Reduction In Global Warming Potential Research Articles

Greenhouse gas emission from direct seeded paddy fields under different soil water potentials in Eastern India

In the anticipated water scarcity and global warming scenario; it is imperative to identify suitable irrigation scheduling strategy in paddy fields for increasing water productivity and mitigating greenhouse gas (GHG) emissions. We conducted a two year (dry season of 2014 and 2015) field experiment for irrigation scheduling based on tensiometric measurement of soil water potential (SWP) in order to quantify temporal and seasonal variations in GHGs emissions and their trade off relationship at five levels of SWPs viz. SWP 1 (−20kPa), SWP 2 (−30kPa), SWP 3 (−40kPa), SWP 4 (−50kPa) and SWP 5 (−60kPa), in addition to the traditional practice of growing flooded rice (CF). Fluxes of methane (CH4) and nitrous oxide (N2O) during the growing period were measured using manual closed chamber-gas chromatograph and the carbon dioxide (CO2) flux was measured using an infrared CO2 analyzer. A significant decrease in seasonal cumulative CH4 emission (30–60.2%) was recorded at different SWPs as compared to CF. In contrast, emission of CO2 and N2O increased by 12.9–26.6% and 16.3–22.1% respectively at SWPs 1 and 2; conversely, a significant decrease in emissions of these gases were observed at higher SWPs (SWPs 3–5). Among different SWP treatments, irrigation scheduling at SWP 2 maintained yield at par with CF with water saving of 32.9–41.1% and reduced CH4 emission (43–44.1%). However, due to increase in CO2 and N2O emission at SWP 2, there was no significant reduction in global warming potential (GWP) as compared with CF. Among different rice growth stages GHGs emission were predominant during vegetative growth stage. Regression relationship of GHGs emission with key soil parameters was employed to predict seasonal emissions of GHGs from paddy field. The results of this study suggest that scheduling irrigation at SWP 2 can be an effective strategy in order to save water, maintain rice yield and mitigate CH4 emission from direct seeded paddy fields in eastern India, however further research is needed to identify suitable management strategy for reducing CO2 and N2O emissions at SWP 2 in order to reduce the GWP.

Sustainability analysis of the electric vehicle use in Europe for CO2 emissions reduction

Electric vehicles are considered the most promising alternative to internal combustion engine vehicles towards a cleaner transportation sector. Having null tailpipe emissions, electric vehicles contribute to fight localized pollution, which is particularly important in overpopulated urban areas. However, the electric vehicle implies greenhouse gas emissions related to its production and to the electricity generation needed to charge its batteries. This study focuses the analysis on how the electric vehicle emissions vary when compared to internal combustion engine vehicles, depending on the electric power plant fleet and the efficiency during the use-phase. For this to be done, the Global Warming Potential (GWP) associated to the electricity generation on the electric vehicle most selling European countries are calculated. Similarly, electric vehicle's use-phase energy efficiency is calculated under a wide range of driving conditions using the Monte Carlo method. The results from energy production and energy use-phases are compared to the GWP calculated for internal combustion engine vehicles for six different driving cycles, to obtain the threshold values for which electric vehicles provide GWP reduction. These threshold values are then matched with the current electricity power plant fleet and the electric vehicle promotion incentives of the European countries considered in the study, showing that some countries (e.g. France or Norway) are better-suited for electric vehicles adoption, while countries like Spain or Portugal should boost electric vehicle promotion policies. Furthermore, other countries in Europe, such as Germany or the UK that are doing an effort on decarbonizing their power plant fleet, do not offer immediate greenhouse gas emission reductions for the uptake of electric vehicles instead of conventional cars.

