Life cycle assessment of an offshore grid interconnecting wind farms and customers across the North Sea

Purpose

This study aims to contribute to an improved understanding of the environmental implications of offshore power grid and wind power development pathways. To achieve this aim, we present two assessments. First, we investigate the impacts of a North Sea power grid enabling enhanced trade and integration of offshore wind power. Second, we assess the benefit of the North Sea grid and wind power through a comparison of scenarios for power generation in affected countries.

Methods

The grid scenario explored in the first assessment is the most ambitious scenario of the Windspeed project and is the result of cost minimization analysis using a transmission-expansion-planning model. We develop a hybrid life cycle inventory for array cables; high voltage, direct current (HVDC) links; and substations. The functional unit is 1 kWh of electricity transmitted. The second assessment compares two different energy scenarios of Windspeed for the North Sea and surrounding countries. Here, we utilize a life cycle inventory for offshore grid components together with an inventory for a catalog of power generation technologies from Ecoinvent and couple these inventories with grid configurations and electricity mixes determined by the optimization procedure in Windspeed.

Results and discussion

Developing, operating, and dismantling the grid cause emissions of 2.5 g CO₂-Eq per kWh electricity transmission or 36 Mt CO₂-Eq in total. HVDC cables are the major cause of environmental damage, causing, for example, half of total climate change effects. The next most important contributors are substations and array cabling used in offshore wind parks. Toxicity and eutrophication effects stem largely from leakages from disposed copper and iron mine tailings and overburden. Results from the comparison of two scenarios demonstrate a substantial environmental benefit from the North Sea grid extension and the associated wind power development compared with an alternative generation of electricity from fossil fuels. Offshore grid and wind power, however, entail an increased use of metals and, hence, a higher metal depletion indicator.

Conclusions

We present the first life cycle assessment of a large offshore power grid, using the results of an energy planning model as input. HVDC links are the major cause of environmental damage. There are differences across impact categories with respect to which components or types of activities that are responsible for damage. The North Sea grid and wind power are environmentally beneficial by an array of criteria if displacing fossil fuels, but cause substantial metal use.     

Life cycle assessment of concentrated solar power (CSP) and the influence of hybridising with natural gas

Purpose

Concentrating solar power (CSP) plants based on parabolic troughs utilise auxiliary fuels (usually natural gas) to facilitate start-up operations, avoid freezing of HTF and increase power output. This practice has a significant effect on the environmental performance of the technology. The aim of this paper is to quantify the sustainability of CSP and to analyse how this is affected by hybridisation with different natural gas (NG) inputs.

Methods

A complete life cycle (LC) inventory was gathered for a commercial wet-cooled 50 MWe CSP plant based on parabolic troughs. A sensitivity analysis was conducted to evaluate the environmental performance of the plant operating with different NG inputs (between 0 and 35 % of gross electricity generation). ReCiPe Europe (H) was used as LCA methodology. CML 2 baseline 2000 World and ReCiPe Europe E were used for comparative purposes. Cumulative energy demands (CED) and energy payback times (EPT) were also determined for each scenario.

Results and discussion

Operation of CSP using solar energy only produced the following environmental profile: climate change 26.6 kg CO₂ eq/KWh, human toxicity 13.1 kg 1,4-DB eq/KWh, marine ecotoxicity 276 g 1,4-DB eq/KWh, natural land transformation 0.005 m²/KWh, eutrophication 10.1 g P eq/KWh and acidification 166 g SO₂ eq/KWh. Most of these impacts are associated with extraction of raw materials and manufacturing of plant components. The utilisation of NG transformed the environmental profile of the technology, placing increasing weight on impacts related to its operation and maintenance. Significantly higher impacts were observed on categories like climate change (311 kg CO₂ eq/MWh when using 35 % NG), natural land transformation, terrestrial acidification and fossil depletion. Despite its fossil nature, the use of NG had a beneficial effect on other impact categories (human and marine toxicity, freshwater eutrophication and natural land transformation) due to the higher electricity output achieved. The overall environmental performance of CSP significantly deteriorated with the use of NG (single score 3.52 pt in solar-only operation compared to 36.1 pt when using 35 % NG). Other sustainability parameters like EPT and CED also increased substantially as a result of higher NG inputs. Quasilinear second-degree polynomial relationships were calculated between various environmental performance parameters and NG contributions.

Conclusions

Energy input from auxiliary NG determines the environmental profile of the CSP plant. Aggregated analysis shows a deleterious effect on the overall environmental performance of the technology as a result of NG utilisation. This is due primarily to higher impacts on environmental categories like climate change, natural land transformation, fossil fuel depletion and terrestrial acidification. NG may be used in a more sustainable and cost-effective manner in combined cycle power plants, which achieve higher energy conversion efficiencies.     

