Understanding the future of lithium: Part 1, resource model

Lithium is a critical energy material in part due to an array of emerging technologies from electric vehicles to renewable energy systems that rely on large‐format lithium ion batteries. Recent growth in demand for lithium is primarily from increased use in batteries, which comprised 46% of total lithium by end use in 2017. These technologies are often deployed to improve environmental sustainability, yet the environmental effects and sustainability of the resources they rely on are often not well understood, especially as demand increases over time. This is the first in a two part article series that together quantify the lithium resource use and its environmental effects over time by coupling a resource production model and life cycle assessment model. In this first part, a novel resource production model is developed to create scenarios of future lithium demand and production characteristics (e.g., timing, location, and ore type). These scenarios are then used to create a life cycle assessment in part two that captures temporal and spatial changes in production systems over time. Results of the resource production model show global lithium resources range from 293 to 527 million metric tons (Mt) of lithium carbonate equivalent (LCE). Global production will likely increase from 237,000 metric tons LCE in 2018 to 4.4–7.5 Mt LCE/year by 2100. Even with rapidly increasing demand, production from high‐grade brines may satisfy most lithium demand through 2035. Though resources can meet demand through 2100, development of lower grade and unfavorable deposits is likely required after 2050.     

Quantifying environmental impacts of primary aluminum ingot production and consumption : A trade‐linked multilevel life cycle assessment

Aluminum is one of the most used metals of modern civilization, but its production is responsible for multiple adverse environmental impacts mostly due to aluminum smelting and alumina refining. Previous life cycle assessments (LCAs) have aggregated alumina refining into a single global process even though refining processes are highly spatially differentiated and alumina is highly traded. Our work improves on existing LCAs of primary aluminum by including temporal and spatial differentiation in alumina refining and aluminum smelting and trade of alumina and primary aluminum ingots. We build country‐level impact factors for primary aluminum ingot production and consumption, with the spatial distributions of environmental impacts, from 2000 to 2017, by combining a trade‐linked multilevel material flow analysis with LCA using six midpoint categories of the ReCiPe method. Climate change impacts of primary aluminum production range from 4.5 to 33.6 kg CO₂ eq./kg. We then estimate the life cycle production‐ and consumption‐based environmental burdens of primary aluminum ingot by country. High spatial variations exist among impact factors of primary aluminum production. Aggregating the alumina refining processes into a single process may cause important deviations on the impact factors of primary aluminum ingot production (up to 38% differences in climate change impacts). Finally, we estimate the climate change impacts of worldwide primary aluminum production at 1.2 Gt CO₂ eq. in 2017 and untangle their spatial origins, localized at 70% in China. Overall, we show the importance of spatial differentiation for highly traded products that rely on highly traded inputs and offer recommendations for LCA practitioners. This article met the requirements for a gold‐gold JIE data openness badge described at http://jie.click/badges .     

Are future recycling benefits misleading? Prospective life cycle assessment of lithium-ion batteries

Life cycle assessment (LCA) quantifies the whole-life environmental impacts of products and is essential for helping policymakers and manufacturers transition toward sustainable practices. However, typical LCA estimates future recycling benefits as if it happens today. For long-lived products such as lithium-ion batteries, this may be misleading since there is a considerable time gap between production and recycling. To explore this temporal mismatch problem, we apply future electricity scenarios from an integrated assessment model—IMAGE—using “premise” in Brightway2 to conduct a prospective LCA (pLCA) on the global warming potential of six battery chemistries and four recycling routes. We find that by 2050, electricity decarbonization under an RCP2.6 scenario mitigates production impacts by 57%, so to reach zero-carbon batteries it is important to decarbonize upstream heat, fuels, and direct emissions. For the best battery recycling case, data for 2020 gives a net recycling benefit of −22 kg CO₂e kWh⁻¹ which reduces the net impact of production and recycling from 71 to 49 kg CO₂e kWh⁻¹. However, for recycling in 2040 with decarbonized electricity, net recycling benefits would be nearly 75% lower (−6 kg CO₂e kWh⁻¹), giving a net impact of 65 kg CO₂e kWh⁻¹. This is because materials recycled in the future substitute lower-impact processes due to expected electricity decarbonization. Hence, more focus should be placed on mitigating production impacts today instead of relying on future recycling. These findings demonstrate the importance of pLCA in tackling problems such as temporal mismatch that are difficult to capture in typical LCA.     