Technological, environmental and social aspects of a recycling process of post-consumer absorbent hygiene products

The waste generated by absorbent hygiene products utilization represents a not negligible fraction of municipal solid waste. In the last decades, different solutions have been proposed worldwide but their sustainability has not been assessed. This paper investigates on a demonstrative scale the technical feasibility, environmental compatibility and social aspects of a recycling process of these wastes. An autoclave, coupled with a sorting machine, sterilizes the waste and separates its cellulosic and plastic fractions. The process recovers the plastics, and utilizes the cellulose in a bubbling fluidized bed gasifier, to produce the steam necessary for the sterilization. The experimental tests assessed the technological feasibility of the process, and identified the operating conditions for an efficient recycling of absorbent hygiene products waste without any external energy support. The results also provide a reliable inventory of environmental burdens for a life cycle assessment of the recycling scheme and the two conventional management options of energy recovery in a municipal solid waste incinerator, and disposal in a sanitary landfill. The recycling scheme provides a strong reduction of global warming potential (−67 kgCO2equiv. vs 215 kgCO2equiv. and 130 kgCO2equiv. for incineration and landfilling, respectively), and non-renewable energy consumption (−4240 MJprimary vs −2180 MJprimary and −245 MJprimary for incineration and landfilling, respectively). Finally, the study investigated the social implications of the three alternative management options, mainly in terms of risk perception, economic advantages for the customers, and the necessary care for citizens' privacy.

High-quality collection and disposal of WEEE: Environmental impacts and resultant issues

Life cycle assessment of the collection, transport and recycling of various types of waste electrical and electronic equipment (WEEE) in Norway shows that small amounts of critical materials (refrigerants, precious/trace metals) are vital for the overall environmental accounts of the value chains. High-quality recycling ensures that materials and energy are effectively recovered from WEEE. This recovery means that responsible waste handling confers net environmental benefits in terms of global warming potential (GWP), for all types of WEEE analysed. For refrigeration equipment, the potential reduction of GWP by high-quality recycling is so large as to be of national significance. For all waste types, the magnitude of the net benefit from recovering materials and energy exceeds the negative consequences of irresponsible disposal. One outcome of this may be widespread misunderstanding of the need for recycling. Furthermore, framing public communication on recycling in terms of avoiding negative consequences, as is essentially universal, may not convey an appropriate message. The issue is particularly important where the consumer regards products as relatively disposable and environmentally benign, and/or where the “null option” of retaining the product at end-of-life is especially prevalent. The paper highlights the implications of all these issues for policy-makers, waste collectors and recyclers, and consumers.

Sustainability Assessment of Road Marking Systems

Environmental issues are becoming increasingly important in the domestic, business and public sectors. Due to population growth and growing number of megacities, Green Public Procurements concepts is also becoming an increasing trend in the road infrastructure sector.This study assessed the environmental impacts of road markings considering the whole life cycle from manufacturing to disposal. For the correctness of the study, an external expert panel reviewed the assessment. By using the LCA-Methodology based on DIN ISO 14040 and 14044, an objective comparison of the following line markings was performed: Solvent-borne paint; Water-based paint; Thermoplastic and Thermo Spray Plastic; Cold Plastic and Cold Spray Plastic. Typical material formulations in characteristic application scenarios have been modelled using the data of corresponding official approval test certificates held by a major local manufacturer of all evaluated technologies. Empirical data was used to determine a typical service life of the various road marking systems at a typical average daily traffic of 10,000–15,000 vehicles per day.The life cycle assessment results, i.e. considering the whole life cycle from manufacturing to disposal, showed that a global warming potential reduction of more than 50% can be achieved by a more durable road marking system.The study concluded that in order to access the actual environmental impact of road markings, a lifetime evaluation including, for instance, production, application, transport, service life, and disposal must be taken into consideration.

