• Energy Research

This paper reviews the many criticisms that Integrated Assessment Models (IAMs)—the bedrock of mitigation analysis—have received in recent years. Critics have asserted that there is a lack of transparency around model structures and input assumptions, a lack of credibility in those input assumptions that are made visible, an over-reliance on particular technologies and an inadequate representation of real-world policies and processes such as innovation and behaviour change. The paper then reviews the proposals and actions that follow from these criticisms, which fall into three broad categories: scrap the models and use other techniques to set out low-carbon futures; transform them by improving their representation of real-world processes and their transparency; and supplement them with other models and approaches. The article considers the implications of each proposal, through the particular lens of how it would explore the role of a key low-carbon technology—bioenergy with carbon capture and storage (BECCS), to produce net negative emissions. The paper concludes that IAMs remain critically important in mitigation pathways analysis, because they can encompass a large number of technologies and policies in a consistent framework, but that they should increasingly be supplemented with other models and analytical approaches.

Abstract The analysis of gas emissions by an input–output subsystem approach provides detailed insight into pollution generation in an economy. Structural decomposition analysis, on the other hand, identifies the factors behind the changes in key variables over time. Extending the input–output subsystem model to account for the changes in these variables reveals the channels by which environmental burdens are caused and transmitted throughout the production system. In this paper we propose a decomposition of the changes in the components of CO2 emissions captured by an input–output subsystems representation. The empirical application is for the Spanish service sector, and the economic and environmental data are for years 2000 and 2005. Our results show that services increased their CO2 emissions mainly because of a rise in the emissions generated by non-services to cover the final demand for services. The decomposed effects show a decrease in CO2 emissions due to technological changes between 2000 and 2005 compensated by an increase in emissions caused by the rise in final demand of services. Finally, large asymmetries exist not only in the quantitative changes in the CO2 emissions of the various services but also in the decomposed effects of these changes.

Abstract Bioenergy with carbon capture and storage (BECCS) is envisaged as a critical element of most deep decarbonisation pathways compatible with the Paris Agreement. Such a transformational upscaling—to 3–7 Gt CO2/yr by 2050—requires an unprecedented technological, economic, socio-cultural and political effort, along with, crucially, transparent communication between all stakeholders. Integrated Assessment Models (IAMs) that underpin the 1.5 °C scenarios assessed by IPCC have played a critical role in building and assessing deep decarbonisation narratives. However, their high-level aggregation and their complexity can cause them to be perceived as non-transparent by stakeholders outside of the IAM community. This paper bridges this gap by offering a comprehensive assessment of BECCS assumptions as used in IAMs so as to open them to a wider audience. We focus on key assumptions that underpin five aspects of BECCS: biomass availability, BECCS technologies, CO2 transport and storage infrastructure, BECCS costs, and wider system conditions which favour the deployment of BECCS. Through a structured review, we find that all IAMs communicate wider system assumptions and major cost assumptions transparently. This quality however fades as we dig deeper into modelling details. This is particularly true for sets of technological elements such as CO2 transport and storage infrastructure, for which we found the least transparent assumptions. We also found that IAMs are less transparent on the completeness of their treatment of the five BECCS aspects we investigated, and not transparent regarding the inclusion and treatment of socio-cultural and institutional-regulatory dimensions of feasibility which are key BECCS elements as suggested by the IPCC. We conclude with a practical discussion around ways of increasing IAM transparency as a bridge between this community and stakeholders from other disciplines, policy decision makers, financiers, and the public.

