04 kt CO2e-2019 compared to the essential renewal in 2050 with the landfill disposal method. The robustness of the strategy choice has been justified, given the variations of analytical time horizon, expected emission trends and repair emissions. In this way, the low-carbon renewal decision method could build a quantitative basis for judging the urgency of functional updating and verifying the low-carbon benefits of immediate concrete recycling in up-coming urban renewals.

Environmental consequences of shifting to timber construction: The case of Denmark

Many life cycle assessments (LCA) studies on wooden buildings show potential to decarbonise the building industry, though often neglecting to consider the systemic changes of such a shift at the building stock scale. This study applies a consequential LCA to evaluate the transition from conventional construction to increased wood-based construction in Denmark from 2022 to 2050. The assessment models a material flow analysis of the two construction scenarios, incorporating an area forecast and case buildings. By that, we assessed suppliers' capacity to likely meet the demand for wood, steel, and concrete, employed an input-output model to enhance completeness and country representativeness for other materials' markets, and considered the competition for land by indirect land use change. We implemented a dynamic IPCC-based assessment of GHG-emissions concurrently with a carbon forest model to anticipate the relationship between the delayed carbon storage resulting from using wood in buildings and forest regrowth management. The findings indicate wood construction is the most climate-friendly option for multifamily houses. In contrast, single-family houses (SFH) and office buildings (OB) exhibit the lowest climate impacts in the conventional scenario. The SFH result could be credible due to the sizable GWP impact gap between construction scenarios despite uncertainties related to the weight proportion of sedum roofs. The less conclusive OB findings relate to the substantial steel quantities in the wood case buildings, requiring further investigation. Generally, metals, cement-based- and biobased materials demonstrate the largest climate impact among the material categories. Across all three building typologies, the change to timber construction increased the impact on nature occupation (biodiversity). In conclusion, this study emphasises the need for further research on forest management model inputs, land use change approaches, potential steel suppliers' impact, and a broader array of case studies. It is because these are influential factors in facilitating informed decision-making of the increased implementation of wood in buildings. As the first study to integrate these modelling characteristics, it contributes to the research gap concerning geographical circumstances, forestry, and markets relevant to decision support for increased wood utilisation in Europe's building industry.

Banning short-haul flights and investing in high-speed railways for a sustainable future?

Long-distance mobility sustainability, high-speed railways (HSR) decarbonization effect, and bans for short-haul flights are debated in Europe. Yet, holistic environmental assessments on these topics are scarce. A comparative life cycle assessment (LCA) was conducted on the Paris-Bordeaux transportation options in France: HSR, plane, coach, personal car, and carpooling. The overall ranking on four environmental indicators, from best to worst, is as follows: coach, HSR, carpooling, private car, and plane. Scenario analyses showed that increasing train occupancy decreases the environmental impact of the mode (-12 %), while decreasing speed does not. Moreover, worldwide carbon footprints of electric HSR modes range 30–120 gCO2eq per passenger-kilometer traveled. Finally, a consequential LCA highlighted carbon paybacks of the HSR project. Under a business-as-usual trip substitution scenario, the HSR gets net-zero 60 years after construction. With a short-haul flight ban, it occurs after 10 years. This advocates for generalizing short-haul flight restrictions and investing in HSR infrastructure.

Using olive and apple pomaces for fattening pig diets: Environmental impacts under an attributional and consequential perspective

The livestock sector plays an essential role in anthropogenic greenhouse gas emissions, where fodder crop production has been largely identified as the main contributor to their environmental impact. This research evaluates the attributional environmental impacts of introducing food industry subproducts such as apple and olive pomaces to reduce the proportion of maize grain in the formulation of diets for fattening pigs, according to four alternatives, including the current diet with 69% maize. For this, the life cycle assessment (LCA) methodology has been used to determine the hotspots associated to these changes, considering a cradle-to-gate approach and two functional units: 1 kg of feed diet (FU1) and 1 kg of weight gain (FU2). Furthermore, the potential environmental consequences of using these subproducts for pig diet have also been considered with a consequential LCA methodology. The results show that the best diet was the one containing about 33% maize and 43% subproducts for all categories analysed. In addition, the allocation method used to assign subproduct loads, including mass, economic, and zero-burdens allocation, is crucial to validate the assumptions and recommendations for this strategy. The consequential LCA results suggest that this strategy could involve both positive and negative impacts (considered as environmental credits), depending on the substitutes for the avoided maize stover and the potential displaced bioproducts that could be obtained from these subproducts, mainly for bioenergy production.