Quantifying changes to the global warming potential of rice wheat systems with the adoption of conservation agriculture in northwestern India

Field trials were conducted in Haryana representing the northwestern Indo-Gangetic Plains (IGP) to assess the changes brought about by management, including conservation agriculture (CA) practices, in the global warming potential (GWP) of conventional rice–wheat systems. Conservation agriculture is an approach to managing agro-ecosystems for improved and sustained productivity, by way of minimal soil disturbance, permanent soil cover with organic matter or cover crops and crop rotation. Methane (CH4) and nitrous oxide (N2O) fluxes were measured using static chambers. Experiments involved four cropping system scenarios with different CA components, and different N rates. In addition, emissions of CH4 and N2O fluxes were measured in farmers’ fields to establish baselines. The dynamics of CH4 emissions were controlled by floodwater levels, and fertilizer N had no effect. On the other hand, N application rates and timing in relation to soil water status determined the N2O emissions in rice fields. Nitrous oxide fluxes could be avoided by applying N fertilizer to wet soil or by irrigating the field not later than 1 day after N application. Applying crop residues on soil surface had no significant effect on the seasonal CH4 and N2O emissions. It was estimated that switching rice crop establishment method from conventional to CA-based practices in Haryana could reduce GWP for rice by 23% or by 1.26 Tg CO2 eqyr−1. An intensive CA-based rice–wheat and maize–wheat system reduced GWP by 16–26% or by 1.3–2.0 Tg CO2 eqyr−1 compared with the conventional rice–wheat system. However, this reduction in GWP would be from a decrease in diesel and electricity consumption and not from direct emissions of CH4 and N2O, which were higher in the maize–wheat system than in the rice–wheat system.

Greenhouse gas emissions from concrete can be reduced by using mix proportions, geometric aspects, and age as design factors

With increased awareness of the emissions of greenhouse gases (GHGs) and the significant contribution from the cement industry, research efforts are being advanced to reduce the impacts associated with concrete production and consumption. A variety of methods have been proposed, one of the most common being the replacement of cement as a binder in concrete with supplementary cementitious materials, such as fly ash (FA), which can have lower environmental effects. The use of FA can change the kinetics of the hydration reactions and, consequently, modify the evolution of the concrete strength over time. Yet the influence of designing structural elements to obtain the required strength at later ages has not been examined in terms of their influence on global warming potential (GWP) of concrete. This research investigates the influence of design age, in addition to mix proportions and geometric aspects, on the GWP associated with making beams, columns, and a concrete building frame. Findings suggest that while the GWP for beams is not highly dependent on concrete mixture strength, the GWP for columns is dependent on strength, thus the influence of required strength at later ages influences GWP of making columns more so than beams. For the concrete frame analyzed, a potential 45% reduction in GWP, depending on mix proportions and design age, was found. Using the findings from this research, the GWP associated with production of concrete in California could be reduced by approximately 1.8 million metric tons of CO2-eq emissions, equivalent to approximately 2% of all industrial GHG emissions in California.

Comparative life cycle assessment of deinking sludge utilization alternatives

The aim of this research was to quantify and compare the environmental impact of a number of different deinking sludge utilization approaches. A comparative life cycle assessment of deinking sludge material and energy recovery was performed for the baseline scenario—landfill disposal, and four alternative scenarios: two cement plants, a lightweight aggregate plant, and a stone wool plant. Sludge pretreatment and transportation processes were included in the scenario analyses. The results of the life cycle assessment showed that the use of dry deinking sludge in a cement plant in Finland, 45 km from the point of supply of the deinking sludge, to substitute 46% of the petcoke and 2.7% of the limestone showed the best performance. Therein, a global warming potential reduction of 13% and an eutrophication potential reduction of 12% – the highest reduction out of all impact categories studied – were achieved. A similar reduction in global warming potential of 12% was achieved when deinking sludge was incinerated and the ash utilized in cement production in a Russian plant located 350 km from the paper mill. However, abiotic depletion potential and acidification potential slightly increased by 2.6 and 1.5%, respectively. A maximum reduction of 2.1% out of al impact categories was achieved when dry sludge was used in a lightweight aggregate plant. That is considerably less compared to the reduction achieved at the cement plants. The use of deinking sludge ash in a stone wool plant to substitute 25% of cement resulted in a maximum reduction of 25% in the ozone layer depletion potential. Thus, the utilization of deinking sludge in construction materials production while preventing its landfilling has beneficial effects on the environment, in particular decreased greenhouse gas emissions.