Life cycle assessment of recirculating aquaculture systems: A case of Atlantic salmon farming in China

Recirculating aquaculture systems (RAS) are an alternative technology to tackle the major environmental challenges associated with conventional cage culture systems. In order to systematically assess the environmental performance of RAS farming, it is important to take the whole life cycle into account so as to avoid ad hoc and suboptimal environmental measures. So far, the application of life cycle assessment (LCA) in aquaculture, especially to indoor RAS, is still in progress. This study reports on an LCA of Atlantic salmon harvested at an indoor RAS farm in northern China. Results showed that 1 tonne live‐weight salmon production required 7,509 kWh farm‐level electricity and generated 16.7 tonnes of CO₂ equivalent (eq), 106 kg of SO₂ eq, 2.4 kg of P eq, and 108 kg of N eq (cradle‐to‐farm gate). In particular, farm‐level electricity use and feed product were identified as primary contributors to eight of nine impact categories assessed (54–95% in total), except the potential marine eutrophication (MEU) impact (dominated by the grow‐out effluents). Among feed ingredients (on a dry‐weight basis), chicken meal (5%) and krill meal (8%) dominated six and three, respectively, of the nine impact categories. Suggested environmental improvement measures for this indoor RAS farm included optimization of stocking density, feeding management, grow‐out effluent treatment, substitution of feed ingredients, and selection of electricity generation sources. In a generic context, this study can contribute to a better understanding of the life cycle environmental impacts of land‐based salmon RAS operations, as well as science‐based communication among stakeholders on more eco‐friendly farmed salmon.     

A scalable and spatiotemporally resolved agricultural life cycle assessment of California almonds

Purpose

California’s Central Valley produces more than 75% of global commercial almond supply, making the life cycle performance of almond production in California of global interest. This article describes the life cycle assessment of California almond production using a Scalable, Process-based, Agronomically Responsive Cropping System Life Cycle Assessment (SPARCS-LCA) model that includes crop responses to orchard management and modeling of California’s water supply and biomass energy infrastructure.

Methods

A spatially and temporally resolved LCA model was developed to reflect the regional climate, resource, and agronomic conditions across California’s Central Valley by hydrologic subregion (San Joaquin Valley, Sacramento Valley, and Tulare Lake regions). The model couples a LCA framework with region-specific data, including water supply infrastructure and economics, crop productivity response models, and dynamic co-product markets, to characterize the environmental performance of California almonds. Previous LCAs of California almond found that irrigation and management of co-products were most influential in determining life cycle CO₂eq emissions and energy intensity of California almond production, and both have experienced extensive changes since previous studies due to drought and changing regulatory conditions, making them a focus of sensitivity and scenario analysis.

Results and discussion

Results using economic allocation show that 1 kg of hulled, brown-skin almond kernel at post-harvest facility gate causes 1.92 kg CO₂eq (GWP₁₀₀), 50.9 MJ energy use, and 4820 L freshwater use, with regional ranges of 2.0–2.69 kg CO₂eq, 42.7–59.4 MJ, and 4540–5150 L, respectively. With a substitution approach for co-product allocation, 1 kg almond kernel results in 1.23 kg CO₂eq, 18.05 MJ energy use, and 4804 L freshwater use, with regional ranges of 0.51–1.95 kg CO₂eq, 3.68–36.5 MJ, and 4521–5140 L, respectively. Almond freshwater use is comparable with other nut crops in California and globally. Results showed significant variability across subregions. While the San Joaquin Valley performed best in most impact categories, the Tulare Lake region produced the lowest eutrophication impacts.

Conclusion

While CO₂eq and energy intensity of almond production increased over previous estimates, so too did credits to the system for displacement of dairy feed. These changes result from a more comprehensive model scope and improved assumptions, as well as drought-related increases in groundwater depth and associated energy demand, and decreased utilization of biomass residues for energy recovery due to closure of bioenergy plants in California. The variation among different impact categories between subregions and over time highlight the need for spatially and temporally resolved agricultural LCA.

