Review of methodological decisions in life cycle assessment (LCA) of biorefinery systems across feedstock categories.

The application of life cycle assessment (LCA) to biorefineries is a necessary step to estimate their environmental sustainability. This review explores contemporary LCA biorefinery studies, across different feedstock categories, to understand approaches in dealing with key methodological decisions which arise, including system boundaries, consequential or attributional approach, allocation, inventory data, land use changes, product end-of-life (EOL), biogenic carbon storage, impact assessment and use of uncertainty analysis. From an initial collection of 81 studies, 59 were included within the final analysis, comprising 22 studies which involved dedicated feedstocks, 34 which involved residue feedstocks (including by-products and wastes), and a further 3 studies which involved multiple feedstocks derived from both dedicated and secondary sources. Many studies do not provide a comprehensive LCA assessment, often lacking detail on decisions taken, omitting key parts of the value chain, using generic data without uncertainty analyses, or omitting important impact categories. Only 28% of studies included some level of primary data, while 39% of studies did not undertake an uncertainty or sensitivity analysis. Just 8% of studies included data related to dLUC with a further 8% including iLUC, and only 14% of studies considering product end of life within their scope. The authors recommend more transparency in biorefinery LCA, with justification of key methodological decisions. A full value-chain approach should be adopted, to fully assess burdens and opportunities for biogenic carbon storage. We also propose a more prospective approach, taking into account future use of renewable energy sources, and opportunities for increasing circularity within bio-based value chains.

Cattle production strategies to deliver protein with less land and lower environmental impact.

Global land resources are over-exploited and natural habitats are declining, often driven by expanding livestock production. In Ireland, pastureland for grazing cattle and sheep account for circa 60% of terrestrial land use. The agriculture, forestry and other land use sector (AFOLU) is responsible for 44% of national greenhouse gas (GHG) emissions. A new Grassland Animal response Model (GLAM) was developed to relate livestock-cohort grass and feed requirements to farm-grassland system areas, enhancing environmental assessment of prospective AFOLU configurations. Although land conversion targets are often well-defined, they tend to lack a clear definition of where land sparing can occur. Through analyses of 10 scenarios of milk and beef production and management strategies, we found that displacing beef cows with dairy cows can increase national protein output while sparing up to 0.75 million ha (18%) of grassland (albeit with a minor increase in overseas land requirement for additional concentrate feed). Reducing slaughter age, increasing exports of male dairy calves and increasing grassland use efficiency on beef farms each achieved between 0.19 and 0.32 million ha of land sparing. Sexed semen to achieve more favourable male-female birth ratios had a minor impact. GHG emissions, ammonia emissions and nutrient leaching were only reduced substantially when overall cattle numbers declined, confirming the need for cattle reductions to achieve environmental objectives. Nonetheless, application of GLAM shows potential for improved grass and cattle management to spare good quality land suitable for productive forestry and wetland restoration. This change is urgently needed to generate scalable carbon dioxide removals from the land sector in Ireland, and globally.

European soybean to benefit people and the environment.

Europe imports large amounts of soybean that are predominantly used for livestock feed, mainly sourced from Brazil, USA and Argentina. In addition, the demand for GM-free soybean for human consumption is project to increase. Soybean has higher protein quality and digestibility than other legumes, along with high concentrations of isoflavones, phytosterols and minerals that enhance the nutritional value as a human food ingredient. Here, we examine the potential to increase soybean production across Europe for livestock feed and direct human consumption, and review possible effects on the environment and human health. Simulations and field data indicate rainfed soybean yields of 3.1 ± 1.2 t ha-1 from southern UK through to southern Europe (compared to a 3.5 t ha-1 average from North America). Drought-prone southern regions and cooler northern regions require breeding to incorporate stress-tolerance traits. Literature synthesized in this work evidenced soybean properties important to human nutrition, health, and traits related to food processing compared to alternative protein sources. While acknowledging the uncertainties inherent in any modelling exercise, our findings suggest that further integrating soybean into European agriculture could reduce GHG emissions by 37-291 Mt CO2e year-1 and fertiliser N use by 0.6-1.2 Mt year-1, concurrently improving human health and nutrition.

Circular wood use can accelerate global decarbonisation but requires cross-sectoral coordination.