Consequential and attributional environmental assessment of biofuels: implications of modelling choices on climate change mitigation strategies

Purpose

The study aims to assess climate change mitigation potentials when using biomass-based fuels to replace fossil energy under consequential and attributional modelling approaches. The objectives are also to determine policy implications and to recommend the specific contexts suitable for each modelling choice by using specific illustrative cases on biofuels.

Methods

Consequential and attributional modelling approaches are chosen for life cycle greenhouse gas emission assessment of several bioenergy options. The assessed functional unit is 1 MJ of energy from molasses-based ethanol, palm-based biodiesel and electricity production from rice straw. The fossil fuel comparators are gasoline (for molasses-based ethanol), diesel (for palm-based biodiesel) and coal and gas (for rice straw). The substituted and substituting product systems are modelled under the global and national markets depending on the market delimitation of each product.

Results and discussion

The climate change mitigation potentials when using different approaches are dissimilar, because the affected product systems being included in the analysis are not the same. The palm biodiesel could reduce greenhouse gas emissions. The molasses-based ethanol and rice straw-based electricity may or may not mitigate the climate change, since it depends on the methodological choices as well as the baseline situations of the product systems being investigated. The main characteristics of consequential modelling as additionality and the inclusion of only actually affected processes under market-based mechanisms while those of attributional modelling as specification and attribution/allocation have limitations. The limitations lead to potential risks on unintended and undesirable consequences (for the attributional model), unfairness and sub-optimisation (for the consequential model) in policy recommendations.

Conclusions

This research clearly illustrates how certain modelling choices affect the climate change mitigation potentials of biomass-based fuels in comparison with fossil energy. Specific questions and conditions which could be more suitable for each modelling choice are addressed. The attributional modelling is more suitable for national environmental taxation and emission labelling/accounting for import-export, while the consequential modelling is more appropriate for new production development and eco-design. Due to the potential environmental risks arising from the modelling limitations, the consideration of both the widely applied approaches could support decisions more comprehensively.

     

Comparative life cycle assessment of current and future electricity generation systems in the Czech Republic and Poland

Purpose

The purpose of the study was to perform a comparative life cycle assessment of current and future electricity generation systems in the Czech Republic and Poland. The paper also outlines the main sources of environmental impact for the different impact categories for the electricity generation technologies analyzed. The analyses covered the years 2000–2050, and were conducted within the framework of the international programme Interreg V-A Czech Republic-Poland, Microprojects Fund 2014–2020 in the Euroregion Silesia.

Methods

Environmental assessment was done using the life cycle assessment (LCA) and ReCiPe Midpoint and Endpoint methods, which allowed the presentation of different categories of environmental impact and damage. The LCA was based on ISO 14040 and ISO 14044, using SimaPro 8.2.3 software with the Ecoinvent 3.2 database. The analyses cover both the current electricity production structures in the Czech Republic and Poland, and the projected energy production.

Results and discussion

The LCA analyses performed for the energy systems under consideration in the Czech Republic and Poland enabled a comparative analysis of current and forecast energy systems in these countries, as well as identification of the main sources of environmental impact. Comparative analysis of the LCA results showed that current and future electricity generation systems in Poland caused higher environmental impact there, than in the Czech Republic.

Conclusions

The assessment of the life cycle of electricity sources showed that the main determinant of the negative impact on the environment of energy systems in both Poland and the Czech Republic was the consumption of solid fuels, and in particular, the consumption of lignite. It is important to highlight that this is the first attempt of a comparative LCA of electricity production in the Czech Republic and Poland. This is also the first approach that contains analyses of the life cycle assessment of both present and future energy systems. The economic assessment and eco-efficiency of current and future electricity generation systems in European Union countries will be addressed in future research.

     

A cradle-to-gate life cycle assessment of wood fibre-reinforced polylactic acid (PLA) and polylactic acid/thermoplastic starch (PLA/TPS) biocomposites

Purpose

Biopolymers are considered to be environmentally friendlier than petroleum-based polymers, but little is known about their environmental performance against petroleum-based products. This paper presents the results of a life cycle assessment (LCA) of two prototype biocomposite formulations produced by extrusion of wood fibre with either polylactic acid (PLA) or a blend of PLA and locally produced thermoplastic starch (TPS).