Ventilation's role in adaptable school buildings: Comparing traditional and adaptable strategies through life cycle assessment

Adaptable buildings are a promising enabler in the transition towards a more circular economy, with the ambition of using materials as efficiently as possible. To exploit adaptable buildings to their full potential, HVAC designers should critically rethink how to design technical services and ventilation systems in particular. This case study illustrates how five ventilation strategies perform from an environmental point of view in a school building where the configuration of the floorplan changes every five years, each of the changes reflecting a pedagogical vision. Consequential LCA is used to assess the environmental impact. A decentralized balanced mechanical ventilation system, which requires almost no adaptations when the configuration changes, has the lowest environmental impact while mechanical exhaust ventilation has the highest. However, when the configuration of the floorplan layout alters more rapidly, the relative environmental impact of the latter decreases substantially. The main conclusion is that, in a flexible context, the material-related environmental impact gains importance over the energy-related impact. With respect to this conclusion, a key finding is that minimizing the material use of ductwork (rather than oversizing ductwork dimensions to decrease the energy consumption of the fan) is more sustainable from an environmental point of view. Finally, distributing the ductwork over two shafts offers more flexibility and results in a lower environmental impact as this allows for the use of smaller dimensions of ductwork.

Designing sustainable circular bioeconomy solutions for the pulse industry: The case of crude pea starch as a substrate for single cell protein production

Valorization of crude pea starch has become a key focus in the pea industry's sustainability pursuit. This study aimed to explore the circularity potential of crude pea starch as a nutrient-dense substrate for the solid-state cultivation of yeast (Saccharomyces cerevisiae) Single Cell Protein (SCP). Following the ISO 2006:14040/44 standard, a life cycle assessment (LCA) was performed to ascertain the environmental performance and operational dynamics of baseline and scenario pea starch-based yeast SCP process designs and identify optimal design considerations. Results demonstrated a higher relative contribution to the toxicity categories, with a relatively less contribution to global warming and land use. The distribution and media enrichment processes were identified as the hotspots, contributing about 32–55 % and 40–56 % to global warming and land use, respectively. Generally, train and air freight were more sustainable than lorry freight, respective of mileage and mass. Regarding system alteration, eliminating the media enrichment process could offset about 26 % of land footprint, with a similar trend for most impact categories. Process benchmarking showed up to a 3-fold reduction in global warming impacts relative to soybean meal, and about 71 % offset relative to fishmeal. Consequential LCA showed a general sustainability preference for substituting the aquacultural feeds with pea starch-based SCP, with a stronger emphasis on fishmeal substitution. Overall, these findings highlight the potential of the proposed SCP design as a sustainable upcycling solution with substitutionary potentials for conventional food and feeds, recommending further exploration in value and wealth creation.

Comparative techno-economic and life cycle analyses of synthetic “drop-in” fuel production from UK wet biomass

Renewable synthetic hydrocarbon “drop-in” fuels can help mitigate greenhouse gas emissions from transport, particularly in hard-to-abate sectors like freight and aviation. However, no study has extensively addressed the concerns over biomass availability, cost viability, and CO2 reduction feasibility that are associated with diverse production configurations and feedstocks. Here, we report detailed techno-economics and life cycle greenhouse gas emission assessments of drop-in fuel productions via hydrothermal liquefaction to assess their economic viabilities, CO2 mitigation potentials, and prospects for scale-up specifically within the UK context. Our approach integrates key production factors which include regional availability of main feedstocks (digestates, food waste, biodegradable municipal waste, and sewage sludge), plant configurations (centralised vs decentralised) and hydrogen sources (grey, blue, green). We demonstrated the economic trade-off between economy-of-scale and feedstock transport distances in the centralised/decentralised configurations, and also the economic and emissions trade-offs associated with the use of different hydrogen sources. We find that co-processing of different waste feedstocks is an important strategy to minimise fuel selling price by enabling better economy of scale and feedstock transport, resulting in a fuel selling price of £14.76 – 20.30 per GJ. The corresponding greenhouse gas emissions from the co-processing case vary from 11.4 to 24.9 kgCO2eqperGJ for 2021, based on the consequential life cycle assessment approach. Furthermore, we estimated that the utilisation of key UK wet feedstocks could only provide 4.5 % of current fuel consumptions and reduce emissions by 4.5–5.4 Mt CO2eq/year, which translates to 3.4–4.0 % reduction in the UK’s 2021 transport emissions.

Achieving Net Zero Carbon Performance in a French Apartment Building?