Predominantly linear use of wood curtails the potential climate-change mitigation contribution of forestry value-chains. Using lifecycle assessment, we show that more cascading and especially circular uses of wood can provide immediate and sustained mitigation by reducing demand for virgin wood, which increases forest carbon sequestration and storage, and benefits from substitution for fossil-fuel derived products, reducing net greenhouse gas emissions. By United Kingdom example, the circular approach of recycling medium-density fibreboard delivers 75% more cumulative climate-change mitigation by 2050, compared with business-as-usual. Early mitigation achieved by circular and cascading wood use complements lagged mitigation achieved by afforestation; and in combination these measures could cumulatively mitigate 258.8 million tonnes CO2e by 2050. Despite the clear benefits of implementing circular economy principles, we identify many functional barriers impeding the structural reorganisation needed for such complex system change, and propose enablers to transform the forestry value-chain into an effective societal change system and lead to coherent action.

Water sector resilience in the United Kingdom and Ireland: The COVID-19 challenge.

The outbreak of COVID-19 led to restrictions on movements and activities, which presented a serious challenge to the resilience of the water sector. It is essential to understand how successfully water companies responded to this unprecedented event so effective plans can be built for future disruptive events. This study aimed to evaluate how the water sectors in the UK and Ireland were affected from a holistic sustainability and resilience-based perspective. Using pre-COVID data for 18 indicators of company performance and comparing them to the first year of the pandemic, the direction and magnitudes of change varied across companies. Financial indicators were significantly negatively affected, with interest cover ratio, post-tax return on regulated equity, and operating profit, exhibiting the greatest average declines of 21%, 21%, and 18%, respectively, a trend that would be dangerous to provisions and company operations if continued. Despite this, service and environmental indicators improved during the first year of the pandemic, exemplified by unplanned outage, risk of sewer storm flooding, and water quality compliance risk decreasing by a mean average of 37%, 32%, and 27%, respectively. Analysis using the Hicks-Moorsteen Productivity Index concluded that average productivity increased by 35%. The results suggest that the water sector was relatively resilient to the COVID-19 pandemic in terms of services, but adverse effects may have manifested in a deteriorated financial position that could exacerbate future challenges arising from exogenous pressures such as climate change. Specific advice for the UK water sector is to scrutinize non-critical spending, such as shareholder payments, during periods of economic downturn to ensure essential capital projects can be carried out. Although results are temporal and indicator selection sensitive, we recommend that policy, regulation, and corporate culture embrace frameworks that support long-term resilience to since the relative success in response to COVID-19 does not guarantee future success against differing challenges. This study generates a timely yet tentative insight into the diverse performance of the water sector during the pandemic, pertinent to the water industry, regulators, academia, and the public.

Heat recovery and water reuse in micro-distilleries improves eco-efficiency of alcohol production.

The number of micro-scale spirit distilleries worldwide has grown considerably over the past decade. With an onus on the distillery sector to reduce its environmental impact, such as carbon emissions, opportunities for increasing energy efficiency need to be implemented. This study explores the potential environmental benefits and financial gains achievable through heat recovery from different process and by-product streams, exemplified for a Scotch whisky distillery, but transferrable to micro-distilleries worldwide. The eco-efficiency methodology is applied, taking into account both climate change and water scarcity impacts as well as economic performance of alcohol production with and without heat recovery. A Life Cycle Assessment, focusing on climate change and water scarcity, is combined with a financial assessment considering investment costs and the present value of the savings over the 20-year service life of the heat recovery system. The proposed heat recovery systems allow carbon emission reductions of 8-23% and water scarcity savings of 13-55% for energy and water provision for 1 L of pure alcohol (LPA). Financial savings are comparatively smaller, at 5-13%, due to discounting of the future savings - but offer a simple payback of the investment costs in under two years. The eco-efficiency of the distillery operations can be improved through all proposed heat recovery configurations, but best results are obtained when heat is recovered from mashing, distillations and by-products altogether. A sensitivity analysis confirmed that the methodology applied here delivers robust results and can help guide other micro-distilleries on whether to invest in heat recovery systems, and/or the heat recovery configuration. Uptake should be enhanced through increased information and planning support, and in cases where the distillery offers insufficient heat and water sinks to use all pre-warmed water, opportunities to link with a heat sink outside the distillery are encouraged. A 10% reduction in heating fuel use through heat recovery has the potential to save 47 kt of CO2 eq. or £7.4 M per annum in United Kingdom malt whisky production alone, based on current fuel types used and current prices (2021).

