Life cycle assessment of renewable diesel production from lignocellulosic biomass

Purpose

Governments around the world encourage the use of biofuels through fuel standard policies that require the addition of renewable diesel in diesel fuel from fossil fuels. Environmental impact studies of the conversion of biomass to renewable diesel have been conducted, and life cycle assessments (LCA) of the conversion of lignocellulosic biomass to hydrogenation-derived renewable diesel (HDRD) are limited, especially for countries with cold climates like Canada.

Methods

In this study, an LCA was conducted on converting lignocellulosic biomass to HDRD by estimating the well-to-wheel greenhouse gas (GHG) emissions and fossil fuel energy input of the production of biomass and its conversion to HDRD. The approach to conduct this LCA includes defining the goal and scope, compiling a life cycle inventory, conducting a life cycle impact assessment, and executing a life cycle interpretation. All GHG emissions and fossil fuel energy inputs were based on a fast pyrolysis plant capacity of 2000 dry tonnes biomass/day. A functional unit of 1 MJ of HDRD produced was adopted as a common unit for data inputs of the life cycle inventory. To interpret the results, a sensitivity analysis was performed to measure the impact of variables involved, and an uncertainty analysis was performed to assess the confidence of the results.

Results and discussion

The GHG emissions of three feedstocks studied—whole tree (i.e., chips from cutting the whole tree), forest residues (i.e., chips from branches and tops generated from logging operations), and agricultural residues (i.e., straw from wheat and barley)—range from 35.4 to 42.3 g CO_2,eq/MJ of HDRD (i.e., lowest for agricultural residue- and highest for forest residue-based HDRD); this is 53.4–61.1 % lower than fossil-based diesel. The net energy ratios range from 1.55 to 1.90 MJ/MJ (i.e., lowest for forest residue- and highest for agricultural residue-based HDRD) for HDRD production. The difference in results among feedstocks is due to differing energy requirements to harvest and pretreat biomass. The energy-intensive hydroprocessing stage is responsible for most of the GHG emissions produced for the entire conversion pathway.

Conclusions

Comparing feedstocks showed the significance of the efficiency in the equipment used and the physical properties of biomass in the production of HDRD. The overall results show the importance of efficiency at the hydroprocessing stage. These findings indicate significant GHG mitigation benefits for the oil refining industry using available lignocellulosic biomass to produce HDRD for transportation fuel.

     

Cost-combined life cycle assessment of ferronickel production

The International Journal of Life Cycle Assessment - Ferronickel is irreplaceable in modern infrastructure construction because of its use in stainless steel production. This study explored the...     

A life cycle sustainability assessment (LCSA) of oxymethylene ether as a diesel additive produced from forest biomass

The International Journal of Life Cycle Assessment - Due to efforts to reduce dependence on limited fossil energy reserves and increasing GHG emissions related to fossil fuel extraction and use in...     

Life cycle assessment of biomass production in microalgae compact photobioreactors

This paper presents a life cycle assessment (LCA) of industrial scale microalgae biomass production in compact photobioreactor (PBR) systems (2 × 5 × 8 m) for supplying biofuel/electricity generation processes and synthesis of new materials. Other objectives are as follows: (i) to compare the impact of various raw materials, substances, and services; and (ii) to evaluate environment‐relevant aspects of the proposed system as compared to microalgae raceway ponds. The life cycle inventory assessment shows that (i) only atmospheric CO₂ is used for PBR microalgae cultivation, whereas in raceway ponds, injection of CO₂ from fossil origin is largely required to allow for microalgae growth; and (ii) the PBR daily production rate of dry biomass is currently at 1.5 kg m^?3 day^?1 for each PBR, which is 12.82 times larger than the reported average 0.117 kg m^?3 day^?1 raceway ponds production. It is found that in general the association of the effects of the production of steel, PVC, and the packaging contribute to more than 85% of the total impact in each analyzed category. Therefore, to achieve PBR biomass production impact reduction and sustainability, PVC and steel utilization need to be minimized, as well as packaging materials. Based on the PBR LCA results, that is, due to no CO₂ injection from fossil origin and low area occupation, it is expected that high density production of truly renewable microalgae biomass could be obtained from PBR systems.     

Cradle-to-gate life cycle assessment of global manganese alloy production

Purpose

Manganese is a metal used extensively in everyday life, particularly in structural steel. Despite the importance of manganese as an essential alloying element in steel and stainless steel, the environmental profile of manganese alloys lacked globally representative, primary industry data. The International Manganese Institute (IMnI) and Hatch completed the first global life cycle assessment (LCA) of manganese alloy production, providing environmental benchmarks and a firm foundation of accurate data with which to inform other industry-led initiatives.