     

The effect of local climate and soil drainage on the environmental impact of grass-based milk production

Purpose

System modelling and life cycle assessment (LCA) were used to assess the climate change, acidification and eutrophication impacts of milk production using spring calving pasture-based system. The objective of the study was to evaluate the effect of climate and soil resources on the environmental impact per unit milk produced at the farm gate from low-cost, grass-based rotational-grazing dairy production.

Methods

A dairy system model, Dairy_sim, designed to identify optimum grass-based spring calving production systems considering the interaction between climate and soil resources was tested using the Irish National Dairy Blueprint and then used to assess regional differences of system management with well, moderately, mixed moderately-poorly and poorly drained soil resources available. Life cycle assessment was used to quantify environmental impacts of climate and soil drainage status. The Dairy_sim output was used as activity data for the LCA model.

Results and discussion

Differences were found in the management tactics influenced by climate and drainage resource. The impact of poor drainage reduced stocking rate, increased housing time and had greater need for later cut silage and more reliance on silage. Climate change, acidification and eutrophication impacts were greater for optimum management on poorly drained soil. The climate change ranged from 1.06 kg CO₂ eq./kg (well drained) to 1.18 kg CO₂ eq./kg (poorly drained) of energy corrected milk (ECM). The acidification and eutrophication ranged from 3.87 to 6.85 g SO₂ eq./kg ECM and 2.69 to 3.64 g PO₄ eq./kg ECM, respectively. Around 50% of poorly drained soil resource can be easily accommodated in dairy systems with little increase in environmental impact, where poor drained portion is utilised for silage.

Conclusions

LCA combined with a system optimization model revealed how dairy farm management practises constrained by poor land resource increased the environmental impact per unit product.

     

Life cycle assessment of cane-sugar on the island of mauritius

Goal, Scope and Background  Agricultural production includes not only crop production, but also food processing, transport, distribution, preparation, and disposal. The effects of all these must be considered and controlled if the food chain is to be made sustainable. The goal of this case study was to identify and review the significant areas of potential environmental impacts across the whole life cycle of cane sugar on the island of Mauritius. Methods  The functional unit was one tonne of exported raw sugar from the island. The life cycle investigated includes the stage of cane cultivation and harvest, cane burning, transport, fertilizer and herbicide manufacture, cane sugar manufacture and electricity generation from bagasse. Data was gathered from companies, factories, sugar statistics, databases and literature. Energy depletion, climate change, acidification, oxidant formation, nutrification, aquatic ecotoxicity and human toxicity were assessed. Results and Discussion  The inventory of the current sugar production system revealed that the production of one tonne of sugar requires, on average, a land area of 0.12 ha, the application of 0.84 kg of herbicides and 16.5 kg of N-fertilizer, use of 553 tons of water and 170 tonne-km of transport services. The total energy consumption is about 14235 MJ per tonne of sugar, of which fossil fuel consumption accounts for 1995 MJ and the rest is from renewable bagasse. 160 kg of CO₂ per tonne of sugar is released from fossil fuel energy use and the net avoided emissions of CO₂ on the island due to the use of bagasse as an energy source is 932,000 tonnes. 1.7 kg TSP, 1.21 kg SO₂,1.26 kgNO_xand 1.26 kg CO are emitted to the air per tonne of sugar produced. 1.7 kg N, 0.002 kg herbicide, 19.1 kg COD, 13.1 kgTSS and 0.37 kg PO₄ ^3- are emitted to water per tonne of sugar produced. Cane cultivation and harvest accounts for the largest environmental impact (44%) followed by fertilizer and herbicide manufacture (22%), sugar processing and electricity generation (20%), transportation (13%) and cane burning (1%). Nutrification is the main impact followed by acidification and energy depletion. Conclusions  There are a number of options for improvement of the environmental performance of the cane-sugar production chain. Cane cultivation, and fertilizer and herbicide manufacture, were hotspots for most of the impact categories investigated. Better irrigation systems, precision farming, optimal use of herbicides, centralisation of sugar factories, implementation of co-generation projects and pollution control during manufacturing and bagasse burning are measures that would considerably decrease resource use and environmental impacts. Recommendation and Outlook  LCA was shown to be a valuable tool to assess the environmental impacts throughout the food production chain and to evaluate government policies on agricultural production systems.     