Abstract Through the Renewable Energies Plan 2000–2010, Spain has fixed the objective of covering 12% of the primary energy demand from renewable sources. The achievement of this objective implies an annual increase of 22.4% of the energy produced from renewable sources. In this context, the objective of this study is to determine if the electricity from biomass produced in Spain would be environmentally competitive with electricity from natural gas or from the Spanish electricity mix. For that, the environmental impacts associated to the whole life cycle of two energetic crops in Spain, Poplar and Ethiopian mustard, used for power generation were evaluated. The overall assessment includes the cultivation and collection of biomass, its transport and the processes of its energetic transformation. We calculated different scenarios of electricity production from biomass in different capacity power plants (10, 25 or 50 MW), different transport scenarios and different productivities for biomass production. Our results show that, given the assumptions of this study, Ethiopian mustard is more impacting than Poplar when used for electricity production. Also, the transportation of biomass from the field to the power plant is an important stage that has to be carefully planned in order to get the maximum amount of electricity with a minimum environmental impact. Compared to electricity from natural gas or the Spanish electricity mix, the electricity obtained from biomass is more impacting in three from six impact categories we present here.

La bioénergie est largement incluse dans les stratégies énergétiques pour son potentiel d'atténuation des GES. Les technologies de la bioénergie devront probablement être déployées à grande échelle pour atteindre les objectifs de décarbonation et, par conséquent, la biomasse devra être de plus en plus cultivée/mobilisée. Les risques de durabilité associés à la bioénergie peuvent s'intensifier avec l'augmentation du déploiement et lorsque les matières premières proviennent du commerce international. Cette recherche applique le modèle d'indicateur de durabilité de la bioéconomie (BSIM) pour cartographier et analyser la performance de la bioénergie sur 126 questions de durabilité, en évaluant 16 études de cas de bioénergie qui reflètent l'étendue des ressources de biomasse, des technologies, des vecteurs énergétiques et des bioproduits. La recherche trouve des tendances communes en matière de performance de durabilité dans tous les projets qui peuvent éclairer la politique et la prise de décision en matière de bioénergie. Les avantages potentiels en matière de durabilité sont identifiés pour les personnes (emplois, compétences, revenus, accès à l'énergie) ; pour le développement (économie, énergie, utilisation des terres) ; pour les systèmes naturels (sol, métaux lourds) ; et pour le changement climatique (émissions, carburants). En outre, des tendances cohérentes des risques de durabilité où une attention particulière est nécessaire pour assurer la viabilité des projets de bioénergie, y compris pour les infrastructures, la mobilisation des matières premières, la techno-économie et les stocks de carbone. L'atténuation des émissions peut être un objectif principal pour la bioénergie, cette recherche révèle que les projets de bioénergie peuvent offrir des avantages potentiels bien au-delà des émissions - il existe un argument en faveur du soutien de projets basés sur les services écosystémiques et/ou la stimulation économique qu'ils peuvent fournir. Compte tenu également de la vaste dynamique et des caractéristiques des projets de bioénergie, une approche rigide de l'évaluation de la durabilité peut être incompatible. L'octroi de « crédits » sur un plus large éventail d'indicateurs de durabilité, en plus d'exiger des performances minimales dans des domaines clés, peut être plus efficace pour assurer la durabilité de la bioénergie. La bioenergía está ampliamente incluida en las estrategias energéticas por su potencial de mitigación de GEI. Es probable que las tecnologías de bioenergía tengan que implementarse a escala para cumplir con los objetivos de descarbonización y, en consecuencia, la biomasa tendrá que crecer/movilizarse cada vez más. Los riesgos de sostenibilidad asociados con la bioenergía pueden intensificarse con el aumento del despliegue y donde las materias primas se obtienen a través del comercio internacional. Esta investigación aplica el Modelo de Indicadores de Sostenibilidad de la Bioeconomía (BSIM) para mapear y analizar el rendimiento de la bioenergía en 126 temas de sostenibilidad, evaluando 16 estudios de casos de bioenergía que reflejan la amplitud de los recursos de biomasa, las tecnologías, los vectores energéticos y los bioproductos. La investigación encuentra tendencias comunes en el desempeño de la sostenibilidad en todos los