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.     

Saving land to feed a growing population: consequences for consumption of crop and livestock products

Purpose

The expected increase in demand for food raises concerns about the expansion of agricultural land worldwide. To avoid expansion, we need to focus on increasing land productivity, reducing waste, and shifting human diets. Studies exploring diet shifts so far have ignored competition for land between humans and animals. Our objective was to study the relation between land use, the share of animal protein in the human diet, population size, and land availability and quality.

Methods

We used linear programming to determine minimum land required to feed a population a diet with 0–80 % of the protein derived from terrestrial domestic animals. Populations ranged from 15 million to the maximum number of people that could be supported by the system. The agricultural system in the Netherlands was used as illustration, assuming no import and export of feed and food. Daily energy and protein requirements of humans were fulfilled by a diet potentially consisting of grain (wheat), root and tuber crops (potato, sugar beet), oil crops (rapeseed), legumes (brown bean), and animal protein from ruminants (milk and meat) and monogastrics (pork).

Results and discussion

Land is used most efficiently if people would derive 12 % of dietary protein from animals (% PA), especially milk. The role of animals in such a diet is to convert co-products from crop production and the human food industry into protein-rich milk and meat. Below 12 % PA, human-inedible products were wasted (i.e., not used for food production), whereas above 12 % PA, additional crops had to be cultivated to feed livestock. Large populations (40 million or more) could be sustained only if animal protein was consumed. This results from the fact that at high population sizes, land unsuitable for crop production was necessary to meet dietary requirements of the population, and contributed to food production by providing animal protein without competing for land with crops.

Conclusions

A land use optimization model including crop and animal production enables identification of the optimal % PA in the diet. Land use per capita was lowest at 12 % PA. At this level, animals optimally consume co-products from food production. Larger populations, furthermore, can be sustained only with diets relatively high in % PA, as land unsuitable for crop production is needed to fulfil their food demand. The optimal % PA in the human diet depended on population size and the relative share of land unsuitable for crop production.

     

The effect of local climate and soil drainage on the environmental impact of grass-based milk production

Purpose

System modelling and life cycle assessment (LCA) were used to assess the climate change, acidification and eutrophication impacts of milk production using spring calving pasture-based system. The objective of the study was to evaluate the effect of climate and soil resources on the environmental impact per unit milk produced at the farm gate from low-cost, grass-based rotational-grazing dairy production.

Methods

A dairy system model, Dairy_sim, designed to identify optimum grass-based spring calving production systems considering the interaction between climate and soil resources was tested using the Irish National Dairy Blueprint and then used to assess regional differences of system management with well, moderately, mixed moderately-poorly and poorly drained soil resources available. Life cycle assessment was used to quantify environmental impacts of climate and soil drainage status. The Dairy_sim output was used as activity data for the LCA model.

Results and discussion

Differences were found in the management tactics influenced by climate and drainage resource. The impact of poor drainage reduced stocking rate, increased housing time and had greater need for later cut silage and more reliance on silage. Climate change, acidification and eutrophication impacts were greater for optimum management on poorly drained soil. The climate change ranged from 1.06 kg CO₂ eq./kg (well drained) to 1.18 kg CO₂ eq./kg (poorly drained) of energy corrected milk (ECM). The acidification and eutrophication ranged from 3.87 to 6.85 g SO₂ eq./kg ECM and 2.69 to 3.64 g PO₄ eq./kg ECM, respectively. Around 50% of poorly drained soil resource can be easily accommodated in dairy systems with little increase in environmental impact, where poor drained portion is utilised for silage.

Conclusions

LCA combined with a system optimization model revealed how dairy farm management practises constrained by poor land resource increased the environmental impact per unit product.

     

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.