Life cycle assessment comparison of wooden and plastic pallets in the grocery industry

Wooden and plastic pallets are used extensively in global trade to transport finished goods and products. This article compares the life cycle performance of treated wooden and plastic pallets through a detailed cradle‐to‐grave life cycle assessment (LCA), and conducts an analysis of the various phytosanitary treatments. The LCA investigates and evaluates the environmental impacts due to the resources consumed and emissions of the product throughout its life cycle. The environmental impacts of the pallets are compared on a one‐trip basis and a 100,000‐trips basis. Impact categories are chosen with respect to environmental concerns. The results show that on a one‐trip basis, wooden pallets with conventional and radio frequency (RF) heat treatment incur an overall carbon footprint of 71.8% and 80.3% lower, respectively, than plastic pallets during their life cycle; and in comparison with wooden pallets treated with methyl bromide fumigation, they incur 20% and 30% less overall carbon footprint. Theoretical calculations of the resource consumption and emissions of RF treatment of pallets suggest that dielectric technology may provide a lower‐carbon alternative to both current ISPM 15‐approved treatments and to plastic pallets. Methyl bromide fumigation (15.95 kg CO₂ equivalent [eq.]) has a larger carbon footprint than conventional heat treatment (12.69 kg CO₂ eq.) of pallets. For the 100,000‐trips basis, the differences are even more significant. The results recommend that wooden pallets are more environmentally friendly than plastic pallets, and conventional and RF heat treatment for wooden pallets is more sustainable than methyl bromide fumigation treatment.     

Life cycle assessment of forest biomass energy feedstock in the Northeast United States

Life cycle assessment (LCA) was combined with primary data from nine forest harvesting operations in New York, Maine, Massachusetts, and Vermont, from 2013 to 2019 where forest biomass (FB) for bioenergy was one of several products. The objective was to conduct a data‐driven study of greenhouse gas emissions associated with FB feedstock harvesting operations in the Northeast United States. Deterministic and stochastic LCA models were built to simulate the current FB bioenergy feedstock supply chain in the Northeast US with a cradle‐to‐gate scope (forest harvest through roadside loading) and a functional unit of 1.0 Mg of green FB feedstock at a 50% moisture content. Baseline LCA, sensitivity analysis, and uncertainty analyses were conducted for three different FB feedstock types—dirty chips, clean chips, and grindings—enabling an empirically driven investigation of differences between feedstock types, individual harvesting process contributions, and literature comparisons. The baseline LCA average impacts were lower for grindings (4.57 kg CO_2eq/Mg) and dirty chips (7.16 kg CO_2eq/Mg) than for clean chips (23.99 kg CO_2eq/Mg) under economic allocation, but impacts were of similar magnitude under mass allocation, ranging from 24.42 to 27.89 kg CO_2eq/Mg. Uncertainty analysis showed a wider range of probable results under mass allocation compared to economic allocation. Sensitivity analysis revealed the impact of variations in the production masses and total economic values of primary products of forest harvests on the LCA results due to allocation of supply chain emissions. The high variability in fuel use between logging contractors also had a distinct influence on LCA results. The results of this study can aid decision‐makers in energy policy and guide emissions reductions efforts while informing future LCAs that expand the system boundary to regional FB energy pathways, including electricity generation, transportation fuels, pellets for heat, and combined heat and power.     

Consideration of carbon dioxide release during shell production in LCA of bivalves

Purpose

Life cycle assessment (LCA) can be used to understand the environmental impacts of the shellfish aquaculture and wild harvest industries. To date, LCA of shellfish exclude carbon dioxide (CO₂) release from bivalve shell production when quantifying global warming potential per functional unit. In this study, we explain the rationale for including CO₂ released during shell production in LCA of bivalves, demonstrate a method for estimating this CO₂ release, and apply the method to previous studies to demonstrate the importance of including CO₂ from shell production in LCA.

