Existing Life Cycle Assessment Studies Research Articles

Comparative life cycle assessment of photovoltaic systems: An evaluation of environmental impacts over time

The production of photovoltaic (PV) systems is subject to continuous technological development and geographical shifts in manufacturing, leading to changes in economic aspects and environmental impacts. This work focuses on evaluating changes in environmental impacts over time using life cycle assessment (LCA). Several existing LCA studies and life-cycle inventory datasets for multi-crystalline silicon (multi-Si), single-crystalline silicon (single-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIS) were compared, and the reasons for deviations were analyzed.The comparison was carried out at the plant level for panel slanted roof systems, and the impact assessment results were compared to their counterparts from the ecoinvent v3.3 life cycle inventory cut-off database for individual datasets.The study found that technological advances in PV manufacturing have reduced environmental impacts. The differences between cell types converged over time, with CdTe having the lowest environmental impact during production. However, this may be relativized when considering the lower life time of CdTe cells in a cradle-to-grave assessment. Single-Si has a higher environmental impact during manufacturing, but it is just about compensated for compared to multi-Si. If a dataset for PV must be selected without cell-type knowledge, multi-Si plants are recommended as a proxy. The analysis provides insights into the environmental impacts of different PV systems over time and highlights the importance of regular updates of life-cycle inventories and consistent modeling.

Improving the life cycle greenhouse gas emissions of transport infrastructure assets – a case study in Brussels, Belgium

Infrastructure transportation assets represent a significant share of environmental effects associated with built stocks. Although there is a growing body of knowledge on the life cycle assessment of buildings and material flow analysis of building stocks, infrastructure assets have received less attention. Existing life cycle assessment studies tend to rely on process analysis which is known to underestimate embodied environmental flows. The aim of this paper is to introduce a bottom-up parametric model for infrastructure transport assets, which can support a detailed characterization of the stock in a consistent and transparent manner. It relies on comprehensive hybrid exchange data for the quantification. This paper establishes the approach and equations used in the proposed model. The model consists of four main steps, namely: developing parametric representations of transport infrastructure assets, quantifying their material stock and replacement-related flows, quantifying life cycle embodied environmental flows and visualizing the results. One pilot case study of a road (including pedestrian sidewalks and bike lanes) and light railway, is used to demonstrate the model. Results assessing this pilot case study over 60 years are presented, including the material stock and replacement flows, as well as life cycle embodied greenhouse gas emissions (LCEGHG). Together these results provide important insights into material/infrastructure asset hotspots assets (e.g. steel lighting posts). Emissions-intensive material products and assets have a notable impact on results of LCEGHG, and they dominate both Initial greenhouse gas emissions (IEGHG) and recurrent greenhouse gas emissions (REGHG). However, they contribute marginally to the total mass. Another important observation is the significance of REGHG representing ~30% of LCEGHG. Interestingly, steel, asphalt and concrete are the main contributors to both REGHG and IEGHG. Future research consists of automating the proposed model and packaging it as a python-based Rhinoceros Grasshopper plugin before conducting testing and verification.

A Supervised Machine Learning Classification Framework for Clothing Products’ Sustainability

These days, many sustainability-minded consumers face a major problem when trying to identify environmentally sustainable products. Indeed, there are a variety of confusing sustainability certifications and few labels capturing the overall environmental impact of products, as the existing procedures for assessing the environmental impact of products throughout their life cycle are time consuming, costly, and require a lot of data and input from domain experts. This paper explores the use of supervised machine learning tools to extrapolate the results of existing life cycle assessment studies (LCAs) and to develop a model—applied to the clothing product category—that could easily and quickly assess the products’ environmental sustainability throughout their life cycle. More precisely, we assemble a dataset of clothing products with their life cycle characteristics and corresponding known total environmental impact and test, on a 5-fold cross-validation basis, nine state-of-the-art supervised machine learning algorithms. Among them, the random forest algorithm has the best performance with an average accuracy of 91% over the five folds. The resulting model provides rapid environmental feedback on a variety of clothing products with the limited data available to online retailers. It could be used to quickly provide interested consumers with product-level sustainability information, or even to develop a unique and all-inclusive environmental label.

