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Approximately a third of all annual greenhouse gas emissions globally are directly or indirectly associated with the food system, and over a half of these are linked to livestock production. In temperate oceanic regions, such as the UK, most meat and dairy is produced in extensive systems based on pasture. There is much interest in the extent to which such grassland may be able to sequester and store more carbon to partially or completely mitigate other greenhouse gas emissions in the system. However, answering this question is difficult due to context-specificity and a complex and sometimes inconsistent evidence base. This paper describes a project that set out to summarize the natural science evidence base relevant to grassland management, grazing livestock and soil carbon storage potential in as policy-neutral terms as possible. It is based on expert appraisal of a systematically assembled evidence base, followed by a wide stakeholders engagement. A series of evidence statements (in the appendix of this paper) are listed and categorized according to the nature of the underlying information, and an annotated bibliography is provided in the electronic supplementary material. [ABSTRACT FROM AUTHOR]

The roles digital media-technologies play in raising public issues relating to emerging technologies and their potential for engaging publics with science and policy assessments is a lively field of inquiry in Science and Technology Studies (STS). This paper presents an analysis of controversies over proposals for the large-scale removal of atmospheric carbon dioxide (CDR). The study combines a digital method (web-querying) with document analysis to map debates about two CDR approaches: bioenergy with carbon capture and storage (BECCS) and afforestation. In the first step, we locate actors using the web to engage with BECCS and afforestation and map their alignments in relation to competing framings of CDR. In a second step, we examine the devices deployed by UK-based actors to evidence and contest the feasibility of BECCS and afforestation. Our analysis shows that policy distinctions between "natural" and "engineered" CDR are used flexibly in practice and do not map neatly onto actor engagement with BECCS and afforestation. We highlight the predominance of cross-cutting techno-economic expertise and argue that framings of CDR as a solution to governing climate change may contribute to public disengagement from climate policy processes. The paper reflects on methods for studying controversies, publics, and issues emerging around processes of technoscientific assessment. [ABSTRACT FROM AUTHOR]

Hydrogen is an emerging technology changing the context of heating with cleaner combustion than traditional fossil fuels. Studies indicate the potential to repurpose the existing natural gas infrastructure, offering consumers a sustainable, economically viable option in the future. The integration of hydrogen in combined heat and power systems could provide residential energy demand and reduce environmental emissions. However, the widespread adoption of hydrogen will face several challenges, such as carbon dioxide emissions from the current production methods and the need for infrastructure modification for transport and safety. Researchers indicated the viability of hydrogen in decarbonizing heat, while some studies also challenged its long-term role in the future of heating. In this paper, a comprehensive literature review is carried out by identifying the following key aspects, which could impact the conclusion on the overall role of hydrogen in heat decarbonization: (i) a holistic view of the energy system, considering factors such as renewable integration and system balancing; (ii) consumer-oriented approaches often overlook the broader benefits of hydrogen in emission reduction and grid stability; (iii) carbon capture and storage scalability is a key factor for large-scale production of low-emission blue hydrogen; (iv) technological improvements could increase the cost-effectiveness of hydrogen; (v) the role of hydrogen in enhancing resilience, especially during extreme weather conditions, raises the potential of hydrogen as a flexible asset in the energy infrastructure for future energy supply; and finally, when considering the UK as a basis case, (vi) incorporating factors such as the extensive gas network and unique climate conditions, necessitates specific strategies. [ABSTRACT FROM AUTHOR]

Meeting the goal of reaching zero emissions by 2050 requires profound changes in the production of bulk materials, cement and concrete. For construction sector, this transition is also dependent on the evolution of demand, stemming from changes in the population structure and practice in structural design. Many timelines have been produced suggesting pathways to zero emissions, but none have looked at the required investment level, or the feasibility of transition looking at the level of single plants being shut, transformed or built within a single country. In this paper, we have looked at transition pathways in the United Kingdom as a function of the available funding and the possible emergence of transformative technologies. We find that trade is a necessary component of the transition, allowing for continued construction while the production apparatus is upgraded. Our results further suggest that the current level of investment is consistent with today's carbon price but falls short of what is necessary to achieve net zero by 2050. Finally we find that pathways assuming that CCS will be available at scale are particularly susceptible to overshoot their emissions target if the technological deployment fails to materialise. This is because they combine heavy investments, immature technology and concentrated risk. [Display omitted] [ABSTRACT FROM AUTHOR]

