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.

     

Life cycle assessment of biodiesel production from microalgae in ponds

This paper analyses the potential environmental impacts and economic viability of producing biodiesel from microalgae grown in ponds. A comparative Life Cycle Assessment (LCA) study of a notional production system designed for Australian conditions was conducted to compare biodiesel production from algae (with three different scenarios for carbon dioxide supplementation and two different production rates) with canola and ULS (ultra-low sulfur) diesel. Comparisons of GHG (greenhouse gas) emissions (g CO₂-e/t km) and costs (¢/t km) are given. Algae GHG emissions (−27.6 to 18.2) compare very favourably with canola (35.9) and ULS diesel (81.2). Costs are not so favourable, with algae ranging from 2.2 to 4.8, compared with canola (4.2) and ULS diesel (3.8). This highlights the need for a high production rate to make algal biodiesel economically attractive.     

Life cycle assessment of bacterial cellulose production

The International Journal of Life Cycle Assessment - Bacterial cellulose (BC), obtained by fermentation, is an innovative and promising material with a broad spectrum of potential applications....     

Life cycle assessment of biodiesel production from beef tallow in Brazil

Purpose

Renewable energy sources, particularly biofuels, are being promoted as possible solutions to address global warming and the depletion of petroleum resources. In this context, biodiesel is a solution to the growing demand for renewable fuels. Beef tallow is the second leading raw material after soybean oil used in biodiesel production in Brazil. Evaluating and addressing the environmental impacts of beef tallow biodiesel are of great importance for its life cycle impact assessment (LCIA).

Methods

Inventory data on tallow and biodiesel production were collected from the literature and from a primary data source provided by a Brazilian biodiesel plant. The modeled system represents the Brazilian reality for the 2005–2015 decade. Subsequently, the environmental impacts of beef tallow biodiesel production were characterized for a selection of environmental impact indicators: global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and water footprint (assessed based on blue water use (BWU) and blue water consumption (BWC) indicators). From the characterization of these environmental burdens, the main sources of environmental impact were evaluated. Sensitivity analysis was conducted to verify the influence of key parameters (emission factor, energy consumption, and prices) on changes in the environmental load of beef tallow biodiesel.

Results and discussion

Carbon flux results indicate that beef tallow biodiesel production acts as a carbon source. Namely, pasture carbon uptake (91% of all carbon input) is lower than combined biogenic and fossil CO₂ emissions, which are controlled by cattle enteric fermentation as methane (72%) and by thermal energy processes (25%). Otherwise, thermal energy production accounts for 80% of total AP emissions, and cattle urine and manure are responsible for 70% of total EP emissions. The BWC and BWU water footprints of the whole process are controlled by electricity usage, which was greater than 90% for each indicator due to the high proportion of total energy (70%) derived from hydropower in Brazil. The environmental burden from transportation is minimal compared to other processes. Tallow biodiesel GWP can be improved if the carbon uptake potential from grass and low fertilizer utilization are accurately considered, as observed in the sensitivity analysis. For each MJ of beef tallow biodiesel produced, 4.6 g of CO₂ is released to the atmosphere.

Conclusions

Methane emissions, mainly due to cattle enteric fermentation, and thermal energy processes at the industrial units were the main sources of environmental GWP, AP, and EP impacts. Otherwise, water footprint indicators were associated with the high proportion of total energy derived from hydropower in Brazil.

     

Life cycle assessment of fuel chip production from eucalypt forest residues

Purpose

Forest residues are becoming an increasingly important bioenergy feedstock. This study evaluates the environmental impacts associated with the production of fuel chips from eucalypt logging residues in Portugal, in order to identify the supply chains and machinery that bring the best environmental performance. Besides, the stages and operations with the largest environmental impact are identified.

Methods

Life cycle assessment methodology is used starting with forest management up to delivery of chips to power plant. Three different configurations for logging residue processing were simulated as follows: roadside chipping of loose residues, terminal chipping of loose residues, and terminal chipping of bundled residues. In addition, the use of different equipment for tree felling and extraction of logging residue was considered. The default impact assessment methodology was the CML. In a sensitivity analysis, calculations were performed using characterization factors recommended by the International Reference Life Cycle Data System (ILCD). Different allocation criteria were tested for partitioning the environmental burdens between wood and forest residues produced during the stage of forest management.