Environmental Impacts of Biosurfactants from a Life Cycle Perspective: A Systematic Literature Review.

Biosurfactants are considered as an environmentally friendly and sustainable alternative to conventional fossil-derived and chemically produced surfactants. Their production pathways, physicochemical properties, and applications are widely researched and discussed in literature. In this context, investigating the different impacts from the entire life cycle of biosurfactants is important to understand and mitigate potential environmental hotspots. Life Cycle Assessment (LCA) is an internationally accepted and standardized methodology to analyze the environmental impacts of products from a holistic view. Therefore, this study provides a detailed overview of existing LCA studies of biosurfactants by means of a systematic literature research. The focus specifically lies on articles that investigated microbial biosurfactants. However, the systematic approach used ensured a broader overview related to bio-based surfactants as well. Furthermore, two related topics, ecotoxicity and biodegradability of biosurfactants, were identified and discussed based on the search findings. After screening over 2,500 documents using Scopus and Google Scholar, six relevant LCA articles of biosurfactants could be identified. The identified articles are divided into LCA studies of alkyl polyglycosides, chemically produced bio-based surfactants, and LCA studies of microbial biosurfactants, their content analyzed and discussed in context. In conclusion, the number of available LCA studies is very limited and their results are often not comparable. To the best of the authors' knowledge, this review is the first of its kind to provide a detailed overview of LCA studies of biosurfactants. Consequently, the need for implementing more LCA studies becomes clear.

Development of Roughness Prediction Models for Life Cycle Assessment Studies of Recycled Pavement Projects

The few existing life cycle assessment studies considering pavement recycling techniques usually omit the stages of maintenance and rehabilitation (M&R) and use. The reason for this omission is the lack of information about how the pavement’s performance evolves over time and absence of methods to determine the M&R frequency and service life for completed projects. As a result, the deterioration of pavement recycling projects in the long term is not clearly understood. Few projects have available data, the majority of which are on low volume primary and secondary roads. This paper describes an approach to develop a family of roughness models for recycling projects in Colorado using functional data analysis, and individual models for selected projects in Virginia to support ongoing life cycle assessment (LCA) studies. In the case of Colorado, full depth reclamation (FDR) projects will most likely deteriorate following an average group rate of 1.4 in./mi/year, with an initial international roughness index (IRI) between 52 and 70 in./mi. For the individual roughness models developed for Virginia projects, the initial IRI values and the rate of change for the treatments analyzed were found to range between 49 and 107 in./mi and between 0.7 and 5.2 in./mi/year, respectively, depending on the recycling method and type of stabilization treatment. The results of an LCA case study show that, in addition to recycling, Virginia Department of Transportation can achieve statewide emission reduction goals if focus is placed on achieving smoother roads while measures are taken to keep the annual rates of deterioration low.

Plastic Waste Management: A Review of Existing Life Cycle Assessment Studies

Life Cycle Assessment (LCA) is a tool that can help to quantify the impacts of different processes to facilitate comparison and decision making. There are many potential methods for managing plastic waste, but it can be difficult to determine which methods are preferable in terms of environmental impact. Suitable existing LCA studies are identified through a screening process and the methodologies used and their outputs are compared. When undertaking an LCA, the researchers must define their scope and select their parameters, according to their aims and context, which leads to a wide variation in the approach taken. In this study, six parameters have been considered to analyze research progress in these fields regarding LCA, i.e., goals and scope, functional units, impact assessment categories, system boundaries, geographical context, and uncertainty analysis. These studies include the similar type of different studies considering plastic waste recycling, each taking a different approach to defining the system boundaries, revealing how the decision to include or exclude factors such as transport can have a significant impact on the outcomes. Additionally, compared to these similar studies on mixed-plastic waste management, different available options are used to quantitatively compare the impact outcomes, revealing how the context and parameter selection can affect the results. This review aims to highlight the prospect of LCA during the development of a waste management framework as an efficient waste recycling tool and recommend a research gap for the development of an improved management framework in the future.