Methods

A simple approach for calculating CO₂ from bivalve shell production was developed utilizing the seacarb package in R statistical software. The approach developed allows for inclusion of site-specific environmental parameters such as water temperature, salinity, pH, and pCO₂ when calculating CO₂ release from shell production. We applied the method to previously published LCA of bivalve production systems to assess the impact of including this CO₂ source in the LCA. The past studies include aquaculture and wild harvest production strategies and multiple bivalve species.

Results and discussion

When we recalculated the total kg CO₂ released in past studies including CO₂ release from shell production, the additional CO₂ release increased the total global warming impact category (CO₂ equivalents) in cradle-to-gate studies by approximately 250% of the original reported value. Discussion of our results focuses on the importance of different components of our calculations and site-specific environmental parameters. We make predictions on how the magnitude and importance of CO₂ released during shell production could change due to climate change and ocean acidification, and provide suggestions on how CO₂ release from shell production can be reduced through careful selection of aquaculture facility location and aquaculture practices.

Conclusions

We provide a method for including CO₂ from shell release in LCA of bivalves and recommend that future LCA of bivalves include this CO₂ as part of the global warming impact category.

     

Life cycle analysis of biochemical cellulosic ethanol under multiple scenarios

Cellulosic ethanol is widely believed to offer substantial environmental advantages over petroleum fuels and grain‐based ethanol, particularly in reducing greenhouse gas emissions from transportation. The environmental impacts of biofuels are largely caused by precombustion activities, feedstock production and conversion facility operations. Life cycle analysis (LCA) is required to understand these impacts. This article describes a field‐to‐blending terminal LCA of cellulosic ethanol produced by biochemical conversion (hydrolysis and fermentation) using corn stover or switchgrass as feedstock. This LCA develops unique models for most elements of the biofuel production process and assigns environmental impact to different phases of production. More than 30 scenarios are evaluated, reflecting a range of feedstock, technology and scale options for near‐term and future facilities. Cellulosic ethanol, as modeled here, has the potential to significantly reduce greenhouse gas (GHG) emissions compared to petroleum‐based liquid transportation fuels, though substantial uncertainty exists. Most of the conservative scenarios estimate GHG emissions of approximately 45–60 g carbon dioxide equivalent per MJ of delivered fuel (g CO₂e MJ^?1) without credit for coproducts, and 20–30 g CO₂e MJ^?1 when coproducts are considered. Under most scenarios, feedstock production, grinding and transport dominate the total GHG footprint. The most optimistic scenarios include sequestration of carbon in soil and have GHG emissions below zero g CO₂e MJ^?1, while the most pessimistic have life‐cycle GHG emissions higher than petroleum gasoline. Soil carbon changes are the greatest source of uncertainty, dominating all other sources of GHG emissions at the upper bound of their uncertainty. Many LCAs of biofuels are narrowly constrained to GHG emissions and energy; however, these narrow assessments may miss important environmental impacts. To ensure a more holistic assessment of environmental performance, a complete life cycle inventory, with over 1100 tracked material and energy flows for each scenario is provided in the online supplementary material for this article.     

Environmental assessment of yield improvements obtained by the use of the enzyme phospholipase in mozzarella cheese production

Background, aim and scope  Phospholipase is an enzyme which is able to increase the yield of cheese in, for instance, mozzarella production. Milk production is the most important source of environmental impacts in cheese production and it is obvious to assume that the milk saving that comes with the use of phospholipase reduces the overall environmental impacts of the final product. Production of industrial phospholipase is, however, also associated with environmental burdens and it is not known whether and to what extent the use of phospholipase is justified by overall environmental improvements. The aim of the present study is therefore to assess the environmental impacts that come with the use of industrial phospholipase in mozzarella production and compare with the savings that come with the avoided milk production. The study addresses mozzarella production in Denmark. Methods  LCA is used as analytical tool and environmental modelling is facilitated in SimaPro 7.1.8 LCA software. Yield improvements refer to full scale industrial application of phospholipase in cheese industry. The study is a comparative analysis and a marginal and market-oriented approach is taken. The study addresses contribution to global warming, acidification, nutrient enrichment, photochemical smog formation, energy consumption and use of agricultural land. Estimation of environmental impact potentials is based on Eco-indicator 95 v.2.1 equivalency factors. Toxicity is addressed by qualitative means. Results  The environmental impacts induced by phospholipase production are small compared with the savings obtained by reduced milk consumption for mozzarella production when all impact indicators are considered. Sensitivity analyses and data quality assessments indicate that this general outcome of the study is robust, although results at the more detailed level are the subject of much variation and uncertainty. Discussion  Transport of the enzyme from producer to mozzarella producer is insignificant and the general outcome of the study is considered applicable to other regions of the world where milk is produced in modern milk production systems. Conclusions  Use of phospholipase as a yield improvement factor is a means of reducing environmental impact of mozzarella production. Recommendations and perspectives  The total annual global warming mitigation potential of phospholipase used in production of mozzarella and other pasta filata products is in the order of 7 × 10⁸ kg CO₂ equivalents. The use of phospholipase is driven by overall cost savings and it is therefore recommended that the enzyme should be given attention as a cost-efficient means of reducing greenhouse gas emissions.     

