Comparison of product carbon footprint standards with a case study on poinsettia (Euphorbia pulcherrima)

Purpose

A method to quantify the climate impact of products called product carbon footprint (PCF) has been gaining popularity in recent years. However, variations of this method have resulted in several competing standards to guide the carbon calculation process. The aim of the current paper was to compare PCF results when calculated according to the different standards.

Methods

The three leading PCF standards are Publicly Available Specification (PAS) 2050:2011, ISO.DIN 2 14067 and Product Life Cycle Accounting and Reporting Standard (PARS) 2011. These standards were compared conceptually, and a case study was performed in which the PCF of a poinsettia plant produced in Germany was calculated according to all three standards.

Results and discussion

The PCF results were 0.45–0.50, 0.53–0.58 and 0.53–0.59 kg carbon dioxide equivalent according to PAS 2050:2011, ISO.DIN 2 14067 and PARS 2011, respectively. According to all standards, the life cycle stage contributing the most greenhouse gases (GHGs) was the production of the poinsettia plant, and the single process with the highest emissions was the electricity use in the production. It was found that if nonrenewable fuels were used for heating instead of wood chips, then heating would be the highest GHG contributor—accounting for over 80 % of emissions of the total PCF.

Conclusions

A key finding was that both the production system used and the decisions taken by the person carrying out the PCF calculation result in greater differences in the PCF result than the use of different standards. Differences among the three standards could be harmonised by more specific cut-off rules and exclusion criteria with the publication of ISO.DIN 2 14067, as well as the development and use of product category rules.     

An appraisal of carbon footprint of milk from commercial grass-based dairy farms in Ireland according to a certified life cycle assessment methodology

Purpose

Life cycle assessment (LCA) studies of carbon footprint (CF) of milk from grass-based farms are usually limited to small numbers of farms (<30) and rarely certified to international standards, e.g. British Standards Institute publicly available specification 2050 (PAS 2050). The goals of this study were to quantify CF of milk from a large sample of grass-based farms using an accredited PAS 2050 method and to assess the relationships between farm characteristics and CF of milk.

Materials and methods

Data was collected annually using on-farm surveys, milk processor records and national livestock databases for 171 grass-based Irish dairy farms with information successfully obtained electronically from 124 farms and fed into a cradle to farm-gate LCA model. Greenhouse gas (GHG) emissions were estimated with the LCA model in CO₂ equivalents (CO₂-eq) and allocated economically between dairy farm products, except exported crops. Carbon footprint of milk was estimated by expressing GHG emissions attributed to milk per kilogram of fat and protein-corrected milk (FPCM). The Carbon Trust tested the LCA model for non-conformities with PAS 2050. PAS 2050 certification was achieved when non-conformities were fixed or where the effect of all unresolved non-conformities on CF of milk was?<?±5 %.

Results and discussion

The combined effect of LCA model non-conformities with PAS 2050 on CF of milk was <1 %. Consequently, PAS 2050 accreditation was granted. The mean certified CF of milk from grass-based farms was 1.11 kg of CO₂-eq/kg of FPCM, but varied from 0.87 to 1.72 kg of CO₂-eq/kg of FPCM. Although some farm attributes had stronger relationships with CF of milk than the others, no attribute accounted for the majority of variation between farms. However, CF of milk could be reasonably predicted using N efficiency, the length of the grazing season, milk yield/cow and annual replacement rate (R ²?=?0.75). Management changes can be applied simultaneously to improve each of these traits. Thus, grass-based farmers can potentially significantly reduce CF of milk.

Conclusions

The certification of an LCA model to PAS 2050 standards for grass-based dairy farms provides a verifiable approach to quantify CF of milk at a farm or national level. The application of the certified model highlighted a wide range between the CF of milk of commercial farms. However, differences between farms’ CF of milk were explained by variation in various aspects of farm performance. This implies that improving farm efficiency can mitigate CF of milk.     

Greenhouse gas emissions from forestry in East Norway

Purpose

So far no calculations have been made for greenhouse gas (GHG) emissions from forestry in East Norway. This region stands for 80 % of the Norwegian timber production. The aim of this study was to assess the annual GHG emissions of Norwegian forestry in the eastern parts of the country from seed production to final felling and transport of timber to sawmill and wood processing industry (cradle-to-gate inventory), based on specific Norwegian data.

Methods

The life cycle inventory was conducted with SimaPro applying primary and secondary data from Norwegian forestry. GHG emissions of fossil-related inputs from the technosphere were calculated for the functional unit of 1 m³ timber extracted and delivered to industry gate in East Norway in 2010. The analysis includes seed and seedling production, silvicultural operations, forest road construction and upgrading, thinning, final felling, timber forwarding and timber transport on road and rail from the forest to the industry. Norwegian time studies of forestry machines and operations were used to calculate efficiency, fuel consumption and transport distances. Due to the lack of specific Norwegian data in Ecoinvent, we designed and constructed unit processes based on primary and secondary data from forestry in East Norway.

