Analyzed Impact Categories Research Articles

Life Cycle Assessment of Single-Story Low-Income Housing: A Brazilian Case Study

This study aims to assess the environmental impacts of different construction systems employed in a single-story low-income housing development utilizing Life Cycle Assessment (LCA). The LCA was applied to the roof, wall, coating, and floor systems, considering the initial and recurring impacts from extraction to material replacement. Data were quantified using the CML 2001 method with OpenLCA 1.9 software. The analyzed impact categories are the potential for the depletion of abiotic resources—non-fossil (ADP); potential for the depletion of abiotic resources—fossil (ADP f); soil and water acidification potential (AP); eutrophication potential (EP); global warming potential—100 (GWP); stratospheric ozone layer depletion potential (ODP); and photochemical oxidation potential (POCP). The results highlight the impacts related to the maintenance and replacement of materials as the most significant, with walls being the system with the highest concentration of impacts, presenting the highest results among five of the seven categories. In the GWP category, the wall system resulted in 42% of total impacts (initial + recurring impacts). These findings show that the selection and definition of construction materials in the design phase can either mitigate or exacerbate environmental burdens. Therefore, this research contribution lies in pinpointing the environmental impacts of each construction system of low-income housing to support architects and engineers in addressing environmental impacts when making project decisions.

Coupling material and energy flow analysis with life cycle assessment to support circular strategies at the urban level

PurposeThis study aims to investigate how the coupling of Material and Energy Flow Analysis (MEFA) with Life Cycle Assessment (LCA) under an urban metabolism (UM) perspective (referred to as the UM-LCA approach) can support the design, evaluation, and monitoring of urban-level circular strategies. For this purpose, we apply the UM-LCA approach to the urban area of Umeå (Sweden) by expanding the goal and scope of a recent MEFA study conducted by the authors of the article.MethodsThe modeling combines MEFA with LCA and is performed both retrospectively and prospectively. The MEFA was performed in the prior study following a bottom-up approach to map and quantify material and energy flows in the urban system at the sectoral level. The quantified flows are used in the present study to construct the life cycle inventory (LCI) model of the urban system. The LCI model is first used as a basis of the retrospective LCA (rLCA), which is conducted to assess the environmental performance of the urban system with its sectors. The LCI model is then modified according to future scenarios and is used as a basis of the prospective LCA (pLCA), which is performed to assess the environmental implications of implementing circular strategies in the future.Results and discussionThe rLCA shows that the construction and household sectors are major drivers of environmental impacts in the urban system, with households being the largest contributors to 11 out of 12 analyzed impact categories. It also reveals the most impacting flows within these sectors, including food in households and steel in the construction sector. These findings indicate that the construction and household sectors and their most impacting flows should be prioritized in a circular strategy. Furthermore, the pLCA highlights that a future circular strategy promoting reductions in the material used in these two sectors could lead to higher reductions in all impact categories, ranging from 4.3 to 8.6%, than a strategy focused only on recycling, which could lead to reductions ranging from 0.2 to 1.2%.ConclusionsThis study concludes that the UM-LCA approach has great potential to comprehensively analyze, both retrospectively and prospectively, the environmental performance of an urban system providing valuable insights that could support policy makers in designing, assessing, and monitoring urban-level circular strategies. However, further research should address identified limitations of the UM-LCA approach (e.g., limited available data, inability to consider social and economic aspects) to facilitate its applicability and enhance its comprehensiveness.