     

Livestock greenhouse gas emissions and mitigation potential in Europe

The livestock sector contributes considerably to global greenhouse gas emissions (GHG). Here, for the year 2007 we examined GHG emissions in the EU27 livestock sector and estimated GHG emissions from production and consumption of livestock products; including imports, exports and wastage. We also reviewed available mitigation options and estimated their potential. The focus of this review is on the beef and dairy sector since these contribute 60% of all livestock production emissions. Particular attention is paid to the role of land use and land use change (LULUC) and carbon sequestration in grasslands. GHG emissions of all livestock products amount to between 630 and 863 Mt CO₂e, or 12–17% of total EU27 GHG emissions in 2007. The highest emissions aside from production, originate from LULUC, followed by emissions from wasted food. The total GHG mitigation potential from the livestock sector in Europe is between 101 and 377 Mt CO₂e equivalent to between 12 and 61% of total EU27 livestock sector emissions in 2007. A reduction in food waste and consumption of livestock products linked with reduced production, are the most effective mitigation options, and if encouraged, would also deliver environmental and human health benefits. Production of beef and dairy on grassland, as opposed to intensive grain fed production, can be associated with a reduction in GHG emissions depending on actual LULUC emissions. This could be promoted on rough grazing land where appropriate.     

Life cycle assessment of concentrated solar power (CSP) and the influence of hybridising with natural gas

Purpose

Concentrating solar power (CSP) plants based on parabolic troughs utilise auxiliary fuels (usually natural gas) to facilitate start-up operations, avoid freezing of HTF and increase power output. This practice has a significant effect on the environmental performance of the technology. The aim of this paper is to quantify the sustainability of CSP and to analyse how this is affected by hybridisation with different natural gas (NG) inputs.

Methods

A complete life cycle (LC) inventory was gathered for a commercial wet-cooled 50 MWe CSP plant based on parabolic troughs. A sensitivity analysis was conducted to evaluate the environmental performance of the plant operating with different NG inputs (between 0 and 35 % of gross electricity generation). ReCiPe Europe (H) was used as LCA methodology. CML 2 baseline 2000 World and ReCiPe Europe E were used for comparative purposes. Cumulative energy demands (CED) and energy payback times (EPT) were also determined for each scenario.

Results and discussion

Operation of CSP using solar energy only produced the following environmental profile: climate change 26.6 kg CO₂ eq/KWh, human toxicity 13.1 kg 1,4-DB eq/KWh, marine ecotoxicity 276 g 1,4-DB eq/KWh, natural land transformation 0.005 m²/KWh, eutrophication 10.1 g P eq/KWh and acidification 166 g SO₂ eq/KWh. Most of these impacts are associated with extraction of raw materials and manufacturing of plant components. The utilisation of NG transformed the environmental profile of the technology, placing increasing weight on impacts related to its operation and maintenance. Significantly higher impacts were observed on categories like climate change (311 kg CO₂ eq/MWh when using 35 % NG), natural land transformation, terrestrial acidification and fossil depletion. Despite its fossil nature, the use of NG had a beneficial effect on other impact categories (human and marine toxicity, freshwater eutrophication and natural land transformation) due to the higher electricity output achieved. The overall environmental performance of CSP significantly deteriorated with the use of NG (single score 3.52 pt in solar-only operation compared to 36.1 pt when using 35 % NG). Other sustainability parameters like EPT and CED also increased substantially as a result of higher NG inputs. Quasilinear second-degree polynomial relationships were calculated between various environmental performance parameters and NG contributions.

Conclusions

Energy input from auxiliary NG determines the environmental profile of the CSP plant. Aggregated analysis shows a deleterious effect on the overall environmental performance of the technology as a result of NG utilisation. This is due primarily to higher impacts on environmental categories like climate change, natural land transformation, fossil fuel depletion and terrestrial acidification. NG may be used in a more sustainable and cost-effective manner in combined cycle power plants, which achieve higher energy conversion efficiencies.     