Methods

The study followed the LCA methodology outlined in the two standards set out by the International Organization for Standardization (ISO): ISO 14040 and ISO 14044 of 2006. A life cycle inventory (LCI) for the biocomposite formulations was developed, and a contribution analysis was performed to identify the significant inputs. Environmental performances of the two formulations were then compared with each other and polypropylene (PP), a petroleum-based polymer. The US Environmental Protection Agency’s impact assessment method, “TRACI: The Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts”, was combined with Cumulative Energy Demand (a European method) in order to characterize the inventory flows. Environmental impact categories chosen for the analysis were the following: global warming, stratospheric ozone depletion, acidification of land and water, eutrophication, smog, human health (respiratory, carcinogenic, and non-carcinogenic) effects and ecotoxicity.

Results and discussion

We found that PLA is the significant input which contributes mostly to fossil fuel consumption, acidification and respiratory and smog effects. Impacts from PLA transport from the faraway source significantly added more burden to its contributions. TPS causes less environmental burden compared to PLA; the environmental performance of the biocomposite improved when a blend of PLA and TPS is used in formulating the biocomposite. The two formulations performed better than PP in all the environmental impact categories except eutrophication effects, which is important on a regional basis.

Conclusions

The following conclusions were drawn from this study:

• PLA is the environmentally significant input among the three raw materials.
• TPS causes less environmental burden than PLA. Environmental performance of the biocomposite improves in the life cycle energy consumption, fossil energy use, ozone depletion and non-carcinogenic impact categories when a blend of PLA and TPS is used.
• The biocomposite can outperform PP in all the impact categories except eutrophication effects if manufactured using hydroelectricity.

The biopolymer could be a potential alternative to PP as it could cause less of a burden to the environment on a cradle-to-gate basis. Environmental impacts at the complete life cycle levels should be looked into in order to fully understand its potential.     

End of life of buildings: three alternatives, two scenarios. A case study

Purpose

The objective of this case study is to identify the relevant processes needed in the environmental assessment of the end of life of a building and to identify the demolition process variables that significantly affect energy consumption and emissions of greenhouse gases. Different scenarios of demolition, based on three alternatives for managing construction and demolition waste (C&DW) generated during demolition works, are analyzed. This study is based upon typical construction and demolition practices and waste management in Spain.

Methods

Life cycle assessment (LCA) methodology is applied to assess objectively and quantitatively different C&DW management plans during the design phase and to identify the significant environmental aspects. The impact categories considered are global warming potential and human toxicity potential. Furthermore, the indicator primary energy (non renewable energy from fossil fuels) is also studied.

Results

Design of C&DW management plans to enhance the recovery of waste, reducing significantly the selected environmental indicators, was assessed in this study. Waste transport from the demolition work to the treatment plant and the transport of the non-recyclable fraction to the final disposal, as well as the fuel consumption in hydraulic demolition equipment and in the loading/unloading equipment of the treatment plants, are the most significant environmental aspects associated with the management plan based on a selective demolition, whereas in a conventional demolition process, the main environmental aspect is waste transport from the demolition work to final disposal.

Conclusions

LCA studies allow an assessment of different demolition processes. A tool for recording environmental data has been developed. This tool provides in a systematic manner life cycle inventory and life cycle impact assessment of the end of life of a building, facilitating the study of management plans in the design phase.     

Life cycle greenhouse gas emissions of electricity generation in the province of Ontario, Canada

Purpose

This paper assesses facility-specific life cycle greenhouse gas (GHG) emission intensities for electricity-generating facilities in the province of Ontario in 2008. It offers policy makers, researchers and other stakeholders of the Ontario electricity system with data regarding some of the environmental burdens from multiple generation technology currently deployed in the province.

Methods

Methods involved extraction of data and analysis from several publically accessible datasets, as well as from the LCA literature. GHG emissions data for operation of power plants came from the Government of Canada GHG registry and the Ontario Power Generation (OPG) Sustainable Development reports. Facility-specific generation data came from the Independent Electricity System Operator in Ontario and the OPG.

Results

Full life cycle GHG intensity (tonnes of CO₂ equivalent per gigawatt hour) estimates are provided for 4 coal facilities, 27 natural gas facilities, 1 oil/natural gas facility, 3 nuclear facilities, 7 run-of-river hydro facilities and 37 reservoir hydro facilities, and 7 wind facilities. Average (output weighted) life cycle GHG intensities are calculated for each fuel type in Ontario, and the life cycle GHG intensity for the Ontario grid as a whole (in 2008) is estimated to be 201 t CO₂e/GWh.

Conclusions

The results reflect only the global warming impact of electricity generation, and they are meant to inform a broader discussion which includes other environmental, social, cultural, institutional and economic factors. This full range of factors should be included in decisions regarding energy policy for the Province of Ontario, and in future work on the Ontario electricity system.     