Are LCA Studies on Bulk Mineral Waste Management Suitable for Decision Support? A Critical Review

Bulk mineral waste materials are one of the largest waste streams worldwide and their management systems can differ greatly depending on regional conditions. Due to this variation, the decision-making context is of particular importance when studying environmental impacts of mineral waste management systems with life cycle assessment (LCA). We follow the premise that LCA results—if applied in practice—are always used in an improvement (i.e., decision-making) context. But how suitable are existing LCA studies on bulk mineral waste management for decision support? To answer this question, we quantitatively and qualitatively assess 57 peer-reviewed bulk mineral waste management LCA studies against 47 criteria. The results show inadequacies regarding decision support along all LCA phases. Common shortcomings are insufficient attention to the specific decision-making context, lack of a consequential perspective, liberal use of allocation and limited justification thereof, missing justifications for excluded impact categories, inadequately discussed limitations, and incomplete documentation. We identified the following significant issues for bulk mineral waste management systems: transportation, the potential leaching of heavy metals, second-order substitution effects, and the choice to include or exclude avoided landfilling and embodied impacts. When applicable, we provide recommendations for improvement and point to best practice examples.

LCA of an industrial luminaire using product environmental footprint method

This paper presents a life cycle assessment (LCA) for the industrial Light Emitting Diode (LED) luminaire by using Product Environmental Footprint (PEF) methodology. The assessment is carried out for raw material, assembly, distribution, use and end of life (EoL) stages, and all upstream emissions are considered. The analysis results show that the electricity consumption in use stage is the significant contributor for the overall impacts. Environmental benefits are identified from the EoL scenario analysis due to the adopted WEEE treatments. Electricity mix for the UK and other European countries are modelled for the comparison study that shows the use of renewable resources for electricity generation has lower overall impacts from the PEF view, but the impact towards land use that is caused by using biomass energy source for electricity production is noticeable, which is barely mentioned in the existing LCA studies. This research has made the following original contributions: 1) it is the first study examining the LED luminaire environmental performance by using the PEF methodology; 2) the electricity mix modelling for the European countries in the comparison study reveals the possible trade-off between using renewable/non-renewable resources for the electricity generation, which would be beneficial for further policy development for lighting and energy sectors; 3) the availability demonstration of the current PEF database for luminaires, and the reported analysis results would assist future similar LCA studies.

A life cycle sustainability assessment of organic and conventional pork supply chains in Sweden

Most existing life cycle assessment studies that have compared the sustainability of organic and conventional pork supply chains are environmental assessments. The economic and social sustainability dimensions of pork supply chains are currently under-researched. The study reported here was designed to assess the environmental, economic and social sustainability of conventional and organic pork in Sweden. Life Cycle Sustainability Assessment was undertaken using 20 indicators expressed per unit product (1000 kg pork fork weight) and per unit area (1000 ha of farmland) for the four main subsystems in pork supply chains: (1) farm and feed production, (2) slaughter, (3) wholesaling and retailing, and (4) consumption. The organic pork supply chain out-performed the conventional chain in 11 of the 20 indicators expressed per unit product and 18 of the 20 indicators expressed per unit area. It was therefore the more sustainable of the two chains in nearly all the indicators expressed per unit area. However, the organic supply chain was less sustainable in some of the indicators expressed per unit product because, more feed per kg of pork was required in organic pork production. Pig welfare improvement leads to higher production costs and environmental impacts. Assessment of all three sustainability dimensions – environmental, economic and social – helps to identify trade-offs between these three pillars of sustainability. However, the selection of indicators influences results, and obtaining environmental, economic and social data simultaneously is challenging.

