Methane flux from flowback operations at a shale gas site.

We report measurements of methane (CH4) mixing ratios and emission fluxes derived from sampling at a monitoring station at an exploratory shale gas extraction facility in Lancashire, England. Elevated ambient CH4 mixing ratios were recorded in January 2019 during a period of cold-venting associated with a nitrogen lift process at the facility. These processes are used to clear the well to stimulate flow of natural gas from the target shale. Estimates of CH4 flux during the emission event were made using three independent modeling approaches: Gaussian plume dispersion (following both a simple Gaussian plume inversion and the US EPA OTM 33-A method), and a Lagrangian stochastic transport model (WindTrax). The three methods yielded an estimated peak CH4 flux during January 2019 of approximately 70 g s-1. The total mass of CH4 emitted during the six-day venting period was calculated to be 2.9, 4.2 ± 1.4(1σ) and 7.1 ± 2.1(1σ) tonnes CH4 using the simple Gaussian plume model, WindTrax, and OTM-33A methods, respectively. Whilst the flux approaches all agreed within 1σ uncertainty, an estimate of 4.2 (± 1.4) tonnes CH4 represents the most confident assessment due to the explicit modeling of advection and meteorological stability permitted using the WindTrax model. This mass is consistent with fluxes calculated by the Environment Agency (in the range 2.7 to 6.8 tonnes CH4), using emission data provided by the shale site operator to the regulator. This study provides the first CH4 emission estimate for a nitrogen lift process and the first-reported flux monitoring of a UK shale gas site, and contributes to the evaluation of the environmental impacts of shale gas operations worldwide. This study also provides forward guidance on future monitoring applications and flux calculation in transient emission events. Implications: This manuscript discusses atmospheric measurements near to the UK's first hydraulic fracturing facility, which has very high UK public, media, and policy interest. The focus of this manuscript is on a single week of data in which a large venting event at the shale gas site saw emissions of ~4 tonnes of methane to atmosphere, in breach of environmental permits. These results are likely to beresults are likely to be reported by the media and may influence future policy decisions concerning the UK hydraulic fracturing industry.

Assessing the environmental sustainability of an emerging energy technology: Solar thermal calcination for cement production.

Cement production is a highly energy-intensive process, contributing 7% to global CO2 emissions. Over 80% of the energy used in cement production is consumed by the calcination process. This paper considers a novel solar thermal technology for calcination, to investigate if it could help mitigate the climate change and other environmental impacts from cement production on a life cycle basis. The following three solar options are compared to conventional fossil-fuel calcination via life cycle assessment: a full solar system, which provides all the required thermal energy, and two hybrid systems, where the solar system provides 14% and 33% of the thermal energy, respectively. The results show that all three solar options have lower impacts than conventional calcination in 14 out of 17 categories. The full solar system is the best alternative, with major reductions in climate change (48%), fossil depletion (75%), photochemical ozone formation (92%) and terrestrial ecotoxicity (79%). Based on insolation levels in different parts of the world, the solar systems could be applied to 26% of current global cement production. This would reduce the climate change impact by 15-40%, as well as most other impacts by 14-87%, depending on the fuel mix. However, a limiting factor might be two times greater land occupation than by the conventional process. Furthermore, the solar system has higher human toxicity-cancer (102%) and metals and minerals depletion (6%) due to the construction of solar facilities. Coupling conventional calcination with carbon capture and storage (CCS) is more efficient in reducing the climate change impact (63%) than the solar system (48%) relative to conventional calcination without CCS. However, adding CCS to the solar calciner would still be a better option, decreasing the impact by 81% relative to conventional calcination without CCS. These findings will be of interest to the solar and cement industries as well as other industrial sectors using high-temperature processes.

Environmental assessment of domestic water supply options for remote communities.