Results and discussion

GHG emissions from forestry in East Norway amounted to 17.893 kg CO₂-equivalents per m³ of timber delivered to industry gate in 2010. Road transport of timber accounted for almost half of the total GHG emissions, final felling and forwarding for nearly one third of the GHG emissions. Due to longer road transport distances, pulpwood had higher impact on the climate change category than saw timber. The construction of forest roads had the highest impact on the natural land transformation category. The net CO₂ emissions of fossil CO₂ corresponded to 2.3 % of the CO₂ sequestered by 1 m³ of growing forest trees and were compared to a calculation of biogenic CO₂ release from the forest floor as a direct consequence of harvesting.

Conclusions

Shorter forwarding and road transport distances, increased logging truck size and higher proportion of railway transport may result in lower emissions per volume of transported timber. A life cycle assessment of forestry may also consider impacts on environmental categories other than climate change. Biogenic CO₂ emissions from the soil may be up to 10 times higher than the fossil-related emissions, at least in a short-term perspective, and are highly dependent on stand rotation length.     

Soil organic matter accounting in the carbon footprint analysis of the wine chain

Purpose

Concerns about global warming led to the calculation of the carbon footprint (CF) left by human activities. The agricultural sector is a significant source of greenhouse gas (GHG) emissions, though cropland soils can also act as sinks. So far, most LCA studies on agricultural products have not considered changes in soil organic matter (SOM). This paper aimed to: (1) integrate the Hénin–Dupuis SOM model into the CF study and (2) outline the impacts of different vineyard soil management scenarios on the overall CF.

Methods

A representative wine chain in the Maremma Rural District, Tuscany (Italy), made up of a cooperative winery and nine of its associated farms, was selected to investigate the production of a non-aged, high-quality red wine. The system boundary was established from vineyard planting to waste management after use. The functional unit (FU) chosen for this study was a 0.75-L bottle of wine, and all data refer to the year 2009. The SOM balance, based on Hénin–Dupuis’ equation, was integrated and run using GaBi4 software. A sensitivity analysis was performed, and four scenarios were developed to assess the impact of vineyard soil management types with decreasing levels of organic matter inputs.

Results and discussion

SOM accounting reduced the overall CF of one wine bottle from 0.663 to 0.531 kg CO₂-eq/FU. The vineyard planting sub-phase produced a loss of SOM while, in the pre-production and production sub-phases, the loss/accumulation of SOM was related to the soil management practices. On average, soil management in the production sub-phase led to a net accumulation of SOM, and the overall vineyard phase was a sink of CO₂. Residue incorporation and grassing were identified as the main factors affecting changes in SOM in vineyard soils.

Conclusions

Our results showed that incorporating SOM accounting into the wine chain’s CF analysis changed the vineyard phase from a GHG source to a modest net GHG sink. These results highlighted the need to include soil C dynamics in the CF of the agricultural product. Here, the SOM balance method proposed was sensitive to changes in management practices and was site specific. Moreover, we were also able to define a minimum data set for SOM accounting. The EU recognises soil carbon sequestration as one of the major European strategies for mitigation. However, specific measures have yet to be included in the CAP 2020. It would be desirable to include soil in the new ISO 14067—Carbon Footprint of Products.     

Spatial and technological variability in the carbon footprint of durum wheat production in Iran

Purpose

The purpose of this study was to quantify the spatial and technological variability in life cycle greenhouse gas (GHG) emissions, also called the carbon footprint, of durum wheat production in Iran.

Methods

The calculations were based on information gathered from 90 farms, each with an area ranging from 1 to 150 ha (average 16 ha). The carbon footprint of durum wheat was calculated by quantifying the biogenic GHG emissions of carbon loss from soil and biomass, as well as the GHG emissions from fertilizer application and machinery use, irrigation, transportation, and production of inputs (e.g., fertilizers, seeds, and pesticides). We used Spearman’s rank correlation to quantify the relative influence of technological variability (in crop yields, fossil GHG emissions, and N₂O emissions from fertilizer application) and spatial variability (in biogenic GHG emissions) on the variation of the carbon footprint of durum wheat.

Results and discussion

The average carbon footprint of 1 kg of durum wheat produced was 1.6 kg CO₂-equivalents with a minimum of 0.8 kg and a maximum of 3.0 kg CO₂-equivalents. The correlation analysis showed that variation in crop yield and fertilizer application, representing technological variability, accounted for the majority of the variation in the carbon footprint, respectively 76 and 21%. Spatial variation in biogenic GHG emissions, mainly resulting from differences in natural soil carbon stocks, accounted for 3% of the variation in the carbon footprint. We also observed a non-linear relationship between the carbon footprint and the yield of durum wheat that featured a scaling factor of ?2/3. This indicates that the carbon footprint of durum wheat production (in kg CO₂-eq kg^?1) typically decreases by 67% with a 100% increase in yield (in kg ha^?1 year^?1).

Conclusions

Various sources of variability, including variation between locations and technologies, can influence the results of life cycle assessments. We demonstrated that technological variability exerts a relatively large influence on the carbon footprint of durum wheat produced in Iran with respect to spatial variability. To increase the durum wheat yield at farms with relatively large carbon footprints, technologies such as site-specific nutrient application, combined tillage, and mechanized irrigation techniques should be promoted.

     

Reducing methane on-farm by feeding diets high in fat may not always reduce life cycle greenhouse gas emissions

Purpose

To consider whether feed supplements that reduce methane emissions from dairy cows result in a net reduction in greenhouse gas (GHG) intensity when productivity changes and emissions associated with extra manufacturing and management are included.