Energy system optimization is needed for optimal sustainable net-zero electricity (NZE) mix even at regional/local scales because of the energy storage needs for addressing the intermittency of renewable energy supply. This study presents a novel regional/local energy planning model for optimum sustainable NZE mix under spatiotemporal climate/meteorological and electrical load demand constraints. A generic robust non-linear constrained mathematical programming (NLP) algorithm has been developed for energy system optimization; it minimizes the levelized cost and greenhouse gas emissions while maximizing reliability against stored energy discharge analysis (RADA). Reliability, defined as the ratio of excess stored renewable power discharge to unmet load demand, is a measure of the extent of unmet load demand met by the excess stored renewable power. Coupled with the NLP, the RADA and energy storage evaluations are used to determine the seasonal energy storage (SES) conditions and realistic renewable proportions for NZE. The significance of the proposed framework lies in determining the maximum hours of viable electrical energy storage beyond which the reliability enhancement is infinitesimal. The significant observations of this work include 96 h of maximum viable electrical energy storage beyond which the reliability enhancement is infinitesimal. While this observation is robust based on previous reports for the case of the United States, a realistic NZE mix for Southern United Kingdom is obtained as follows. Direct wind and solar sources can meet 63%, 62%, and 55% of the electricity demands in the southwest, Greater London, and southeast regions of the United Kingdom, respectively; further, battery energy storage systems can increase the renewable proportions by 21%, 22%, and 13% in these three regions. The unmet demands can be met by renewable electricity through SES. Compressed air energy storage (CAES) and pumped hydro storage offer viable SES. Following these, natural gas with carbon capture and storage (CCS), bioenergy, and hydrogen SES are the choices based on increasing cost per lifecycle climate impact potential to meet the electricity demands. [ABSTRACT FROM AUTHOR]

Delivering low-carbon heat will require the substitution of natural gas with low-carbon alternatives such as electricity and hydrogen. The objective of this paper is to develop a method to soft-link two advanced, investment-optimising energy system models, RTN (Resource-Technology Network) and WeSIM (Whole-electricity System Investment Model), in order to assess cost-efficient heat decarbonisation pathways for the UK while utilising the respective strengths of the two models. The linking procedure included passing on hourly electricity prices from WeSIM as input to RTN, and returning capacities and locations of hydrogen generation and shares of electricity and hydrogen in heat supply from RTN to WeSIM. The outputs demonstrate that soft-linking can improve the quality of the solution, while providing useful insights into the cost-efficient pathways for zero-carbon heating. Quantitative results point to the cost-effectiveness of using a mix of electricity and hydrogen technologies for delivering zero-carbon heat, also demonstrating a high level of interaction between electricity and hydrogen infrastructure in a zero-carbon system. Hydrogen from gas reforming with carbon capture and storage can play a significant role in the medium term, while remaining a cost-efficient option for supplying peak heat demand in the longer term, with the bulk of heat demand being supplied by electric heat pumps. [Display omitted] • A multi-model approach is proposed to link two established energy system models. • Iterating between the two models focused on low-carbon heat and electricity sectors. • Various technologies are considered for electricity and heat decarbonisation. • Contributions of hydrogen and electricity to heat supply are assessed until 2050. • Evolution of the cost-effective portfolio of hydrogen sources is characterised. [ABSTRACT FROM AUTHOR]

Hydrogen has been identified as a potential gamechanger and ambitious national targets have been announced by many governments around the world. However, the lack of clear policy signals at the country level remains a barrier and significant cost reduction progress is unlikely to be made unless the issue is addressed. The paper aims to assess whether current UK energy policies support an economic case for low-carbon and competitive H2 production. A financial model is developed for hypothetical H2 projects based in the UK. Price assumptions are assigned to a specific set of policies in combination with the key technical considerations for H2 production and estimated return. The study concludes that H2 development featuring electrolysers or carbon capture and storage cannot rely on market forces alone to reach full commercialisation and competitiveness in the UK. While policies improve the economic case for H2 in some key areas, existing frameworks are not ambitious enough to advance the transition to low carbon options such as Blue and Green H2. Moreover, current policies do not sufficiently disincentivise investments in emission-intensive alternatives. • Explore potential for power-to-gas and steam methane reforming H2 with CCS in the UK. • Consider how current energy policy impacts the economics of both H2 production types. • Power-to-gas H2 can profit from security of supply policies and market-based support. • Blue H2 represents high-risk investment due to depleting domestic gas resources. • Current carbon price is too low to stimulate investment in low-carbon H2 projects. [ABSTRACT FROM AUTHOR]