Identification of an environmentally friendly symbiotic process for the reuse of industrial byproduct – an LCA perspective

There are various technologies that have been developed to reduce nitrogen oxide (NOx) gas emissions from nitric acid plants. The current study, however, focused on chemical absorption with the following key objectives. First, the paper assessed several reaction pathways that entail the use of combination of common industrial absorbents and oxidants for the absorption of NOx. Second, an analysis on the production of potassium nitrate (KNO3) fertilizer using the byproducts formed from chemical absorption was studied. In addition, a life cycle assessment (LCA) on the environmental implications of NOx absorption and byproducts utilisation for the production of fertiliser through industrial symbiosis was evaluated. This was performed to find the combination of absorbent and oxidant with the least environmental impacts for industrial symbiotic formation. The goal of the LCA was set as the production of 1 kg of potassium nitrate fertiliser.The analysis has shown that use of hydrogen peroxide in combination with calcium hydroxide had the least environmental impacts per kg KNO3 produced. These were a global warming potential (GWP) of 9 kg CO2 equivalent emissions (CO2-e), acidification potential (AP) of −0.073 kg sulphur dioxide equivalent (kg SO2-e), eutrophication potential (EP) of −0.058 kg phosphate equivalent (kg PO4−-e), 0.1 kg of solid waste generated, and 15.7 L of water used. The most striking finding was that this combination reduced the overall GWP, AP and EP per kg KNO3 produced by 7.8 kg of CO2-e, 0.12 kg SO2-e and 0.08 kg PO4−-e respectively in comparison to the production of conventional KNO3 fertilizer. The hotspots for all reaction pathways were water and energy use. Water use could not be reduced due to effects on reaction efficiencies for all pathways. However, a solution to reduce the carbon footprint from energy use is the substitution of energy generated from fossils with wind energy. This was evaluated to have the potential of reducing GHG emissions of ozone use by up to 93%, leading to overall GWP reduction of about 86% and 80% for calcium hydroxide and sodium hydroxide use with ozone respectively.

Implementing ternary supplementary cementing binder for reduction of the heat of hydration of concrete

The purpose of the present study was to examine the high-volume use of by-products as supplementary cementitious materials (SCMs) in order to control the hydration heat of concrete and enhance its sustainability. The prepared ternary binders were composed of varying combinations of fly ash, ground granulated blast-furnace slag, and ordinary Portland cement (OPC). Isothermal hydration tests were conducted on the pastes produced using the prepared ternary binders and OPC under constant temperatures (T) of 13, 23, and 33 °C. Adiabatic hydration tests were also conducted on the concrete mixes at T of 23 °C. The heat production rate curve clearly showed that the induction and acceleratory periods increased with increasing SCM amount, whereas the maximum value of the curve and the decelerator period decreased; as a result, the activation energy of the cementitious pastes tended to increase with increasing SCM amount. The maximum values of total heat production determined from the adiabatic hydration tests also increased with increasing water–to–binder ratio. The relationship between the degree of reaction and the compressive strength development of the concrete was very similar in both the isothermal and the adiabatic hydration tests. The environmental impact assessment demonstrated that the very-high-volume SCM concrete had a reduction in global warming potential of 75–86% and in abiotic depletion of 73–82% as compared with OPC concrete.