Silvopastoral systems for offsetting livestock emissions in the tropics: a case study of a dairy farm in Costa Rica.

Ways are being sought to reduce the environmental impact of ruminant livestock farming. Integration of trees into farming systems has been advocated as a measure to deliver ecosystem services, inter alia climate regulation and adaptation, water quality regulation, provisioning of fibre, fuel and habitats to support biodiversity. Despite the rapid expansion of cattle farming in the tropics, notably in Latin America, there is little robust evidence on the extent to which trees are able to mitigate the effects of cattle farming in this ecological zone. This article describes a case study conducted on a large, specialised dairy farm in Costa Rica, where two-thirds of the field boundaries are live tree fences. For the first time, this study quantifies the offset potential of trees by estimating rate of carbon sequestration in a silvopastoral system (SPS) in the tropics. It was found that over a 30-month interval, trees sequestered 1.43 Mg C ha-1 year-1 above and below ground. Attributional life cycle assessment (LCA) (cradle to farm gate) was applied to calculate the carbon footprint of milk produced on the farm for the years 2016 to 2018. Trees in live fences offset 21-37% of milk footprints, resulting in residual net footprints of 0.75±0.25 to 0.84±0.26 kg CO2 eq. kg-1 milk. Exclusion of life cycle emissions that may not fall within national emission inventory accounting (e.g. fertiliser manufacture and feed production) increased the mean offset from 27 to 34% of gross milk footprint. Although based on temporally limited data (30 months), our findings indicate that a live fence SPS could play an important role in short- to medium-term climate mitigation from livestock production, buying time for deployment of long-term mitigation and adaptation planning. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-022-00834-z.

Responsible agriculture must adapt to the wetland character of mid-latitude peatlands.

Drained, lowland agricultural peatlands are greenhouse gas (GHG) emission hotspots and a large but vulnerable store of irrecoverable carbon. They exhibit soil loss rates of ~2.0 cm yr-1 and are estimated to account for 32% of global cropland emissions while producing only 1.1% of crop kilocalories. Carbon dioxide emissions account for >80% of their terrestrial GHG emissions and are largely controlled by water table depth. Reducing drainage depths is, therefore, essential for responsible peatland management. Peatland restoration can substantially reduce emissions. However, this may conflict with societal needs to maintain productive use, to protect food security and livelihoods. Wetland agriculture strategies will, therefore, be required to adapt agriculture to the wetland character of peatlands, and balance GHG mitigation against productivity, where halting emissions is not immediately possible. Paludiculture may substantially reduce GHG emissions but will not always be viable in the current economic landscape. Reduced drainage intensity systems may deliver partial reductions in the rate of emissions, with smaller modifications to existing systems. These compromise systems may face fewer hurdles to adoption and minimize environmental harm until societal conditions favour strategies that can halt emissions. Wetland agriculture will face agronomic, socio-economic and water management challenges, and careful implementation will be required. Diversity of values and priorities among stakeholders creates the potential for conflict. Successful implementation will require participatory research approaches and co-creation of workable solutions. Policymakers, private sector funders and researchers have key roles to play but adoption risks would fall predominantly on land managers. Development of a robust wetland agriculture paradigm is essential to deliver resilient production systems and wider environmental benefits. The challenge of responsible use presents an opportunity to rethink peatland management and create thriving, innovative and green wetland landscapes for everyone's future benefit, while making a vital contribution to global climate change mitigation.

Packaging choice and coordinated distribution logistics to reduce the environmental footprint of small-scale beer value chains.