Carbon capture usage and storage (CCUS) is emerging as an important solution in delivering deep emissions reductions in energy-intensive industries, enabling hydrogen production, and possibly directly capturing existing carbon dioxide (CO 2) from the atmosphere. The potential for associated new industry activity – for example in CO 2 Transport and Storage (T&S) – could also be important in transitioning economies with legacy investment in oil and gas extraction. This paper addresses the question of how introducing a nascent T&S industry may impact the wider UK economy in the presence of persisting national labour supply constraints. It does so by refining a multi-sector economy-wide computable general equilibrium (CGE) model of the UK to run scenarios focussed on the emergence of a nascent sector, involving identification of benchmark activity – here, the existing oil and gas industry – where that nascent sector is not currently represented in national accounting data. Crucially, the CGE model embeds a theoretically and empirically tested wage bargaining function to consider how cost and price pressures triggered will condition dynamic outcomes for producers, consumers and government budgets. Results suggest that emergence of a new T&S industry is likely to deliver sustained net gains in UK employment and GDP. However, maximising T&S-linked jobs gains while minimising displacement of employment and price pressures elsewhere in the economy requires policy action to alleviate labour supply and skills constraints. This reinforces policy and industry recommendations around the need for net zero workforce planning and attention to the potential fiscal implications of taking action, or not/in different timeframes. • Introducing a new CO 2 Transport and Storage industry could boost the UK economy. • Wage responses in a supply constrained labour market substantially condition outcomes. • Wage-cost driven price impacts affect all producers, consumers and government budgets. • Mitigating wage bargaining pressure requires policy action on workforce planning. • Findings reinforce the need for economy-wide and fiscal analysis of net zero actions. [ABSTRACT FROM AUTHOR]

From an economic perspective, Scots pine (Pinus sylvestris L.) is one of Europe's most important tree species. It is characterized by its wide ecological adaptability across its natural range. This research aimed to evaluate the forest structure, productivity and especially radial growth of heterogenous pine stands in 16 research plots in the Czech Republic, Poland, Spain and Great Britain. The study assessed the tree-ring formation and its relationship to climate change for each country, using 163 dendrochronological samples. The stand volume of mature pine forest ranged between 91 and 510 m3 ha−1, and the carbon sequestration in the tree biomass was 40–210 t ha−1. The stands had a prevailing random distribution of trees, with a high vertical structure close to selection forests (forest stands with typical very diverse height, diameter and age structure). Spectral analyses showed a substantial decrease in fluctuations in the tree-ring index and a loss in natural growth cyclicity in the last thirty years. The results also evinced that mean air temperature was the most important factor influencing the radial growth compared to precipitation totals. Pine thrives in precipitation-stable locations, as shown by the results from Great Britain. The conclusions of this study confirm the fundamental effect of ongoing global climate change on the dynamics and growth of pine forests in Europe. [ABSTRACT FROM AUTHOR]

Ponds are aquatic habitats defined by their small size. Although small they are found on every continent, they are disproportionately rich in aquatic biodiversity, benefit terrestrial wildlife and have important ecosystem function benefits. One of these benefits might be carbon sequestration, a possibility suggested by (1) their abundance, (2) the intensity of their biogeochemical activity. Whilst greenhouse gas fluxes from ponds have been monitored widely, quantifying the stocks of organic carbon buried in sediment is a gap in our knowledge. Here we summarise measures of organic carbon in pond sediments cores from a diverse range of lowland ponds in England. We estimate a general measure of 9.38 kg OC in a 1 m2 × 20 cm block of pond sediment and scale this up to an overall estimate for Great Britain of 2.63 million tons of OC in pond sediment, with 95% CI of 1.41 to 3.84 million tons. The relationship between sediment carbon and gas fluxes remains a significant unknown. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) emissions occur as a consequence of the turnover of soil nitrogen (N), but gross N transformations and N2O production are often not studied in combination, so the relationships are poorly understood. Here, we quantified gross N transformations and the N2O production pathway of alkaline fluvo-aquic soils under different fertilization regimes collected from a long-term field experiment in the North China Plain and compared them with six acidic UK soils (one was alkaline for reference) with high soil organic carbon (SOC). We found that nitrification was the dominant N2O production pathway in the alkaline Chinese soil with a contribution of nitrification to N2O emissions (N2Onit) of 81%. By contrast, denitrification was the main N2O production pathway for the acidic UK soils with the contribution of denitrification to N2O emissions (N2Oden) of 66%. Long-term manure applications significantly increased N2Oden, compared to the synthetic N and no N treatments (25% vs. 18%). The N2Onit was positively correlated with gross autotrophic nitrification rates and pH but negatively correlated with gross N mineralization, SOC, soil total N content, and C:N ratios. Our findings highlight the importance of soil pH in controlling the N2O production in cropland soils, and suggest that the increased contribution of denitrification to N2O emissions should be considered, when increasing SOC through long-term manure and straw management for carbon sequestration and soil fertility improvement. [ABSTRACT FROM AUTHOR]