Methods

A life cycle assessment was undertaken using a model farm based on dairy farms in Victoria, Australia. The system boundary included the creation of farm inputs and on-farm activities up to the farm gate where the functional unit was 1 L of fat and protein corrected milk (FPCM). Electricity and diesel (scaled per cow), and fertiliser inputs (scaled on farm size) to the model farm were based on average data from a survey of farms. Fertiliser applied to crops was calculated per area of crop. Animal characteristics were based on available data from farms and literature. Three methane-reducing diets (containing brewers grain, hominy or whole cotton seed) and a control diet (cereal grain) were modelled as being fed during summer, with the control diet being fed for the remainder of the year in all cases.

Results and discussion

Greenhouse gas intensity (kg CO₂-eq/L FPCM) was lower than the control diet when the hominy (97 % compared with control) and brewers grain (98 %) diets were used but increased when the whole cottonseed diet was used (104 %). On-farm GHG emissions (kg CO₂-eq) were lower than the control diet when any of the methane-reducing diets were used (98 to 99.5 % of emissions when control diet fed). Diesel use in production and transport of feed supplements accounted for a large portion (63 to 93 %) of their GHG intensity (kg CO₂-eq/t dry matter). Adjusting fertiliser application, changing transport method, changing transport fuel, and using nitrification inhibitors all had little effect on GHG emissions or GHG intensity.

Conclusions

Although feeding strategies that reduce methane emissions from dairy cows can lower the GHG emissions up to the farm gate, they may not result in lower GHG intensities (g CO₂-eq/L FPCM) when pre-farm emissions are included. Both transport distance and the effect of the feed on milk production have important impacts on the outcomes.     

Carbon footprint and air emissions inventories for US honey production: case studies

Purpose

The primary purpose of this study is to estimate the life cycle greenhouse gas (GHG) emissions (carbon footprint) and criteria pollutant emissions during honey production and processing for US conditions based on several case studies of different scale beekeeping and processing operations. Commercial beekeeping operations yield two coproducts, honey and pollination services. These two products present an interesting coproduct allocation problem since beekeeping operations cannot be clearly subdivided, pollination services do not have a substitutable product or service, and pollination services cannot be characterized by physical properties for value-based allocation. Thus, a secondary purpose is to identify an appropriate allocation method and to discuss how the choice of allocation strategies influences the outcomes.

Methods

The commercial honey production supply chain comprises the following two primary steps: raw honey production by beekeepers and honey processing and packaging by processors. A case study approach was used based on detailed operation data provided by several beekeepers and processors from key honey-producing regions in the USA. Process-based life cycle assessment was conducted following the ISO guidelines, and economic allocation was used as a baseline method for coproduct allocation.

Results and discussion

Life cycle modeling of one complete commercial supply chain (raw honey production, transport to a processer, and processing) shows that total life cycle GHG emissions range from 0.67 to 0.92 kg CO₂ equivalent/kg of processed honey; however, outcomes show significant variability. Results show commercial honey production emits more GHGs and criteria pollutants than processing. Truck transport of bees is the dominant contributor of both GHG emissions and criteria pollutants within the life cycle of raw honey production. However, honey processing, which depends on natural gas and electricity, contributes a significant fraction of SO _x . These results are based on economic allocation among beekeeping coproducts. In addition to economic allocation, subdivision was applied to beekeeping activities. Because hive management (feed and medication) could not be further subdivided, a bounded range was generated for raw honey production, where the lower and upper bounds represent two extremes where all the environmental burdens associated with hive management were allocated to pollination or honey production.

Conclusions

Economic allocation tends to fall near or below the lower bound for the subdivision method. Interestingly, some beekeepers reported that their hive management practices were driven more by demand for pollination services than honey, which seems to be reflected in the coordination of lower-bound subdivision and economic allocation results.     

A comparison of the GHG emissions caused by manufacturing tissue paper from virgin pulp or recycled waste paper

Purpose

The aim of this work is to compare greenhouse gas (GHG) emissions from producing tissue paper from virgin pulp (VP) or recycled waste paper (RWP). In doing so, the study aims to inform decision makers at both company and national levels which are the main causes of emissions and to suggest the actions required to reduce pollution.

Methods

An attributional life cycle assessment (LCA) was performed in order to estimate and compare the GHG emissions of the two processes. LCA allows us to assess how the choice of raw material for VP and RWP processes influences total GHG emissions of tissue paper production, what are the main drivers behind these emissions and how do the direct materials; energy requirements and transportation contribute to the generation of emissions. The cradle-to-gate approach is carried out.

Results and discussion

The results show that demands for both thermal energy and electricity are higher for the RWP than for the VP if only the manufacturing stages are considered. However, a different picture emerges when the analysis looks at the entire life cycle of the production. GHG from the VP are about 30 % higher than the RWP, over the life cycle emitting 568 kg CO₂ eq more per kilogram of tissue paper. GHG emissions from the wood pulping alone were 559 g CO₂ eq per kilogram of tissue paper, three times higher than waste paper collection and transportation.