This study assesses the extent to which packaging and distribution impacts can be mitigated as environmental hotspots in the life cycle of micro-brewed beer. We conduct life cycle assessment (LCA) of seven breweries and compare their existing packaging and distribution practises with three mitigation options; use of aluminium cans or reusable glass bottles instead of single use glass bottles or use of polyethylene terephthalate (PET) kegs instead of steel kegs. Findings show that all participating breweries can achieve reductions across multiple impact categories if single use glass bottles are changed to aluminium cans or reusable glass, and further reductions are possible if mode of transport is changed from small delivery vans to lorries for distribution to retailers. The use of PET keg as an alternative to reusable steel keg is a less environmentally sustainable option when beer is delivered short distances, but some savings are possible in long distance scenarios using vans. Carbon footprints per litre beer range from 727 to 1336 g CO2 eq. across the case study breweries, with reductions of 6-27% or 3-27% by changing to aluminium can or reusable glass bottle, respectively, when beer is delivered by van. The optimal combination of reusable glass bottle delivered by lorry reduces carbon footprints by between 45 and 55% but will require significant investment and coordination across the wider food and drink sector to implement. Identifying the best packaging material requires a holistic approach that considers interactions and burdens across packaging manufacturing, distribution, use and end-of-life stages.

Optimized ratoon rice system to sustain cleaner food production in Jianghan Plain, China: a comprehensive emergy assessment.

Ratoon rice (RR) is regarded as a labor-saving and efficient approach to rice cultivation; however, sub-optimal production techniques (fertilization, irrigation, harvesting) may lead to serious environmental problems and unsustainable agriculture. In this study, emergy analysis was combined with indicators of soil fertility, global warming potential (GWP), and profitability to comprehensively assess the sustainability performance of three cultivation modes: (i) traditional farm practice (TRA), (ii) optimized mode (OPT), and (iii) OPT plus green manure planting (OPTM). Over 2 years, compared with the TRA mode, OPT and OPTM modes increased total rice yield by 10% and 19% on average and improved profit by 233.7 and 456.5 Yuan ha-1, respectively. Single emergy analysis results showed that, compared with the TRA mode, OPT and OPTM (2-year average value) modes increased production efficiency by 10% and 8%, reduced renewable fraction and emergy sustainability index by 14-19% and 18-23%, respectively, and increased environmental loading ratio by 31% and 22%. Multiple EMA analysis results showed that, compared with the TRA mode, OPT and OPTM (2-year average value) modes reduced UEVNmin by 23% and 21% and increased UEVGWP 32% and 51%, respectively. The UEVTotal revenue and UEVBenefit of OPT and OPTM increased by 8-29% and 4-37%, respectively, compared with TRA mode. The comprehensive assessment indicated that, despite OPT and OPTM modes have a range of improvements and dis-improvements versus the TRA mode, OPTM was the more sustainable mode of RR production overall. However, some sustainability indicators remained poor, and there remains scope for further optimization via, e.g., precision application of enhanced-efficiency fertilizers, application of a straw-decomposing inoculant to improve soil fertility, and use of new improved rice varieties with high regenerative ability to improve the yield of ratoon crops.

Pitfalls in international benchmarking of energy intensity across wastewater treatment utilities.

The collection, treatment and disposal of wastewater is estimated to consume more than 2% of the world's electrical energy, whilst some wastewater treatment plants (WWTPs) can account for over 20% of electrical consumption within municipalities. To investigate areas to improve wastewater treatment, international benchmarking on energy (electrical) intensity was conducted with the indicator kWh/m3 and a quality control of secondary treatment or better for ≥95% of treated volume. The core sample included 321 companies from 31 countries, however, to analyse regional differences, 11 countries from an external sample made up of various studies of WWTPs was also used in places. The sample displayed a weak-negative size effect with energy intensity, although Kruskal-Wallace analyses showed there was a significant difference between the size of groups (p-value of 0.015), suggesting that as companies get larger; they consume less electricity per cubic metre of wastewater treated. This relationship was not completely linear, as mid to large companies (10,001-100,000 customers) had the largest average consumption of 0.99 kWh/m3. In the regional analysis, EU states had the largest average kWh/m3 with 1.18, which appeared a result of the higher wastewater effluent standards of the region. This was supported by Denmark being the second largest average consuming country (1.35 kWh/m3), since it has some of strictest effluent standards in the world. Along with energy intensity, the associated greenhouse gas (GHG) emissions were calculated enabling the targeting of regions for improvement in response to climate change. Poland had the highest carbon footprint (0.91 kgCO2e/m3) arising from an energy intensity of 0.89 kWh/m3; conversely, a clean electricity grid can affectively mitigate wastewater treatment inefficiencies, exemplified by Norway who emit just 0.013 kgCO2e per cubic meter treated, despite consuming 0.60 kWh/m3. Finally, limitations to available data and the analysis were highlighted from which, it is advised that influent vs. effluent and net energy, as opposed to gross, data be used in future analyses. The large international sample size, energy data with a quality control, GHG analysis, and specific benchmarking recommendations give this study a novelty which could be of use to water industry operators, benchmarking organisations, and regulators.