Previous research investigating the UK economy impacts of introducing a new Scottish CO2 Transport and Storage (T&S) industry linked to carbon capture and storage (CCS) has focussed on supply chain and funding requirements in introducing such a new sector to service proximate Scottish industrial emissions via onshore pipelines. However, Scottish plans extend to shipping CO2 from outside Scotland for storage in North Sea reservoirs by also servicing sequestration requirements from elsewhere in the UK and/or overseas. This will involve investment in greater industry capacity but could ease associated domestic funding requirements. Here, we introduce improved economy-wide structural (input-output) data reflecting how a Scottish T&S sector may emerge from current Oil and Gas industry supply chain capacity to a computable general equilibrium (CGE) model, extending to simulate emergence of an export base. Our central finding is that exploiting overseas T&S export opportunities is crucial where the policy aim is to generate greater economic activity without increasing demands on the public purse. However, any extent of real wage bargaining and consequent producer cost pressure as labour demand increases will act to dampen expansionary power, displacing export production and employment, while driving consumer price impacts that limit real income and public budget gains. [ABSTRACT FROM AUTHOR]

Peatlands are a vast global carbon store. Both climate change and management have shaped peatlands over millennia, sometimes negatively, sometimes positively. Across the globe, prescribed fire is an important and well-recognised vegetation management tool used to promote biodiversity, increase habitat heterogeneity and mitigate uncontrolled wildfires. However, in the UK, there is an ongoing debate about the efficacy and legitimacy of using prescribed fire as a vegetation management tool. The debate centres around the extent to which prescribed burning is associated with a decline in habitat status and ecological function, especially in relation to carbon storage within heather-dominated blanket bog peatlands. Robust reviews of the evidence base are thus required to disentangle this debate and inform land management policies that ensure the protection and enhancement of blanket bog ecological functioning. Here, we critically review "Carbon storage and sequestration by habitat: a review of the evidence (second edition)" by Gregg et al., 2021. We see the value in synthesising the evidence on this topic but question the methodological approach used by Gregg et al. Another concern is their misrepresentation of evidence relating to prescribed burning impacts on blanket bog ecosystems and carbon budgets. We highlight these issues by focusing on the relevant peatland sections within the review by Gregg et al. and conclude by making a series of recommendations to improve the review's scientific robustness and, thereby, its value to academics, land managers and policymakers. [ABSTRACT FROM AUTHOR]