Replacing location-based electricity consumption with market-based residual mixes in background data to avoid possible double counting: a quantitative analysis of effects and challenges

PurposeMost life cycle inventory (LCI) datasets include location-based electricity mixes. Using these LCI datasets in combination with market-based electricity accounting in life cycle assessments (LCAs) leads to double counting of electricity from specific sources, such as renewable energy. The goal of this paper is to analyze market-based accounting by replacing location-based electricity consumption with market-based residual mixes in all processes of the ecoinvent database. The python script for this replacement procedure is openly available.Materials and methodsWe use the Brightway 2 software package to replace European location-based electricity consumption in all 21,238 processes of the ecoinvent database with residual electricity mixes on the corresponding voltage level. The ecoinvent database provides residual electricity mixes for all countries involved in European trade with market-based energy attribute certificates—Guarantees of Origin. We analyze the induced changes to the database both on an individual process level and on a database-wide level. The analysis focusses on the impact category climate change but is further extended to the impact categories terrestrial acidification, freshwater eutrophication, marine eutrophication, ozone depletion, and particulate matter formation.Results and discussionFor European processes, the implementation of the residual electricity mixes leads to average changes in the life cycle impact assessment (LCIA) results for climate change of 1%, 10%, 20%, and 50% for 2958, 733, 387, and 107 processes, respectively. Changes are especially pronounced for Norwegian and Icelandic processes due to the large differences among their location-based and residual electricity mixes. For the other analyzed impact categories, the changes in LCIA results are particularly high for freshwater eutrophication. With the push towards more primary data in LCA and GHG accounting, the impacts of using residual electricity mixes instead of location-based electricity mixes need further research on basis of quantified figures, which we present in this paper.ConclusionThis paper presents an approach towards enabling more consistent market-based accounting throughout LCAs and thereby contributes to the avoidance of double counting. Since only European residual mixes are considered, the database of this paper leads to distortion of LCA results. Further, research is needed to address double counting beyond the European electricity sector. This includes an expansion of this research to a global level and other industrial sectors. Furthermore, research is needed regarding industry-specific electricity sources in LCI datasets, which may also lead to double counting.

Environmental and economic impacts of improper materials in the recycling of separated collected food waste through anaerobic digestion and composting

Separately collected food waste (SC-FW) is effectively recycled through industrial anaerobic digestion (AD) and composting. However, the presence of improper materials in SC-FW not only generates technical problems to AD and composting, but also lowers the quality of the outputs of the processes. As a consequence, improper materials found in SC-FW cause not negligible environmental and economic burdens.In this study, the environmental and economic impacts due to the presence of unsuitable materials in the SC-FW, determined through compositional analysis, were estimated through life cycle assessment and environmental life cycle costing approaches. Three different scenarios were analysed for both AD and composting processes: (i) the current situation (CS); (ii) the improved scenario (AS) with an amount of improper materials in SC-FW reduced to 3 % (w/w); (iii) the ideal scenario (IS) with the total absence of foreign materials.Environmental benefits were determined for the AS and IS scenarios in 17 of the 19 analysed impact categories. Considering the GHG emissions, higher savings were measured for AD in AS and IS scenarios (47 % and 79 %, respectively) than in CS scenario. Similarly, savings of −10.4 kg fossil oil eq/tonSC-FW (AS) and − 17.1 kg fossil oil eq/tonSC-FW (IS) for AD could be obtained with respect to the CS scenario. Greater economic benefits were calculated for AD (−76.4 €/tonSC-FW) and composting (−52.2 €/tonSC-FW) in the IS scenario. Savings up to € 2,249,780 and € 3,888,760 could have been obtained in 2022 by reducing to 3 % (w/w) and eliminating, respectively, the amount of improper materials in the SC-FW.The results of the compositional analyses of SC-FW allowed to identify the incorrect behaviours in FW source-sorting activity and to plan interventions to improve the current FW management system. The quantified environmental and economic benefits could further motivate citizens to correctly differentiate FW.