Methods

The study compiled primary data from 16 ore and alloy producers worldwide, covering 18 % of global ore production and 8 % of global alloy production for 2010. This peer-reviewed, ISO 14040 compliant LCA covers the cradle-to-gate life cycles of silicomanganese, ferromanganese, and refined ferromanganese. The study provides a comprehensive picture of global environmental performance, quantifying energy consumption, global warming potential (GWP), acidification potential (AP), photochemical ozone creation potential (POCP), primary water use, and primary waste generation. A novel model architecture was devised to generate process, site, and cradle-to-gate LCAs for single and multiple sites simultaneously, extracting greater value from the LCA process by facilitating environmental and operational benchmarking within the industry.

Results and discussion

The results of the study show that total GWP, AP, and POCP for 1 kg of average manganese alloy was 6.0 kg CO₂e, 45 g SO₂e, and 3 g C₂H₄e, respectively. Electricity demand and coal and coke consumption during smelting are the dominant operating parameters contributing to environmental performance. On-site air emission measures (GWP, POCP, NO_X, and particulate matter (PM)) contributed 25 to 35 % of total life cycle emissions. Overburden and waste rock were the most significant primary solid waste flows by mass. The study provides a resource for improvement at the global industry and site scales by establishing benchmarks, identifying hotspots, and quantifying the benefits of efficiency savings through process optimization.

Conclusions

This LCA provides accurate primary data to improve steel and stainless steel product LCAs and communicate the environmental performance of the industry in quantitative terms. It facilitates dialogue between manganese producers and consumers through a shared understanding of the environmental profile of the industry. Through leveraging the study to identify hotspots within the manganese supply chain, producers can work both independently and collectively towards improving the environmental and economic performance of manganese alloys.

     

Comparative life cycle assessment and social life cycle assessment of used polyethylene terephthalate (PET) bottles in Mauritius

Purpose

Improper disposal of used polyethylene terephthalate (PET) bottles constitute an eyesore to the environmental landscape and is a threat to the flourishing tourism industry in Mauritius. It is therefore imperative to determine a suitable disposal method of used PET bottles which not only has the least environmental load but at the same time has minimum harmful impacts on peoples employed in waste disposal companies. In this respect, the present study investigated and compared the environmental and social impacts of four selected disposal alternatives of used PET bottles.

Methods

Environmental impacts of the four disposal alternatives, namely: 100 % landfilling, 75 % incineration with energy recovery and 25 % landfilling, 40 % flake production (partial recycling) and 60 % landfilling and 75 % flake production and 25 % landfilling, were determined using ISO standardized life cycle assessment (ISO 14040:2006) and with the support of SimaPro 7.1 software. Social life cycle assessments were performed based on the UNEP/SETAC Guidelines for Social Life Cycle Assessment of products. Three stakeholder categories (worker, society and local community) and eight sub-category indicators (child labour, fair salary, forced labour, health and safety, social benefit/social security, discrimination, contribution to economic development and community engagement) were identified to be relevant to the study. A new method for aggregating and analysing the social inventory data is proposed and used to draw conclusions.

Results and discussion

Environmental life cycle assessment results indicated that highest environmental impacts occurred when used PET bottles were disposed by 100 % landfilling while disposal by 75 % flake production and 25 % landfilling gave the least environmental load. Social life cycle assessment results indicated that least social impacts occurred with 75 % flake production and 25 % landfilling. Thus both E-LCA and S-LCA rated 75 % flake production and 25 % landfilling to be the best disposal option.

Conclusions

Two dimensions of sustainability (environmental and social) when investigated using the Life Cycle Management tool, favoured scenario 4 (75 %?% flake production and 25 % landfilling) which is a partial recycling disposal route. One hundred percent landfilling was found out to be the worst scenario. The next step will be to explore the third pillar of sustainability, economic, and devise a method to integrate the three dimensions with a view to determine the sustainable disposal option of used PET bottles in Mauritius.     

A life cycle assessment case study of ground rubber production from scrap tires

Purpose

The number of scrap tires generated in China has grown dramatically every year. Generation of ground rubber from scrap tires is the dominant management option in China. It is necessary to assess the environmental impacts of ground rubber production from scrap tires to provide technical advices on a cleaner production.

Methods

Production of ground rubber from recycled scrap tires consist of three steps: rubber powder preparation, devulcanization, and refining. A process life cycle assessment (LCA) of ground rubber production from scrap tires is carried out, and Eco-indicator 99 method coupled with ecoinvent database is applied to evaluate the environmental impacts of this process.

Results and discussion

During the ground rubber production stage, the impact factor of respiratory inorganic is the most serious one. Devulcanization has the highest environmental load of about 66.2 %. Moreover, improvement on the flue gas treatment contributes to a cleaner production and a more environmental-friendly process. Applying clean energy can largely reduce environmental load by about 21.5 %.