The UK government has pledged to achieve net-zero greenhouse gas emissions by 2050. Ambitious targets have been set to plant nearly a million hectares of new woodland in the UK by 2050 to meet these net-zero commitments. More than 70% of UK's land is used for agricultural production and to meet these targets the Climate Change Committee has estimated that by 2050 approximately 21% of agricultural land will be required for tree planting, agroforestry and the extension of farm hedges. Achieving this creates a potential conflict between land for food production and land for carbon sequestration. However, trees and woodlands, when integrated into farming systems, can be multifunctional and play a significant role in helping farmers adapt and become more resilient in the face of climate change. Over the last 100 years numerous government policies and incentive schemes have endeavoured to encourage more tree planting activities amongst farmers and landowners with varying degrees of success. This paper reviews the role of policy in determining the presence of trees in the UK's agricultural landscape over the past 100 years. We quantify the current extent of woodland and tree cover and aim to put the UK's net-zero tree planting targets in the context of historical agricultural land use patterns. We evaluate drivers behind the current extent of trees, woodland and agroforestry on UK farms and identify key elements of success in current and previous policies and incentive schemes to help inform future policy mechanisms for the UK to meet its tree planting targets. Farmers are increasingly under pressure to deliver a wide range of environmental goals as well as producing food. The effectiveness of financial incentives to influence tree planting is dependent on the pre-existing interest and values of the farmer or landowner and grants alone may not be sufficient to encourage farmers to plant trees. Scheme complexity, bureaucracy and insufficient payment rates are barriers to the success of woodland grants and agri-environment schemes. Simplicity is important to encourage uptake, however oversimplification of schemes can lead to unintended consequences. Advice and guidance are key elements in the successful adoption of any new land management methods. A key to future progress will be scheme flexibility to enable farmers to choose to plant trees where it best suits local conditions, to align policy tools with farmer values and to ensure that farmers and landowners have the knowledge and support to make these decisions. • The effectiveness of financial incentives to influence tree planting depends on the pre-existing interest and values of the farmer or landowner. • Key to future progress will be enabling farmers to choose to plant trees where it best suits local conditions. • Tree planting grants co-designed with stakeholders, ensuring barriers are considered are likely to have improved uptake. • Scheme simplicity and flexibility are important, but care is needed that a simplification of schemes does not allow for undesirable outcomes. • Policy tools need to be aligned with farmer values and tailored high-quality advice and guidance available. [ABSTRACT FROM AUTHOR]

• Clusters approach can support industrial decarbonisation, essential for net zero. • Cluster activities mapped against seven pillars of social licence to operate (SLO). • Industrial decarbonisation needs social licence for different scales and systems. • Stakeholder narratives and networks support CCS SLO in industrial clusters. • Important to recognise local benefits, align priorities and develop partnerships. This paper explores the opportunities for, and progress in, establishing a social licence to operate (SLO) for CCS in industrial clusters in the UK, focusing on the perspectives of key stakeholders. The evolution of narratives and networks relating to geographical clusters as niches for CCS in industrial decarbonisation is evaluated in relation to seven pillars supporting SLO. Evidence is drawn from a combination of cluster mapping, documentary analysis and stakeholder interviews to identify the wider contexts underpinning industrial decarbonisation, stakeholder networks, interaction and communication, critical narratives, the conditions for establishing trust and confidence, different scales of social licence and maintaining a SLO. The delivery of a sustainable industrial decarbonisation strategy will depend on multiple layers of social licence involving discourses at different scales and, potentially, for different systems (heat, transport, different industrial processes). Despite setbacks as a result of funding cancellations and changes to government policy, the UK is positioned to be at the forefront of CCS deployment. While there is a high ambition and a strong narrative from government of the urgency to accelerate projects involving CCS, clear coordinated strategy and funding frameworks are necessary to build confidence that UK policy is both compatible with net zero and economically viable. [ABSTRACT FROM AUTHOR]

• I develop a novel method for public appraisal of five policy relevant CDR methods. • The British public support the inclusion of CDR in UK climate policy. • 'Natural' CDR is preferred but likely a result of prevailing Romanticist thought. • 'Technological' CDR is less polarising and may be held back by the nature framing. • Highest support is from egalitarians, older people, men, and higher social grades. Efforts to deliver on net zero emissions targets are set to rely on carbon dioxide removal (CDR) methods. Democratic, trustworthy and socially intelligent research, development, demonstration and deployment of CDR methods in aid of net zero will be highly dependent on how different publics evaluate them, and ultimately which groups support or oppose them. This paper develops a novel, nationally representative method for the multi-criteria appraisal of five policy relevant CDR methods – plus an option not to pursue CDR at all – by members of the British public (n = 2,111). The results show that the public supports the inclusion of CDR in UK climate policy. CDR methods often characterised as 'natural' or 'nature-based' are appraised more highly than 'technological' ones, in the descending order: habitat restoration, afforestation, wood in construction, bioenergy with carbon capture and storage, and direct air carbon capture and storage. Yet, there is no significant disagreement in the appraisal of technological methods and they therefore may be less polarizing, suggesting that popular preconceptions of what is natural – and therefore more attractive – may be holding them back. CDR methods being mainly developed by public sector and non-governmental organisations are also appraised more highly than those being developed by private interests. Regional differences in option appraisal reveal where particular CDR methods are more or less likely to be supported or opposed; stressing the importance of matching physical requirements for CDR with appropriate social contexts. Demographic and socio-economic analyses show that people who appraise CDR methods most highly tend to be older respondents, male, or of a higher social grade. Finally, those with hierarchical worldviews and who voted 'leave' in the UK's referendum on EU membership are less supportive of CDR than those with egalitarian worldviews and who voted 'remain'. [ABSTRACT FROM AUTHOR]