Containing global warming to 1.5 °C implies staying on a given carbon budget and therefore being able to design net zero carbon buildings by 2050. A case study corresponding to a French residential building is used to assess the feasibility of achieving this target. Starting from an actual construction built in 2016, various improvement measures are studied: lowering heating energy needs, implementing bio-sourced materials and renewable energy systems (geothermal heat pump, solar domestic hot water production, and photovoltaic electricity production). Dynamic thermal simulation is used to evaluate energy consumption and overheating risk in hot periods. Greenhouse gas emissions are quantified using a consequential life cycle assessment approach, considering that during a transition period, exporting electricity avoids impacts corresponding to marginal production on the grid. Avoided impacts decrease and become zero when the grid is ultimately “decarbonized”. From this point, the building should be net zero emissions, but there remain unavoidable emissions. Residual GhG (greenhouse gas) emissions account for 5.6 kgCO2 eq/m2 annually. The possibility of offsetting these emissions is investigated, considering sequestration in forests or vegetation systems. A net zero emission level can be achieved, but on a national level, it would require that the whole sequestration potential of forest growth be devoted to offset emissions of new construction. A circular economy for construction products and equipment and considering water use will be needed to further decrease environmental impacts.

Environmental impacts of a novel biorefinery platform integrated with power-to-protein technology to decrease dependencies on soybean imports

The consistent population growth is directly tied to the annual rise in livestock production, placing a substantial burden on the crop sector that supplies animal feed. The Danish government has been relying on importing soybeans and soybean meal to be used as animal feed. However, this sparked environmental concerns that require more environmentally friendly solutions, such as self-sufficiency in animal feed production. The rise of green biorefineries allows new avenues of animal proteinaceous feed production using green biomass to produce leaf protein concentrate (LPC) and utilize side-stream products, such as brown juice and press cake, for feed-quality products. This study evaluated the combination of grass-clover biorefinery and the power-to-X concept, including power-to-protein technology, for its environmental sustainability through a consequential life cycle assessment (CLCA). The production of protein concentrate from organic grass clover exhibits optimal environmental performance when press cake and brown juice are used for bioenergy recovery. The findings indicate that combining a green biorefinery with power-to-protein to fully valorize the carbon and nitrogen content of brown juice and press cake into feed-grade protein can increase the environmental benefits. Such an integration resulted in an avoided impact of −995.9 kg CO2-eq/tonne of protein concentrate. The avoided impacts of climate change could be higher within the first 20 years due to a higher carbon sequestration rate. However, even after 20 years when a new carbon balance in the soil is reached, the environmental gain could be big enough to encourage the production and use of organic grass-clover protein concentrate.

Prospective consequential life cycle assessment: Identifying the future marginal suppliers using integrated assessment models

Previous research efforts have focused on developing prospective life cycle inventory databases that build upon projections from integrated assessment models but were limited to attributional system models. A novel approach is required to construct consequential LCI databases that can be applied consistently on a large scale. To this end, the heuristic approach from Bo Weidema was selected as a basis for this study. This approach has been validated with historical data and was adapted in this study to identify the marginal suppliers in a prospective context. The different steps within the approach were analyzed, and alternative techniques for each step within the heuristic method were proposed. The techniques were tested on the future electricity sector using projections from two integrated assessment models (IMAGE and REMIND). Results show the sensitivity of results on the modelling technique selected in each step. The most sensitive step is the selection of the time interval, with even small changes resulting in a noticeable difference. In addition, the results also showed a substantial difference between the projections of the two models. The relevance and goals of the alternative techniques for each step were discussed to guide users in forming the heuristic method for their study.

Environmental and land use consequences of replacing milk and beef with plant-based alternatives

The consumption of meat and dairy products raise enormous environmental concerns. Circa 80% of global greenhouse gas emissions (GHG) from the livestock industry originate from beef, milk and pork production. Changing the production and consumption of meat and dairy products is considered to offer an important contribution to achieving the Paris Agreement climate targets (UNFCCC, 2015), and could reduce the import of soybean meal to Europe from countries where it is linked with deforestation. However, individual diet substitutions may have indirect and unintended environmental consequences across interlinked livestock systems – hence a wider assessment of impacts of consumption changes is required using consequential life cycle assessment (LCA). In this study, we investigated the environmental consequences of two independent yet interconnected diet choices in a German context: (i) replacing dairy milk with soy milk, and; (ii) replacing beef meatballs with pea protein balls. We related commodity demand to detailed agricultural rotations and land use changes via farm scale economic modelling coupled with consequential LCA. The substitution of beef meatballs with pea-derived protein balls can result in GHG savings of 2.4 kg CO2e per 100 g serving, and up to 7.3 kg CO2e per 100 g serving if spared land is afforested. Environmental problems related to nutrient leakage such as acidification and eutrophication are also mitigated. Meanwhile, unless accompanied by dramatic reductions in beef consumption, the substitution of cow milk with soy-based milk does not lead to significant GHG mitigation owing to the displacement of dairy-beef production to less efficient suckler-beef systems. Nonetheless, land sparing by cow milk substitution could support overall GHG mitigation if combined with afforestation. This study confirms that legumes can play an important role in diet transitions towards climate neutrality, especially via substitution of meat (as opposed to dairy) products.