Access to clean water is one of the targets in the UN Sustainable Development Goals. However, millions of people are still without basic water services, predominantly in rural areas in developing nations. Previous studies have investigated the environmental impacts of water provision, but they mostly focused on large-scale urban systems. This paper considers for the first time the life cycle environmental impacts of different water supply options applicable to remote communities in developing countries. Focusing on the Southeast Asia-Pacific (SEAP) context, a cradle-to-grave approach is followed to estimate the impacts of locally-sourced groundwater, surface water and desalinated seawater as well as externally-sourced bottled water. The results reveal that surface water is environmentally the most sustainable alternative. Locally desalinated water, powered by diesel electricity, has two orders of magnitude higher impacts than surface water. However, externally-sourced water in plastic bottles is the worst option with 4-155 times higher impacts than desalinated water and up to three orders of magnitude higher impacts than surface water. This is largely due to the impacts related to the production of bottles. Doubling their recycling would reduce the impacts by 7-23% but bottled water would still be environmentally the least sustainable option. Although water in single-use bottles currently provides only 3% of the water supply of a representative remote community in the SEAP region considered in this study, it accounts on average for more than 50% of the total impacts from water consumption. By 2030, population increase could lead to greater reliance of remote communities on bottled water and 60-73% higher impacts of water consumption per household. Relying solely on local surface, ground and water desalinated using solar power and avoiding bottled water would reduce the impacts by 33-99% relative to the current situation. This would also improve considerably water availability and security in remote communities. The findings of this study will be of interest to national and local governments developing future policies aimed at increasing access of remote communities to clean water.

Environmental sustainability of cooking fuels in remote communities: Life cycle and local impacts.

Access to clean cooking fuels and technologies is essential for achieving the Sustainable Development Goals, particularly in developing countries, to minimise human health and environmental impacts. This paper assesses for the first time the environmental sustainability of household cooking, focusing on remote communities in developing countries in the Southeast Asia-Pacific (SEAP) region and considering both life cycle and local impacts. To guide rural development policies, the impacts of the following cooking fuels are considered: liquefied petroleum gas, kerosene, wood, charcoal, crop residues, biogas and electricity. Both the present situation and three future (2030) scenarios are evaluated on 18 life cycle impacts, as well as on local environmental and health impacts caused by cooking. The results show that electricity is the worst option in 13 out of 18 life cycle categories since it is generated from diesel in off-grid communities. Biogas from manure is the best fuel with 16 lowest life cycle impacts. Biomass fuels can have lower life cycle impacts than fossil fuels but they have high combustion emissions which lead to higher local environmental and health impacts. Future scenarios with higher biomass utilisation have up to 47 times lower life cycle impacts than at present, but 4-23% higher local impacts. Health impacts related to fuel combustion are higher in Vietnam, the Philippines, Cambodia, Laos and Myanmar compared to the other SEAP countries due to regional background pollutant concentrations and health trends. A fuel mix with liquefied petroleum gas, biogas and renewable electricity offers considerable reductions in 13 life cycle impacts compared to the present situation, while also reducing local health impacts by 78-97%. A self-sufficient fuel mix with local biomass and renewable electricity would reduce 17 out of 18 life cycle impacts, but all local impacts, including on health, would be 11-28% higher than at present. The results from this study can be used by policy makers and other stakeholders to develop policies for clean cooking in remote communities and reduce both environmental and human health impacts.

Assessing the Climate Change Mitigation Potential of Stationary Energy Storage for Electricity Grid Services.

This paper presents a life cycle assessment for three stationary energy storage systems (ESS): lithium iron phosphate (LFP) battery, vanadium redox flow battery (VRFB), and liquid air energy storage (LAES). The global warming potential (GWP) is assessed in relation to uncertainties in usage of the storage, use-phase energy input, cell replacement, and round-trip efficiency parameters. Relative climate change mitigation potential in comparison with equivalent diesel electric and natural gas generation is discussed, as is the effect of recycling at end of life. With variations in input electricity source, recycling, and efficiency, the life cycle global warming potential for LFP ranges from 185 to 440 kg CO2 eq/MWh, for VRFB from 121 to 443 kg CO2 eq/MWh, and for LAES from 48 to 203 kg CO2 eq/MWh. In all cases, there are climate change mitigation benefits compared to fossil fuel alternatives. Use of renewable energy for charging and operation, ease of component recycling/reuse, and reduced parts replacement is shown to reduce GWP. The climate change mitigation potential of ESS for electricity grid operation is further enhanced by increasing use of the storage assets. Recycling of ESS is shown to reduce terrestrial acidification, freshwater eutrophication, and particulate matter impacts. Reduced ozone depletion potential for VRFB and LFP can be achieved by reducing nafion and PVDF components, respectively.