proyectos que pueden informar la política de bioenergía y la toma de decisiones. Se identifican posibles beneficios de sostenibilidad para las personas (empleos, habilidades, ingresos, acceso a la energía); para el desarrollo (economía, energía, utilización de la tierra); para los sistemas naturales (suelo, metales pesados) y para el cambio climático (emisiones, combustibles). Además, las tendencias consistentes de los riesgos de sostenibilidad donde se requiere un enfoque para garantizar la viabilidad de los proyectos de bioenergía, incluida la infraestructura, la movilización de materias primas, la tecnoeconomía y las reservas de carbono. La mitigación de emisiones puede ser un objetivo principal para la bioenergía, esta investigación encuentra que los proyectos de bioenergía pueden proporcionar beneficios potenciales mucho más allá de las emisiones: existe un argumento para apoyar proyectos basados en los servicios ecosistémicos y/o la estimulación económica que pueden brindar. También dada la amplia dinámica y características de los proyectos de bioenergía, un enfoque rígido de evaluación de la sostenibilidad puede ser incompatible. La concesión de "créditos" a través de una gama más amplia de indicadores de sostenibilidad, además de requerir rendimientos mínimos en áreas clave, puede ser más eficaz para garantizar la sostenibilidad de la bioenergía. Bioenergy is widely included in energy strategies for its GHG mitigation potential. Bioenergy technologies will likely have to be deployed at scale to meet decarbonisation targets, and consequently biomass will have to be increasingly grown/mobilised. Sustainability risks associated with bioenergy may intensify with increasing deployment and where feedstocks are sourced through international trade. This research applies the Bioeconomy Sustainability Indicator Model (BSIM) to map and analyse the performance of bioenergy across 126 sustainability issues, evaluating 16 bioenergy case studies that reflect the breadth of biomass resources, technologies, energy vectors and bio-products. The research finds common trends in sustainability performance across projects that can inform bioenergy policy and decision making. Potential sustainability benefits are identified for People (jobs, skills, income, energy access); for Development (economy, energy, land utilisation); for Natural Systems (soil, heavy metals), and; for Climate Change (emissions, fuels). Also, consistent trends of sustainability risks where focus is required to ensure the viability of bioenergy projects, including for infrastructure, feedstock mobilisation, techno-economics and carbon stocks. Emission mitigation may be a primary objective for bioenergy, this research finds bioenergy projects can provide potential benefits far beyond emissions - there is an argument for supporting projects based on the ecosystem services and/or economic stimulation they may deliver. Also given the broad dynamics and characteristics of bioenergy projects, a rigid approach of assessing sustainability may be incompatible. Awarding 'credit' across a broader range of sustainability indicators in addition to requiring minimum performances in key areas, may be more effective at ensuring bioenergy sustainability. يتم تضمين الطاقة الحيوية على نطاق واسع في استراتيجيات الطاقة لإمكانات التخفيف من غازات الدفيئة. من المرجح أن يتم نشر تقنيات الطاقة الحيوية على نطاق واسع لتحقيق أهداف إزالة الكربون، وبالتالي سيتعين زيادة نمو/تعبئة الكتلة الحيوية. قد تزداد مخاطر الاستدامة المرتبطة بالطاقة الحيوية مع زيادة الانتشار وحيث يتم الحصول على المواد الأولية من خلال التجارة الدولية. يطبق هذا البحث نموذج مؤشر استدامة الاقتصاد الحيوي (BSIM) لرسم وتحليل أداء الطاقة الحيوية عبر 126 قضية استدامة، وتقييم 16 دراسة حالة للطاقة الحيوية تعكس اتساع موارد الكتلة الحيوية والتقنيات وناقلات الطاقة والمنتجات الحيوية. وجد البحث اتجاهات مشتركة في أداء الاستدامة عبر المشاريع التي يمكن أن تسترشد بها سياسة الطاقة الحيوية وصنع القرار. يتم تحديد فوائد الاستدامة المحتملة للناس (الوظائف والمهارات والدخل والوصول إلى الطاقة) ؛ للتنمية (الاقتصاد والطاقة واستخدام الأراضي) ؛ للنظم الطبيعية (التربة والمعادن الثقيلة)، و ؛ لتغير المناخ (الانبعاثات والوقود). أيضًا، الاتجاهات المتسقة لمخاطر الاستدامة حيث يكون التركيز مطلوبًا لضمان استمرارية مشاريع الطاقة الحيوية، بما في ذلك البنية التحتية وتعبئة المواد الوسيطة والاقتصاد التقني ومخزونات الكربون. قد يكون تخفيف الانبعاثات هدفًا أساسيًا للطاقة الحيوية، ويجد هذا البحث أن مشاريع الطاقة الحيوية يمكن أن توفر فوائد محتملة تتجاوز الانبعاثات - هناك حجة لدعم المشاريع القائمة على خدمات النظام الإيكولوجي و/أو التحفيز الاقتصادي الذي قد تقدمه. أيضًا نظرًا للديناميكيات والخصائص الواسعة لمشاريع الطاقة الحيوية، قد يكون النهج الصارم لتقييم الاستدامة غير متوافق. قد يكون منح "الائتمان" عبر مجموعة أوسع من مؤشرات الاستدامة بالإضافة إلى طلب الحد الأدنى من الأداء في المجالات الرئيسية أكثر فعالية في ضمان استدامة الطاقة الحيوية.