Life cycle assessment of potential energy uses for short rotation willow biomass in Sweden

Purpose

Two different bioenergy systems using willow chips as raw material has been assessed in detail applying life cycle assessment (LCA) methodology to compare its environmental profile with conventional alternatives based on fossil fuels and demonstrate the potential of this biomass as a lignocellulosic energy source.

Methods

Short rotation forest willow plantations dedicated to biomass chips production for energy purposes and located in Southern Sweden were considered as the agricultural case study. The bioenergy systems under assessment were based on the production and use of willow-based ethanol in a flexi fuel vehicle blended with gasoline (85 % ethanol by volume) and the direct combustion of willow chips in an industrial furnace in order to produce heat for end users. The standard framework for LCA from the International Standards Organisation was followed in this study. The environmental profiles as well as the hot spots all through the life cycles were identified.

Results and discussion

According to the results, Swedish willow biomass production is energetically efficient, and the destination of this biomass for energy purposes (independently the sort of energy) presents environmental benefits, specifically in terms of avoided greenhouse gases emissions and fossil fuels depletion. Several processes from the agricultural activities were identified as hot spots, and special considerations should be paid on them due to their contribution to the environmental impact categories under analysis. This was the case for the production and use of the nitrogen-based fertilizer, as well as the diesel used in agricultural machineries.

Conclusions

Special attention should be paid on diffuse emissions from the ethanol production plant as well as on the control system of the combustion emissions from the boiler.     

Resource depletion assessment of renewable electricity generation technologies—comparison of life cycle impact assessment methods with focus on mineral resources

Purpose

Renewable energies are promoted in order to reduce greenhouse gas emissions and the depletion of fossil fuels. However, plants for renewable electricity production incorporate specifically higher amounts of materials being rated as potentially scarce. Therefore, it is in question which (mineral) resources contribute to the overall resource consumption and which of the manifold impact assessment methods can be recommended to cover an accurate and complete investigation of resource use for renewable energy technologies.

Methods

Life cycle assessment is conducted for different renewable electricity production technologies (wind, photovoltaics, and biomass) under German conditions and compared to fossil electricity generation from a coal-fired power plant. Focus is given on mineral resource depletion for these technologies. As no consensus has been reached so far as to which impact assessment method is recommended, different established as well as recently developed impact assessment methods (CML, ReCiPe, Swiss Ecoscarcity, and economic scarcity potential (ESP)) are compared. The contribution of mineral resources to the overall resource depletion as well as potential scarcity are identified.

Results and discussion

Overall resource depletion of electricity generation technologies tends to be dominated by fossil fuel depletion; therefore, most renewable technologies reduce the overall resource depletion compared to a coal-fired power plant. But, in comparison to fossil electricity generation from coal, mineral resource depletion is increased by wind and solar power. The investigated methods rate different materials as major contributors to mineral resource depletion, such as gallium used in photovoltaic plants (Swiss Ecoscarcity), gold and copper incorporated in electrical circuits and in cables (CML and ReCiPe), and nickel (Swiss Ecoscarcity and ReCiPe) and chromium (ESP) for stainless steel production. However, some methods lack characterization factors for potentially important materials.

Conclusions

If mineral resource use is investigated for technologies using a wider spectrum of potentially scarce minerals, practitioners need to choose the impact assessment method carefully according to their scope and check if all important materials are covered. Further research is needed for an overall assessment of different resource compartments.

     

Heating systems LCA: comparison of biomass-based appliances

Purpose

Biomass provides an attractive solution for residential heating systems based on renewable fuels, even though biomass-based domestic heating systems are recognized as significant particulate matter emitters; thus, a life cycle assessment (LCA) approach was used in the study to compare two different appliances: a wood stove and a pellet stove, both modeled according to the best available technologies definition.

Methods

System boundaries of each scenario refer to a cradle-to-grave approach, including production, use and disposal of the heating appliance, as well as the preparation of biomass feedstock. The assessment of environmental impacts was performed assuming 1 MJ of thermal energy as the reference flow, considering the categories of particulate matter formation, human toxicity, climate change, and fossil fuel depletion, according to the ReCiPe 1.07 method. Finally, the comparison was extended to certain innovative heating systems in order to qualitatively evaluate potential improvements in residential heating performances.

Results and discussion

The results show that the wood stove reaches the highest scores in the categories of particulate matter formation and negative effects for human toxicity, as a consequence of the stove’s lower combustion efficiency, which would lead to a preference for the pellet stove. However, when climate change affecting human health and the ecosystem, and fossil depletion are considered, the choice appears more uncertain due to the energy consumption from the pelletizing step. Alternative technologies (e.g., solar panels in combination with a gas boiler) show better scores related to fine particles emission reduction, even if a worsening in other categories is observed. The results were validated by a sensitivity analysis.