Agrivoltaics: The Environmental Impacts of Combining Food Crop Cultivation and Solar Energy Generation

The demand for food and renewable energy is increasing significantly, whereas the availability of land for agricultural use is declining. Agrivoltaic systems (AVS), which combine agricultural production with solar energy generation on the same area, are a promising opportunity with the potential to satisfy this demand while avoiding land-use conflicts. In the current study, a Consequential Life-Cycle Assessment (CLCA) was conducted to holistically assess the environmental consequences arising from a shift from single-use agriculture to AVS in Germany. The results of the study show that the environmental consequences of the installation of overhead AVS on agricultural land are positive and reduce the impacts in 15 of the 16 analysed impact categories especially for climate change, eutrophication and fossil resource use, as well as in the single score assessment, mainly due to the substitution of the marginal energy mix. It was demonstrated that, under certain conditions, AVS can contribute to the extension of renewable energy production resources without reducing food production resources. These include maintaining the agricultural yields underneath the photovoltaic (PV) modules, seeking synergies between solar energy generation and crop production and minimising the loss of good agricultural land.

Life cycle environmental impacts of consumer packaging products in Japan.

Several Japanese companies and the government are recently promoting a plastic ban and imposing a tax levy to curb litter and reduce greenhouse gas emissions. This has led to a rapid rise of nonplastic packaging alternatives. While plastics and litter are pressing concerns, it is paramount to examine environmental risks of other alternatives before wide application and legislative action, to not further the risk of environmental damage. This study aims to quantify and compare plastic products such as polyethylene-terephthalate (PET) bottles and high-density polyethylene (HDPE) bags with widely available alternatives in Japan like glass bottles, aluminum bottles, paper bags, and textile bags, to find a product with the least environmental impact. A life cycle assessment is conducted from a cradle-to-grave environmental impact approach that includes raw material extraction, production, transportation, end-of-life treatment, and disposal. Sixteen impact categories including climate change, acidification, aquatic-toxicity, so forth, and weighing is assessed using the MiLCA software. The functional unit is one piece of each packaging product, and impacts of product-filling, storage, recycling, and reuse are excluded for a consistent comparison. HDPE bags performed better than paper and textile bags in 15 of the 16 analyzed impact categories. Similarly, PET bottles outperformed aluminum and glass bottles in 12 out of the 16 impact categories analyzed. Weighted results also highlight the heightened negative environmental impacts of replacing plastic packaging with widely available alternatives.

Eco-efficient transformation of mineral wool wastes into lightweight aggregates at low firing temperature and associated environmental assessment

Waste recycling is one of the key elements to mitigate the environmental problems that threaten our society. Mineral wool is currently the most widely used insulation material in the European Union, so the amount of waste generated in the demolition and restoration of buildings has increased alarmingly. This work investigates for the first time the use of glass wool (GW) and rock wool (RW) as a component in the manufacture of lightweight aggregates, showing that both can be suitable raw materials considering the density (1.3–1.5 g/cm3) and mechanical strength (2–6 MPa) obtained. In addition, the use of GW would help to reduce the firing temperature significantly (700 °C) compared to that normally used in the manufacture of these materials (around 1200 °C), which would imply significant energy savings. Considering that thermal insulation materials and lightweight aggregates are among the most widely used materials in the construction sector, the work presented here also evaluates the environmental impact associated with the manufacture of lightweight aggregates with RW and GW in comparison with the traditional process, using the Life Cycle Assessment (LCA) methodology. A significant environmental improvement has been observed in almost all the analyzed impact categories of the artificial aggregates manufactured with mineral wool with respect to traditional LWAs.

Environmental Impact Analysis of Natural Cork Stopper Manufacturing

For both wine makers and customers, natural cork stoppers are a symbol of quality. Moreover, they are essential for maintaining the organoleptic properties of bottled wines throughout their lifespan. This research relied on the life-cycle assessment (LCA) methodology to analyze the relationship between the efficient usage of cork planks and the environmental impact of the cork stopper manufacturing industry. The goals of this research were to analyze and determine the environmental impact of producing 1 kg of natural cork stoppers. The analysis considered cork stoppers of two sizes—24 × 44 mm and 26 × 44 mm—and two manufacturing methods—punching and turning. Our findings indicated that the 24 × 44 mm cork stoppers produced with the punching method had a slightly lower environmental impact (1.36 kg CO2 eq/kg) across the ten analyzed impact categories. Conversely, 26 × 44 mm turned corks had the highest impact on the environment (1.49 kg CO2 eq/kg). Additionally, a comparison of same-sized punched and turned cork stoppers showed that the former had a lower environmental impact. This phenomenon is directly related to plank usage. In conclusion, there is a clear relationship between environmental impact and the efficient usage of raw material. In turn, an efficient usage of raw material depends on both the manufacturing method and stopper size.