Results and discussion

Roadside chipping of loose residues seems to have less impacts regardless of the equipment used in tree felling and residue forwarding. However, for photochemical oxidant formation, this is not the case when trees are felled with a chainsaw when the CML methodology is applied. For the systems with terminal chipping, the better option will depend both on type of machinery used and distances traveled between the forest site and the power plant. The forest management stage has a relevant contribution to all the supply chains analyzed. Chipping and bundling have also important impacts, as well as forwarding when this operation is accomplished with a modified farm tractor. Moreover, transports have a significant impact when loose residues are chipped in a terminal.

Conclusions

The choice of the allocation method between wood and residues affects significantly the absolute results, but it is irrelevant when the objective is to select the best supply chain configuration. The results obtained are valid for the input data considered, which rely on average values representative of the current most typical practices in Portugal. However, this methodology can also be applied as a decision supporting tool to select the supply chain with the best environmental performance on a case by case basis, using site-specific data.     

Life cycle assessment of the district heat distribution system

Goal, Scope and Background  

District heating, the utilization of centrally produced heat for space heating and domestic hot water generation, has the potential to contribute to the eco-efficient use of energy resources in the parts of the world where space heating is needed. In literature, environmental studies on district heating mainly consider the emissions from heat generation; the environmental impact from the distribution system is seldom discussed. This paper presents a life cycle assessment of the production of district heating pipes, based on a cradle-to-gate life cycle inventory commissioned by the Swedish District Heating Association. No external review has been performed but a reference group of district heating experts familiar with the practice was involved in the choice of cases as well as in reviewing parts of the study.     

Life cycle assessment of a pyrolysis/gasification plant for hazardous paint waste

Goal, Scope and Background Life Cycle Assessment (LCA) remains an important tool in Dutch waste management policies. In 2002 the new National Waste Management Plan 2002–2012 (NWMP) became effective. It was supported by some 150 LCA studies for more than 20 different waste streams. The LCA results provided a benchmark level for new waste management technologies. Although not new, operational techniques using combined pyrolysis/gasification are still fairly rare in Europe. The goal of this study is to determine the environmental performance of the only full scale pyrolysis/gasification plant in the Netherlands and to compare it with more conventional techniques such as incineration. The results of the study support the process of obtaining environmental permits. Methods In this study we used an impact assessment method based on the guidelines described by the Centre of Environmental Science (CML) of Leiden University. The functional unit is defined as treatment of 1 ton of collected hazardous waste (paint packaging waste). Similar to the NWMP, not only normalized scores are presented but also 7 aggegated scores. All interventions from the foreground process (land use, emissions, final waste) are derived directly from the site with the exception of emissions to soil which were calculated. Interventions are accounted to each of the different waste streams by physical relations. Data from background processes are taken from the IVAM LCA database 4.0 mostly originating from the Swiss ETH96 database and adapted to the Dutch situation. Allocation was avoided by using system enlargement. The study has been peer reviewed by an external expert. Results and Discussion It was possible to determine an environmental performance for the pyrolysis/ gasification of paint packaging waste. The Life Cycle Inventory was mainly hampered by the uncertainty occurred with estimated air emissions. Here several assumptions had to be made because several waste inputs and two waste treatment installations profit from one flue gas cleaning treatment thus making it difficult to allocate the emission values from the flue gasses. Compared to incineration in a rotary kiln, pyrolysis/gasification of hazardous waste showed better scores for most of the considered impact categories. Only for the impact categories biodiversity and life support the incineration option proved favorable due to a lower land use. Several impact categories had significant influence on the conclusions: acidification, global warming potential, human toxicity and terrestrial ecotoxicity. The first three are related to a better energy efficiency for pyrolysis/gasification leading to less fossil energy consumption. Terrestrial ecotoxicity in this case is related to specific emissions of mercury and chromium (III). A sensitivity analysis has been performed as well. It was found that the environmental performance of the gasification technique is sensitive to the energy efficiency that can be reached as well as the choice for the avoided fossil energy source. In this study a conservative choice for diesel oil was made whereas a choice for heavy or light fuel oil would further improve the environmental profile. Conclusions Gasification of hazardous waste has a better environmental performance compared to the traditional incineration in rotary kilns mainly due to the high energy efficiency. As was determined by sensitivity analysis the differences in environmental performance are significant. Improvement options for a better performance are a decrease of process emissions (especially mercury) and a further improvement of the energy balance by decreasing the electricity consumption for shredders and oxygen consumption or making more use of green electricity. Recommendations and Perspectives Although the life cycle inventory was sufficiently complete, still some assumptions had to be made in order to establish sound mass balances on the level of individual components and substances. The data on input of waste and output of emissions and final waste were not compatible. It was recommended that companies put more emphasis on data storage accounted to particular waste streams. This is even more relevant since more companies in the future are expected to include life cycle impacts in their environmental performance.     