Conclusions

The study suggests that a LCA approach can support the choice of the best domestic heating system, helping to promote policy initiatives on a sound basis and to understand which are the main key levers to act for reducing the total environmental burdens of biomass-based heating appliances.     

Environmental evaluation and comparison of selected industrial scale biomethane production facilities across Europe

Purpose

The two main reasons for producing biomethane as renewable fuel are reduction of climate impacts and depletion of fossil resources. Biomethane is expected to be sustainable, but how sustainable is it actually? This article contributes to the clarification. Therefore, the environmental impacts of several biomethane facilities all over Europe were assessed. A special focus is put on the differences between the facilities as they follow different production routes.

Methods

The method used for evaluation is life cycle assessment (LCA) applied in a well-to-wheel approach. This enables to show the overall performance in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP) and PE fossil. The system boundary includes the entire chain from biogas production to upgrading, distribution and use. For evaluating the different production routes several years of measuring data, calculating and improving the LCA models in close cooperation with the plant operators were carried out.

Results and discussion

The evaluation of the production routes shows a high reduction potential compared to fossil fuels. Regarding the depletion of fossil resources, the amounts vary between the sites, but the reduction is at least 50 % and reaches almost 100 % reductions at some sites. The reduction of GWP is at least 65 %, because waste flows free of environmental burdens are used almost exclusively as substrate. Other dominant factors are power and heat demand, methane losses to the environment and the use of by-products, e.g. fertilizer.

Conclusions

Despite this caveat, the evaluated systems demonstrate the possible positive results of renewable fuel production if done properly.     

Life cycle assessment of the Danish electricity distribution network

Purpose

This article provides life cycle inventory data for electricity distribution networks and a life cycle assessment (LCA) of the Danish transmission and distribution networks. The aim of the study was to evaluate the potential importance of environmental impacts associated with distribution, in current and future electricity systems.

Methods

The functional unit was delivery of 1 kWh of electricity in Denmark. The focus of the assessment was distribution of electricity, and the related impacts were compared to the generation and transmission of electricity, in order to evaluate the importance of electricity distribution in Denmark. The 2010 Danish electricity distribution network was modeled, including power lines (50, 10, 0.4 kV), transformers (50/10 and 10/0.4 kV), and relevant auxiliary infrastructure (e.g., cable ditches, poles, and substations). Two types of 50 kV power lines (underground and overhead) and 0.4 kV (copper and aluminum) were modeled.

Results and discussion

Electricity transmission and distribution provided nonnegligible impacts, related mainly to power losses. Impacts from electricity distribution were larger than those from transmission because of higher losses and higher complexity and material consumption. Infrastructure provided important contributions to metal depletion and freshwater eutrophication (copper and aluminum for manufacturing of the cables and associated recycling being the most important). Underground 50-kV lines had larger impacts than overhead lines, and 0.4-kV aluminum lines had lower impacts than comparable copper lines.

Conclusions

A new specific dataset for infrastructure in the distribution network was provided and used to evaluate the role of electricity distribution in Denmark. Both transmission and distribution provided nonnegligible impacts. It was argued that the impacts from electricity distribution are likely to increase in the future, owing to more renewables and decentralized electricity generation, and that impacts from infrastructure may become significant compared to electricity generation itself. It was recommended that impacts from electricity distribution and related infrastructure are included in relevant LCA studies. The data provided here make this possible.     

Life cycle assessment of fuel ethanol from cane molasses in Thailand

Background, aim and scope

After China and India, Thailand is considered another emerging market for fuel ethanol in Asia. At present, ethanol in the country is mainly a fermentation/distillery product of cane molasses, although cassava and cane juice are considered other potential raw materials for the fuel. This study aims to evaluate the environmental impacts of substituting conventional gasoline (CG) with molasses-based gasohol in Thailand.

Materials and methods

The life cycle assessment (LCA) procedure carried out follows three interrelated phases: inventory analysis, characterization and interpretation. The functional unit for the comparison is 1 l gasoline equivalent consumed by a new passenger car to travel a specific distance.

Results

The results of the study show that molasses-based ethanol (MoE) in the form of 10% blend with gasoline (E10), along its whole life cycle, consumes less fossil energy (5.3%), less petroleum (8.1%) and provides a similar impact on acidification compared to CG. The fuel, however, has inferior performance in other categories (e.g. global warming potential, nutrient enrichment and photochemical ozone creation potential) indicated by increased impacts over CG.