Environmental performance of an integrated water supply and wastewater system through life cycle assessment — A Brazilian case study

The objective of this study was to evaluate the environmental performance of an integrated water supply and wastewater system that employs a system of ponds at the wastewater treatment system. Additionally, this study aimed to understand the contribution of each stage of the system to the analyzed impact categories, and to evaluate alternative scenarios that consider the reduction of water losses in distribution, as well as the operation of an upflow anaerobic sludge blanket (UASB) reactor in the wastewater treatment plant (WWTP). The evaluation was performed through life cycle assessment (LCA) that considered the stages of water withdrawal, treatment, and distribution along with wastewater collection and treatment. The system was modeled in the OpenLCA software using the Ecoinvent 3.7.1 database. Environmental impacts were assessed using the ReCiPe method and cumulative energy demand. The results show that the water withdrawal stage is the potential source of the greatest environmental impacts. There are exceptions in the categories of climate change and photochemical oxidant formation, which are most impacted by the WWTP. Analysis of alternative scenarios revealed that the decrease in water loss rates during distribution contribute to a linear reduction in potential environmental impacts of the analyzed categories. The operation of a UASB reactor in the WWTP leads to a reduction in impacts on the categories of climate change (41.4%) and formation of photochemical oxidants (11.6%), and to increases in impacts on the other categories analyzed. The data presented provide important information for the improvement of public policies aimed at sanitation in developing countries.

Environmental Valorization of Rice Waste as Adsorbent Material for the Removal of Nitrates from Water

An innovative water-treatment process consisting in reducing the nitrate concentration by using an active silica filter obtained from ashes produced during rice-straw thermal treatment has been developed by the LIFE LIBERNITRATE project. A life-cycle assessment (LCA) was carried out to evaluate the environmental impacts of this innovative process, from the production of ashes and extraction and activation of silica to the water treatment. These results were compared to the environmental impact derived from the use of bottled water, instead of tap water, where traditional water treatments (i.e., reverse osmosis) may not be available due to the high installation and operating costs. The comparison showed that the proposed innovative process could contribute to reducing the environmental impact in almost all analyzed impact categories (from 20% for photochemical oxidation to 90% for abiotic depletion) with respect to the use of bottled water. In addition, if conveniently optimized (for example reducing the amount of active silica used per day), the innovative process could further reduce the ecological footprint and be more eco-friendly than the use of bottled water and could be applied to treating water in small towns where reverse osmosis may not be installed. The LCA proved that the innovative process could contribute to reducing the environmental impact of water-treatment technologies resulting in lower environmental indicators with respect to the use of bottled water.

Assessment of Critical Resource Use in Aircraft Manufacturing

The global aircraft fleet has been expanding worldwide, leading to a high demand for primary resources. Simultaneously, recycling initiatives for decommissioned aircraft are still incipient. Following circular economy principles, the aims of this paper are to identify potentially critical resources used and related environmental impacts, to derive recommendations regarding recycling, and to analyze the influence of increasing utilization of lightweight composite materials in aircraft manufacturing. It was identified that the engine is the structure containing resources with the highest scarcity, with tantalum dominating seven of the eleven analyzed impact categories. Aluminum, titanium, and nickel were shown to lead to the highest environmental impacts. Hotspots in the criticality and environmental assessment often occur due to alloying resources with a low mass share. It was shown that aluminum and steel alloy recycling should be prioritized. A higher lightweight composite material share in the aircraft increases impacts in the categories climate change and fossil resource depletion by 12% and 20%, respectively, whereas the impact of the category acidification, political stability, and demand growth decreases by 16%, 35%, and 60%, respectively.