Are LCA Studies on Bulk Mineral Waste Management Suitable for Decision Support? A Critical Review

Bulk mineral waste materials are one of the largest waste streams worldwide and their management systems can differ greatly depending on regional conditions. Due to this variation, the decision-making context is of particular importance when studying environmental impacts of mineral waste management systems with life cycle assessment (LCA).We follow the premise that LCA results—if applied in practice—are always used in an improvement (i.e., decision-making) context. But how suitable are existing LCA studies on bulk mineral waste management for decision support? To answer this question, we quantitatively and qualitatively assess 57 peer-reviewed bulk mineral waste management LCA studies against 47 criteria. The results show inadequacies regarding decision support along all LCA phases. Common shortcomings are insufficient attention to the specific decision-making context, lack of a consequential perspective, liberal use of allocation and limited justification thereof, missing justifications for excluded impact categories, inadequately discussed limitations, and incomplete documentation. We identified the following significant issues for bulk mineral waste management systems: transportation, the potential leaching of heavy metals, second-order substitution effects, and the choice to include or exclude avoided landfilling and embodied impacts. When applicable, we provide recommendations for improvement and point to best practice examples.

Estimating carbon emissions from road use, maintenance and rehabilitation through a hybrid life cycle assessment approach – A case study

Road infrastructure is an important source of carbon emissions. To estimate the carbon emissions of roads, life cycle assessment (LCA) methods are widely used. Due to budget constraints, road maintenance and rehabilitation (M&R) is preferred by road agencies over new construction. However, existing LCA studies on roads have limited considerations on the emissions from the use and M&R phases. This study aims to propose and illustrate a structured hybrid LCA approach that can be adopted by road agencies to evaluate carbon emissions of the use and M&R phases of roads. A path exchange LCA method and a tiered hybrid LCA method are integrated in the proposed approach. To illustrate the proposed approach, a case study of a road network in Western Australia is conducted, which includes 17,764 road segments. The results show that from 2017 to 2026, the GWP of use and M&R phases is increased from 467.8 t CO2-e/km to 589.5 t CO2-e/km·with an increasing trend. The use phase has much higher global warming potential than the M&R phase during the service life of roads. The results are the most sensitive to annual average daily traffic (AADT). In addition, heavy traffic roads in the metropolitan area and freeways with AADT higher than 20,000 are identified to be the most carbon intensive. The proposed approach is believed to have better accuracy when compared to a process-based approach and a tiered approach, which provide the results of 128.6–164.4 t CO2-e/km and 468.0–608.9 t CO2-e/km, respectively. The results can provide implications for road authorities to evaluate their priorities when allocating limited M&R funds to achieve sustainable objectives.

Toward a cell‐chemistry specific life cycle assessment of lithium‐ion battery recycling processes

AbstractOn the basis of a review of existing life cycle assessment studies on lithium‐ion battery recycling, we parametrize process models of state‐of‐the‐art pyrometallurgical and hydrometallurgical recycling, enabling their application to different cell chemistries, including beyond‐lithium batteries such as sodium‐ion batteries. These processes are used as benchmark for evaluating an advanced hydrometallurgical recycling process, which is modeled on the basis of primary data obtained from a recycling company, quantifying the potential reduction of environmental impacts that can be achieved by the recycling of different cell chemistries. Depending on the cell chemistry, recycling can reduce significantly the potential environmental impacts of battery production. The highest benefit is obtained via advanced hydrometallurgical treatment for lithium nickel manganese cobalt oxide and lithium nickel cobalt aluminum oxide‐type batteries, mainly because of the recovery of cobalt and nickel. Especially under resource depletion aspects, recycling of these cells can reduce their impact to an extent that even leads to a lower “net impact” than that of cells made from majorly abundant and cheap materials like lithium iron phosphate, which shows a more favorable performance when recycling is disregarded. For these cells, recycling does not necessarily provide benefits but can rather cause additional environmental impacts. This indicates that maximum material recovery might not always be favorable under environmental aspects and that, especially for the final hydrometallurgical treatment, the process would need to be adapted to the specific cell chemistry, if one wants to obtain maximum environmental benefit.