Discussion

In most cases, higher impacts from the upstream of molasses-based ethanol tend to govern its net life cycle impacts relative to CG. This makes the fuel blend less environmentally friendly than CG for the specific conditions considered. However, as discussed later, this situation can be improved by appropriate changes in energy carriers.

Conclusions

The LCA procedure helps identify the key areas in the MoE production cycle where changes are required to improve environmental performance. Specifically, they are: (1) use of coal as energy source for ethanol conversion, (2) discharge of distillery spent wash into an anaerobic pond, and (3) open burning of cane trash in sugar cane production.

Recommendations and perspectives

Measures to improve the overall life cycle energy and environmental impacts of MoE are: (1) substituting biomass for fossil fuels in ethanol conversion, (2) capturing CH₄ from distillery spent wash and using it as an energy supply, and (3) utilizing cane trash for energy instead of open burning in fields.     

Environmental footprint of cooking fuels: a life cycle assessment of ten fuel sources used in Indian households

Purpose

Cooking energy is an essential requirement of any human dwelling. With the recent upsurge in petroleum prices coupled with intrinsic volatility of international oil markets, it is fast turning into a politico-socio-economic dilemma for countries like India to sustain future subsidies on liquefied petroleum gas (LPG) and kerosene. The aim of this paper is to evaluate and compare the environmental performance of various cooking fuel options, namely LPG (NG), LPG (CO), kerosene, coal, electricity, firewood, crop residue, dung cake, charcoal, and biogas, in the Indian context. The purpose of this study is to find environmentally suitable alternatives to LPG and kerosene for rural and urban areas of the country.

Methods

The study assessed the cooking fuel performance on 13 ReCiPe environmental impact categories using the life cycle assessment methodology. The study modeled the system boundary for each fuel based on the Indian scenario and prepared a detailed life cycle inventory for each cooking fuel taking 1 GJ of heat energy transferred to cooking pot as the functional unit.

Results and discussion

The cooking fuels with the lowest life cycle environmental impacts are biogas followed by LPG, kerosene, and charcoal. The environmental impacts of using LPG are about 15 to 18 % lower than kerosene for most environmental impact categories. LPG derived from natural gas has about 20 to 30 % lower environmental impact than LPG derived from crude oil. Coal and dung cake have the highest environmental impacts because of significant contributions to climate change and particulate formation, respectively. Charcoal produced from renewable wood supply performs better than kerosene on most impact categories except photochemical oxidation, where its contribution is 19 times higher than kerosene.

Conclusions

Biogas and charcoal can be viewed as potentially sustainable cooking fuel options in the Indian context because of their environmental benefits and other associated co-benefits such as land farming, local employment opportunities, and skill development. The study concluded that kerosene, biogas, and charcoal for rural areas and LPG, kerosene, and biogas for urban areas have the lower environmental footprint among the chosen household cooking fuels in the study.     

A comparative life cycle assessment of two treatment technologies for the Grey Lanaset G textile dye: biodegradation by Trametes versicolor and granular activated carbon adsorption

Purpose

The aim of this study is to use life cycle assessment (LCA) to compare the relative environmental performance of the treatment using Trametes versicolor with a common method such as activated carbon adsorption. This comparison will evaluate potential environmental impacts of the two processes. This work compiles life cycle inventory data for a biological process that may be useful for other emergent biotechnological processes in water and waste management. LCA was performed to evaluate the use of a new technology for the removal of a model metal-complex dye, Grey Lanaset G, from textile wastewater by means of the fungus T. versicolor. This biological treatment was compared with a conventional coal-based activated carbon adsorption treatment to determine which alternative is preferable from an environmental point of view.

Materials and methods

The study is based on experimental research that has tested the novel process at the pilot scale. The analysis of the biological system ranges from the production of the electricity and ingredients required for the growth of the fungus and ends with the composting of the residual biomass from the process. The analysis of the activated carbon system includes the production of the adsorbent material and the electricity needed for the treatment and regeneration of the spent activated carbon. Seven indicators that measure the environmental performance of these technologies are included in the LCA. The indicators used are climate change, ozone depletion, human toxicity, photochemical oxidant formation, terrestial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, metal depletion and fossil depletion.

Results

The results show that the energy use throughout the biological process, mainly for sterilisation and aeration, accounts for the major environmental impacts with the inoculum sterilisation being the most critical determinant. Nevertheless, the biological treatment has lower impacts than the physicochemical system in six of these indicators when steam is generated directly on site. A low-grade carbon source as an alternative to glucose might contribute to reduce the eutrophication impact of this process.