AbstractBioenergy is expected to have a prominent role in limiting global greenhouse emissions to meet the climate change target of the Paris Agreement. Many studies identify negative emissions from bioenergy generation with carbon capture and storage (BECCS) as its key contribution, but assume that no other CO2 removal technologies are available. We use a global integrated assessment model, TIAM‐UCL, to investigate the role of bioenergy within the global energy system when direct air capture and afforestation are available as cost‐competitive alternatives to BECCS. We find that the presence of other CO2 removal technologies does not reduce the pressure on biomass resources but changes the use of bioenergy for climate mitigation. While we confirm that when available BECCS offers cheaper decarbonization pathways, we also find that its use delays the phase‐out of unabated fossil fuels in industry and transport. Furthermore, it displaces renewable electricity generation, potentially increasing the likelihood of missing the Paris Agreement target. We found that the most cost‐effective solution is to invest in a basket of CO2 removal technologies. However, if these technologies rely on CCS, then urgent action is required to ramp up the necessary infrastructure. We conclude that a sustainable biomass supply is critical for decarbonizing the global energy system. Since only a few world regions carry the burden of producing the biomass resource and store CO2 in geological storage, adequate international collaboration, policies and standards will be needed to realize this resource while avoiding undesired land‐use change.

Abstract Residential space heating is one of the major contributors to greenhouse gas (GHG) emissions and hence a priority sector to decarbonise in the transition to Net Zero target by 2050 in the UK. To assess environmental impacts of a current heating system and potential alternatives in the UK, this study conducted a comparative LCA of a condensing gas boiler and a hybrid heating pump for a common type of UK’s existing houses (a semi-detached house). The functional unit of this study is defined as delivering space heating for the whole lifetime (20 years) of heating system. The results suggest that the hybrid heat pump potentially saves 30% of GHG emissions as compared to the condensing gas boiler in the core scenarios (4.5E + 04 kg CO2-eq/FU vs 6.4 E + 04 kg CO2-eq/FU respectively). The hybrid heat pump also shows 13% to 48% emission reduction as compared to the condensing gas boiler in terrestrial acidification, photochemical oxidant formation, particulate matter formation and fossil depletion. However, the hybrid heat pump emits 3 to 6 times more emissions in terms of human toxicity, water depletion and metal depletion than the condensing gas boiler. The production phase contributes around 50% of the impact for metal depletion and human toxicity in both core scenarios, while the use phase dominates in other selected impact categories. The combustion of natural gas and the electricity production are the major causes for the dominance of the use phase for all selected impact categories excepting metal depletion and human toxicity. The sensitivity scenarios support the robustness of the results. Further work is needed to understand the role hybrid heat pumps can play in the residential sector decarbonisation under different scenarios of residential uptake, household behaviour and wider UK energy system decarbonisation.

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