Global warming potential

As a result of the Kyoto Protocol, the use of R134a in air conditioning system of new cars is going to be forbidden in the EU due to the high Global Warming Potential (GWP) of this substance. Carbon dioxide (CO2) is one of the possible alternatives as a cooling agent in mobile air conditioning applications and is desirable since it is a natural refrigerant. Cooling cycles using CO2 are currently achieving COP simi-lar to those of R134a cycles but there are promising options to further improve COP. One possibility is the application of an ejector instead of the valve. A Modelica library was developed that allows compu-tation of ejector cooling cycles in steady state with simplified component models that can be used as a design tool for the construction of an ejector proto-type. The library uses a new object-oriented library that serves as an interface to external medium librar-ies to compute thermodynamic and transport proper-ties for the refrigerant.

Within the ENDURE activity RA3, a goal of sub-activity RA3.4 is to calculate the environmental impacts of apple and wheat production strategies by life cycle assessment with a focus on pesticide applications. The analysis of production systems includes the actual production from cultivation, specifically from the preparation of orchards up to harvesting and finally the uprooting of the orchards, as

Background, aims and scope The environmental aspects of companies and their products are becoming more significant in delivering competitive advantage. Formway Furniture, a designer and manufacturer of office furniture products, is a New Zealand-based company that is committed to sustainable development. It manufactures two models of the light, intuitive, flexible and environmental (LIFE) office chair: one with an aluminium base and one with a glass-filled nylon (GFN) base. It was decided to undertake a life cycle assessment (LCA) study of these two models in order to: (1) determine environmental hotspots in the life cycle of the two chairs (goal 1); (2) compare the life cycle impacts of the two chairs (goal 2); and (3) compare alternative potential waste-management scenarios (goal 3). The study also included sensitivity analysis with respect to recycled content of aluminium in the product. Materials and methods The LIFE chair models consist of a mix of metal and plastic components manufactured by selected Formway suppliers according to design criteria. Hence, the research methodology included determining the specific material composition of the two chair models and acquisition of manufacturing data from individual suppliers. These data were compiled and used in conjunction with pre-existing data, specifically from the ecoinvent database purchased in conjunction with the SimaPro7 LCA software, to develop the life cycle inventory of the two chair models. The life cycle stages included in the study extended from raw-material extraction through to waste management. Impact assessment was carried out using CML 2 baseline 2000, the methodology developed by Leiden University’s Institute for Environmental Sciences. Results This paper presents results for global warming potential (GWP100). The study showed a significant impact contribution from the raw-material extraction/refinement stage for both chair models; aluminium extraction and refining made the greatest contribution to GWP100. The comparison of the two LIFE chair models showed that the model with the aluminium base had a higher GWP100 impact than the model with the GFN base. The waste-management scenario compared the GWP100 result when (1) both chair models were sent to landfill and (2) steel and aluminium components were recycled with the remainder of the chair sent to landfill. The results showed that the recycling scenario contributed to a reduced GWP100 result. Since production and processing of aluminium was found to be significant, a sensitivity analysis was carried out to determine the impact of using aluminium with different recycled contents (0%, 34% and 100%) in both waste-management scenarios; this showed that increased use of recycled aluminium was beneficial. The recycling at end-of-life scenarios was modelled using two different end-of-life allocation approaches, i.e. consequential and attributional, in order to illustrate the variation in results caused by choice of allocation approach. The results using the consequential approach showed that recycling at end-of-life was beneficial, while use of the attributional method led to a similar GWP100 as that seen for the landfill scenario. Discussion The results show that the main hotspot in the life cycle is the raw-material extraction/refinement stage. This can be attributed to the extraction and processing of aluminium, a material that is energy intensive. The LIFE chair model with the aluminium base has a higher GWP100 as it contains more aluminium. Sensitivity analysis pertaining to the recycled content of aluminium showed that use of aluminium with high recycled content was beneficial; this is because production of recycled aluminium is less energy intensive than production of primary aluminium. The waste-management scenario showed that recycling at end-of-life resulted in a significantly lower GWP100 than landfilling at end-of-life. However, this result is dependent upon the modelling approach used for recycling. Conclusions With respect to goal 1, the study found that the raw-material extraction/refinement stage of the life cycle was a significant factor for both LIFE chair models. This was largely due to the use of aluminium in the product. For goal 2, it was found that the LIFE chair model with the aluminium base had a higher GWP100 than the GFN model, again due to the material content of the two models. Results for goal 3 illustrated that recycling at end-of-life is beneficial when using a system expansion (consequential) approach to model recycling; if an attributional ‘cut-off’ approach is used to model recycling at end-of-life, there is virtually no difference in the results between landfilling and recycling. Sensitivity analysis pertaining to the recycled content of aluminium showed that use of higher recycled contents leads to a lower GWP100 impact. Recommendation and perspectives Most of the GWP100 impact was contributed during the raw-material extraction/refinement stage of the life cycle; thus, the overall impact of both LIFE chair models may be reduced through engaging in material choice and supply chain environmental management with respect to environmental requirements. The study identified aluminium components as a major contributor to GWP100 for both LIFE chair models and also highlighted the sensitivity of the results to its recycled content. Thus, it is recommended that the use of aluminium in future product designs be limited unless it is possible to use aluminium with a high recycled content. With respect to waste management, it was found that a substantial reduction in the GWP100 impact would occur if the chairs are recycled rather than landfilled, assuming an expanding market for aluminium. Thus, recycling the two LIFE chair models at end-of-life is highly recommended.

