• Energy Research
• 7. Clean energy close

Carbon capture and storage of CO2 from combustion of biomass, i.e., bio-energy carbon capture and storage (BECCS), makes it possible to obtain so-called negative emissions – the atmosphere is cleansed from carbon dioxide. The purpose of the present study was to investigate the suitability of different manganese ores as oxygen carriers in chemical-looping combustion of biomass fuels. For this screening study, a laboratory-scale, circulating fluidized-bed CLC system with a nominal fuel input of 300 Wth was used. The primary focus was to investigate the reactivity of these oxygen carriers towards biomass fuels, and find a reactive oxygen carrier with sufficient mechanical stability that could be suitable for large-scale chemical-looping combustion of biomass. A synthetic “biomass volatiles” gas was used to study how the different gas components react with the oxygen-carrier particles. Additional experiments were conducted with methane and a syngas. Parameter studies concerning temperature and specific fuel-reactor bed mass (bed mass per fuel thermal power in kg/MWth) were carried out. With the synthetic biomass volatiles, conversion of fuel carbon to CO2 as high as 97.6% was achieved. For a majority of the investigated ores, essentially all C2 and C3 hydrocarbons were converted, as well as a very high fraction of the CO. Reactivity towards CH4 was generally lower, but improved at higher temperatures. The resistance of the oxygen carriers towards mechanical degradation was measured in a jet-cup attrition test rig. The measured attrition was estimated as “intermediate” for four of the five tested materials, while one of the ores displayed high attrition.

Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

AbstractThe global warming is directly related to the increased greenhouse gas emissions from both natural and anthropogenic origins. There has been a drastic rise in the concentration of CO2 and other greenhouse gases since the industrial revolution primarily due to the intensifying consumption of fossil fuels. With the need to reduce carbon emissions and mitigate global warming certain strategies relating to carbon capturing and sequestration are indispensable. This paper comprehensively describes several physicochemical, biological and geological routes for carbon capture and sequestration. The trend of the increase in greenhouse gases over the years is illustrated along with the global statistics for fossil fuels usage and biofuels production. The physicochemical carbon capturing technologies discussed include absorption, adsorption, membrane separation and cryogenic distillation. The algal and bacterial systems, dedicated energy crops and coalbed methanogenesis have been vividly explained as the biological routes for carbon sequestration. The geological carbon sequestering route centers on biochar application and oceanic carbon storage. A systematic survey has been made on the origin and impact of greenhouse gases along with the potential for sequestration based on some fast‐track and long‐term sequestration technologies.

Scenarios avoiding global warming greater than 1.5 or 2 ∘C, as stipulated in the Paris Agreement, may require the combined mitigation of anthropogenic greenhouse gas emissions alongside enhancing negative emissions through approaches such as afforestation–reforestation (AR) and biomass energy with carbon capture and storage (BECCS). We use the JULES land surface model coupled to an inverted form of the IMOGEN climate emulator to investigate mitigation scenarios that achieve the 1.5 or 2 ∘C warming targets of the Paris Agreement. Specifically, within this IMOGEN-JULES framework, we focus on and characterise the global and regional effectiveness of land-based (BECCS and/or AR) and anthropogenic methane (CH4) emission mitigation, separately and in combination, on the anthropogenic fossil fuel carbon dioxide (CO2) emission budgets (AFFEBs) to 2100. We use consistent data and socio-economic assumptions from the IMAGE integrated assessment model for the second Shared Socioeconomic Pathway (SSP2). The analysis includes the effects of the methane and carbon–climate feedbacks from wetlands and permafrost thaw, which we have shown previously to be significant constraints on the AFFEBs. Globally, mitigation of anthropogenic CH4 emissions has large impacts on the anthropogenic fossil fuel emission budgets, potentially offsetting (i.e. allowing extra) carbon dioxide emissions of 188–212 Gt C. This is because of (a) the reduction in the direct and indirect radiative forcing of methane in response to the lower emissions and hence atmospheric concentration of methane and (b) carbon-cycle changes leading to increased uptake by the land and ocean by CO2-based fertilisation. Methane mitigation is beneficial everywhere, particularly for the major CH4-emitting regions of India, the USA, and China. Land-based mitigation has the potential to offset 51–100 Gt C globally, the large range reflecting assumptions and uncertainties associated with BECCS. The ranges for CH4 reduction and BECCS implementation are valid for both the 1.5 and 2 ∘C warming targets. That is the mitigation potential of the CH4 and of the land-based scenarios is similar for regardless of which of the final stabilised warming levels society aims for. Further, both the effectiveness and the preferred land management strategy (i.e. AR or BECCS) have strong regional dependencies. Additional analysis shows extensive BECCS could adversely affect water security for several regions. Although the primary requirement remains mitigation of fossil fuel emissions, our results highlight the potential for the mitigation of CH4 emissions to make the Paris climate targets more achievable.