Intensification of dairy production can increase the GHG mitigation potential of the land use sector in East Africa

Sub‐Saharan Africa (SSA) could face food shortages in the future because of its growing population. Agricultural expansion causes forest degradation in SSA through livestock grazing, reducing forest carbon (C) sinks and increasing greenhouse gas (GHG) emissions. Therefore, intensification should produce more food while reducing pressure on forests. This study assessed the potential for the dairy sector in Kenya to contribute to low‐emissions development by exploring three feeding scenarios. The analyses used empirical spatially explicit data, and a simulation model to quantify milk production, agricultural emissions and forest C loss due to grazing. The scenarios explored improvements in forage quality (Fo), feed conservation (Fe) and concentrate supplementation (Co): FoCo fed high‐quality Napier grass (Pennisetum purpureum), FeCo supplemented maize silage and FoFeCo a combination of Napier, silage and concentrates. Land shortages and forest C loss due to grazing were quantified with land requirements and feed availability around forests. All scenarios increased milk yields by 44%–51%, FoCo reduced GHG emission intensity from 2.4 ± 0.1 to 1.6 ± 0.1 kg CO₂eq per kg milk, FeCo reduced it to 2.2 ± 0.1, whereas FoFeCo increased it to 2.7 ± 0.2 kg CO₂eq per kg milk because of land use change emissions. Closing the yield gap of maize by increasing N fertilizer use reduced emission intensities by 17% due to reduced emissions from conversion of grazing land. FoCo was the only scenario that mitigated agricultural and forest emissions by reducing emission intensity by 33% and overall emissions by 2.5% showing that intensification of dairy in a low‐income country can increase milk yields without increasing emissions. There are, however, risks of C leakage if agricultural and forest policies are not aligned leading to loss of forest to produce concentrates. This approach will aid the assessment of the climate‐smartness of livestock production practices at the national level in East Africa.     

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.     

Global food supply: land use efficiency of livestock systems

Purpose

Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, we need a measure for land use efficiency of livestock systems.

Methods

Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1 kg ASF over the amount of HDP in that 1 kg ASF. We illustrated our concept for three case systems.

Results and discussion

The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1 kg HDP from laying hens could directly yield 2.08 kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR <1.0 is considered efficient in terms of global food supply and implies that animals produce more HDP per square metre than crops.

Conclusions

Values <1.0 demonstrate that livestock produce HDP more efficiently than crops. Such livestock systems (with a LUR?<?1.0), therefore, do have a role in future food supply and therefore contribute to food security. Our LUR offers identification of livestock production systems that contribute to global food supply, i.e. systems that value land with low opportunity costs for arable production and/or by-products from crop cultivation or the food or energy industry.

     

Consequential LCA of switching from maize silage-based to grass-based dairy systems

Purpose

This study aimed to investigate the environmental consequences (on climate change and land use) of an increase in preference for grass-based milk in France using a consequential life cycle assessment (CLCA) approach. This increase in preference was assumed to be satisfied domestically, by converting maize silage-based dairy farms (MS farm) to grass-based dairy farms (G farm) while keeping on-farm usable agricultural area and total milk production of farm constant.

Methods

The possible consequences of an increase in preference for grass-based milk were identified based on cause and effect relationships. The conversion from MS to G farm reduced the use of soybean meal, changed the on-farm cropping pattern and produced more animals but less wheat and no rapeseed. Effects on on-farm soil C were predicted with the RothC model and on global land use change (LUC) with models of global agricultural markets (Global Trade Analysis Project (GTAP) and Landbouw Economisch Instituut Trade Analysis Project (LEITAP)). System expansion using animals from a suckler beef production system was applied to estimate the impacts of milk and animal co-products from the dairy system. Land occupation and climate change impacts were estimated. The consequences of farm conversion were attributed only to the milk, as preference for grass-based milk drove the conversion process.

Results and discussion

The conversion from the MS to G farm increases land occupation and climate change impacts for the G farm, respectively, by 9 and 7 % according to GTAP and 14 and 51 % according to LEITAP. Land occupation and climate change impacts of milk produced by the G farm after conversion increased, respectively, by 82 and 13 % with GTAP and 123 and 97 % with LEITAP relative to those for the MS farm (before conversion). The production of additional wheat and rapeseed outside the G farm increased impacts of the G farm (by 29–69 % depending on impacts and model used). Results indicate that the farm conversion would probably have consequences on global LUC and that it is important to account for this in a LCA approach.