Defining national biogenic methane targets: Implications for national food production & climate neutrality objectives.

Methane is a short-lived greenhouse gas (GHG) modelled distinctly from long-lived GHGs such as carbon dioxide and nitrous oxide to establish global emission budgets for climate stabilisation. The Paris Agreement requires a 24-47% reduction in global biogenic methane emissions by 2050. Separate treatment of methane in national climate policies will necessitate consideration of how global emission budgets compatible with climate stabilisation can be downscaled to national targets, but implications of different downscaling rules for national food production and climate neutrality objectives are poorly understood. This study addresses that knowledge gap by examining four methods to determine national methane quotas, and two methods of GHG aggregation (GWP100 and GWP*) across four countries with contrasting agriculture, forestry and other land use (AFOLU) sectors and socio-economic contexts (Brazil, France, India and Ireland). Implications for production of methane-intensive food (milk, meat, eggs and rice) in 2050 and national AFOLU climate neutrality targets are explored. It is assumed that methane quotas are always filled by food production where sufficient land is available. Global methane budgets for 1.5 °C scenarios are downscaled to national quotas based on: grand-parenting (equal percentage reductions across countries); equity (equal per capita emissions); ability (emission reductions proportionate to GDP); animal protein security (emissions proportionate to animal protein production in 2010). The choice of allocation method changes national methane quotas by a factor of between 1.7 (India) and 6.7 (Ireland). Despite projected reductions in emission-intensities, livestock production would need to decrease across all countries except India to comply with quotas under all but the most optimistic sustainable intensification scenarios. The extent of potential afforestation on land spared from livestock production is decisive in achieving climate neutrality. Brazil and Ireland could maintain some degree of milk and beef export whilst achieving territorial climate neutrality, but scenarios that comply with climate neutrality in India produce only circa 30% of national calorie and protein requirements via rice and livestock. The downscaling of global methane budgets into national policy targets in an equitable and internationally acceptable manner will require simultaneous consideration of the interconnected priorities of food security and (land banks available for) carbon offsetting.

Commercial afforestation can deliver effective climate change mitigation under multiple decarbonisation pathways.

Afforestation is an important greenhouse gas (GHG) mitigation strategy but the efficacy of commercial forestry is disputed. Here, we calculate the potential GHG mitigation of a UK national planting strategy of 30,000 ha yr-1 from 2020 to 2050, using dynamic life cycle assessment. What-if scenarios vary: conifer-broadleaf composition, harvesting, product breakouts, and decarbonisation of substituted energy and materials, to estimate 100-year GHG mitigation. Here we find forest growth rate is the most important determinant of cumulative mitigation by 2120, irrespective of whether trees are harvested. A national planting strategy of commercial forest could mitigate 1.64 Pg CO2e by 2120 (cumulative), compared with 0.54-1.72 Pg CO2e for planting only conservation forests, depending on species composition. Even after heavy discounting of future product substitution credits based on industrial decarbonisation projections, GHG mitigation from harvested stands typically surpasses unharvested stands. Commercial afforestation can deliver effective GHG mitigation that is robust to future decarbonisation pathways and wood uses.

Aligning efficiency benchmarking with sustainable outcomes in the United Kingdom water sector.

The provision of fundamental services by water and sewage companies (WaSCs) requires substantial energy and material inputs. A sustainability assessment of these companies requires a holistic evaluation of both performance and efficiency. The Hicks-Moorsteen productivity index was applied to 12 WaSCs in the United Kingdom (UK) over a 6-year period to benchmark their sustainability, based on eight approaches using different input and output variables for efficiency assessment. The choice of variables had a major influence on the ranking and perceived operational efficiency among WaSCs. Capital expenditure (utilised as part of total expenditure) for example, is an important input for tracking company operations however, potential associated efficiency benefits can lag investment, leading to apparent poor short-term performance following capital expenditure. Furthermore, water supplied and wastewater treated was deemed an unconstructive output from a sustainability perspective since it contradicts efforts to improve sustainability through reduced leakage and consumption per capita. Customer satisfaction and water quality measures are potential suitable alternatives. Despite these limitations, total expenditure and water supplied and wastewater treated were used alongside customer satisfaction and self-generated renewable energy for a holistic sustainability assessment within a small sample. They indicated the UK water sector has improved in productivity by 1.8% on average for 2014-18 and still had room for improvement, as a technical decline was evident for both the best and worst performers. Collectively the sample's production frontier was unchanged but on average companies moved 2.1% closer to it, and further decomposition of productivity revealed this was due to improvements in economies of scale and scope. Careful selection of appropriate input and output variables for efficiency benchmarking across water companies is critical to align with sustainability objectives and to target future investment and regulation within the water sector.