Life Cycle Based CO2 Emission Credits: Options for Improving the Efficiency and Effectiveness of Current Tailpipe Emissions Regulation in the Automotive Industry

The current focus on the use phase in automotive carbon dioxide (CO₂) legislation bares a risk of unintended consequences as often reductions in the use phase come along with increasing CO₂ emissions in other life cycle (LC) phases. This study presents voluntary policy options in form of LC‐based CO₂ emission credits. They were developed by desk research considering existing applications of LCA in practice (e.g., environmental reports) and feedback obtained in a structured stakeholder dialogue. A variety of credit options were identified, including rather simple ones based on life cycle thinking (LCT) and more advanced options which rely on quantitative LCA: LCT options that reward innovations leading to CO₂ reductions, for example, in the production phase. LCA‐based options reward CO₂ reductions along the LC (credits for an International Organization for Standardization [ISO] 14044 conforming externally reviewed LCA showing a continuous improvement) or reductions of other environmental impacts. It was shown that the credit options can be implemented throughout a simplified and robust methodology, for example, with defined rules for conducting the LCA based on international standards and established industry practice, and for calculating the credits (e.g., a credit of 1 gram [g] of CO₂/km [kilometer] for savings of 10 g of CO₂/km). Voluntary credit options as a complementary modality to the current automotive tailpipe‐based CO₂ regulations would help to improve its efficiency and effectiveness and support and reward efforts on achieving real net CO₂ emission reductions. The credit options were developed with a first focus on CO₂ and automotive industry, but can generally be transferred to other environmental impacts and sectors as well.     

Including albedo in time‐dependent LCA of bioenergy

Albedo change during feedstock production can substantially alter the life cycle climate impact of bioenergy. Life cycle assessment (LCA) studies have compared the effects of albedo and greenhouse gases (GHGs) based on global warming potential (GWP). However, using GWP leads to unequal weighting of climate forcers that act on different timescales. In this study, albedo was included in the time‐dependent LCA, which accounts for the timing of emissions and their impacts. We employed field‐measured albedo and life cycle emissions data along with time‐dependent models of radiative transfer, biogenic carbon fluxes and nitrous oxide emissions from soil. Climate impacts were expressed as global mean surface temperature change over time (?T) and as GWP. The bioenergy system analysed was heat and power production from short‐rotation willow grown on former fallow land in Sweden. We found a net cooling effect in terms of ?T per hectare (?3.8 × 10^–11 K in year 100) and GWP₁₀₀ per MJ fuel (?12.2 g CO₂e), as a result of soil carbon sequestration via high inputs of carbon from willow roots and litter. Albedo was higher under willow than fallow, contributing to the cooling effect and accounting for 34% of GWP₁₀₀, 36% of ?T in year 50 and 6% of ?T in year 100. Albedo dominated the short‐term temperature response (10–20 years) but became, in relative terms, less important over time, owing to accumulation of soil carbon under sustained production and the longer perturbation lifetime of GHGs. The timing of impacts was explicit with ?T, which improves the relevance of LCA results to climate targets. Our method can be used to quantify the first‐order radiative effect of albedo change on the global climate and relate it to the climate impact of GHG emissions in LCA of bioenergy, alternative energy sources or land uses.     