Conclusions

Land use and land use change (LULUC) contributed to the impacts of grass-based milk, and results were highly sensitive to the LULUC model used. The many possible chain-of-event pathways that follow a change in preference for a given product yield high uncertainty in CLCA results. This study only assessed one possible way to meet the increase in preference for grass-based milk; it is necessary to perform a sensitivity analysis to investigate other possible scenarios resulting from this increase in preference.     

Opportunities for avoidance of land‐use change through substitution of soya bean meal and cereals in European livestock diets with bioethanol coproducts

An analysis is presented which quantifies the potential for distillers dried grains with solubles (DDGS, a coproduct of wheat bioethanol production) to replace soya bean meal (SBM) and cereals in livestock rations. A major proportion of the SBM imported into Europe as a protein‐rich feedstuff for livestock comes from South America, where land‐use change (LUC) is associated with high carbon emissions. Production of DDGS can therefore reduce LUC in South America by substitution of SBM in animal feed. The analysis indicates that a single bioethanol distillery processing 1 million tonnes of wheat, and producing ca. 330 000 tonnes of DDGS per annum, would substitute at least 136 493 tonnes of whole soya beans grown on 47 725 ha of land, and save greenhouse gas emissions equivalent to 0.63 million tonnes CO₂ per annum. By growing sugar beet and wheat in an average ratio of 0.06 : 0.94 on 1 ha of land in Europe, the net area of agricultural land required to produce feed ingredients equivalent to 6.08 t of sugar beet pulp (SBP) and 1.72 t of DDGS associated with 2363 L of bioethanol, is reduced to 0.40 ha. This accounts for 0.42 ha of soya that is not required when DDGS displaces SBM, and 0.18 ha of wheat that is not required when DDGS and SBP displace wheat in livestock rations.     

Crop residue incorporation negates the positive effect of elevated atmospheric carbon dioxide concentration on wheat productivity and fertilizer nitrogen recovery

Background and purpose

Rapid increases in atmospheric carbon dioxide concentration ([CO₂]) may increase crop residue production and carbon: nitrogen (C:N) ratio. Whether the incorporation of residues produced under elevated [CO₂] will limit soil N availability and fertilizer N recovery in the plant is unknown. This study investigated the interaction between crop residue incorporation and elevated [CO₂] on the growth, grain yield and the recovery of ¹⁵N-labeled fertilizer by wheat (Triticum aestivum L. cv. Yitpi) under controlled environmental conditions.

Methods

Residue for ambient and elevated [CO₂] treatments, obtained from wheat grown previously under ambient and elevated [CO₂], respectively, was incorporated into two soils (from a cereal-legume rotation and a cereal-fallow rotation) 1 month before the sowing of wheat. At the early vegetative stage ¹⁵N-labeled granular urea (10.22 atom%) was applied at 50 kg?N ha^?1 and the wheat grown to maturity.

Results

When residue was not incorporated into the soil, elevated [CO₂] increased wheat shoot (16 %) and root biomass (41 %), grain yield (19 %), total N uptake (4 %) and grain N removal (8 %). However, the positive [CO₂] fertilization effect on these parameters was absent in the soil amended with residue. In the absence of residue, elevated [CO₂] increased fertilizer N recovery in the plant (7 %), but when residue was incorporated elevated [CO₂] decreased fertilizer N recovery.

Conclusions

A higher fertilizer application rate will be required under future elevated [CO₂] atmospheres to replenish the extra N removed in grains from cropping systems if no residue is incorporated, or to facilitate the [CO₂] fertilization effect on grain yield by overcoming N immobilization resulting from residue amendment.     

Defining a nutritionally healthy,environmentally friendly,and culturally acceptable Low Lands Diet

Purpose

The purpose of this study is to demonstrate that linear programming can support to define nutritionally healthy, environmentally friendly, and culturally acceptable diets, using the Low Lands as an illustrative example.