Conclusions

The LCA shows that the biological treatment process using the fungus T. versicolor to remove Grey Lanaset G offers important environmental advantages in comparison with the traditional activated carbon adsorption method. This study also provides environmental data and an indication of the potential impacts of characteristic processes that may be of interest for other applications in the field of biological waste treatment and wastewater treatment involving white-rot fungi.     

Environmental assessment of sewage effluent disinfection system: electron beam, ultraviolet, and ozone using life cycle assessment

Purpose

This study assesses the impacts of three different disinfection processes of sewage effluent, namely the electron beam (E-beam), ultraviolet (UV), and ozone systems, on the environment by using life cycle assessment (LCA).

Methods

The LCA employed was the comparative LCA which consists of three parts according to life cycle stages. Electricity consumption was the reference flow that can yield 99% disinfection efficiency for microorganisms present in a 1?×?10⁵?m³?day^?1 sewage treatment plant effluent over 20?years.

Results

The comparison of the LCA results indicated that the environmental impact of the UV disinfection system was the lowest, followed by the E-beam and ozone disinfection systems. The key issues of the E-beam, UV, and ozone disinfection systems are electricity consumption and SF₆ usage, electricity consumption and UV lamp, and electricity consumption and liquid oxygen feeding system, respectively.

Conclusions

Electricity consumption is the key input parameter that determines the LCA results.     

Environmental impacts of hybrid and electric vehicles—a review

Purpose

A literature review is undertaken to understand how well existing studies of the environmental impacts of hybrid and electric vehicles (EV) address the full life cycle of these technologies. Results of studies are synthesized to compare the global warming potential (GWP) of different EV and internal combustion engine vehicle (ICEV) options. Other impacts are compared; however, data availability limits the extent to which this could be accomplished.

Method

We define what should be included in a complete, state-of-the-art environmental assessment of hybrid and electric vehicles considering components and life cycle stages, emission categories, impact categories, and resource use and compare the content of 51 environmental assessments of hybrid and electric vehicles to our definition. Impact assessment results associated with full life cycle inventories (LCI) are compared for GWP as well as emissions of other pollutants. GWP results by life cycle stage and key parameters are extracted and used to perform a meta-analysis quantifying the impacts of vehicle options.

Results

Few studies provide a full LCI for EVs together with assessment of multiple impacts. Research has focused on well to wheel studies comparing fossil fuel and electricity use as the use phase has been seen to dominate the life cycle of vehicles. Only very recently have studies begun to better address production impacts. Apart from batteries, very few studies provide transparent LCIs of other key EV drivetrain components. Estimates of EV energy use in the literature span a wide range, 0.10?C0.24?kWh/km. Similarly, battery and vehicle lifetime plays an important role in results, yet lifetime assumptions range between 150,000?C300,000?km. CO₂ and GWP are the most frequently reported results. Compiled results suggest the GWP of EVs powered by coal electricity falls between small and large conventional vehicles while EVs powered by natural gas or low-carbon energy sources perform better than the most efficient ICEVs. EV results in regions dependant on coal electricity demonstrated a trend toward increased SO _x emissions compared to fuel use by ICEVs.

Conclusions

Moving forward research should focus on providing consensus around a transparent inventory for production of electric vehicles, appropriate electricity grid mix assumptions, the implications of EV adoption on the existing grid, and means of comparing vehicle on the basis of common driving and charging patterns. Although EVs appear to demonstrate decreases in GWP compared to conventional ICEVs, high efficiency ICEVs and grid-independent hybrid electric vehicles perform better than EVs using coal-fired electricity.     

Life cycle assessment of castor-based biorefinery: a well to wheel LCA

Purpose

Diminishing fossil resources and environmental concerns associated with their vast utilization have been in focus by energy policy makers and researchers. Among the different scenarios put forth to commercialize biofuels, various biorefinery concepts have aroused global interests because of their ability in converting biomass into a spectrum of marketable products and bioenergies. This study was aimed at developing different novel castor-based biorefinery scenarios for generating biodiesel and other co-products, i.e., ethanol and biogas. In these scenarios, glycerin, heat, and electricity were also considered as byproducts. Developed scenarios were also compared with a fossil reference system delivering the same amount of energy through the combustion of neat diesel.

Materials and methods

Life cycle assessment (LCA) was used to investigate the environmental consequences of castor biodiesel production and consumption with a biorefinery approach. All the input and output flows from the cultivation stage to the combustion in diesel engines as well as changes in soil organic carbon (SOC) were taken into account. Impact 2002+ method was used to quantify the environmental consequences.