Environmental life cycle assessment study of an external wall

In the current economic scenario, sustainable development goals are pursued with the aim of creating a sustainable industrial scenario. Industrial sectors responsible for high levels of emissions and consumption, such as the construction industry, need to be thoroughly analysed, focusing on the use of recyclable and eco-sustainable materials. In this regard, this work proposes an environmental life cycle assessment study, which aims to quantify the environmental impacts of a standard designed external wall and evaluate the use of recycled materials in its insulation layer. An external wall with expanded polystyrene insulation has been chosen. Six environmental impact categories have been considered: 'acidification'; 'eutrophication'; 'global warming potential'; 'abiotic depletion – elements'; 'abiotic depletion – fossil fuels'; 'ozone layer depletion'. Results show that the reinforced concrete layer has the most significant contribution to all the analysed impact categories. Moreover, comparing the insulation layer with different percentages of recycled expanded polystyrene, it has been found that the impact categories majorly influenced are the 'global warming potential' and the 'abiotic depletion – fossil fuel'.

Life cycle assessment of a leather shoe supply chain

ABSTRACT The fashion industry is responsible for a significant contribution to environmental pressure in the European Union. The present study aims to quantify the environmental impacts of a leather shoe production chain and identify the most criticalities in terms of companies, processes, and materials. The Life Cycle Assessment (LCA) methodology was used to assess the impacts related to the production of a pair of classic man leather shoes. Slaughtering and tanning resulted in the less environmentally sustainable stages for almost all the analysed impact categories, except water resource depletion and ozone layer depletion. Such outcomes are mainly due to the high distance from animals’ skin suppliers to slaughterhouses and tanneries, the use of lorries transport, and the large use of unsustainable chemicals to treat the leather. Going downstream, the main hot spot refers to the use of cotton during upper manufacturing and shoe assembly and finishing. Three alternative realistic production scenarios were simulated to find the best sustainable mix. They focused on alternative means of transport, the substitution of cotton, and green purchasing of upper and lining. An environmental impact reduction of about 30% can be obtained if all the suggested scenarios are implemented.

Environmental performance of dye-sensitized solar cells based on natural dyes

Dye-sensitized solar cells (DSSCs) are promising alternatives to silicon-based solar cells due to their compatibility with flexible substrates and their ability to work under low-light conditions. The performance of these solar cells mainly depends on the sensitizer structure. Sensitizers based on synthetic dyes typically exhibit the best conversion efficiency; however, they have many problems such as scarcity of metals, lengthy purification steps, high synthesis costs, and high environmental impact. Natural dyes extracted from plants have been proposed as alternatives due to their nontoxicity, facile preparation, and low production cost, although they have lower efficiencies. This study used a life cycle assessment (LCA) metohodology to investigate the environmental performances of DSSCs based on natural sensitizers. We fabricated three DSSCs based on natural dyes, obtained from the juice, pomace, and leaves of black chokeberries, and another with synthetic N719 sensitizer. The results showed that the photovoltaic module containing synthetic N719 dye had the lowest environmental impact among all analyzed impact categories. Among the modules containing natural dyes, cells with chokeberry juice dyes had the highest environmental performance.