Methods

Our study quantifies the historical Dutch diet of 75 years ago, based on a cultural history research. We calculate the greenhouse gas emissions (GHGE) and land use (LU) of this diet, using actual life cycle assessment (LCA) data for the 206 most consumed products, and the health score, based on ten nutritional characteristics. In order to meet the current requirements, we optimize this diet for adult males using linear programming. We compare the diet with the present Dutch, Mediterranean, and New Nordic Diet.

Results and discussion

An optimized Low Lands Diet has the same healthy nutritional characteristics (Health Score 123) as the Mediterranean Diet (122) and results in a lower environmental impact than the Mediterranean and New Nordic Diet (higher Combined GHGE-LU Score 121 versus 90 and 91). GHGE are 2.60 kg CO₂eq per day and LU 2.86 m²?*?year per day.

Conclusions

Through applying the method of linear programming, it is possible to calculate an optimal diet for the Low Lands with a short cultural distance, that is, as healthy as and more sustainable than a transition to more foreign European diets.

     

Life cycle environmental impacts of decommissioning Magnox nuclear power plants in the UK

Purpose

Full life cycle assessment (LCA) impacts from decommissioning have rarely been assessed, largely because few sites have been decommissioned so that the impacts of decommissioning are currently uncertain. This paper presents the results of an LCA study of the ongoing decommissioning of the Magnox power plant at Trawsfynydd in the UK. These results have been used to estimate the potential environmental impacts for the whole UK Magnox fleet of 11 reactors that will have to be decommissioned during this century.

Methods

The functional unit is defined as ‘decommissioning one Magnox power plant’. The system boundary considers all stages in the life cycle of decommissioning, including site management, waste retrieval, plant deconstruction, packaging and storage of intermediate- and low-level wastes (ILW and LLW). High-level waste, i.e. waste fuel is excluded as it was being removed from the site to be reprocessed at Sellafield. The environmental impacts have been estimated using the CML 2001 methodology. Primary data have been sourced from the Trawsfynydd site and the background from Ecoinvent.

Results and discussion

Most impacts from decommissioning are due to the plant deconstruction (25–75 %) and ILW storage and disposal (25–70 %). For the example of global warming potential (GWP), estimated at 241 kt CO₂ eq./functional unit, or 3.5 g CO₂ eq./kWh of electricity generated during the lifetime of the plant, 55 % of the impact is from plant deconstruction and 30 % from ILW disposal. The results for the whole UK Magnox fleet indicate that the impacts vary greatly for different sites. For example, the GWP ranges from 0.89 to 7.14 g CO₂ eq./kWh. If the impacts from storage of waste fuel at Sellafield are included in the estimates, the GWP increases on average by four times. Overall, decommissioning of the UK Magnox reactors would generate 2 Mt of CO₂ eq. without and 11 Mt of CO₂ eq. with the waste from Sellafield. This represents 0.4 and 2 % of the total UK annual emissions, respectively.

Conclusions

The impacts of decommissioning can vary greatly at different sites depending on the amount of waste and electricity generated by the plants. Delaying decommissioning to allow the energy system to decarbonise could reduce the environmental impacts, e.g. GWP could be reduced by 50 %. The impacts could also be reduced by reducing the volume of waste and increasing recycling of materials. For example, recycling 70 % of steel would reduce the impacts on average by 34 %.     

Hyperaccumulation of thallium is population-specific and uncorrelated with caesium accumulation in the thallium hyperaccumulator, Biscutella laevigata

Purpose

This study investigated the residual contribution of legume and fertilizer nitrogen (N) to a subsequent crop under the effect of elevated carbon dioxide concentration ([CO₂]).

Methods

Field pea (Pisum sativum L.) was labeled in situ with ¹⁵N (by absorption of a ¹⁵N-labeled urea solution through cut tendrils) under ambient and elevated (700 μmol mol^–1) [CO₂] in controlled environment glasshouse chambers. Barley (Hordeum vulgare L.) and its soil were also labeled under the same conditions by addition of ¹⁵N-enriched urea to the soil. Wheat (Triticum aestivum L.) was subsequently grown to physiological maturity on the soil containing either ¹⁵N-labeled field pea residues (including ¹⁵N-labeled rhizodeposits) or ¹⁵N-labeled barley plus fertilizer ¹⁵N residues.