Reaching net‐zero for global greenhouse gas emissions by the year 2050 will require a portfolio of new technologies and approaches, potentially requiring direct removal and sequestration of atmospheric carbon dioxide using negative emissions technologies (NETs). Since energy and climate systems are fundamentally interconnected it is important that we understand the impacts of policy decisions and their associated controversies in other related technologies and sectors. Using a secondary analysis of data from a series of deliberative workshops conducted with lay publics in the United Kingdom, we suggest that perceptions of CO2 removal technologies were negatively impacted by risk perceptions and recent policy decisions surrounding shale gas and fracking. Using the social amplification of risk framework, we argue that heightened risk perceptions have extended via "ripple effects" across these technologies. Participants' attitudes were underpinned by deeper misgivings regarding the actions and motives of experts and policymakers; a pervasive discourse of "but they told us it was safe" regarding fracking negatively affected people's trust in assurances of the safety and efficacy of CO2 removal. This has the potential to undermine attempts to build societal agreement around future deployment of CO2 removal technologies. [ABSTRACT FROM AUTHOR]

• Thermoeconomic models of electricity- and hydrogen-driven technologies are developed. • Technologies are compared from a homeowner's and a whole-energy system perspective. • Hydrogen competitiveness depends on ability to produce it in a cost-effective way. • Electric heat pumps are the least-cost decarbonisation pathway in most scenarios. • Hydrogen-driven absorption heat pumps are competitive to hydrogen boilers. Proposed sustainable transition pathways for moving away from natural gas in domestic heating focus on two main energy vectors: electricity and hydrogen. Electrification would be implemented by using vapour-compression heat pumps, which are currently experiencing market growth in many countries. On the other hand, hydrogen could substitute natural gas in boilers or be used in thermally–driven absorption heat pumps. In this paper, a consistent thermodynamic and economic methodology is developed to assess the competitiveness of these options. The three technologies, along with the option of district heating, are for the first time compared for different weather/ambient conditions and fuel-price scenarios, first from a homeowner's and then from a whole-energy system perspective. For the former, two-dimensional decision maps are generated to identify the most cost-effective technologies for different combinations of fuel prices. It is shown that, in the UK, hydrogen technologies are economically favourable if hydrogen is supplied to domestic end-users at a price below half of the electricity price. Otherwise, electrification and the use of conventional electric heat pumps will be preferred. From a whole-energy system perspective, the total system cost per household (which accounts for upstream generation and storage, as well as technology investment, installation and maintenance) associated with electric heat pumps varies between 790 and 880 £/year for different scenarios, making it the least-cost decarbonisation pathway. If hydrogen is produced by electrolysis, the total system cost associated with hydrogen technologies is notably higher, varying between 1410 and 1880 £/year. However, this total system cost drops to 1150 £/year with hydrogen produced cost-effectively by methane reforming and carbon capture and storage, thus reducing the gap between electricity- and hydrogen-driven technologies. [ABSTRACT FROM AUTHOR]

The current editorial summarized some of the scientific works presented in the Sustainable Energy and Environmental Protection (SEEP) conference-held at the University of the West of Scotland, UK, 2018. The selected work was directly related to the scope of the Renewable, Sustainable Energy Reviews (RSER) journal. During the conference activities, experts from all around the world in the subjects of: renewable energy, climate change, optimization, and economics presented and discussed the progress made in renewable energy sources, as well as the new strategies for protecting the environment from the hazards connected with fossil fuel utilization. The methods presented in the conference focused on several directions: the development of efficient energy conversion systems with low/no environmental impacts; the suggested policies to widespread renewable energies; the restriction in the emission of greenhouse gases, and the recent progresses in CO 2 capture. This editorial focused on the renewable energy developments and their positive effect on the climate change, and briefly summarized the accepted manuscripts in this issue. • Effects of renewable energy on climate change. • Background on the International Conference on Sustainable Energy and Environmental Protection SEEP. • Summary of selected papers of SEEP 2018. [ABSTRACT FROM AUTHOR]