Conclusions

The results can be a guidance to reduce environmental load when producing ground rubber from scrap tires. Meanwhile, increasing energy efficiency, improving environmental protection equipment, and applying clean energy are the effective measures to achieve this goal.     

A global life cycle assessment for primary zinc production

Purpose

The purpose of this study was to update the average environmental impacts of global primary zinc production using a life cycle assessment (LCA) approach. This study represents the latest contribution from zinc producers, which historically established the first life cycle inventory for primary zinc production in 1998 (Western Europe) and the first global LCA-based cradle-to-gate study for zinc concentrate and special high-grade zinc (SHG; 99.99 %) in 2009. Improvements from the previous studies were realized through expanded geographical scope and range of production technologies.

Methods

The product system under study (SHG zinc) was characterized by collecting primary data for the relevant production processes, including zinc ore mining and concentration, transportation of the zinc concentrate, and zinc concentrate smelting. This data was modeled in GaBi 6 and complemented with background data from the GaBi 2013 databases to create the cradle-to-gate LCA model. Allocation was used to distribute the inputs and outputs among the various co-products produced during the production process, with mass of metal content being the preferred allocation approach, when applicable.

Results and discussion

In total, this global study includes primary data from 24 mines and 18 smelters, which cover 4.7?×?10⁶ MT of zinc concentrate and 3.4?×?10⁶ MT of SHG zinc, representing 36 and 27 % of global production, respectively. While the LCA model generated a full life cycle inventory, selected impact categories and indicators are reported in this article (global warming potential, acidification potential, eutrophication potential, photochemical ozone creation potential, ozone creation potential, and primary energy demand). The results show that SHG zinc has a primary energy demand of 37,500 MJ/t and a climate change impact of 2600 kg CO₂-eq./t. Across all impact categories and indicators reported here, around 65 % of the burden are associated with smelting, 30 % with mining and concentration, and 5 % with transportation of the concentrate. Sensitivity analyses were carried out for the allocation method (total mass versus mass of metal content) and transportation of zinc concentrate.

Conclusions

This study generated updated LCA information for the global production of SHG zinc, in line with the metal industry’s current harmonization efforts. Through the provision of unit process information for zinc concentrate and SHG zinc production, greater transparency is achieved. Technological and temporal representativeness was deemed to be high. Geographical representativeness, however, was found to be moderate to low. Future studies should focus on increasing company participation from underrepresented regions.

     

Ammonium nitrate fertiliser production based on biomass - environmental effects from a life cycle perspective

Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914kg of nitrogen can be produced every year from 1ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615kg of nitrogen can be produced annually from 1ha, after that 0.6% of the nitrogen has been returned.     

Attributional versus consequential life cycle assessment and feed optimization: alternative protein sources in pig diets

Purpose

Feed production is responsible for the majority of the environmental impact of livestock production, especially for monogastric animals, such as pigs. Some feeding strategies demonstrated that replacing one ingredient with a high impact, e.g. soybean meal (SBM), with an alternative protein source, e.g. locally produced peas or rapeseed meal, has potential to reduce the environmental impact. These studies, however, used an attributional life cycle assessment (ALCA), which solely addresses the direct environmental impact of a product. A replacement of SBM with alternative protein sources, however, can also have indirect environmental consequences, which might change environmental benefits of using alternative protein sources. This study aims to explore differences in results when performing an ALCA and a CLCA to reduce the environmental impact of pig production. We illustrated this for two case studies: replacing SBM with rapeseed meal (RSM), and replacing SBM with waste-fed larvae meal in diets of finishing-pigs.

Methods

We used an ALCA and CLCA to assess global warming potential (GWP), energy use (EU) and land use (LU) of replacing SBM with RSM and waste-fed larvae meal, for finishing-pigs. The functional unit was 1 kg of body weight gain.

Results and discussion

Based on an ALCA, replacing SBM with RSM showed that GWP (3%) and EU (1%) were not changed, but LU was decreased (14%). ALCA results for replacing SBM with waste-fed larvae meal showed that EU did not change (1%), but GWP (10%) and LU (56%) were decreased. Based on a CLCA, replacing SBM with RSM showed an increased GWP (15%), EU (12%) and LU (10%). Replacing SBM with waste-fed larvae meal showed an increased GWP (60%) and EU (89%), but LU (70%) was decreased. Furthermore, the results of the sensitivity analysis showed that assumptions required to perform a CLCA, such as definition of the marginal product, have a large impact on final results but did not affect the final conclusions.