Results

Elevated [CO₂] increased the total biomass of field pea (21 %) and N-fertilized barley (23 %), but did not significantly affect the biomass of unfertilized barley. Elevated [CO₂] increased the C:N ratio of residues of field pea (18 %) and N-fertilized barley (19 %), but had no significant effect on that of unfertilized barley. Elevated [CO₂] increased total biomass (11 %) and grain yield (40 %) of subsequent wheat crop regardless of rotation type in the first phase. Irrespective of [CO₂], the grain yield and total N uptake by wheat following field pea were 24 % and 11 %, respectively, higher than those of the wheat following N-fertilized barley. The residual N contribution from field pea to wheat was 20 % under ambient [CO₂], but dropped to 11 % under elevated [CO₂], while that from fertilizer did not differ significantly between ambient [CO₂] (4 %) and elevated [CO₂] (5 %).

Conclusions

The relative value of legume derived N to subsequent cereals may be reduced under elevated [CO₂]. However, compared to N fertilizer application, legume incorporation will be more beneficial to grain yield and N supply to subsequent cereals under future (elevated [CO₂]) climates.     

Effects of high dietary fibre diets formulated from by-products from vegetable and agricultural industries on plasma metabolites in gestating sows

The aim of the present study was to examine the biochemical influence of feeding high dietary fibre (DF) diets formulated from by-products from the vegetable and agricultural industries to sows during early to mid-gestation. The effect of feeding frequency (once vs. twice daily) on diurnal plasma metabolites patterns was also examined. The study included a total of 48 gestating sows from four blocks (12 gestating sows in each block). The sows were fed four different diets containing varying levels of starch (304–519 g/kg dry matter (DM)) and DF (171–404 g/kg DM) but with equal amounts of net energy. The low-DF diet (control) was based on barley and wheat, and the three high-DF diets formulated by replacing barley and wheat by pectin residue, sugar beet pulp and potato pulp, respectively. The experimental design comprised two periods of 4 weeks each. Half the sows were fed once daily at 08:00 h in the first period and twice daily at 08:00 and 15:00 h during the second period, and vice versa for the other half of the sows. Plasma samples from vena jugularis were collected by venipuncture at 07:00, 09:00, 12:00 and 19:00 h. Feeding high-DF increased plasma short-chain fatty acids (p = 0.02) and non-esterified fatty acids (p < 0.001). However, there was no clear effect of DF on glucose and insulin responses. A negative correlation between amount of DF in the diets and plasma creatine (R ² = 1.00; diet effect: p = 0.02) suggested that plasma creatine concentrations was an indicator for the level of glucose–glycogen interchange. Furthermore, an explorative approach using nuclear magnetic resonance spectroscopy-based metabonomics identified betaine (p < 0.001), dimethyl sulfone (DMSO₂; p < 0.001) and scyllo-inositol (p < 0.001) as biomarkers for the different by-products; pectin residue was related to high plasma levels of DMSO₂, sugar beet pulp to plasma betaine, DMSO₂ and scyllo-inositol, and potato pulp to plasma DMSO₂ and scyllo-inositol. In conclusion, replacing starch by DF affected surprisingly few metabolites in peripheral plasma. No negative effects were found in feeding pectin residue, sugar beet pulp or potato pulp for gestating sows as judged from the minor metabolic changes.     

FoodPrints of households

Purpose

Food consumption is one of the main drivers of environmental impacts. To develop meaningful strategies for the reduction of impacts, food consumption patterns need to be understood on the household level, as purchasing decisions are taken on this level. The goals of this study were to develop a model that estimates food demand and environmental impact as a function of household characteristics, to assess variability between households, and to provide a basis for the development of consumer-targeted political interventions. We titled the study “FoodPrints of households,” as we assessed food consumption in terms of carbon footprint (in analogy to (Stoessel et al. Environ Sci Technol 46(6):3253–3262 2012)).