Review and new life cycle assessment for rare earth production from bastnäsite, ion adsorption clays and lateritic monazite

Rare Earth Elements (REEs) are one of the most important--albeit critical--commodities for our green technologies. However, there is a general perception that REEs are produced using mining and processing techniques that are unsustainable. Life Cycle Assessment (LCA) is the most widely accepted methodology to evaluate the environmental impacts of rare earth oxide (REO) production. This article aims to provide a synthesis of the currently existing LCA studies on REEs using two strategies. Firstly, an overview of published LCA results of REO production. Secondly, a detailed LCA using the best available life cycle inventories (LCIs) in order to: i). evaluate the state-of-the-art LCI for this sector ii). Understand better the impacts related to each of the three main production routes and iii). Contribute to the development of a preliminary benchmark for the sector. The analysis of the published LCA results reveal that the three main methodological issues with published LCAs are data gaps, allocation, and waste management. The dominating contributor to the global warming potential of the production of REOs in all two of the three routes is chemical extraction and separation.

A review of life cycle greenhouse gas (GHG) emissions of commonly used ex-situ soil treatment technologies

Abstract GHG emissions are important footprints because of increasing concern over climate change. Remediation methods produces GHGs in varying quantities based on which activities are involved through its entire life cycle and which contaminants are present, often because some contaminants are more difficult to remove from soil than others. Accounting for emissions from all phases of the project requires a life cycle assessment (LCA) approach. LCA can help in choosing the best available technology to reduce the environmental burden of the remediation technology or to improve the sustainability of the technology by implementing systematic approaches to ensure that future developments are optimized for environmental performance throughout the life cycle. The primary objective of this paper is to review existing LCA studies that report GHG emissions (CO2-eq) or Global warming potential (GWP) from six ex-situ soil remediation technologies (ESRTs), including excavation and disposal, ex-situ thermal desorption, ex-situ soil vapor extraction, ex-situ bioremediation, excavation and incineration, and soil washing, and present the variability in GHG/GWP results and how this data can help in selecting an ex-situ soil remediation technology with a lower global warming potential. A second objective of this study is to compare the GWP levels of ex-situ remediation to the GWP levels of typical in situ remediation methods. Our results showed a large variation in GHG emissions of treated soil from six ESRTs varying from 3.1 × 10−7 t to 8.2 t CO2-eq/m3. Incineration had the highest mean GHG emissions (0.7 t CO2-eq/m3) and thermal desorption the lowest (0.07 t CO2-eq/m3). It was also found that there was a large variation range of GHG emissions from the ex-situ excavation and disposal method soil treatment technologies, varying from 3.1 × 10−7 t to 8.2 t CO2-eq/m3 of treated soil. This knowledge provides opportunities to increase sustainability of soil remediation throughout the investigation, design, construction, operation, and monitoring phases of site remediation regardless of the selected cleanup remedy. This shows data on LCA GHGs are useful to assess the impact of different scenarios and management practices on ESRTs.

Accounting for the environmental impacts of sulfidic tailings storage in the Life Cycle Assessment of copper production: A case study

Most of the existing Life Cycle Assessment studies addressing the environmental impacts of copper production exclude the emissions generated by tailings. This study aims at compiling the life cycle inventory related to the storage of tailings from sulfidic copper ore concentration, in the specific case of a plant located in south-west Poland. The environmental impacts induced by these tailings are compared with the rest of the environmental impacts of copper production. This study demonstrates that, when considering toxicity-related environmental impact categories, the potential impacts related to the storage of tailings in dedicated facilities are a key issue in the life cycle impact assessment of copper concentrate production, and consequently of copper production. Depending on the temporal perspective considered in the study, the disposal of sulfidic tailings induces impacts that may be several orders of magnitude larger than those of copper concentrate production. Yet, when limiting the considered temporal perspective to 100 years, tailings storage has a relatively low contribution to the impacts of concentrate production. The discrepancy between the impacts related to copper concentrate production and those of tailings disposal is highly dependent on both the temporal perspective considered in the LCA study and the actual conditions of tailings management in the future.