Environmental impacts of bioenergy wood production from poplar short‐rotation coppice grown at a marginal agricultural site in Germany

For avoiding competition with food production, marginal land is economically and environmentally highly attractive for biomass production with short‐rotation coppices (SRCs) of fast‐growing tree species such as poplars. Herein, we evaluated the environmental impacts of technological, agronomic, and environmental aspects of bioenergy production from hybrid poplar SRC cultivation on marginal land in southern Germany. For this purpose, different management regimes were considered within a 21‐year lifetime (combining measurements and modeling approaches) by means of a holistic Life Cycle Assessment (LCA). We analyzed two coppicing rotation lengths (7 × 3 and 3 × 7 years) and seven nitrogen fertilization rates and included all processes starting from site preparation, planting and coppicing, wood chipping, and heat production up to final stump removal. The 7‐year rotation cycles clearly resulted in higher biomass yields and reduced environmental impacts such as nitrate (NO₃) leaching and soil nitrous oxide (N₂O) emissions. Fertilization rates were positively related to enhanced biomass accumulation, but these benefits did not counterbalance the negative impacts on the environment due to increased nitrate leaching and N₂O emissions. Greenhouse gas (GHG) emissions associated with the heat production from poplar SRC on marginal land ranged between 8 and 46 kg CO₂‐eq. GJ^?1 (or 11–57 Mg CO₂‐eq. ha^?1). However, if the produced wood chips substitute oil heating, up to 123 Mg CO₂‐eq. ha^?1 can be saved, if produced in a 7‐year rotation without fertilization. Dissecting the entire bioenergy production chain, our study shows that environmental impacts occurred mainly during combustion and storage of wood chips, while technological aspects of establishment, harvesting, and transportation played a negligible role.     

Utilization of woody biomass in Singapore: technological options for carbonization and economic comparison with incineration

Background, aim and scope  The interest in the use of biomass as a renewable energy resource has rapidly grown over the past few years. In Singapore, biomass resources are mostly from waste wood. This article presents a few technological options, namely carbonization, for the conversion of woody biomass into a solid fuel, charcoal. Materials and methods  In the first stage, a life cycle assessment (LCA) ‘gate-to-gate’ system was developed for a conventional carbonizer system, a modern carbonizer from Japan, and a proposed four-stage partial furnace carbonizer from Tunisia. The potential environmental impacts were generated for global warming potential, acidification, human toxicity and photochemical oxidant potential. Based on the first set of results, the second LCA investigation was carried out comparing the selected carbonizer from Japan and an existing incinerator in Singapore. The second LCA adopted a unique approach combining social costs of pollution with the economic factors of the two biomass conversion technologies. Results  The carbonizer from Japan resulted in approximately 85% less greenhouse gases than the conventional carbonization system and 54% less than the proposed four-stage carbonizer from Tunisia. In terms of acidification and human toxicity, the carbonizers from Japan and Tunisia display nearly similar results—both were considerably lower than the conventional carbonizer. For photochemical oxidant potential, very minimal emissions are generated from the four-stage carbonizer and nearly zero impact is realized for the carbonization technology from Japan. Discussion  From the first set of LCA results, the Japanese carbonizer is favored in terms of its environmental results. The highest environmental impacts from the conventional carbonizer were due to large and uncontrolled emissions of acidic gases, greenhouse gases (particularly CO₂ and CH₄), particulates, and non-methane volatile organic compounds from both fugitive sources and energy requirements. The second LCA addressed the performance of the carbonizer from Japan against an existing incinerator in terms of environmental as well as cost performances. This unique approach translated pollution emissions into monetary costs to highlight the impacts of social health. Conclusions  For the first LCA, the accumulated impacts from the Japanese carbonizer proved to display significantly lower environmental impacts, especially for global warming potential. The overall environmental performance of the four-stage carbonizer from Tunisia ranked slightly lower than the one from Japan and much higher than the conventional carbonizer. The second LCA results displayed a noteworthy improvement of 90% for human health from the modern Japanese carbonizer technology—when compared against conventional incinerators. Without considering health issues or social costs, the total value per ton of wood treated is nearly similar for both incinerator and carbonizer. Recommendations and perspectives  The interest in biomass as raw material for producing energy has emerged rapidly in many countries. However, careful analysis and comparison of technologies are necessary to ensure favorable environmental outcomes. A full life cycle study, along with costs and the impact of pollution on society, should be performed before any large-scale biomass conversion technology is implemented. LCA can be applied to quantify and verify the overall environmental performance of a particular technology of interest as well as further explore the proposed technology in terms of costs and social implications.     