Methods

We used data from the Swiss household budget survey and applied multiple linear regressions based on generalized linear models to quantify food and beverage demand of individual households. Seven household characteristics, such as size, income, and educational level, served as input variables for the regressions. In a case study, food and beverage demand of 3238 individual households of a Swiss municipality was environmentally assessed with life cycle assessment, and scenarios for different reduction strategies were evaluated.

Results and discussion

We found that the carbon footprints of in-home food consumption per household member and year vary from 0.08 t CO₂ eq. to 5 t CO₂ eq. with a median value of 1 t CO₂ eq. This variability is significantly smaller than the carbon footprint variability for the consumption areas of housing and mobility, where 25 % of the people are responsible for 50 % of the environmental impacts. Differences between high- and low-impact households can be primarily explained by differences in meat and dairy consumption.

Conclusions

This paper presents a model for quantifying food demand and impacts on a household level in Switzerland and represents a basis for developing targeted political measures to mitigate food consumption impacts. Household budget data is also available for many other countries, and the methods presented in this paper could therefore also be applied to other geographical regions.

     

Exploring variability in methods and data sensitivity in carbon footprints of feed ingredients

Purpose

Production of feed is an important contributor to life cycle greenhouse gas emissions, or carbon footprints (CFPs), of livestock products. Consequences of methodological choices and data sensitivity on CFPs of feed ingredients were explored to improve comparison and interpretation of CFP studies. Methods and data for emissions from cultivation and processing, land use (LU), and land use change (LUC) were analyzed.

Method

For six ingredients (maize, wheat, palm kernel expeller, rapeseed meal, soybean meal, and beet pulp), CFPs resulting from a single change in methods and data were compared with a reference CFP, i.e., based on IPCC Tier 1 methods, and data from literature.

Results and discussion

Results show that using more detailed methods to compute N₂O emissions from cultivation hardly affected reference CFPs, except for methods to determine $ \mathrm{NO}_3^{-} $ leaching (contributing to indirect N₂O emissions) in which the influence is about ?7 to +12 %. Overall, CFPs appeared most sensitive to changes in crop yield and applied synthetic fertilizer N. The inclusion of LULUC emissions can change CFPs considerably, i.e., up to 877 %. The level of LUC emissions per feed ingredient highly depends on the method chosen, as well as on assumptions on area of LUC, C stock levels (mainly aboveground C and soil C), and amortization period.

Conclusions

We concluded that variability in methods and data can significantly affect CFPs of feed ingredients and hence CFPs of livestock products. Transparency in methods and data is therefore required. For harmonization, focus should be on methods to calculate $ \mathrm{NO}_3^{-} $ leaching and emissions from LULUC. It is important to consider LUC in CFP studies of food, feed, and bioenergy products.     

Life cycle energy use and CO<Subscript>2</Subscript> emissions of small-scale gold mining and refining processes in the Philippines

Purpose

Gold is one of the most significant metals in the world, with use in various sectors including the electronic, health, and fashion industries. The Philippines has the world’s third largest known Au deposits and is ranked 20th in global gold production. Of the country’s annual production, about 80% is from the small-scale gold mining (SSGM) sector. This work estimates the first location-specific life cycle energy use and CO₂ emissions of SSGM establishments in the Philippines.

Methods

Process-based LCA was used with functional unit of 100 g Au and observed data from 2010 to 2011 for mining, comminution, recovery, and refining. Four gold production paths were observed in the provinces of Benguet and Camarines Norte, namely, amalgamation, cyanidation with carbon-in-leach (CIL), cyanidation with leaching with zinc, and combination of amalgamation and cyanidation with CIL.