RUBISCO PROTEIN PRODUCTION – LCA APPROACH

The objective of this paper was to assess the environmental performance of the system of RuBisCo protein extraction and isolation from sugar beet leaves. Life cycle assessment (LCA) calculations have been completed to identify and quantify the environmental impacts from a cradle-to-cradle perspective covering seven subsystems: milling and extraction, heat treatment, centrifugation, microfiltration, ultrafiltration, chromatography and spray drying. In this paper, six environmental impact categories were analyzed: global warming potential, ozone layer depletion, energy demand, eutrophication potential, acidification potential, and land use. When RuBisCo protein extraction and isolation from different raw materials are compared, the only crop that has a lower environmental impact than sugar beet leaves is alfalfa, while the higher environmental impact has yellow mustard, ryegrass (mixture), Italian ryegrass, Brussels sprouts, English ryegrass, carrot leaves, leaf radish, and chicory. The comparison of environmental impact categories of different protein concentrates indicated that protein powder containing RuBisCo affected the environment less than egg protein concentrate. Direct comparison to other highly functional plant proteins was not possible as these are not in the market or have no LCA data available. RuBisCo was more environmentally impacting than regular soy protein. Our results for RuBisCo were in accordance with the low end of the range of results for microalgae, which is representing Chlorella HTF (heterotrophic fermenter), for most of the analyzed impact categories. This study found that the largest contributor to the environmental profile of the entire system of RuBisCo protein extraction and isolation from sugar beet leaves is the usage of electricity, while mitigation options for optimization of environmental impacts rely on the energy pinch approach for spray drying.

Flax fiber for technical textile: A life cycle inventory

Flax fiber appears as a suitable feedstock in the endeavor of deploying a sustainable biobased economy. Its environmental performance as reinforcement in composite materials has been studied in previous Life Cycle Assessments (LCAs). However, these studies only present a coarse Life cycle Inventory (LCI) and often fail to detail all processes of the supply chain or to represent the co-products. This paper aims to bridge this gap and provide data for future LCAs on flax fiber production and transformation.The study focuses on the impacts of producing a bio-based reinforcement material (a fabric product for non-aesthetic purposes) with a system expansion perspective. The functional unit is defined as the production of 2400 m2 flax-based technical textile per year, this corresponds to 1 ha of cultivated land. The geographical scope considers that the production occurs in France and that some manufacturing process are outsourced in China. A Sensitivity Analysis was carried out to assess the influence of the electricity mix in the various countries involved in the manufacturing cycle.A detailed life cycle inventory for flax fiber production and transformation was built and the environmental performance of a flax technical textile was assessed as a cradle-to-gate LCA. The fate of co-products was documented and was shown to contribute to the reduction of the generated environmental impacts.Through a cradle-to-gate LCA, a broader understanding of the environmental performance of a flax-based technical textile was presented by including the valorization of co-products and a wider set of analyzed impact categories, going therefore beyond the existing state-of-the-art. Results show agricultural activities and electricity production to be the biggest contributors to the environmental impacts of flax technical textile; contributions due to land use changes were minor in comparison. Very specifically for this case study, a sensibility analysis showed the influence of an all-French production to be more efficient from an environmental point of view.

Life Cycle Assessment of the Mesophilic, Thermophilic, and Temperature-Phased Anaerobic Digestion of Sewage Sludge

In this study the environmental impact of the anaerobic digestion (AD) of sewage sludge within an activated sludge wastewater treatment plant (WWTP) was investigated. Three alternative AD systems (mesophilic, thermophilic, and temperature-phased anaerobic digestion (TPAD)) were compared to determine which system may have the best environmental performance. Two life cycle assessments (LCA) were performed considering: (i) the whole WWTP (for a functional unit (FU) of 1 m3 of treated wastewater), and (ii) the sludge line (SL) alone (for FU of 1 m3 of produced methane). The data for the LCA were obtained from previous laboratory experimental work in combination with full-scale WWTP and literature. According to the results, the WWTP with TPAD outperforms those with mesophilic and thermophilic AD in most analyzed impact categories (i.e., Human toxicity, Ionizing radiation, Metal and Fossil depletion, Agricultural land occupation, Terrestrial acidification, Freshwater eutrophication, and Ozone depletion), except for Climate change where the WWTP with mesophilic AD performed better than with TPAD by 7%. In the case of the SL alone, the production of heat and electricity (here accounted for as avoided environmental impacts) led to credits in most of the analyzed impact categories except for Human toxicity where credits did not balance out the impacts caused by the wastewater treatment system. The best AD alternative was thermophilic concerning all environmental impact categories, besides Climate change and Human toxicity. Differences between both LCA results may be attributed to the FU.

