However, the technology is yet to be demonstrated at large scales and remains more costly and energy intensive than biomass-based removals it therefore plays a lesser role in most pathways, with a median of 30 Gt captured in the 1.5✬ pathways with limited overshoot and 109 Gt in those with high overshoot (Chapter 3). Despite these large volumes, BECCS actually captures less carbon dioxide in the mitigation pathways compared with previous IPCC reports, in recognition of the land use and other societal and economic challenges associated with the use of such large quantities of biomass (Chapter 7).Īnother notable change from previous IPCC assessments is a greater role for DACCS, which has progressed significantly in the last five years to merit inclusion in several countries’ mitigation plans. The scale and timing of deployment will depend on the trajectories of gross emission reductions in different sectors.” – Summary for Policymakers (SPM), p.47īy 2100, a median average of 334 Gt of biomass-derived carbon dioxide from BECCS is stored by IPCC pathways which achieve 1.5✬ with no or limited overshoot, and even more (464 Gt) by those with more chance of overshoot – higher overshoot pathways need more removals to reverse the effect of slower emissions reductions early in the century. “The deployment of CDR to counterbalance hard-to-abate residual emissions is unavoidable if net zero CO 2 or GHG emissions are to be achieved. BECCS and DACCS play a central role in the IPCC mitigation pathwaysĬarbon dioxide removal (CDR) from both BECCS and DACCS is also heavily relied on in most IPCC mitigation pathways, though the role of BECCS is smaller than in past IPCC reports: Even the IMP based on particularly high uptake of renewable energy still requires more than 3 Gt of carbon dioxide to be captured and stored annually by 2050 (Figure 3.15 in the full report). However, this scenario requires global energy demand to nearly halve in the next 30 years, which is socio-politically unrealistic given the existing energy poverty around the world and that energy demand must increase as much of the world industrializes and urbanizes. Only one of the seven IMPs includes no carbon capture. WGIII also identifies seven specific pathways, termed ‘Illustrative Mitigation Pathways’ (IMPs) that best summarize and highlight different decarbonization strategies – four that achieve 1.5✬ and three that keep temperatures ‘likely below 2✬. Among the 97 assessed pathways that keep global warming to below 1.5✬ with ‘no or limited overshoot’ (meaning a reduced chance of exceeding 1.5✬ in the near term), there is a broad range of possible deployment levels for the technology, with a median average of 665 gigatonnes (Gt) of carbon dioxide cumulatively captured and stored between now and 2100. WGIII made clear that carbon capture and storage is a critical decarbonization strategy in most mitigation pathways. Carbon capture and storage (including DACCS and BECCS) is central to IPCC mitigation pathways Below are the key findings with accompanying quotes from the Summary for Policymakers. The report gives a balanced assessment of the opportunities and challenges for carbon capture. DACCS removes existing carbon dioxide from the atmosphere, whereas BECCS captures and stores carbon dioxide released from biomass-based processes. DACCS and BECCS are important subsets of carbon capture and storage in that they are able to reduce atmospheric concentrations of carbon dioxide – also known as carbon dioxide removal (CDR). All three technologies use a similar type of chemistry to ‘capture’ carbon dioxide, and all three rely on the same geologies for permanent underground storage. One of the technologies about which WGIII had much to say was carbon capture and storage (identified throughout the report as CCS), and its derivatives direct air carbon capture and storage (DACCS) and bioenergy with carbon capture and storage (BECCS). Nevertheless, the IPCC’s WGIII report clarifies that humanity has the tools (in various stages of commercialization) to decarbonize. Yes, emissions rose throughout the past decade, and yes, keeping global warming to 1.5 degrees Celsius will require an unparalleled transformation of our energy system. Zooming out for a minute, however, the overall import of the report is hopeful. It makes clear that we need nothing short of an immediate, overwhelming, and coordinated global effort to fend off the worst effects of climate change. At 2,913 pages in length, the organization’s latest salvo – Working Group III’s (WGIII) Contribution to the Sixth Assessment Report (AR6) – is sobering. IPCC Reports are not for the faint of heart. Toby Lockwood Carbon capture and storage remain central to climate mitigation strategies in Working Group III’s contribution to AR6
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