Environomic optimal design of power plants with CO2 capture

Life cycle impact assessment indicators are integrated for studying the process integration of renewable resources and CO2 capture and storage (CCS) in power plants. Besides the expected reduction in global warming potential (GWP), CCS induces energy and cost penalties. This paper presents a systematic multi-objective optimisation framework for the optimal design of power plants with CO2 capture considering environomic criteria to systematically assess the trade-off between environmental impacts, efficiency and costs. Life cycle assessment is combined with flowsheeting, energy integration, economic evaluation and multi-objective optimisation techniques. Post- and pre-combustion CO2 capture options for electricity generation processes, using fossil and renewable resources, are assessed. Multi-objective optimisations are performed for various objectives to reveal the influence on the decision making. The calculated CO2 emissions, allow to assess the impact of the CO2 tax, considering not only the on-site emissions but taking into account the overall life cycle of the fuel supply, electricity generation and CO2 capture. The results show that the environomic optimal process design and competitiveness of CO2 capture highly depends on the considered environmental impact and on the introduction of a carbon tax.

Environmental advantage by choice: Ex-ante LCA for a new Kraft pulp fibre reinforced polypropylene composite in comparison to reference materials

This study analyses the circumstances of environmental advantage by benchmarking a novel Kraft pulp fibre reinforced polypropylene against its matrix material and two other composites with talcum and glass fibres. With one exception, all composites use less non-renewable energy (−1% to −29%), but only the Kraft pulp fibre reinforced polypropylene achieves a reduction in global warming potential (14% to 35%) considering different functional units compared to polypropylene. The comparisons on basis of function–strength and stiffness in this case study–show that the adequate application of specific material properties, are key to achieve environmental advantages.

Practical Asymmetric Synthesis of an Edivoxetine·HCl Intermediate via an Efficient Diazotization Process

A convergent synthesis of (S)-(4-benzylmorpholin-2-yl)(morpholino)methanone methanesulfonate (1), a key regulatory starting material for edivoxetine·HCl, was developed at Eli Lilly & Company. This novel synthesis utilizes d-serine as the source of chirality, which is preserved throughout the synthesis. Key features include the development of a scalable diazotization process to produce (S)-epoxy acid 7, which was optimized to improve the process safety profile. The final (S)-morpholino acid intermediate 11 was converted to the title compound using T3P with >99.9% purity in 75% yield. Life cycle analysis of the new route revealed a 69% reduction in global warming potential (GWP) for solvent usage relative to the prior route of manufacture.

Performance optimization of an air source heat pump water heater using mathematical modelling

In South Africa, there is an ongoing constraint on the electricity supply at the national grid to meet the demand. Eskom is implementing various measures such as the Integrated Demand Management and the promotion and encouragement of the use of energy efficient devices like an Air Source Heat pump (ASHP) water heater to replace the high electrical energy consuming conventional geysers for sanitary hot water production. The ASHP water heater market is fast gaining maturity. A critical mathematical model can lead to performance optimization of the systems that will further result in the conservation of energy and significant reduction in global warming potential. The ASHP water heater comprises of an ASHP unit and a hot water storage tank. In this study, a data acquisition system (DAS) was designed and built which monitored the energy used by the geyser and the whole building, the temperature at the evaporator, condenser, tank outlet hot water, tank inlet cold water, the ambient temperature and relative humidity in the vicinity of the ASHP evaporator. It is also worthy to mention that the DAS also included to a flow meter and two additional temperature sensors that measured the volume of water heated and inlet and outlet water temperature of the ASHP. This work focused on using the mathematical equation for the Coefficient of Performance (COP) of an ideal Carnot’s heat pump (CHP) water heater to develop basic computation in M-file of MATLAB software in order to model the system based on two reservoir temperatures: evaporator temperatures (Tevp) of 0°C to 40°C (approximated to ambient temperature, Ta) and condenser temperatures (TCon) set at 50°C, 55°C and 60°C (approximated to the hot water set temperature of 50°C, 55°C and 60°C) respectively. Finally, an analytical comparison of a CHP water heater to the practical ASHP water heater was conducted on a hot water set point temperature of 55°C. From the modelling results, it can be deduced that at 0°C Tevp, the COP was 5.96 and 2.63 for CHP and ASHP water heater respectively, at a hot water set temperature of 55°C. Above 20°C Tevp, the rate of change of COP increased exponentially for the ideal CHP system, but was constant at 0.01/°C for the practically modelled ASHP water heater.