Conclusions

In terms of GHG emissions from cradle to gate, the recycled process less intensive than the virgin one for two reasons. First, as shown in the results the total GHG emissions from RWP are lower than those from VP due to relatively lower energy and material requirements. Second is the non-recyclability nature of tissue paper. Because the tissue paper is the last use of fibre, using RWP as an input would be preferable over using VP. The environmental profile of the tissue products both from RWP and VP can be improved if the following conditions are considered by the company. First, the company should consider implementing a cogeneration unit to simultaneously generate both useful heat and electricity. Second, it may consider changing the VP mix, in order to avoid the emissions associated with long distance transpiration effort. Third, there is the option of using sludge as fuel, which would reduce the total fossil fuel requirement.     

Life cycle assessment of bio-based ethanol produced from different agricultural feedstocks

Purpose

Bio-based products are often considered sustainable due to their renewable nature. However, the environmental performance of products needs to be assessed considering a life cycle perspective to get a complete picture of potential benefits and trade-offs. We present a life cycle assessment of the global commodity ethanol, produced from different feedstock and geographical origin. The aim is to understand the main drivers for environmental impacts in the production of bio-based ethanol as well as its relative performance compared to a fossil-based alternative.

Methods

Ethanol production is assessed from cradle to gate; furthermore, end-of-life emissions are also included in order to allow a full comparison of greenhouse gas (GHG) emissions, assuming degradation of ethanol once emitted to air from household and personal care products. The functional unit is 1 kg ethanol, produced from maize grain in USA, maize stover in USA, sugarcane in North-East of Brazil and Centre-South of Brazil, and sugar beet and wheat in France. As a reference, ethanol produced from fossil ethylene in Western Europe is used. Six impact categories from the ReCiPe assessment method are considered, along with seven novel impact categories on biodiversity and ecosystem services (BES).

Results and discussion

GHG emissions per kilogram bio-based ethanol range from 0.7 to 1.5 kg CO₂ eq per kg ethanol and from 1.3 to 2 kg per kg if emissions at end-of-life are included. Fossil-based ethanol involves GHG emissions of 1.3 kg CO₂ eq per kg from cradle-to-gate and 3.7 kg CO₂ eq per kg if end-of-life is included. Maize stover in USA and sugar beet in France have the lowest impact from a GHG perspective, although when other impact categories are considered trade-offs are encountered. BES impact indicators show a clear preference for fossil-based ethanol. The sensitivity analyses showed how certain methodological choices (allocation rules, land use change accounting, land use biomes), as well as some scenario choices (sugarcane harvest method, maize drying) affect the environmental performance of bio-based ethanol. Also, the uncertainty assessment showed that results for the bio-based alternatives often overlap, making it difficult to tell whether they are significantly different.

Conclusions

Bio-based ethanol appears as a preferable option from a GHG perspective, but when other impacts are considered, especially those related to land use, fossil-based ethanol is preferable. A key methodological aspect that remains to be harmonised is the quantification of land use change, which has an outstanding influence in the results, especially on GHG emissions.     

Assessment of carbon sustainability under different tillage systems in a double rice cropping system in Southern China

Purpose

Adoption of the carbon (C)-friendly and cleaner technology is an effective solution to offset some of the anthropogenic emissions. Conservation tillage is widely considered as an important sustainable technology and for the development of conservation agriculture (CA). Thus, the objective of this study was to assess the C sustainability of different tillage systems in a double rice (Oryza sativa L.) cropping system in southern China.

Methods

The experiment was established with no-till (NT), rotary tillage (RT), and conventional tillage (CT) treatments since 2005. Emission of greenhouse gasses (GHG), C footprint (CF), and ecosystem service through C sequestration in different tillage systems were compared.

Result and discussion

Emission of GHG from agricultural inputs (Mg CO₂-eq ha^?1 year^?1) ranged from 1.81 to 1.97 for the early rice, 1.82 to 1.98 for the late rice, and 3.63 to 3.95 for the whole growing season, respectively. The CF (kg CO₂-eq kg^?1 of rice year^?1) in the whole growing seasons were 1.27, 1.85, and 1.40 [excluding soil organic carbon (SOC) storage] and 0.54, 1.20, and 0.72 (including SOC storage) for NT, RT, and CT, respectively. The value of ecosystem services on C sequestration for the whole growing seasons ranged from ¥3,353 to 4,948 ha^?1 year^?1 and followed the order of NT > CT > RT. The C sustainability under NT was better than that under RT for the late, but reversed for the early rice. However, NT system had better C sustainability for the whole cropping system compared with CT.

Conclusions

Therefore, NT is a preferred technology to reduce GHG emissions, increase ecosystem service functions of C sequestration, and improve C sustainability in a double rice cropping region of Southern China.     

Carbon footprint and embodied energy assessment of a civil works program in a residential estate of Western Australia

Purpose

With building construction and demolition waste accounting for 50 % of land fill space, the diversion of reusable materials is essential for Perth”s environment. The reuse and recovery of embodied energy-intensive construction materials during civil engineering works programs can offer significant energy savings and assist in the mitigation of the carbon footprint.

Methods

A streamlined life cycle assessment, with limited focus, was carried out to determine the carbon footprint and embodied energy associated with a 100-m section of road base. A life cycle inventory of inputs (energy and materials) for all processes that occurred during the development of a 100-m road section was developed. Information regarding the energy and materials used for road construction work was obtained from the Perth-based firm, Cossill and Webley, Consulting Engineers. These inputs were inserted into Simapro LCA software to calculate the associated greenhouse gas emissions and embodied energy required for the construction and maintenance of a 100-m road section using. Two approaches were employed; a traditional approach that predominantly employed virgin materials, and a recycling approach.