Background, aim, and scope The aim of this study has been to estimate the carbon footprint of bread produced and consumed in the UK. Sliced white and wholemeal bread has been considered for these purposes and the functional unit is defined as “one loaf of sliced bread (800 g) consumed at home”. The influence on the carbon footprint of several parameters has been analysed, including country of origin of wheat (UK, Canada, France, Germany, Spain and USA), type of flour (white, brown and wholemeal) and type of packaging (plastic and paper bags). The effect on the results of the type of data (primary and secondary) has also been considered. Materials and methods The carbon footprint has been estimated in accordance with the PAS 2050 methodology. The results have also been calculated following the ISO 14044 methodology to identify any differences in the two approaches and the results. Primary data for the PAS 2050-compliant study have been collected from a UK bread supply chain. Secondary data have been sourced from the UK statistics, life cycle inventory databases and other published sources. Results and discussion The carbon footprint results range from 977 to 1,244 g CO2 eq. per loaf of bread. Wholemeal thick-sliced bread packaged in plastic bags has the lowest carbon footprint and white medium-sliced bread in paper bag the highest. The main hot spots are wheat cultivation and consumption of bread (refrigerated storage and toasting), contributing 35% and 25% to the total, respectively. Conclusions The carbon footprint could be reduced on average by 25% by avoiding toasting and refrigerated storage of bread. Further reductions (5–10%) could be achieved by reducing the amount of waste bread discarded by consumers. The contribution of transport and packaging to the overall results is small. Similar trends in the results are also found in the study based on the secondary data and following the ISO 14044 methodology.

This paper explores an experimental investigation of an alternative eco-friendly refrigerant for R134a with a
better Coefficient Of Performance (COP), reduced Global Warming Potential (GWP) and Ozone Depletion
Potential(ODP). This investigation has been accessed using a hydrocarbon refrigerant mixture composing of
R32/R600a/R290 in the ratio of 70:5:25 by weight. The performance characteristics of the domestic
refrigerator were predicted using continuous running tests under different ambient temperatures and cyclic
running (On/Off) tests at the fixed temperatures i.e., evaporation temperature (-5˚C) and condensation
temperature (30˚C). The obtained results showed that the hydrocarbon mixture has lower values of energy
consumption; pull down time and ON time ratio also higher Coefficient of Performance (COP). Thus, the
performance of the alternate refrigerant derives the better choice than R134a.
Keywords: Domestic refrigerator, Alternative refrigerant, R32, R600a, R290, R134a

Life cycle assessment (LCA) is the best tool available to evaluate the environmental
impact of alkali-activated cements and concretes (AACC). However, recently
published LCAs provide conflicting results. We propose a new way to compare
AACC with conventional concrete able to emphasize the intrinsic quality of the
binder. This method is based on the Feret equation, which requires the concrete
strength and a constant volume of paste (cement + water). Results show that not all
alkali-activated cement mixes have a lower global warming potential (GWP) than
current alternatives provided by blended cements. When environmental impacts other
than GWP are considered, the environmental benefit of alkali-activated cement is
drastically reduced. The three future trends of AACC are hybrid cement, one partgeopolymer
and bricks.

We investigated how amending maize with wastewater at 120 kg N ha−1 affected crop growth, soil characteristics and emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) compared to plants fertilized with urea. Maize growth response was similar when fertilized with urea or wastewater despite a delayed release of nutrients upon mineralization of the organic material in the wastewater. Applying wastewater to soil significantly increased the mean CO2 emission rate 2.4 times to 1.74 µg C kg−1 soil h−1 compared to the unamended soil (0.74 µg C kg−1 soil h−1), and cultivating maize further increased it 3.2 times (5.61 µg C kg−1 soil h−1). Irrigating soil with wastewater, cultivating it with maize or applying urea had no significant effect on the emission of N2O compared to the unamended soil (1.49 × 10−3 µg N kg−1 soil h−1). Adding urea to soil did no affect the CH4 oxidation rate (0.1 × 10−3 µg C kg−1 soil h−1), nor did cultivating maize in the urea-amended soil, but adding wastewater to soil resulted in a significant production of CH4 (128.4 × 10−3 µg C kg−1 soil h−1). Irrigating soil with wastewater increased the global warming potential (GWP) 2.5 fold compared to the urea amended soil, while in soil cultivated with maize GWP increased 1.4 times. It was found that irrigating crops with wastewater might limit the use of N fertilizer and water from aquifers, but the amount applied should be limited because nitrate (NO 3 − ) leaching and emissions of CO2, N2O and CH4 will be substantial and the increased soil salt content will limit crop growth.