Consequential life cycle assessment of biogas, biofuel and biomass energy options within an arable crop rotation

AbstractFeed in tariffs (FiTs) and renewable heat incentives (RHIs) are driving a rapid expansion in anaerobic digestion (AD) coupled with combined heat and power (CHP) plants in the UK. Farm models were combined with consequential life cycle assessment (CLCA) to assess the net environmental balance of representative biogas, biofuel and biomass scenarios on a large arable farm, capturing crop rotation and digestate nutrient cycling effects. All bioenergy options led to avoided fossil resource depletion. Global warming potential (GWP) balances ranged from −1732 kg CO2e Mg−1 dry matter (DM) for pig slurry AD feedstock after accounting for avoided slurry storage to +2251 kg CO2e Mg−1 DM for oilseed rape biodiesel feedstock after attributing indirect land use change (iLUC) to displaced food production. Maize monoculture for AD led to net GWP increases via iLUC, but optimized integration of maize into an arable rotation resulted in negligible food crop displacement and iLUC. However, even under best‐case assumptions such as full use of heat output from AD‐CHP, crop–biogas achieved low GWP reductions per hectare compared with Miscanthus heating pellets under default estimates of iLUC. Ecosystem services (ES) assessment highlighted soil and water quality risks for maize cultivation. All bioenergy crop options led to net increases in eutrophication after displaced food production was accounted for. The environmental balance of AD is sensitive to design and management factors such as digestate storage and application techniques, which are not well regulated in the UK. Currently, FiT payments are not dependent on compliance with sustainability criteria. We conclude that CLCA and ES effects should be integrated into sustainability criteria for FiTs and RHIs, to direct public money towards resource‐efficient renewable energy options that achieve genuine climate protection without degrading soil, air or water quality.

Identifying strategies for mitigating the global warming impact of the EU-25 economy using a multi-objective input–output approach

Global warming mitigation has recently become a priority worldwide. A large body of literature dealing with energy related problems has focused on reducing greenhouse gases emissions at an engineering scale. In contrast, the minimization of climate change at a wider macroeconomic level has so far received much less attention. We investigate here how to mitigate global warming by performing changes in an economy. To this end, we make use of a systematic tool that combines three methods: linear programming, environmentally extended input output models, and life cycle assessment principles. The problem of identifying key economic sectors that contribute significantly to global warming is posed in mathematical terms as a bi-criteria linear program that seeks to optimize simultaneously the total economic output and the total life cycle CO2 emissions. We have applied this approach to the European Union economy, finding that significant reductions in global warming potential can be attained by regulating specific economic sectors. Our tool is intended to aid policy makers in the design of more effective public policies for achieving the environmental and economic targets sought.

Environmental impact assessment of regional switchgrass feedstock production comparing nitrogen input scenarios and legume-intercropping systems