Results and discussion

The LCA results demonstrated that in comparison with the fossil reference system, only one scenario (i.e., Sc-3 with co-production of significant amounts of biodiesel and biomethane) had 16% lower GHG emissions without even considering the improving effect of SOC. Moreover, resource damage category of this scenario was 50% lower than that of neat diesel combustion. The results proved that from a life cycle perspective, energy should be given priority in biorefineries because it is essential for a biorefinery to have a positive energy balance in order to be considered as a sustainable source of energy. Despite a positive effect on energy and GHG balances, these biorefineries had negative environmental impacts on the other damage categories like Human Health and Ecosystem Quality.

Conclusions

Although biorefineries offer unique features as promising solutions for mitigating climate change and reducing dependence on fossil fuels, the selection of biomass processing options and management decisions can affect the final results in terms of environmental evaluations and energy balance. Moreover, if biorefineries are focused on transportation fuel production, a great deal of effort should still be made to have better environmental performance in Human Health and Ecosystem Quality damage categories. This study highly recommends that future studies focus towards biomass processing options and process optimization to guarantee the future of the most sustainable biofuels.

     

Comparing technologies for municipal solid waste management using life cycle assessment methodology: a Belgian case study

Purpose

The present study aims at identifying the best practice in residual municipal solid waste management using specific data from Liège, a highly industrialized and densely populated region of Belgium. We also illustrate the importance of assumptions relative to energy through sensitivity analyses and checking uncertainties regarding the results using a Monte Carlo analysis.

Methods

We consider four distinct household waste management scenarios. A life cycle assessment is made for each of them using the ReCiPe method. The first scenario is sanitary landfill, which is considered as the base case. In the second scenario, the refuse-derived fuel fraction is incinerated and a sanitary landfill is used for the remaining shredded organic and inert waste only. The third scenario consists in incinerating the whole fraction of municipal solid waste. In the fourth scenario, the biodegradable fraction is collected and the remaining waste is incinerated. The extracted biodegradable fraction is then treated in an anaerobic digestion plant.

Results and discussion

The present study shows that various scenarios have significantly different environmental impact. Compared to sanitary landfill, scenario 4 has a highly reduced environmental impact in terms of climate change and particulate matter formation. An environmental gain, equal to 10, 37, or 1.3 times the impact of scenario 1 is obtained for, respectively, human toxicity, mineral depletion, and fossil fuel depletion categories. These environmental gains are due to energetic valorization via the incineration and anaerobic digestion. Considering specific categories, greenhouse gas emissions are reduced by 17 % in scenario 2 and by 46 % in scenarios 3 and 4. For the particulate matter formation category, a 71 % reduction is achieved by scenario 3. The figures are slightly modified by the Monte Carlo analysis but the ranking of the scenarios is left unchanged.

Conclusions

The present study shows that replacing a sanitary landfill by efficient incineration significantly reduces both emissions of pollutants and energy depletion, thanks to electricity recovery.     

Comparative LCA of ethanol versus gasoline in Brazil using different LCIA methods

Purpose

The main objective of this study is to expand the discussion about how, and to what extent, the environmental performance is affected by the use of different life cycle impact assessment (LCIA) illustrated by the case study of the comparison between environmental impacts of gasoline and ethanol form sugarcane in Brazil.

Methods

The following LCIA methods have been considered in the evaluation: CML 2001, Impact 2002+, EDIP 2003, Eco-indicator 99, TRACI 2, ReCiPe, and Ecological Scarcity 2006. Energy allocation was used to split the environmental burdens between ethanol and surplus electricity generated at the sugarcane mill. The phases of feedstock and (bio)fuel production, distribution, and use are included in system boundaries.

Results and discussion

At the midpoint level, comparison of different LCIA methods showed that ethanol presents lower impacts than gasoline in important categories such as global warming, fossil depletion, and ozone layer depletion. However, ethanol presents higher impacts in acidification, eutrophication, photochemical oxidation, and agricultural land use categories. Regarding to single-score indicators, ethanol presented better performance than gasoline using ReCiPe Endpoint LCIA method. Using IMPACT 2002+, Eco-indicator 99, and Ecological Scarcity 2006, higher scores are verified for ethanol, mainly due to the impacts related to particulate emissions and land use impacts.

Conclusions

Although there is a relative agreement on the results regarding equivalent environmental impact categories using different LCIA methods at midpoint level, when single-score indicators are considered, use of different LCIA methods lead to different conclusions. Single-score results also limit the interpretability at endpoint level, as a consequence of small contributions of relevant environmental impact categories weighted in a single-score indicator.