Results and discussion

The GHG emissions and embodied energy associated with the construction of a 100-m road section using virgin materials are 180 tonnes of CO₂-e and 10.7 terajoules (TJ), respectively. The substitution of crushed rock with recycled brick road base does not appear to reduce the carbon footprint in the pre-construction stage (i.e. from mining to material construction, plus transportation of materials to the construction site). However, this replacement could potentially offer environmental benefits by reducing quarrying activities, which would not only conserve native bushland but also reduce the loss of biodiversity along with reducing the space and cost requirements associated with landfill. In terms of carbon footprint, it appears that GHG emissions are reduced significantly when using recycled asphalt, as opposed to other materials. About 22 to 30 % of greenhouse gas (GHG) emissions can be avoided by replacing 50 to 100 % of virgin asphalt with Reclaimed Asphalt Pavement (RAP) during the maintenance period.

Conclusions

The use of recycled building and road construction materials such as asphalt, concrete, and limestone can potentially reduce the embodied energy and greenhouse gas emissions associated with road construction. The recycling approach that uses 100 % reused crushed rock base and recycled concrete rubble, and 15 % RAP during the maintenance period could reduce the total carbon footprint by approximately 6 %. This large carbon saving in pavement construction is made possible by increasing the percentage of RAP in the wearing course.     

Life cycle greenhouse gas emissions of palm oil production by wet and dry extraction processes in Thailand

Purpose

The crude palm oil (CPO) extraction is normally done by a wet extraction process, and wastewater treatment of the wet process emits high levels of greenhouse gases (GHGs). A dry process extracts mixed palm oil (MPO) from palm fruit without using water and has no GHG emissions from wastewater treatment. This work is aimed at determining the GHG emissions of a dry process and at evaluating GHG savings on changing from wet to dry process, including land use change (LUC) effects.

Methods

Life cycle assessment from cradle to gate was used. The raw material is palm fruits. The dry process includes primary production, oil room, and utilities. MPO is the main product, while palm cake and fine palm residue are co-products sold for animal feed. Case studies were undertaken without and with carbon stocks of firewood and of nitrogen recycling at plantations from fronds. Allocations by mass, economic, and heating values were conducted. The trading of GHG emissions from co-products to GHG emissions from animal feed was assessed. The GHG emissions or savings from direct LUC (dLUC) and from indirect LUC (iLUC) effects and for the change from wet to dry process were determined.

Results and discussion

Palm fruit and firewood were the major GHG emission sources. Nitrogen recycling on plantations from fronds significantly affects the GHG emissions. With the carbon stocks, the GHG emissions allocated by energy value were 550 kg CO₂ eq/t MPO. The GHG emissions were affected by ?3 to 37% for the change from wet to dry process. When the plantation area was increased by 1 ha and the palm oil extraction was changed from wet to dry process, and the change included dLUC and iLUC, the GHG savings ranged from ?0.94 to 5.08 t CO₂ eq/ha year. The iLUC was the main GHG emission source. The GHG saving mostly originated from the change of extraction process and from the dLUC effect. Based on the potential use of biodiesel production from oil palm, during 2015–2036 in Thailand, when the extraction process was changed and dLUC and iLUC effects were included, the saving in GHG emissions was estimated to range from ?35,454 to 274,774 t CO₂ eq/year.

Conclusions

The change of palm oil extraction process and the LUC effects could minimize the GHG emissions from the palm oil industry. This advantage encourages developing policies that support the dry extraction process and contribute to sustainable developments in palm oil production.

     

Quantifying the greenhouse benefits of the use of wood products in two popular house designs in Sydney, Australia

Purpose

As the average wood products usage per unit of floor area in Australia has decreased significantly over time, there is potential for increased greenhouse gas (GHG) mitigation benefits through an increased use of wood products in buildings. This study determined the GHG outcomes of the extraction, manufacture, transport, use in construction, maintenance and disposal of wood products and other building materials for two popular house designs in Sydney, Australia.

Methods

The life cycle assessment (LCA) was undertaken using the computer model SimaPro 7.1, with the functional unit being the supply of base building elements for domestic houses in Sydney and its subsequent use over a 50-year period. The key data libraries used were the Australian Life Cycle Inventory library, the ecoinvent library (with data adapted to Australian circumstances where appropriate) and data for timber production from an Australian study for a range of Australian forestry production systems and wood products. Two construction variations were assessed: the original intended construction, and a “timber-maximised” alternative. The indicator assessed was global warming, as the focus was on GHG emissions, and the effect of timber production, use and disposal on the fate of carbon.

Results and discussion

The timber maximised design resulted in approximately half the GHG emissions associated with the base designs. The sub-floor had the largest greenhouse impact due to the concrete components, followed by the walls due to the usage of bricks. The use of a “timber maximised” design offset between 23 and 25 % of the total operational energy of the houses. Inclusion of carbon storage in landfill made a very significant difference to GHG outcomes, equivalent to 40–60 % of total house GHG emissions. The most beneficial options for disposal from a GHG perspective were landfill and incineration with energy recovery.