The sustainability of rice-crayfish coculture systems: a mini review of evidence from Jianghan plain in China.

BACKGROUND: Rice-crayfish coculture (RC) uses 10% of the paddy field area for crayfish ditches, with rice cultivated in the remaining area, providing staple carbohydrates alongside fish rich in protein and essential oils. These systems rely on complex interactions, involving nutrient cycling, fish feeding, soil physicochemical modification, and insect-pest predation, and have important socio-economic effects. Past studies have considered only one or a few of these aspects pertinent to food system sustainability, and there remains a need for an integrated assessment of RC systems. In this mini-review, we collate data from two field experiments and three field surveys published across eight papers to synthesize the overall sustainability of RC systems in Jianghan Plain in China. RESULTS: In deep groundwater fields, the RC rice yield was 30-55% lower than for typical rice-rapeseed (RR) rotations, while CH4 emission and pesticide use were 41-96% and 50% lower, respectively. In shallow groundwater fields, RC rice yield was similar to typical rice monoculture (RM) cultivation, while CH4 emission and pesticide use were 28-41% and 17% lower for RC cultivation. Field survey data indicated that RC can improve soil nutrient and organic matter content significantly compared with RM cultivation, and also increase the diversity of fauna and flora in the paddy field whilst reducing the incidence of chilo suppressalis (a major rice pest). Feed inputs to RC systems increased crayfish yield by 31-71% and reduced the fraction of N inputs lost to the environment from 71% to 41%. CONCLUSION: We conclude that RC systems with feed inputs in areas with shallow groundwater can deliver improved food security, sustainability, and resilience through ecological intensification. © 2020 Society of Chemical Industry.

Key traits for ruminant livestock across diverse production systems in the context of climate change: perspectives from a global platform of research farms.

Ruminant livestock are raised under diverse cultural and environmental production systems around the globe. Ruminant livestock can play a critical role in food security by supplying high-quality, nutrient-dense food with little or no competition for arable land while simultaneously improving soil health through vital returns of organic matter. However, in the context of climate change and limited land resources, the role of ruminant-based systems is uncertain because of their reputed low efficiency of feed conversion (kilogram of feed required per kilogram of product) and the production of methane as a by-product of enteric fermentation. A growing human population will demand more animal protein, which will put greater pressure on the Earth's planetary boundaries and contribute further to climate change. Therefore, livestock production globally faces the dual challenges of mitigating emissions and adapting to a changing climate. This requires research-led animal and plant breeding and feeding strategies to optimise ruminant systems. This study collated information from a global network of research farms reflecting a variety of ruminant production systems in diverse regions of the globe. Using this information, key changes in the genetic and nutritional approaches relevant to each system were drawn that, if implemented, would help shape more sustainable future ruminant livestock systems.

Maintaining production while reducing local and global environmental emissions in dairy farming.