Abstract In order to mitigate the effects of climate change, a lot of research has been devoted to reduce carbon dioxide (CO2) emissions, develop capture and storage technologies (CCS), as well as direct carbon dioxide removal (CDR) from the atmosphere. The 2014 “Summary for Policymakers” of the Intergovernmental Panel on Climate Change 5th report (working group III) preponderantly mentions CCS and CDR. Although many scientific publications cite “greenhouse gas removal“, to our knowledge none of them has yet proposed innovative solutions to effectively remove greenhouse gases other than CO2 from the atmosphere. This article proposes a combination of disrupting techniques to transform or destroy the halogenated gases in the atmosphere, which are harmful for the ozone layer, and possess high global warming potential as well as long atmospheric lifetimes.

Pledges embodied in the nationally determined contributions (NDCs) represent an interim step from a global “no policy” path towards an optimal long-term global mitigation path. However, the goals of the Paris Agreement highlight that current pledges are insufficient. It is, therefore, necessary to ratchet-up parties’ future mitigation pledges in the near-term. The ambitious goals of remaining well below 2 °C and pursuing reductions towards 1.5 °C mean that any delay in ratcheting-up commitments could be extremely costly or may even make the targets unachievable. In this chapter, we consider the impacts of delaying ratcheting until 2030 on global emissions trajectories towards 2 °C and 1.5 °C, and the role of offsets via negative emissions technologies (NETs). The analysis suggests that delaying action makes pursuing the 1.5 °C goal especially difficult without extremely high levels of negative emissions technologies (NETs), such as carbon capture and storage combined with bioenergy (BECCS). Depending on the availability of biomass, other NETs beyond BECCS will be required. Policymakers must also realise that the outlook for fossil fuels are closely linked to the prospects for NETs. If NETs cannot be scaled, the levels of fossil fuels suggested in this analysis are not compatible with the Paris Agreement goals i.e. there are risks of lock-in to a high fossil future. Decision makers must, therefore, comprehend fully the risks of different strategies.

AbstractThe concept of combining bioenergy with carbon capture and storage (BECCS) has been identified as one mechanism to achieve energy production with a net negative atmospheric carbon emission. Conventional geological carbon capture and storage involves large capital outlay and recurring expense. Therefore there is increased interest in coupling biological carbon capture and sequestration with biomass production. Systems such as low‐input high‐diversity native grasslands and biochar production have been heralded as carbon negative biofuels. Another potential production system for bioenergy with biological carbon capture and storage (BEBCCS) is the large‐scale cultivation of seaweed (macroalgae) for biofuels. Marine biofuels offer considerable advantages over terrestrial first‐generation biofuels in terms of their low land use, fresh water and fertilizer requirements. In addition, they also offer considerable potential in the field of BEBCCS. Macroalgae rapidly accumulate biomass and as part of this process, a significant proportion (estimates range up to 60%) of the carbon they fix photosynthetically is released into the water. A proportion of this released dissolved organic carbon (DOC) is highly labile and enters the bacterial loop and is rapidly remineralized back to CO2. However, a proportion is known to be resistant to biological degradation and enters the refractory DOC pool. The marine DOC pool is the largest organic carbon pool on the planet and the refractory component is known to have a turnover period of 100s‐1000s years. The release of refractory DOC from macroalgae combined with biofuel production offers the potential for large scale carbon negative fuel production. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

Stringent mitigation pathways frame the deployment of second-generation bioenergy crops combined with carbon capture and storage (CCS) to generate negative CO2 emissions. This bioenergy with CCS (BECCS) technology facilitates the achievement of the long-term temperature goal of the Paris Agreement. Here, we use five state-of-the-art Earth system models (ESMs) to explore the consequences of large-scale BECCS deployment on the climate-carbon cycle feedbacks under the CMIP6 SSP5-3.4-0S overshoot scenario keeping in mind that all these models use generic crop vegetation to simulate BECCS. First, we evaluate the land cover representation by ESMs and highlight the inconsistencies that emerge during translation of the data from integrated assessment models (IAMB) that are used to develop the scenario. Second, we evaluate the land-use change (LUC) emissions of ESMs against bookkeeping models. Finally, we show that an extensive cropland expansion for BECCS causes ecosystem carbon loss that drives the acceleration of carbon turnover and affects the CO2 fertilization effect- and climate-change-driven land carbon uptake. Over the 2000-2100 period, the LUC for BECCS leads to an offset of the CO2 fertilization effect-driven carbon uptake by 12.2 % and amplifies the climate-change-driven carbon loss by 14.6 %. A human choice on land area allocation for energy crops should take into account not only the potential amount of the bioenergy yield but also the LUC emissions, and the associated loss of future potential change in the carbon uptake. The dependency of the land carbon uptake on LUC is strong in the SSP5-3.4-OS scenario, but it also affects other Shared Socioeconomic Pathway (SSP) scenarios and should be taken into account by the IAM teams. Future studies should further investigate the trade-offs between the carbon gains from the bioenergy yield and losses from the reduced CO2 fertilization effect-driven carbon uptake where BECCS is applied. Earth System Dynamics, 13 (2) ISSN:2190-4987 ISSN:2190-4979