Conclusions

The study showed that significant GHG emission savings were achieved by optimising the use of wood products for two common house designs in Sydney. The switch of the sub-floor and floor covering components to a “wood” option accounted for most of the GHG savings. Inclusion of end of life parameters significantly impacted on the outcomes of the study.     

Life cycle environmental impacts of carbonated soft drinks

Purpose

The UK carbonated drinks sector was worth £8 billion in 2010 and is growing at an annual rate of 4.9 %. In an attempt to provide a better understanding of the environmental impacts of this sector, this paper presents, for the first time, the full life cycle impacts of carbonated soft drinks manufactured and consumed in the UK. Two functional units are considered: 1 l of packaged drink and total annual production of carbonated drinks in the UK. The latter has been used to estimate the impacts at the sectoral level. The system boundary is from ‘cradle to grave’. Different packaging used for carbonated drinks is considered: glass bottles (0.75 l), aluminium cans (0.33 l) and polyethylene terephthalate (PET) bottles (0.5 and 2 l).

Materials and methods

The study has been carried out following the ISO 14040/44 life cycle assessment (LCA) methodology. Data have been sourced from a drink manufacturer as well as the CCaLC, Ecoinvent and Gabi databases. The LCA software tools CCaLC v2.0 and GaBi 4.3 have been used for LCA modelling. The environmental impacts have been estimated according to the CML 2001 method.

Results and discussion

Packaging is the main hotspot for most environmental impacts, contributing between 59 and 77 %. The ingredients account between 7 and 14 % mainly due to sugar; the manufacturing stage contributes 5–10 %, largely due to the energy for filling and packaging. Refrigeration of the drink at retailer increases global warming potential by up to 33 %. Transport contributes up to 7 % to the total impacts.

Conclusions

The drink packaged in 2 l PET bottles is the most sustainable option for most impacts, including the carbon footprint, while the drink in glass bottles is the worst option. However, reusing glass bottles three times would make the carbon footprint of the drink in glass bottles comparable to that in aluminium cans and 0.5 l PET bottles. If recycling of PET bottles is increased to 60 %, the glass bottle would need to be reused 20 times to make their carbon footprints comparable. The estimates at the sectoral level indicate that the carbonated drinks in the UK are responsible for over 1.5 million tonnes of CO₂ eq. emissions per year. This represented 13 % of the GHG emissions from the whole food and drink sector or 0.26 % of the UK total emissions in 2010.     

Mitigation of greenhouse gas emissions from reed canary grass in paludiculture: effect of groundwater level

Background and aims

Combination of rewetting and wetland crop cultivation (paludiculture) is pursued as a wider carbon dioxide (CO₂) mitigation option in drained peatland. However, information on the overall greenhouse gas (GHG) balance for paludiculture is lacking. We investigated the GHG balance of peatlands grown with reed canary grass (RCG) and rewetted to various extents.

Methods

Gas fluxes of CO₂, methane (CH₄) and nitrous oxide (N₂O) were measured with a static chamber technique for 10 months from mesocosms sown with RCG and manipulated to ground water levels (GWL) of 0, ?10, ?20, ?30 and ?40 cm below the soil surface. Gross primary production (GPP) was estimated from the above ground biomass yield.

Results

The mean dry biomass yield across all water table treatments was 6 Mg ha^?1 with no significant differences between the treatments. Raising the GWL to the surface decreased both the net ecosystem exchange (NEE) of CO₂ and N₂O emissions whereas CH₄ emissions increased. Total cumulative GHG emissions (for 10 months) corresponded to 0.08, 0.13, 0.61, 0.68 and 0.98 kg CO₂ equivalents m^?2 from the GWL treatments at 0, ?10, ?20, ?30 and ?40 cm below the soil surface, respectively.

Conclusions

The results showed that a reduction in total GHG emission can be achieved without losing the productivity of newly established RCG when GWL is maintained close to the surface. Further studies should address the practical constrains and long-term productivity of RCG cultivation in rewetted peatlands.     

Climate change impacts on life cycle greenhouse gas (GHG) emissions savings of biomethanol from corn and soybean

Purpose

The purpose of this study is to assess and calculate the potential impacts of climate change on the greenhouse gas (GHG) emissions reduction potentials of combined production of whole corn bioethanol and stover biomethanol, and whole soybean biodiesel and stalk biomethanol. Both fuels are used as substitutes to conventional fossil-based fuels. The product system includes energy crop (feedstock) production and transportation, biofuels processing, and biofuels distribution to service station.

Methods

The methodology is underpinned by life cycle thinking. Crop system model and life cycle assessment (LCA) model are linked in the analysis. The Decision Support System for Agrotechnology Transfer – crop system model (DSSAT-CSM) is used to simulate biomass and grain yield under different future climate scenarios generated using a combination of temperature, precipitation, and atmospheric CO₂. Historical weather data for Gainesville, Florida, are obtained for the baseline period (1981–1990). Daily minimum and maximum air temperatures are projected to increase by +2.0, +3.0, +4.0, and +5.0 °C, precipitation is projected to change by ±20, 10, and 5 %, and atmospheric CO₂ concentration is projected to increase by +70, +210, and +350 ppm. All projections are made throughout the growing season. GaBi 4.4 is used as primary LCA modelling software using crop yield data inputs from the DSSAT-CSM software. The models representation of the physical processes inventory (background unit processes) is constructed using the ecoinvent life cycle inventory database v2.0.