Assessing the environmental footprints and material flow of 2,3-butanediol production in a wood-based biorefinery

This study aims to scrutinize and compare the environmental impacts of biobased 2,3-butanediol (BDO) and its fossil-based counterpart. BDO is a fundamental chemical in various industries, traditionally derived from petroleum sources. Wood residues, largely available in Nordic countries, are sustainable alternative feedstocks, offering potential environmental benefits. Material flow analysis followed by consequential life cycle assessment (LCA) were employed to quantify the potential environmental burdens associated with various biorefinery stages of wood-based BDO production. The findings indicated that refraining from wood combustion and, instead, utilizing wood in a biorefinery to produce BDO as the main product, with methane and fertilizer as coproducts from the waste residue, resulted in 125%, 52%, and 90% better environmental performance regarding human health, climate change, and resource scarcity, respectively, compared to fossil-based BDO production. The results offer valuable insights for technology developers and policymakers, empowering them to make informed decisions and support sustainable practices.

Attributional and consequential life cycle perspectives of second-generation polylactic acid: The benefits of integrating a recycling strategy

The climate crisis calls for a shift from petrochemicals to bio-based products to reduce environmental consequences. Polylactic acid (PLA) is one of the most widely used biopolymers, due to its mechanical properties and renewable origin, to produce bio-based compostable plastic for food packaging. The objective of this study is to determine the environmental feasibility of a second-generation PLA production based on wheat straw; and the role of a chemical recycling plant on the environmental performance of a bioproduct at an early design stage. A holistic assessment was performed through the Life Cycle Assessment (LCA) methodology considering both attributional and consequential perspectives, through a cradle-to-grave approach. The attributional LCA results show that lactic acid production was the main contributor due to the wheat straw pre-treatment and downstream separation and purification (DSP) processes. The integration of a recycling plant leads to a significant reduction of burdens, ranging from 1.38 to 0.44 kg CO2eq in the Global Warming category. Furthermore, consequential LCA results shows that the increased demand for substitute products for activities such as feeding, fertilisation and energy generation and the indirect emissions from land use change related to the conversion of land for the cultivation of raw materials are relevant factors in the environmental effects associated with the possible implementation of straw-based bioPLA production system.

LCA to evaluate the environmental opportunity cost of biological performances in finfish farming

PurposeMortality and suboptimal biological performance are a widespread problem in finfish farming. The associated losses constitute an environmental opportunity cost that needs to be thoroughly assessed to prioritize actions aiming at reducing the environmental impacts of finfish aquaculture. We here propose and demonstrate the use of a new parameterized and consequential LCA model of sea-trout production designed to assess the environmental opportunity costs of suboptimal biological performances, considering distinct mortalities and biological feed conversion ratios (FCRs) along the rearing process.MethodsPrimary data was collected in Danish and Italian farms to reconstitute the whole production process for sea-reared trouts. The level of detail allowed us to divide this production into seven different growth stages for which mortality and biological FCR can be assessed and modified. Excretion and valorization of fish sludge were modeled with a calibrated mass-balance model. Together with fish sludge, dead fish was modeled as valorized by anaerobic digestion. The foreground system was linked to the consequential version of ecoinvent 3.8 for which the embedded uncertainty was considered in Monte Carlo simulations. The model was used to assess the current environmental opportunity costs and evaluate the effect of losses happening at different timings along the rearing process.Results and discussionResults showed a low environmental opportunity cost for the current mortality rate of 5% as suppressing this mortality decreased impacts by 3.5 to 5% across impact categories. Decreasing the biological FCR decreased the environmental impacts proportionally. The timing of the losses was shown to greatly influence the environmental opportunity cost, and the same mortality rate happening in the late stages had substantially more impact than in the first stages. The valorization of the dead fish showed a negligible contribution to the reduction of impacts in the current system but showed a substantial contribution in the case of higher mortalities, such as observed for other farms and foreseen in the future.ConclusionThe model demonstrated that assessing an opportunity cost by multiplying the lost biomass by a unique impact factor constitutes an oversimplification neglecting the losses timing and the fact that fish biomass is not a marketable product. Even though the current environmental opportunity cost for losses appeared neglectable, suboptimal biological FCR should be tackled. The model and approach can be used to project trout farming within future disease regimes and assess the trade-offs regarding fish health issues and new treatments and practices.