Life cycle assessment of Portland cement production in Myanmar

The International Journal of Life Cycle Assessment - Cement manufacturing is associated with global and local environmental issues. Many studies have employed life cycle assessment (LCA) to...     

Life cycle assessment of commodity chemical production from forest residue via fast pyrolysis

Purpose

This life cycle assessment evaluates and quantifies the environmental impacts of renewable chemical production from forest residue via fast pyrolysis with hydrotreating/fluidized catalytic cracking (FCC) pathway.

Methods

The assessment input data are taken from Aspen Plus and greenhouse gases, regulated emissions, and energy use in transportation (GREET) model. The SimaPro 7.3 software is employed to evaluate the environmental impacts.

Results and discussion

The results indicate that the net fossil energy input is 34.8 MJ to produce 1 kg of chemicals, and the net global warming potential (GWP) is ?0.53 kg CO₂ eq. per kg chemicals produced under the proposed chemical production pathway. Sensitivity analysis indicates that bio-oil yields and chemical yields play the most important roles in the greenhouse gas footprints.

Conclusions

Fossil energy consumption and greenhouse gas (GHG) emissions can be reduced if commodity chemicals are produced via forest residue fast pyrolysis with hydrotreating/FCC pathway in place of conventional petroleum-based production pathways.     

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.     

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.     

Life cycle assessment of chitosan production in India and Europe

Purpose

The aim of this article is to present the first life cycle assessment of chitosan production based on data from two real producers located in India and Europe. The goal of the life cycle assessment (LCA) was to understand the main hot spots in the two supply chains, which are substantially different in terms of raw materials and production locations.

Methods

The LCA is based on consequential modelling principles, whereby allocation is avoided by means of substitution, and market mixes include only flexible, i.e. non-constrained suppliers. The product system is cradle to gate and includes the production of raw materials, namely waste shells from snow crab and shrimp in Canada and India, respectively, the processing of these in China and India and the manufacture of chitosan in Europe and India. Primary data for chitin and chitosan production were obtained from the actual producers, whereas raw material acquisition as well as waste management activities were based on literature sources. The effects of indirect land use change (iLUC) were also included. Impact assessment was carried out at midpoint level by means of the recommended methods in the International Life Cycle Data (ILCD) handbook.

Results and discussion

In the Indian supply chain, the production of chemicals (HCl and NaOH) appears as an important hot spot. The use of shrimp shells as raw material affects the market for animal feed, resulting in a credit in many impact indicators, especially in water use. The use of protein waste as fertilizer is also an important source of greenhouse-gas and ammonia emissions. In the European supply chain, energy use is the key driver for environmental impacts, namely heat production based on coal in China and electricity production in China and Europe. The use of crab shells as raw material avoids the composting process they would be otherwise subject to, leading to a saving in composting emissions, especially ammonia. In the Indian supply chain, the effect of iLUC is relevant, whereas in the European one, it is negligible.

Conclusions

Even though we assessed two products from the same family, the results show that they have very different environmental profiles, reflecting their substantially different supply chains in terms of raw material (shrimp shells vs. crab shells), production locations (locally produced vs. a global supply chain involving three continents) and the different applications (general-purpose chitosan vs. chitosan for the medical sector).

     

Life cycle environmental and economic assessment of coal seam gas-based electricity generation

The International Journal of Life Cycle Assessment - A large portion of coal seam gas is directly wasted and emitted to the environment, especially China, which is the world’s largest global...     