Energy Recovery from Olive Pomace by Hydrothermal Carbonization on Hypothetical Industrial Scale: a LCA Perspective

This work aimed to analyze and compare the environmental impacts of hydrothermal carbonization (HTC) process performed on olive pomace, aimed at energy recovery. Twelve alternative pathways, considering variable process conditions in terms of temperature (260, 280 and 305 °C), heat recovery layouts and the subsequent combustion of the generated solid product, were analyzed. Results, related only to the processing phases (i.e. without including avoided effects), showed, as expected, that the final environmental performance depends on the HTC process temperature. Moreover, it was noted that the resulting impacts are from 1.4 to 2.0 lower for the layouts with heat recovery, for all the analyzed impact categories, with exception of Freshwater Toxicity. It was also reported that by substituting the fuel in marginal processes of heat production, environmental load reduction potential, regarding all impact categories, can be achieved. The highest benefits were achieved by substituting coal with HTC pellet in the heat production, followed by wood pellets and natural gas. Concerning the contribution analysis, the combustion processes of HTC and wood pellet represent the major contributions to the Climate Change and Acidification impacts, the combustion processes of HTC and wood pellet represent the major contributions, around the 95% and the 75% of the total, respectively, for the cases with the highest HTC temperature and no recovery scheme. For the Eutrophication potential, biomass production contributes significantly to the final effect. Regarding the Freshwater Ecotoxicity, the major part of the impact is coming from the HTC process and the relative liquid phase emissions assumed to be composed by phenols and furfurals released from the process. However, this part of the system needs to be further analyzed in detail.

Emissions down the drain: Balancing life cycle energy and greenhouse gas savings with resource use for heat recovery from kitchen drains

Although the food service sector is a major user of water, the potential for heat recovery from commercial kitchens’ drain water remains largely unexplored. For the first time, we compare the life cycle environmental burdens of producing and installing a heat recovery system with the environmental credits arising from energy savings for a restaurant case study, and for the entire UK food service sector. Life Cycle Assessment was applied to determine the impacts of heat recovery systems made from different materials and comprising a heat exchanger in the shape of a concentric double-walled pipe, pipework and fittings. The design option with the smallest environmental footprint combined a heat exchanger made out of polypropylene-graphite (PP-GR) with polyethylene pipework, exhibiting 80–99% less environmental impact compared with components made out of (35% recycled) copper. Contrasting the environmental impacts of two heat recovery set-ups with energy savings shows that a PP-GR based system pays back all burdens of the seven assessed environmental impact categories, within two years, while payback times for the copper-based system vary depending on the replaced energy source, and can exceed the 10 year operational lifetime of the system. When looking at typical flow-rates in UK food outlets, net environmental savings can be realised across all analysed impact categories above a threshold water consumption of 555 L/day, using current technology. Extrapolation to the UK food service sector indicates annual greenhouse gas emission mitigation potential of about 500 Gg CO2 equivalent.

Life cycle assessment of wood chips supply chain in Serbia

Two most common systems of forest biomass supply chains in Serbia are evaluated by using the Life Cycle Assessment (LCA) approach: ‘cut-to-length’ system with penduculate oak (CLO) on flat terrains with a tractor equipage, and ‘tree-length’ system with moesian beech (TLB) on more steep terrains, with a skidder. The main focus is put on the fuel consumption and its environmental impact on various stages of wood chips supply chain. Results indicate chipping as a most environmentally burdensome due to the low process productivity and high diesel combustion in outdated machines. CLO system exhibits lower environmental burden due to the 2%–35% lower impact in six out of eleven analysed impact categories compared to the TLB. The main reason is the skidding performed on a more steep terrain with a more powerful machine consuming more diesel than the tractor equipage. The higher impact of the felling operation in CLO system is caused by additional time for processing short oak assortments. The evaluated environmental impacts are consequence of the machinery old age used in Serbian forests. The application of a modern, energy efficient, combined machines such as harvesters and forwarders is recommended though it could have a lot of drawbacks.