Systematic Review and Meta‐Analysis of Life Cycle Assessments for Wood Energy Services

SummaryEnvironmental impacts of the provision of wood energy have been analyzed through life cycle assessment (LCA) techniques for many years. Systems for the generation of heat, power, and combined heat and power (CHP) differ, and methodological choices for LCA can vary greatly, leading to inconsistent findings. We analyzed factors that promote these findings by conducting a systematic review and meta‐analysis of existing LCA studies for wood energy services. The systematic review investigated crucial methodological and systemic factors, such as system boundaries, allocation, transportation, and technologies, for transformation and conversion of North American and European LCA studies. Meta‐Analysis was performed on published results in the impact category global warming (GW). A total of 30 studies with 97 systems were incorporated. The studies exhibit great differences in their systemic and methodological choices, as well as their functional units, technologies, and resulting outcomes. A total of 44 systems for the generation of power, with a median impact on GW of 0.169 kilograms (kg) of carbon dioxide equivalents (CO2‐eq) per kilowatt‐hour (kWhel), were identified. Results for the biomass fraction only show a median impact on GW of 0.098 kg CO2‐eq * kWhel−1. A total of 31 systems producing heat exhibited a median impact on GW of 0.040 kg CO2‐eq * kWhth−1. With a median impact on GW of 0.066 kg CO2‐eq * kWhel+th−1, CHP systems show the greatest variability among all analyzed wood energy services. To facilitate comparisons, we propose a methodological approach for the description of system boundaries, the basis for calculations, and reporting of findings.

Facility arrangements and the environmental performance of disposable and reusable cups

This paper integrates two complementary life cycle assessment (LCA) studies with the aim to advice facility managers on the sustainable use of cups, either disposable or reusable. Study 1 compares three disposable cups, i.e., made from fossil-based polystyrene (PS), biobased and compostable plastic (polylactic acid; PLA) and paper lined with PLA (biopaper). Study 2 compares the disposable PS cup with reusable cups that are handwashed or dishwashed. Existing LCA studies show inconsistent and sometimes conflicting results, due to differences in used data and modeling choices. The comparison of disposable cups, study 1, deliberately applied multiple inventory data sets for relevant life cycle processes and multiple crediting principles for recycling. Included waste treatment options in study 1 were incineration, recycling, composting, and anaerobic digestion (last two not for the disposable PS cup). The PS cup is next compared with handwashed and dishwashed reusable cups (study 2). LCAs for the reusable cups use single data sets, and explore the influence of an increasing number of reuses. Cup LCA results were only compared within, and not across impact categories. All data relate to cups used with hot beverage vending machines in Dutch office settings. Impact results for each disposable cup show large and overlapping spreads. This prevents identifying a preferable disposable cup material, though still allows cautious preferences about waste treatment processes. Composting biocups is less good than other waste treatment processes. Average impact results for anaerobic digestion perform in almost all impact categories better than incineration for the PLA cup. Average impact results for recycling perform slightly better than incinerating for both biocups, but not for the PS cup. This comparison is affected, however, by the relatively large credits for avoided Dutch electricity production. Impact results for reusable cups do not perform better than disposable cups if both are used once. Impact results for the reusable cups contain large uncertainty due to widely varying user behavior. Overall results do not allow any preference for one of the disposable cups or for disposable versus reusable cups. All cups can be used for more than one consumption. This gives a considerable environmental gain for the second and third hot beverage consumption with all cups. Facility managers can encourage a second or third serving with the same cup by financial incentives, only putting on dishwashers around noon and after working time, and/or consumer awareness activities.

20 years of life cycle assessment (LCA) in the forestry sector: state of the art and a methodical proposal for the LCA of forest production