Results and discussion

It was estimated that 3–18 g of Au was extracted for every ton of ore within 57–159 man-hours from mining to refining. Energy use estimates ranged from 3501 to 67,325 MJ/100 g Au, while CO₂ emission estimates ranged from 398 to 5340 kg CO₂/100 g Au. The combination of amalgamation and cyanidation with CIL processes was the least energy and carbon intensive, while cyanidation with CIL process was the most intensive. Electricity use accounted for 95–100% of total emissions, except in cyanidation with CIL where kerosene accounts for 77% of the total. Since SSGMs contributed 80% of the 40 tons of Au produced in the Philippines in 2014, the SSGM energy use was estimated to be between 1120 and 21,544 TJ and the CO₂ emissions to be between 129 and 1726 ktons CO₂. Energy estimates are most sensitive to refining process yield and electrical equipment efficiency.

Conclusions

The estimated life cycle emissions rate for SSGM in the Philippines is lower than available estimates of large-scale mining. Notwithstanding, given the sector’s reliance on fossil fuels for its energy needs and the Philippines’ pledge to reduce its CO₂ footprint by 70% in 2030, every effort to mitigate energy use and CO₂ emission counts. Three main recommendations toward energy consumption and CO₂ emissions reduction in SSGMs are proposed: (1) policy to promote technologies that are energy-efficient and processes that maximize gold process yield, (2) effective Minahang Bayan (SSGM mining zone mandated by law) implementation to ensure use of higher-grade ores, and (3) adoption of renewable energy in Minahang Bayans to promote energy independence and mitigate CO₂ emissions.

     

Quantifying greenhouse gases from the production,transportation and utilization of charcoal in developing countries: a case study of Kampala,Uganda

Purpose

This study aims to quantify greenhouse gases (GHGs) from the production, transportation and utilization of charcoal and to assess the possibilities of decreasing greenhouse gases (GHGs) from the charcoal industry in general in Uganda. It also aims to assess the emission intensity of the Ugandan “charcoal production” sector compared to that of some other major charcoal producing nations.

Methods

This work was done in accordance with ISO 14040 methodology for life-cycle assessment (LCA), using GABi 4.0—a software for life-cycle assessment. A cradle-to-grave study was conducted, excluding emissions arising from machinery use during biomass cultivation and harvesting. The distance from charcoal production locations to Kampala was estimated using ArcGIS 10.0 software and a GPS tool. Emission data from a modern charcoal production process (PYREG methane-free charcoal production equipment), which complies with the German air quality standards (TA-Luft), was compared with emissions from a traditional charcoal production process. Four coupled scenarios were modelled to account for differences in the quantity of greenhouse gases emitted from the “traditional charcoal production phase”, “improved charcoal production phase (biomass feedstock sourced sustainably and unsustainably)”, “transportation phase” and “utilization phase”. Data for this study was obtained via literature review and onsite measurements.

Results and discussion

The results showed that greenhouse gases emitted due to charcoal supply and use of traditional production technique in Kampala was 1,554,699 tCO₂eq, with the transportation phase accounting for approximately 0.15 % of total greenhouse gases emitted. The utilization phase (charcoal cookstoves) emitted 723,985 tCO₂eq (46.6 %), while the charcoal production phase emitted 828,316 tCO₂eq (53.3 %). Changing the charcoal production technology from a traditional method to an improved production method (PYREG charcoal process) resulted in greenhouse gases reductions for the city of 230,747 tCO₂eq; however, by using sustainably sourced biomass, this resulted in reductions of 801,817 tCO₂eq.

Conclusions

This study showcased and quantified possible GHG emission reduction scenarios for the charcoal industry in Uganda. The result of 3 tCO₂eq emitted per tonne of charcoal produced, using earth mound method, can be applied to other countries in Eastern Africa where similar charcoal production methods are used; this will allow for somewhat better regional estimates of the inventory of greenhouse gas emissions from the production of charcoal. The results of this study also suggests that the primary use of charcoal for cooking will lead to increases in GHG emissions and increases in deforestation on the long term, if legal frameworks are not made to ensure that biomass used for charcoal production is obtained via sustainable sources or if alternative cheap energy-generating technologies for cooking are not developed and deployed to the masses.