Results and discussion

Under current baseline climate condition, net greenhouse gas (GHG) emissions savings per hectare from corn-integrated biomethanol synthesis (CIBM) and soybean-integrated biomethanol synthesis (SIBM) were calculated as ?8,573.31 and ?3,441 kg CO₂-eq. ha^?1 yr^?1, respectively. However, models predictions suggest that these potential GHG emissions savings would be impacted by changing climate ranging from negative to positive depending on the crop and biofuel type, and climate scenario. Increased atmospheric level of CO₂ tends to minimise the negative impacts of increased temperature.

Conclusions

While policy measures are being put in place for the use of renewable biofuels driven by the desire to reduce GHG emissions from the use of conventional fossil fuels, climate change would also have impacts on the potential GHG emissions reductions resulting from the use of these renewable biofuels. However, the magnitude of the impact largely depends on the biofuel processing technology and the energy crop (feedstock) type.     

Evaluating the carbon footprint of Chilean organic blueberry production

Purpose

Chile is the second largest blueberry producer and exporter worldwide. At the global level, there is a lack of information by means of field data about greenhouse gas emissions from organic cultivation of this fruit. This study obtains a resource use inventory and assesses the cradle-to-farm gate carbon footprint (CF) of organic blueberry (Vaccinium corymbosum) production in the main cultivation area of Chile in order to identify CF key factors and to provide improvement measures.

Methods

The method used in this study follows the ISO 14040 framework and the main recommendations in the PAS 2050 guide as well as its specification for horticultural products PAS 2050-1. Primary data were collected for three consecutive production seasons from five organic Chilean blueberry orchards and calculations conducted with the GaBi 4 software. Agricultural factors such as fertilizers, pesticides, fossil fuels, electricity, materials, machinery, and direct land use change (LUC) are included. Only three orchards present direct LUC.

Results and discussion

The direct LUC associated with the conversion from annual crops to perennial crops is a key factor in the greenhouse gas removals from the orchards. When accounting for direct LUC, the CF of organic blueberry production in the studied orchards ranges from removals (reported as negative value) of ?0.94 to emissions of 0.61 kg CO₂-e/kg blueberry. CF excluding LUC ranges from 0.27 to 0.69 kg CO₂-e/kg blueberry. The variability in the results of the orchards suggests that the production practices have important effects on the CF. The factors with the greatest contribution to the greenhouse emissions are organic fertilizers followed by energy use causing, on average, 50 and 43 % of total emissions, respectively.

Conclusions

The CF of the organic blueberry orchards under study decreases significantly when taking into account removals related to LUC. The results highlight the importance of reporting separately the greenhouse gas (GHG) emissions from LUC. The CF of blueberry production could be reduced by optimizing fertilizer application, using cover crops and replacing inefficient tractors and large irrigation pumps. The identification of improvement measures would be a useful guide for changing grower practices.

     

Improving the integrated hybrid LCA in the upstream scope 3 emissions inventory analysis

Purpose

The protocols of carbon footprints generally define three scopes for different greenhouse gas (GHG) emissions levels. The most important carbon footprint emissions source comes from upstream indirect emissions of scope 3 for products that do not consume energy during their use phase. Upstream scope 3 GHG inventory can usually be analyzed through input–output or hybrid LCA analysis. The economic input–output life cycle analysis (EIO-LCA) and the hybrid LCA model have been widely used for this purpose. However, a cutoff error exists in the hybrid model, and the lack of a truncation criterion between process and IO inventory may lead to a high level of uncertainty in the hybrid model. This study attempts to improve the problem of cutoff uncertainty in hybrid LCA and proposes a method to minimize the cutoff uncertainty.

Methods

The way to improve the cutoff uncertainty could follow two steps. First, through the IO inventory analysis of EIO-LCA, we can define the emissions by various tiers of product components. The IO inventory indicator can provide a definitive criterion for the process inventory of the hybrid model. Second, we connect the process- and IO-LCI according to the IO inventory result. The advantage of the process inventory is that it provides detailed manufacturing information on the target while the IO encompasses a complete system boundary. For improvements, the process inventory can catch the most important process of the GHG emissions, and the IO inventory could compensate for the remainder of the incomplete system inventory.

Results and discussion

In this case study, the printed circuit board production process is used to evaluate the efficiency of the improved method. The threshold M was set to 70 in this case study, and the IO inventory provides the remaining 30 %. For the integrated hybrid model, the tier 3 process inventory takes only 64 % while the incorporation of the proposed method can include 92 % of the total emissions, which shows the cutoff uncertainty can be reduced through the improvement.

Conclusions

This study provides a clear guideline for process and IO cutoff criteria, which can help the truncation uncertainty. When higher precision is required, process LCI will need to play an important role, and thus, a higher M value should be set. In this situation, the emissions from IO-LCI would be smaller than the emissions from the process LCI. The appropriate solution would attain a comfortable balance between data accuracy and time and labor consumption.     