Collaborating constructively for sustainable biotechnology.

Tackling the pressing sustainability needs of society will require the development and application of new technologies. Biotechnology, emboldened by recent advances in synthetic biology, offers to generate sustainable biologically-based routes to chemicals and materials as alternatives to fossil-derived incumbents. Yet, the sustainability potential of biotechnology is not without trade-offs. Here, we probe this capacity for sustainability for the case of bio-based nylon using both deliberative and analytical approaches within a framework of Constructive Sustainability Assessment. We highlight the potential for life cycle CO2 and N2O savings with bio-based processes, but report mixed results in other environmental and social impact categories. Importantly, we demonstrate how this knowledge can be generated collaboratively and constructively within companies at an early stage to anticipate consequences and to inform the modification of designs and applications. Application of the approach demonstrated here provides an avenue for technological actors to better understand and become responsive to the sustainability implications of their products, systems and actions.

Environmental impacts of copper­indium­gallium-selenide (CIGS) photovoltaics and the elimination of cadmium through atomic layer deposition.

Thin-film technologies have been part of the rapidly-expanding solar photovoltaics (PV) market for many years, led by cadmium-telluride (CdTe) and copper­indium­gallium-selenide (CIGS). However, their environmental impacts remain largely unknown, particularly considering state-of-the-art CIGS manufacturing techniques. This study estimates the life cycle environmental impacts of CIGS PV installations in the UK and Spain, including balance-of-system components, using real manufacturing data. It also analyses newly-developed CIGS, replacing the cadmium sulphide (CdS) buffer layer with zinc oxysulphide (Zn(O,S)) via atomic layer deposition (ALD). The results show that UK installations have 72% higher impacts than those in Spain, including climate change (25.1 vs 14.6 g CO2 eq./kWh). The inverter and electrical components are the main contributors (46% on average), followed by the PV modules (41%). In comparison to CdTe, mono-Si and multi-Si PV, CIGS has 6%-90% lower impacts in 16 out of 18 categories, including climate change (16%-50% lower). However, metal depletion is five times higher, and land use 12%-31% greater. The replacement of CdS has a small but positive effect, demonstrating that cadmium can be eliminated from the CIGS life cycle without environmental penalties. These results will be of interest to PV manufacturers and policy makers, indicating improvement opportunities and areas for policy intervention.

Environmental sustainability assessment of ready-made baby foods: Meals, menus and diets.

Although there is a growing body of literature on the environmental impacts of food, virtually none of the studies has addressed baby foods. Therefore, this work explored the life cycle environmental impacts of different ready-made baby foods, both at the level of individual meals and their combinations within a weekly menu. Twelve different meals were considered, based on baby food products available on the UK market, spanning breakfast, lunch and dessert. Menus following four different diets - omnivorous, vegetarian, pescatarian and dairy-free - were also evaluated. The results showed that, on average, lunch meals had the highest impacts and desserts the lowest. Breakfast has either intermediate (wet porridge) or low (dry porridge) impacts. Among the lunch meals, spaghetti Bolognese and salmon risotto had the highest impacts and among the desserts, strawberry, raspberry and banana as well as apple, pear and banana purees had the lowest. The key hotspots across the meals were raw materials and packaging. Meals with more meat and cream were found to have higher impacts. Manufacturing also played a significant role for global warming potential as well as depletion of fossil resources and the ozone layer due to the fossil fuels used in the process. When the impacts were analysed per mass of baby food consumed weekly, the dairy-free diet had higher impacts than the other three, but the difference among them was relatively small. The trends changed when nutritional value was taken into account, with the dairy-free diet exhibiting considerably higher impacts per unit of energy content. In that case, the pescatarian diet became the best option for most impacts. There was little difference between the omnivore and vegetarian diets. It is expected that these results will be of interest to baby food manufacturers and consumers, helping them to make more informed manufacturing and purchasing decisions.