Abstract As the use of second-generation biofuel crops increases, so do questions about sustainability, particularly their potential to affect fossil energy consumption and greenhouse gas emissions. This study used a life-cycle approach to compare environmental impacts associated with three switchgrass (Panicum virgatum L.) production scenarios: i) regional production from a pool of Tennessee farmers based on in-field inputs and biomass yield; ii) varying nitrogen (N)-input levels from a replicated field study for 8-yrs i.e., a 100% and 9% decrease, and an 81% and 172% increase from 'baseline levels' of N inputs used under objective i; and, iii) a legume-intercrop system compared to baseline levels in order to determine effects of displacing synthetic-N with legumes. When compared across all agricultural inputs, nitrogen fertilizer production and breakdown resulted in the greatest environmental impacts. Although fertilization increased lignocellulosic yields, a 100% reduction in N-inputs from baseline levels reduced the formation of carbon, methane, and nitrous oxides per unit of production, (or dry tonne of biomass over 10-yrs) compared to a 172% increase. Switchgrass yield response indicated a 'less is more' scenario, as inputs beyond the current recommended input level (67 kg N ha−1) are not environmentally remunerating. During switchgrass biomass production, inputs with lesser impacts included phosphorus, herbicides, pesticides, and diesel fuel. Legume-intercropping reduced greenhouse gas emissions and groundwater acidification (5% and 27% reduction in global warming potential and formation of acidifying species, respectively) compared with the 67 kg N ha−1rate. Although N-fertilizers impact environmental sustainability of regional switchgrass feedstock production, environmental consequences can be reduced under proper N-management i.e., ≤67 kg N ha−1 or legume intercropping. However, given that the aim of second-generation feedstocks is to reduce the current reliance on fossil fuels, their production still requires fossil energy-based inputs. Consequently, greenhouse gas reductions and the extent of cleaner feedstock production during the agricultural biofuel supply chain is contingent upon input management and optimizing synthetic fertilizer usage.

Life cycle assessment of beef cow‐calf systems with and without grazing on abandoned cultivated lands in Japan

AbstractBeef production contributes to environmental problems, such as climate change, air pollution and water pollution. Our objective was to determine how much the introduction of beef cow grazing on abandoned lands into a housing system (housed in barns throughout the year) alters environmental impacts. We used life cycle assessment to evaluate the environmental impacts of beef cow‐calf systems with and without grazing on abandoned cultivated lands, on 11 Japanese farms. The functional unit was one marketed beef calf (Japanese Black) at 8 months of age. A reduction of global warming potential (GWP), acidification potential (AP) and eutrophication potential (EP) was found in all five grazing systems (including an experimental farm), compared with the average values for housing systems. A reduction of energy consumption was also found in the five grazing systems; however, the reduction was not large in one farm. Feed transportation and production were the main contributors to energy consumption, and unless there is a decrease in the energy consumption associated with these two processes, the energy consumption throughout the life cycle will not decrease. Thus, the introduction of grazing on abandoned lands can reduce environmental impacts, but the effects can be weakened or offset depending on the amount of imported feed. In the experimental farm with a grazing system, the reduction of GWP, AP, EP and energy consumption compared with the average values for the housing systems was 32, 48, 48 and 45%, respectively. In the four commercial farms with grazing systems, the reduction of GWP, AP, EP and energy consumption was 11–24, 13–22, 19–24 and 2–21%, respectively, which we regard as possible reductions in a real life situation. We conclude that a large reduction of environmental impacts could not be achieved solely through the introduction of grazing.

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

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

An attributional and consequential life cycle assessment of substituting concrete with bricks

Abstract Singapore introduced the Concrete Utilization Index to promote the substitution of concrete products with alternate building materials. This study examined the environmental impacts of replacing concrete with bricks. Using an attributional life cycle approach, it was found that replacing concrete with bricks may actually increase the net environmental impacts. In the first ever consequential life cycle assessment done for bricks in the literature, we found that replacing concrete with bricks may result in small reduction in global warming potential, provided there is no change to the amounts of bricks and concrete constituents being imported into Singapore. Considering there are changes to the import quantities, we derived a mathematical relation that enables us to know how much the import of concrete constituents must decrease in order to nullify the increased global warming potential resulted from the increase in import of bricks. In all these assessments, we found that the environmental impacts (including global warming potential) of the manufacturing stage of bricks need to be reduced. To achieve this, we reviewed a few new brick-making approaches that can produce more sustainable bricks; we also proposed a way of creating a “green demand” for these bricks and utilizing policies such as Singapore's Business Angel Scheme to finance the upgrading of brick-making technologies through international partnership.