The United Kingdom (UK) has a decarbonisation strategy that includes energy from both hydrogen and biomethane. The latter comes from the growing anaerobic digestion (AD) market, which in 2020 produced 23.3 TWh of energy in the form of biogas. According to the strategy, this must be upgraded to biomethane by removal of carbon dioxide (CO2): a goal that could also be fulfilled through CO2 biomethanisation, alleviating the need for carbon capture and storage. Results are presented from a survey of publicly available datasets coupled with modelling to identify potential scale and knowledge gaps. Literature data were used to estimate maximum biomethane concentrations by feedstock type: these ranged from 79% for food wastes to 93% for livestock manures. Data from various government sources were used to estimate the overall potential for CO2 biomethanisation with current AD infrastructure. Values for the uplift in biomethane production ranged from 57% to 61%, but the need for more consistent data collection methodologies was highlighted. On average, however, if CO2 biomethanisation was applied in all currently operating UK AD plants an energy production uplift of 12,954 GWh could be achieved based on 2020 figures. This is sufficient to justify the inclusion of CO2 biomethanisation in decarbonisation strategies, in the UK and worldwide. [ABSTRACT FROM AUTHOR]

Agroforestry has a potentially important role in helping agriculture address both the climate and biodiversity crises. It provides a means of producing additional marketable goods from agricultural land and enhancing biodiversity at the same time as increasing carbon sequestration and, in silvo-pastural systems, reducing carbon emissions if livestock stocking rates are reduced. However, the uptake of agroforestry in the UK has been limited. This paper adopts Real Options techniques to explore how the decision to adopt agroforestry is influenced by the relative levels of returns from agriculture, forestry and the price of carbon under the scenario where there are financial penalties from livestock Greenhouse Gas (GHG) emissions, financial benefits from carbon sequestration in trees and reversibility in land use decisions. The results are compared to the equivalent findings from a Land Equivalent Value capital budgeting approach to agroforestry adoption. Analysis is based on data from a case study upland livestock farm in Scotland, comparing the impacts of introducing agroforestry into the hill sheep enterprise or the low ground cattle and sheep enterprise. The results suggest that the adoption of agroforestry is far less likely than would be suggested by standard budgeting approaches, especially in more extensive upland enterprises (hill area) where sequestration benefits are low relative to more productive farmland areas (low ground area). Upfront support payments are shown to increase the likelihood of agroforestry adoption. They also have the effect of reducing the rotation length of forestry in such systems. • Real Options techniques are useful for understanding agroforestry adoption. • Agroforestry adoption is unlikely at current carbon price levels. • Biophysical factors have a significant influence on agroforestry adoption. • Upfront payments will significantly increase agroforestry adoption. • Standard budgeting approaches fail to recognise key barriers to agroforestry. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) is an essential tool in the fight against climate change. Any prospective storage site must meet various criteria that ensure the effectiveness, safety and economic viability of the storage operations. Finding the most suitable site for the storage of the captured CO 2 is an essential part of the CCS chain of activity. This work addresses the site selection of a second site for the Acorn CCS project, a project designed to develop a scalable, full-chain CCS project in the North Sea (offshore northeast Scotland). This secondary site has been designed to serve as a backup and upscaling option for the Acorn Site, and has to satisfy pivotal project requirements such as low cost and high storage potential. The methodology followed included the filtering of 113 input sites from the UK CO 2 Stored database, according to general and project-specific criteria in a multi-staged approach. This criteria-driven workflow allowed for an early filtering out of the less suitable sites, followed by a more comprehensive comparison and ranking of the 15 most suitable sites. A due diligence assessment was conducted of the top six shortlisted sites to produce detailed assessment of their storage properties and suitability, including new geological interpretation and capacity calculations for each site. With the new knowledge generated during this process, a critical comparison of the sites led to selection of East Mey as the most suitable site, due to its outstanding storage characteristics and long-lasting hydrocarbon-production history, that ensure excellent data availability to risk-assess storage structures. A workshop session was held to present methods and results to independent stakeholders; feedback informed the final selection criteria. This paper provides an example of a criteria-driven approach to site selection that can be applied elsewhere. • CO 2 storage site selection for the Acorn CCS project in the North Sea. • Criteria-driven approach based on geological, economic, and safety aspects. • Multi-staged methodology including filtering, comparison and ranking of sites. • East Mey selected thanks to its storage characteristics and hydrocarbon history. [ABSTRACT FROM AUTHOR]