基于生命周期评价的上海市水稻生产的碳足迹

碳足迹是指由企业、组织或个人引起的碳排放的集合。参照PAS2050规范并结合生命周期评价方法对上海市水稻生产进行了碳足迹评估。结果表明:(1)目前上海市水稻生产的碳排放为11.8114 t CO2e/hm2,折合每吨水稻生产周期的碳足迹为1.2321 t CO2e;(2)稻田温室气体排放是水稻生产最主要的碳排放源,每吨水稻生产的总排放量为0.9507 t CO2e,占水稻生产全部碳排放的77.1%,其中甲烷(CH4)又是最主要的温室气体,对稻田温室气体碳排放的贡献率高达96.6%;(3)化学肥料的施用是第二大碳排放源,每吨水稻生产的总排放量为0.2044 t CO2e,占水稻生产总碳排放的16.5%,其中N最高,排放量为0.1159 t CO2e。因此,上海低碳水稻生产的关键在降低稻田甲烷的排放,另外可通过提高氮肥利用效率,减少氮肥施用等方法减少种植过程中碳排放。     

Life cycle assessment standards

The newly emerging LCA standards provide an opportunity to review and improve upon the current LCA methodology. As more industrial practitioners enter the arena, the opportunity arises to not only demand environmental improvement from industrial service and product providers but also to fill LCA data gaps. A framework is suggested for improvement in the current LCA framework that focuses on the business relationships of the industrial practitioner. The framework seeks to promote environmental improvement from industrial sectors through the identification of state-of-the-art technologies used throughout a life cycle. Basing LCAs on the best performers in an industry will create a market for a high level of environmental performance, disperse the responsibility of inventory data gathering, and improve upon the advancements already anticipated through the widespread application of LCA.     

Life cycle assessment of cheese and whey production in the USA

Purpose

A life cycle assessment was conducted to determine a baseline for environmental impacts of cheddar and mozzarella cheese consumption. Product loss/waste, as well as consumer transport and storage, is included. The study scope was from cradle-to-grave with particular emphasis on unit operations under the control of typical cheese-processing plants.

Methods

SimaPro© 7.3 (PRé Consultants, The Netherlands, 2013) was used as the primary modeling software. The ecoinvent life cycle inventory database was used for background unit processes (Frischknecht and Rebitzer, J Cleaner Prod 13(13–14):1337–1343, 2005), modified to incorporate US electricity (EarthShift 2012). Operational data was collected from 17 cheese-manufacturing plants representing 24 % of mozzarella production and 38 % of cheddar production in the USA. Incoming raw milk, cream, or dry milk solids were allocated to coproducts by mass of milk solids. Plant-level engineering assessments of allocation fractions were adopted for major inputs such as electricity, natural gas, and chemicals. Revenue-based allocation was applied for the remaining in-plant processes.

Results and discussion

Greenhouse gas (GHG) emissions are of significant interest. For cheddar, as sold at retail (63.2 % milk solids), the carbon footprint using the IPCC 2007 factors is 8.60 kg CO₂e/kg cheese consumed with a 95 % confidence interval (CI) of 5.86–12.2 kg CO₂e/kg. For mozzarella, as sold at retail (51.4 % milk solids), the carbon footprint is 7.28 kg CO₂e/kg mozzarella consumed, with a 95 % CI of 5.13–9.89 kg CO₂e/kg. Normalization of the results based on the IMPACT 2002+ life cycle impact assessment (LCIA) framework suggests that nutrient emissions from both the farm and manufacturing facility wastewater treatment represent the most significant relative impacts across multiple environmental midpoint indicators. Raw milk is the major contributor to most impact categories; thus, efforts to reduce milk/cheese loss across the supply chain are important.

Conclusions

On-farm mitigation efforts around enteric methane, manure management, phosphorus and nitrogen runoff, and pesticides used on crops and livestock can also significantly reduce impacts. Water-related impacts such as depletion and eutrophication can be considered resource management issues—specifically of water quantity and nutrients. Thus, all opportunities for water conservation should be evaluated, and cheese manufacturers, while not having direct control over crop irrigation, the largest water consumption activity, can investigate the water use efficiency of the milk they procure. The regionalized normalization, based on annual US per capita cheese consumption, showed that eutrophication represents the largest relative impact driven by phosphorus runoff from agricultural fields and emissions associated with whey-processing wastewater. Therefore, incorporating best practices around phosphorous and nitrogen management could yield improvements.