While milk is a major agricultural commodity, dairy farming also supports a large share of global beef production. In Life Cycle Assessment (LCA) studies of dairy farming systems, dairy-beef production is often ignored or 'allocated off', which may give a distorted view of production efficiencies. This study combines LCA with Data Envelopment Analysis (DEA) to develop an indicator of eco-efficiency for each of 738 UK dairy farms (3624 data points in 15 years) that aggregates multiple burdens and expresses them per unit of milk and dairy-beef produced. Within the DEA framework, the importance (weight) of dairy-beef relative to milk is iteratively increased to quantify the environmental losses from heavily focussing on milk-production, via e.g. higher yields per cow, with consequent lower burdens per unit of milk, yet with lower dairy-beef production levels, where burdens for beef production are externalized. Then, the relationship between DEA eco-efficiency and a series of indicators of dairy farming intensity at animal- and farm-levels was studied with Generalized Additive Models (GAM). For all sets of DEA weights (proportion of deviance explained ranged between 68% and 82%) indicate that milk yield per cow and forage area, and larger dairy herds all have a positive effect on eco-efficiency, while concentrate fed per unit of milk and the forage area both have a negative effect (p < 0.05 for all modelled relationships). These findings suggest that more intensive and consolidated dairy farms can positively impact on eco-efficiency. However, as the DEA weight for dairy-beef relative to milk increases, the relationship between environmental efficiency and farming specialization (expressed as L milk per kg dairy-beef produced) reverses from positive to negative. In conclusion, dairy-beef production is pivotal in determining the wider environmental efficiency of dairy (and ruminant food) systems, and its under-representation in efficiency studies has generated a misleading approach to meeting emission targets.

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

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

Recycling of European plastic is a pathway for plastic debris in the ocean.

Polyethylene (PE) is one of the most common types of plastic. Whilst an increasing share of post-consumer plastic waste from Europe is collected for recycling, 46% of separated PE waste is exported outside of the source country (including intra-EU trade). The fate of this exported European plastic is not well known. This study integrated data on PE waste flows in 2017 from UN Comtrade, an open repository providing detailed international trade data, with best available information on waste management in destination countries, to model the fate of PE exported for recycling from Europe (EU-28, Norway and Switzerland) into: recycled high-density PE (HDPE) and low-density PE (LDPE) resins, "landfill", incineration and ocean debris. Data uncertainty was reflected in three scenarios representing high, low and average recovery efficiency factors in material recovery facilities and reprocessing facilities, and different ocean debris fate factors. The fates of exported PE were then linked back to the individual European countries of export. Our study estimated that 83,187 Mg (tonnes) (range: 32,115-180,558 Mg), or 3% (1-7%) of exported European PE in 2017 ended up in the ocean, indicating an important and hitherto undocumented pathway of plastic debris entering the oceans. The countries with the greatest percentage of exported PE ending up as recycled HDPE or LDPE were Luxembourg and Switzerland (90% recycled for all scenarios), whilst the country with the lowest share of exported PE being recycled was the United Kingdom (59-80%, average 69% recycled). The results showed strong, significant positive relationships between the percentage of PE exported out of Europe and the percentage of exports which potentially end up as ocean debris. Export countries may not be the ultimate countries of origin owing to complex intra-EU trade in PE waste. Although somewhat uncertain, these mass flows provide pertinent new evidence on the efficacy and risks of current plastic waste management practices pertinent to emerging regulations around trade in plastic waste, and to the development of a more circular economy.

Key performance indicators to explain energy & economic efficiency across water utilities, and identifying suitable proxies.

Water companies consume up to 8% of global energy demand, at billions of dollars' cost. Benchmarking of performance between utilities can facilitate improvements in efficiency; however, inconsistencies in benchmarking practices may obscure pathways to improvement. The aspiration was to conduct an unbiased efficiency comparison within a sample of 17 water only companies and water and sewerage companies in England and Wales, accounting for exogenous factors, whilst evaluating the accuracy of common proxies. Proxies were tested, and bias-corrected energy and economic efficiency scores with explanatory factors were analysed using a double-bootstrap data envelopment method. Bias correction altered the rankings of two companies for energy efficiency only. Results imply that on average, companies could reduce energy inputs by 91.7%, and economic inputs by 92.3%, which was symptomatic of the companies specialising in drinking water supply considerably out-performing combined water and sewerage companies. As exogenous influences were likely to be a factor in the disparity between the companies, five indicators were evaluated. The results varied but of note were average pumping head height, which displayed a significant negative effect for energy efficiency, and proportion of water passing through the largest four treatment works, that exhibited a significant negative effect on economic efficiency. Within proxy performance, population served for drinking water was an adequate replacement for volume of water produced, with results matching the core variable apart from two companies changing rank in the economic analysis. Conversely, length of water mains performed poorly when replacing capital expenditure, implying companies were on average 12.6% more efficient, resulting in ten companies changing their rank and causing explanatory variables to contradict direction of influence and significance. The findings contribute new insights for benchmarking, including how different types of water companies perform under bias-correcting methods, the degree to which factors affect efficiency and how appropriate some proxies are.