Life cycle assessment (LCA) techniques have been developed since the late 1960s in order to analyze environmental impacts of various products or companies. Although LCA techniques of forest production have been already conducted since the early 1990s, consistent and comprehensive LCA studies are still lacking for the forestry sector. In order to support better comparability between LCA studies, we analyzed the problems and differences by conducting a descriptive and quantitative analysis of existing LCA studies of forest production with special focus on Global Warming Potential (GWP). We analyzed 22 different peer-reviewed studies, four original reports and two databases. Important issues were, among others, the goal of the studies, system boundaries, functional units, impact categories and involved processes. In addition, a quantitative analysis was purchased where the results of the GWP of the reviewed studies were analyzed. The studies showed large differences between methodical assumptions and their subsequent results. For the GWP, we found a range of 2.4–59.6 kg CO2-equiv.*m−3 over bark (ob; median = 11.8; n = 41) from site preparation to forest road and 6.3–67.1 kg CO2-equiv.*m−3 ob (median = 17.0; n = 36) from site preparation to plant gate or consumer. Results varied as a function of the included processes and decisive assumptions, e.g., regarding productivity rates or fuel consumption of machineries. Raw wood products are widely declared as “carbon neutral,” but the above-mentioned results show that absolute carbon neutrality is incorrect, although the GWP is low compared with the carbon storage of the raw wood product (range of C-emitted/C-stored in wood is 0.008–0.09 from forest to plant gate or consumer). Thereby, raw wood products can be described as “low emission raw materials” if long-term in situ carbon losses by changed forest management or negative direct or indirect land use change effects (LUC, iLUC) can be excluded. In order to realize improved comparisons between LCA studies in the forestry sector in the future, we propose some methodical approaches regarding the harmonization of system boundaries, functional units, considered processes, and allocation assumptions. These proposals could help to specify the description of the forest production outlined in existing Product Category Rules for Environmental Product Declarations (e.g., EN ISO 16485 2014 or EN ISO 15804 2012) following EN ISO 14025 (2011) and for carbon footprinting standards like the Publicly Available Specification (PAS) 2050 (2011) or the European Environmental Footprinting Initiative.

Greenhouse gas emissions from renewable energy sources: A review of lifecycle considerations

Abstract Electricity and heat generation are key contributors to global emissions of greenhouse gases (GHG). In this paper, specific attention is paid to renewable energy technologies (RETs) for electricity and heat generation and reviews current understanding and estimates of life cycle GHG emissions from a range of renewable electricity and heat generation technologies. Comprehensive literature reviews for each RET were carried out. The 79 studies reviewed involved the life cycle assessment (LCA) of renewable electricity and heat generation based on onshore and offshore winds, hydropower, marine technologies (wave power and tidal energy), geothermal, photovoltaic (PV), solar thermal, biomass, waste, and heat pumps. The study demonstrates the variability of existing LCA studies (results) in tracking GHG emissions for electricity and heat generation from RETs. This review has shown that the lowest GHG emissions were associated with offshore wind technologies (mean life cycle GHG emissions could be 5.3–13 g CO2 eq/kWh). Results compared with GHG estimates by fossil fuel heat and electricity indicated that life cycle GHG emissions are comparatively higher in conventional sources as compared to renewable sources with the exception of nuclear-based power electricity generation. In this present study, considering renewable energy sources, waste treatment and dedicated biomass technologies (DBTs) were found to potentially have high GHG emissions based on the feedstock, selected boundary and the inputs required for their production. The study identifies additional impacts associated with renewable electricity and heat technologies, points out the effectiveness of life cycle analysis (LCA) as a tool for assessing environmental impacts of renewable energy sources and concludes with opportunities for improvement in the future.

Life cycle assessment of a floating offshore wind turbine

A development in wind energy technology towards higher nominal power of the wind turbines is related to the shift of the turbines to better wind conditions. After the shift from onshore to offshore areas, there has been an effort to move further from the sea coast to the deep water areas, which requires floating windmills. Such a concept brings additional environmental impact through higher material demand. To evaluate additional environmental burdens and to find out whether they can be rebalanced or even offset by better wind conditions, a prospective life cycle assessment (LCA) study of one floating concept has been performed and the results are presented in this paper. A comparison with existing LCA studies of conventional offshore wind power and electricity from a natural gas combined cycle is presented. The results indicate similar environmental impacts of electricity production using floating wind power plants as using non-floating offshore wind power plants. The most important stage in the life cycle of the wind power plants is the production of materials. Credits that are connected to recycling these materials at the end-of-life of the power plant are substantial.