Economic sustainability of food supply chains: Life cycle costs and value added in the confectionary and frozen desserts sectors.

The confectionary and frozen desserts sectors are important parts of the food industry but have received relatively little attention from a life cycle cost perspective. Thus, the purpose of the current study is to evaluate the life cycle costs (LCC) and value added (VA) in these sectors in the UK, focusing on four major product categories: biscuits, cakes (ambient and frozen), chocolates and ice cream. In total, 18 products are considered along their life cycles, including the raw materials, manufacturing, packaging, distribution, retail, consumption and waste management stages. The results suggest that cakes have the highest LCC (£1.52-2.64/kg) and the biscuits the lowest (£0.72-0.91/kg). The LCC of chocolates and ice cream fall within a similar range (£1.16-1.46/kg and £1.03-1.30/kg, respectively). Divergent trends are noted between LCC and VA: for instance, 'premium' ice creams have only 18% higher costs than their 'regular' counterparts, but a four-fold higher VA. For all the products, raw materials contribute most to the costs (43%-95%), followed by packaging (1%-29%) and manufacturing (1%-14%). The annual LCC at the sectoral level are estimated at £3.455 billion, to which biscuits contribute 42%. The share of chocolates and cakes is 24% and 19%, respectively, with ice cream contributing the remaining 15%. By contrast, chocolates contribute more than 50% of the total sectoral VA, which is five-fold higher than that of ice cream. The study also demonstrates how LCC can be used to evaluate the eco-efficiency of products and sectors. With respect to global warming potential, whole cakes are the most eco-efficient and vanilla regular ice cream the least efficient products. Overall, the confectionary sector is nearly 60% more eco-efficient than the frozen desserts sector. These results can be used for benchmarking and to drive innovation towards more economically-sustainable and eco-efficient confectionary and frozen desserts supply chains.

Aligning sustainability assessment with responsible research and innovation: Towards a framework for Constructive Sustainability Assessment.

Emerging technologies are increasingly promoted on the promise of tackling the grand challenge of sustainability. A range of assessment and governance approaches seek to evaluate these claims, but these tend to be applied disparately and lack widespread operationalisation. They also face specific challenges, such as high levels of uncertainty, when it comes to emerging technologies. Building and reflecting on both theory and practice, this article develops a framework for Constructive Sustainability Assessment (CSA) that enables the application of sustainability assessments to emerging technologies as part of a broader deliberative approach. In order to achieve this, we discuss and critique current approaches to analytical sustainability assessment and review deliberative social science governance frameworks. We then develop the conceptual basis of CSA - blending life-cycle thinking with principles of responsible research and innovation. This results in four design principles - transdisciplinarity, opening-up, exploring uncertainty and anticipation - that can be followed when applying sustainability assessments to emerging technologies. Finally, we discuss the practical implementation of the framework through a three-step process to (a) formulate the sustainability assessment in collaboration with stakeholders, (b) evaluate potential sustainability implications using methods such as anticipatory life-cycle assessment and (c) interpret and explore the results as part of a deliberative process. Through this, CSA facilitates a much-needed transdisciplinary response to enable the governance of emerging technologies towards sustainability. The framework will be of interest to scientists, engineers, and policy-makers working with emerging technologies that have sustainability as an explicit or implicit motivator.

Assessing the environmental sustainability of electricity generation in Chile.