Life cycle assessment of cheese and whey production in the USA

Purpose

A life cycle assessment was conducted to determine a baseline for environmental impacts of cheddar and mozzarella cheese consumption. Product loss/waste, as well as consumer transport and storage, is included. The study scope was from cradle-to-grave with particular emphasis on unit operations under the control of typical cheese-processing plants.

Methods

SimaPro© 7.3 (PRé Consultants, The Netherlands, 2013) was used as the primary modeling software. The ecoinvent life cycle inventory database was used for background unit processes (Frischknecht and Rebitzer, J Cleaner Prod 13(13–14):1337–1343, 2005), modified to incorporate US electricity (EarthShift 2012). Operational data was collected from 17 cheese-manufacturing plants representing 24 % of mozzarella production and 38 % of cheddar production in the USA. Incoming raw milk, cream, or dry milk solids were allocated to coproducts by mass of milk solids. Plant-level engineering assessments of allocation fractions were adopted for major inputs such as electricity, natural gas, and chemicals. Revenue-based allocation was applied for the remaining in-plant processes.

Results and discussion

Greenhouse gas (GHG) emissions are of significant interest. For cheddar, as sold at retail (63.2 % milk solids), the carbon footprint using the IPCC 2007 factors is 8.60 kg CO₂e/kg cheese consumed with a 95 % confidence interval (CI) of 5.86–12.2 kg CO₂e/kg. For mozzarella, as sold at retail (51.4 % milk solids), the carbon footprint is 7.28 kg CO₂e/kg mozzarella consumed, with a 95 % CI of 5.13–9.89 kg CO₂e/kg. Normalization of the results based on the IMPACT 2002+ life cycle impact assessment (LCIA) framework suggests that nutrient emissions from both the farm and manufacturing facility wastewater treatment represent the most significant relative impacts across multiple environmental midpoint indicators. Raw milk is the major contributor to most impact categories; thus, efforts to reduce milk/cheese loss across the supply chain are important.

Conclusions

On-farm mitigation efforts around enteric methane, manure management, phosphorus and nitrogen runoff, and pesticides used on crops and livestock can also significantly reduce impacts. Water-related impacts such as depletion and eutrophication can be considered resource management issues—specifically of water quantity and nutrients. Thus, all opportunities for water conservation should be evaluated, and cheese manufacturers, while not having direct control over crop irrigation, the largest water consumption activity, can investigate the water use efficiency of the milk they procure. The regionalized normalization, based on annual US per capita cheese consumption, showed that eutrophication represents the largest relative impact driven by phosphorus runoff from agricultural fields and emissions associated with whey-processing wastewater. Therefore, incorporating best practices around phosphorous and nitrogen management could yield improvements.     

European renewable energy directive: Critical analysis of important default values and methods for calculating greenhouse gas (GHG) emissions of palm oil biodiesel

Purpose

The aim of this paper is to evaluate assumptions and data used in calculations  related to palm oil produced for biodiesel production relative to the European Renewable Energy Directive (EU-RED). The intent of this paper is not to review all assumptions and data, but rather to evaluate whether the methodology is applied in a consistent way and whether current default values address relevant management practices of palm oil production systems.

Methods

The GHG calculation method provided in Annex V of the EU-RED was used to calculate the GHG-emissions from palm oil production systems. Moreover, the internal nitrogen recycling on the plantation was calculated based on monitoring data in North Sumatra.

Results and discussion

A calculation methodology is detailed in Annex V of the EU-RED. Some important aspects necessary to calculate the GHG emission savings correctly are insufficiently considered, e.g.: ? “Nitrogen recycling” within the plantation due to fronds remaining on the plantation is ignored. The associated organic N-input to the plantation and the resulting nitrous oxide emissions is not considered within the calculations, despite crop residues being taken into account for annual crops in the BIOGRACE tool. ? The calculation of GHG-emissions from residue and waste water treatment is inappropriately implemented despite being a hot-spot for GHG emissions within the life cycle of palm oil and palm oil biodiesel. Additionally, no distinction is made between palm oil and palm kernel oil even though palm kernel oil is rarely used for biodiesel production. ? The allocation procedure does not address the most relevant oil mill management practices. Palm oil mills produce crude palm oil (CPO) in addition either nuts or palm kernels and nut shells. In the first case, the nuts would be treated as co-products and upstream emissions would be allocated based on the energy content; in the second case the kernels would be treated as co-products while the shelöls are considered as waste without upstream emissions. This has a significant impact on the resulst or GHG savings, respectively. ? It is not specified whether indirect GHG emissions from nitrogen oxide emission from the heat and power unit of palm oil mills should be taken into account.

Conclusions and recommendations

In conclusion, the existing calculation methodology described in Annex V of the EU-RED and default values are insufficient for calculating the real GHG emission savings from palm oil and palm oil biodiesel. The current default values do not reflect relevant management practices. Additionally, they protect poor management practices, such as the disposal of empty fruit bunches (EFB), and lead to an overestimation of GHG savings from palm oil biodiesel. A default value for EFB disposal must be introduced because resulting GHG emissions are substantial. Organic nitrogen from fronds must be taken into account when calculating real GHG savings from palm oil biodiesel. Further, more conservative data for FFB yield and fugitive emissions from wastewater treatment should be introduced in order to foster environmental friendly management options. Moreover, credits for bioenergy production from crop residues should be allowed in order to foster the mobilization of currently unused biomass.