Conclusions

The CLCA results seem to contradict the ALCA results. CLCA results for both case studies showed that using co-products and waste-fed larvae meal currently not reduces the net environmental impact of pork production. This would have been overlooked when results were only based on ALCA. To gain insight into the environmental impact of feed, animal nutritionists can use an ALCA. If policy makers or the feed industry, however, want to assess the net environmental impact of a potential feeding strategy, it is recommended to perform a CLCA. Feed and food markets are, however, highly dynamic. Pig feed optimization is based on least cost optimization and a wide range of ingredients are available; diet compositions can, therefore, change easily, resulting in different environmental impacts. Ideally, therefore, a CLCA should include a sensitivity analysis (e.g. different feed prices or different marginal products) to provide a range of possible outcomes to make the results more robust.

     

Comparative life cycle assessment (LCA) of Tilapia in two production systems: semi-intensive and intensive

Purpose

In order to meet the upscaling demand of food products worldwide, the aquaculture industry has been expanding within the last few years in developed countries. Major expansions of aquaculture farming occurred in many developed countries such as Bangladesh, Indonesia, and Egypt. Egypt ranks ninth in fish farming production worldwide and first on Africa. Egypt has the largest aquaculture industry in Africa which represents two-thirds of African aquaculture production. Tilapia production accounts for 75.5 % of aquaculture production in Egypt. Tilapia aquaculture production has grown exponentially in recent decades until it reached 4.5 million tonnes in 2012 placing Egypt as the second worldwide producer of tilapia after China. The production of tilapia is practiced in different production systems including intensive and semi-intensive systems. These production systems require different resources and impact differently on the environment. The aim of the current study was to model the environmental performance of tilapia production and compare semi-intensive and intensive production systems. The main questions were the following: What are the different impacts of tilapia production on the environment? Which production system is more environmentally friendly? What are the preferable practices for better environmental performance and sustainable ecofriendly industry of Tilapia production?

Methods

Life cycle assessment (LCA) was employed to determine the environmental impacts of tilapia production and compare semi-intensive and intensive production systems. Data for life cycle inventory were collected from two case study farms for tilapia production in Egypt. Four impact categories were taken into consideration: Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), and Cumulative Energy Demand (CED).

Results and discussion

LCA revealed that production of tilapia in intensive farming has less impact on GWP, AP, and CED, while its impact on EP is higher than in semi-intensive farming. The identified impacts from 1-tonne live weight production of tilapia were the following: GWP 960.7 and 6126.1 kg CO₂ eq; AP 9.8 and 24.4 kg SO₂ eq; EP 14.1 and 6.3 kg PO₂ eq; and CED 52.8 GJ and 238.3 GJ eq in intensive and semi-intensive systems, respectively.

Conclusions

Fish meal production and energy consumption were the major contributors to different impact indicators in both systems. An overall improvement in environmental performance for tilapia production can be achieved by novel feed formulations that have better environmental performance. Energy consumption is a major area for improvement as well, as proper energy management practices will reduce the overall impact on the environment.

     

Comparative life cycle assessment of fired brick production in Thailand

The International Journal of Life Cycle Assessment - Fired bricks are an essential construction material in Thailand where the majority of fired brick kilns use rice husk as feedstock. Given the...     

Life cycle assessment (LCA) of industrial milk production

A Life Cycle Assessment (LCA) was carried out for milk production extending from the origin of the inputs to the agricultural step to the consumer phase and the waste management of the packaging. Three Norwegian dairies of different sizes and degree of automation were studied. The main objectives were to find any hot spots in the life cycle of milk, to determine the significance of the dairy size and degree of automation, and to study the influence of transport. The agriculture was found to be the main hot spot for almost all the environmental themes studied, although the dairy processing, packaging, consumer phase and waste management were also of importance. The consumer phase was the main contributor to photo-oxidant formation and important regarding eutrophication. The small dairy was found to have a greater environmental impact than the middle-sized and the largest dairies. The transport did not have any major influence.     

Improving the environmental performance of bio-waste management with life cycle thinking (LCT) and life cycle assessment (LCA)

The International Journal of Life Cycle Assessment - Globally, many countries worldwide aim at increasing the environmental sustainability of waste management activities. Special attention is...     

Energy production from biomass (Part 1): Overview of biomass

The use of renewable energy sources is becoming increasingly necessary, if we are to achieve the changes required to address the impacts of global warming. Biomass is the most common form of renewable energy, widely used in the third world but until recently, less so in the Western world. Latterly much attention has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuel energy sources. The type of biomass required is largely determined by the energy conversion process and the form in which the energy is required. In the first of three papers, the background to biomass production (in a European climate) and plant properties is examined. In the second paper, energy conversion technologies are reviewed, with emphasis on the production of a gaseous fuel to supplement the gas derived from the landfilling of organic wastes (landfill gas) and used in gas engines to generate electricity. The potential of a restored landfill site to act as a biomass source, providing fuel to supplement landfill gas-fuelled power stations, is examined, together with a comparison of the economics of power production from purpose-grown biomass versus waste-biomass. The third paper considers particular gasification technologies and their potential for biomass gasification.