Life cycle assessment of fuel ethanol from sugarcane in Argentina

Purpose

The production of bioethanol in Argentina is based on the sugarcane plantation system, with extensive use of agricultural land, scarce use of fertilizers, pesticides, and artificial irrigation, and burning of sugarcane prior to harvesting. The objective of this paper is to develop a life cycle assessment (LCA) of the fuel ethanol from sugarcane in Tucumán (Argentina), assessing the environmental impact potentials to identify which of them cause the main impacts.

Methods

Our approach innovatively combined knowledge about the main impact pathways of bioethanol production with LCA which covers the typical emission-related impact categories at the midpoint life cycle impact assessment. Real data from the Argentinean industry subsystems have been used to perform the study: S1—sugarcane production, S2—milling process, S3—sugar production, and S4—ethanol production from molasses, honey, or sugarcane juice.

Results and discussion

The results are shown in the three alternative pathways to produce bioethanol. Different impact categories are assessed, with global warming potential (GWP) having the highest impact. So, the production of 1 kg of ethanol from molasses emitted 22.5 kg CO₂ (pathway 1), 19.2 kg CO₂ from honey (pathway 2), and 15.0 kg CO₂ from sugarcane juice (pathway 3). Several sensitivity analyses to study the variability of the GWP according to the different cases studied have been performed (changing the agricultural yield, including economic and calorific allocation in sugar production, and modifying the sugar price).

Conclusions

Agriculture is the subsystem which shows the highest impact in almost all the categories due to fossil fuel consumption. When an economic and calorific allocation is considered to assess the environmental impact, the value is lower than when mass allocation is used because ethanol is relatively cheaper than sugars and it has higher calorific value.     

Life cycle assessment of California unsweetened almond milk

Purpose

Plant-based alternatives to dairy milk have grown in popularity over the last decade. Almond milk comprises the largest share of plant-based milk in the US market and, as with so many food products, stakeholders in the supply chain are increasingly interested in understanding the environmental impacts of its production, particularly its carbon footprint and water consumption. This study undertakes a life cycle assessment (LCA) of a California unsweetened almond milk.

Methods

The scope of this LCA includes the production of almond milk in primary packaging at the factory gate. California produces all US almonds, which are grown under irrigated conditions. Spatially resolved modeling of almond cultivation and primary data collection from one almond milk supply chain were used to develop the LCA model. While the environmental indicators of greatest interest are global warming potential (GWP) and freshwater consumption (FWC), additional impact categories from US EPA’s TRACI assessment method are also calculated. Co-products are accounted for using economic allocation, but mass-based allocation and displacement are also tested to understand the effect of co-product allocation choices on results.

Results and discussion

The GWP and FWC of one 48 oz. (1.42 L) bottle of unsweetened almond milk are 0.71 kg CO₂e and 175 kg of water. A total of 0.39 kg CO₂e (or 55%) of the GWP is attributable to the almond milk, with the remainder attributable to packaging. Almond cultivation alone is responsible for 95% of the FWC (167 kg H₂O), because of irrigation water demand. Total primary energy consumption (TPE) is estimated at 14.8 MJ. The 48 oz. (1.42 L) PET bottle containing the almond milk is the single largest contributor to TPE (42%) and GWP (35%). Using recycled PET instead of virgin PET for the bottle considerably reduces all impact indicators except for eutrophication potential.

Conclusions

For the supply chain studied here, packaging choices provide the most immediate opportunities for reducing impacts related to GWP and TPE, but would not result in a significant reduction in FWC because irrigation water for almond cultivation is the dominant consumer. To provide context for interpretation, average US dairy milk appears to have about 4.5 times the GWP and 1.8 times the FWC of the studied almond milk on a volumetric basis.