Mapping the sustainability of bioenergy to maximise benefits, mitigate risks and drive progress toward the Sustainable Development Goals

Demand for biomass resources will continue to grow as bioenergy is increasingly targeted within energy strategies. Sustainability is a primary issue for large scale bioenergy, with potential to generate both risks and benefits for people, development, natural systems and for climate change – this balance of risks and benefits determining overall sustainability performance. A new sustainability mapping framework is introduced that provides a flexible tool (BSIM) to map the performances of biomass resources, supply chains, technologies and/or whole value chains against 126 indicators of sustainability. Sustainability maps are developed and assessments undertaken for case studies in the UK and Colombia. This research finds sustainability of bioenergy covers far more issues than those targeted within legislation – where land, carbon and biodiversity are prioritised. Mapping sustainability is a valuable tool to identify the leading risks and benefits to enable targeted actions to mitigate risks and to maximise and promote benefits. Mapping sustainability at different resolutions and analysing the trade-offs enables greater rationalisation of potential risks through also identifying the potential broader benefits gained. Bioenergy is intrinsically linked to the SDGs more so than other renewable technologies and should be used as a mechanism to drive sustainable development

Generating low-carbon heat from biomass:Life cycle assessment of bioenergy scenarios

Bioenergy systems will play a key role in many countries achieving their climate change, emission reduction and renewable energy contribution targets. It is important that implemented bioenergy pathways maximise GHG reductions, particularly since demand and competition for biomass resource is likely to increase in future. This research analyses the actual GHG performance of utilising different biomass resources to generate heat. Life cycle assessment (LCA) is undertaken to evaluate 2092 variants of bioheat options focused on utilising: UK agricultural and food wastes through anaerobic digestion pathways; UK straw agricultural residues and UK grown energy crops through combustion pathways. The results show a very broad range of GHG performances. Many pathways demonstrate GHG savings compared to conventional generation, although some have potential to actually increase GHG emissions, rather than reduce them. Variations in GHG performance do not correlate with feedstocks or technologies, but are most sensitive to the inclusion of specific processing steps and the displacement of certain counterfactuals. This suggests that policies should be developed that target resources with high GHG intensity counterfactuals, and where possible avoid energy intensive processing steps such as pelletisation

A review of the role of bioenergy modelling in renewable energy research & policy development

Transition towards renewable low carbon energy is a fundamental element of climate change mitigation, energy from biomass technologies are targeted within many country's decarbonisation strategies. Decision makers globally face many challenges developing strategies to drive this transition; models are increasingly used to road-test policy interventions before their implemented. A Bioenergy Literature Database was developed of 124,285 papers published 2000–2018. These document an exponential rise in research focusing on biomass and bioenergy. On average 35.4% of papers apply modelling analyses, 99.5% of these use bespoke models rather than high profile Integrated Assessment Models (IAMs) or Energy System Models – although it is these high profile models that are widely used in policy development. A review of the role of bioenergy within energy models is undertaken with a key objective of critiquing their performances in analysing bioenergy research questions. IAMs are found to be widely applied to investigate the impact of bioenergy within wider energy and environmental systems, e.g. for reducing emissions. Energy System Models focus on bioenergy processes, technologies and feedstocks, although don't capture wider environmental, economic and social themes. Specialist Bioenergy Models offer methods for bespoke analyses of all bioenergy issues, their narrow system boundaries generate targeted outputs but wider effects such as land-use change may not be captured. Caution is required when interpreting modelling outputs, particularly when used to inform policy. It's not feasible to develop all-encompassing bioenergy models covering all nuances between systems, but there is strong argument for using multiple models in parallel to build robust overall conclusions

Greenhouse gases (GHG) performance of refurbishment projects - Lessons from UK higher education student accommodation case studies

The student accommodation sector in now the best-performing asset in the UK and US property markets and this is projected to further accelerate, with building refurbishment of existing student accommodations being the preferred method to satisfy growing demand. However, there are no published research studies on refurbishment projects within the student accommodation sector. Refurbishment is an emergent trend to upgrade existing stock to ensure that buildings meet rising energy efficiency demands. Moreover, it is widely affirmed that greenhouse gases contribute to climate change and notably the built environment is a significant contributor, both through its construction and during its operation and use. This paper demonstrates through a comparative case study approach, how greenhouse gases levels can be effectively measured during refurbishment works. There are multiple metrics used for quantification/assessment of greenhouse gases performance and this paper aims to make well-argued recommendations for their best use. Four student accommodation refurbishment projects are presented to compare and contrast differing emission datasets. The results dictate that project cost and duration cannot alone be used to gauge greenhouse gases emissions; more too, in the instance of student accommodation refurbishment, gross internal floor area and the number of rooms offers a more predictable indicator. It is recommended that refurbishment developers reflect on these recommendations when reporting the primary energy and GHG performance of their refurbishment works. Best practice from this research may be adopted into domestic buildings refurbishment projects

The potential of coffee stems gasification to provide bioenergy for coffee farms:a case study in the Colombian coffee sector

The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas

Exploring temporal aspects of climate-change effects due to bioenergy

The greenhouse gas emissions associated with bioenergy are often temporally dispersed and can be a mixture of long-term forcers (such as carbon dioxide) and short-term forcers (such as methane). These factors affect the timing and magnitude of climate-change impacts associated with bioenergy in ways that cannot be clearly communicated with a single metric. This is critical as key comparisons that determine incentives and policy for bioenergy are based upon climate-change impacts expressed as carbon dioxide equivalent calculated with GWP100. This paper explores these issues further and presents a spreadsheet tool to facilitate quick assessment of these temporal effects. The potential effect of (i) a mix of GHGs and (ii) emissions that change with time are illustrated through two case studies. In case study 1, variations in the mix of greenhouse gases mean that apparently similar impacts after 100-years, mask radically different impacts before then. In case study 2, variations in the timing of emissions cause their climate-change impacts (integrated radiative-forcing and temperature change) to differ from the impacts that an emissions-balance would suggest. The effect of taking alternative approaches to considering “CO2-equivalence” are also assessed. In both cases, a single metric for climate-change effects was found to be wanting. A simple tool has been produced to help practitioners evaluate whether this is the case for any given system. If complex dynamics are apparent, it is recommended that additional metrics, more detailed inventory, or full time-series impact results are used in order to accurately communicate these climate-change effects.</p