Around 40% of electricity in Chile is supplied by renewables and the rest by fossil fuels. Despite the growing electricity demand in the country, its environmental impacts are as yet unknown. To address this gap, the current study presents the first comprehensive assessment of the life cycle environmental sustainability of electricity generation in Chile. Both the individual sources and the electricity mix over the past 10 years are considered. The following sources present in the electricity mix are evaluated: coal, oil, natural gas, biogas, biomass, wind, solar photovoltaics (PV) and hydropower. In total, 10 electricity technologies and 174 power plants installed across the country have been considered. Eleven environmental impacts have been estimated, including global warming, human toxicity, ecotoxicities, as well as resource and ozone layer depletion. The results reveal that hydropower is environmentally the most sustainable option across the impacts, followed by onshore wind and biogas. Electricity from natural gas has 10%-84% lower impacts than biomass for seven categories. It is also 13%-98% better than solar PV for six impacts and 17%-66% than wind for four categories. Solar PV has the highest abiotic depletion potential due to the use of scarce elements in the manufacture of panels. While electricity generation has grown by 44% in the past 10 years, all the impacts except ozone layer depletion have increased by 1.6-2.7 times. In the short term, environmental regulations should be tightened to improve the emissions control from coal and biomass plants. In the medium term, the contribution of renewables should be ramped up, primarily increasing the hydro, wind and biogas capacity. Coal and oil should be phased out, using natural gas as a transitional fuel to help the stability of the grid with the increasing contribution of intermittent renewables.

Environmental impacts of chocolate production and consumption in the UK.

This study evaluates life cycle environmental impacts associated with chocolate products made and consumed in the UK. The paper focuses on three representative chocolate products occupying 90% of the market: 'moulded chocolate', 'chocolate countlines' and 'chocolates in bag'. The impacts were estimated using life cycle assessment (LCA) as a tool and following the ReCiPe impact assessment method. The water footprint was also considered. For example, the global warming potential ranges between 2.91 and 4.15 kg CO2 eq., primary energy demand from 30 to 41 MJ and the water footprint, including water stress, from 31 to 63 l per kilogram of chocolate. The raw materials are the major hotspot across all impact categories for all three product types, followed by the chocolate production process and packaging. The raw material impacts are mainly due to milk powder, cocoa derivatives, sugar and palm oil. The sensitivity analysis shows that the results for global warming potential are sensitive to land-use change (LUC) associated with cocoa production, increasing the impact of the chocolate products by three to four times if LUC is involved. The improvement opportunities targeting the key contributing stages suggest that GWP of chocolates could be reduced by 14%-19%. Chocolate countlines have the highest contribution to the total impacts at the UK level (37%-43%), followed by chocolates in bag (28%-33%). Moulded chocolates and other chocolate confectionary make up the rest of the impacts, with a roughly equal share each. Chocolate consumption in the UK contributes 4.7% to the primary energy consumption and 2.4% to the GHG emissions from the whole food and drink sector. The results of this work will be of interest to policy makers, chocolate producers and consumers, helping them to make more informed decisions towards sustainable production and consumption of chocolate products.

Sustainability of UK shale gas in comparison with other electricity options: Current situation and future scenarios.

Many countries are considering exploitation of shale gas but its overall sustainability is currently unclear. Previous studies focused mainly on environmental aspects of shale gas, largely in the US, with scant information on socio-economic aspects. To address this knowledge gap, this paper integrates for the first time environmental, economic and social aspects of shale gas to evaluate its overall sustainability. The focus is on the UK which is on the cusp of developing a shale gas industry. Shale gas is compared to other electricity options for the current situation and future scenarios up to the year 2030 to investigate whether it can contribute towards a more sustainable electricity mix in the UK. The results obtained through multi-criteria decision analysis suggest that, when equal importance is assumed for each of the three sustainability aspects shale gas ranks seventh out of nine electricity options, with wind and solar PV being the best and coal the worst options. However, it outranks biomass and hydropower. Changing the importance of the sustainability aspects widely, the ranking of shale gas ranges between fourth and eighth. For shale gas to become the most sustainable option of those assessed, large improvements would be needed, including a 329-fold reduction in environmental impacts and 16 times higher employment, along with simultaneous large changes (up to 10,000 times) in the importance assigned to each criterion. Similar changes would be needed if it were to be comparable to conventional or liquefied natural gas, biomass, nuclear or hydropower. The results also suggest that a future electricity mix (2030) would be more sustainable with a lower rather than a higher share of shale gas. These results serve to inform UK policy makers, industry and non-governmental organisations. They will also be of interest to other countries considering exploitation of shale gas.