Abstract: Bioenergy with carbon capture and storage (BECCS) is one of the most mature negative emissions technologies. Implementing it at scale may be needed to meet end-of-century climate targets. Recently in Nature Climate Change, Hanssen and co-authors evaluate the energy and sequestration potential of BECCS through 2100. Their findings further support that substantial emissions mitigation is, at least biophysically, possible. Bioenergy with carbon capture and storage (BECCS) is one of the most mature negative emissions technologies. Implementing it at scale may be needed to meet end-of-century climate targets. Recently in Nature Climate Change, Hanssen and co-authors evaluate the energy and sequestration potential of BECCS through 2100. Their findings further support that substantial emissions mitigation is, at least biophysically, possible. The world’s energy infrastructure is undergoing a gradual shift toward low-carbon generation sources. Even under optimistic scenarios of accelerated fossil fuel infrastructure displacement with renewable energy production, meeting Paris Agreement targets of limiting global warming to 1.5°C or 2°C of pre-industrial levels by 2100 may not be achievable without negative emissions technologies (NETs). NETs actively remove greenhouse gases from the atmosphere and return it to the geosphere. Bioenergy with carbon capture and storage (BECCS) is one of the most mature NETs. It has a central role in many proposed climate change mitigation pathways, including those by the Intergovernmental Panel on Climate Change (IPCC).1Masson-Delmotte V. Zhai P. Pörtner H.O. Roberts D. Skea J. Shukla P.R. Pirani A. Moufouma-Okia W. Péan C. Pidcock R. et al.IPCC, 2018: global warming of 1.5°C. World Meteorological Organization, 2018Google Scholar Yet its realistic sequestration potential remains a nebulous topic of frequent debate. Recently in Nature Climate Change, Hanssen and co-authors conducted a spatially explicit greenhouse gas life cycle analysis for lignocellulosic-based BECCS, quantifying its global negative emissions potential.2Hanssen S.V. Daioglou V. Steinmann Z.J.N. Doelman J.C. Van Vuuren D.P. Huijbregts M.A.J. The climate change mitigation potential of bioenergy with carbon capture and storage.Nat. Clim. Chang. 2020; (Published online August 24, 2020)https://doi.org/10.1038/s41558-020-0885-yCrossref Scopus (18) Google Scholar BECCS involves growing biofuel crops to be burned on-site, generating power, while capturing the exhaust CO2 and sequestering it. Plants absorb CO2 during their growth, and the combustion process is carbon neutral due to greenhouse gas capture. This makes the entire process capable of carbon negative energy generation. A schematic of a BECCS process is shown in Figure 1. In addition to being an overall costly form of energy production relative to unconstrained fossil fuel combustion, the land requirements for BECCS to have a meaningful impact on climate mitigation are a commonly debated drawback. Depending on the land use change and supply chain for crop production, implementations of BECCS may be carbon negative or carbon positive. Hanssen and co-authors use the Lund-Potsdam-Jena managed land model3Potsdam Institute for Climate Impact ResearchLPJmL - Lund-Potsdam-Jena managed land.https://www.pik-potsdam.de/en/institute/departments/activities/biosphere-water-modelling/lpjmlDate: 2020Google Scholar to assess the emissions per unit bioenergy—termed emission factors—of both bioelectricity and liquid biofuels produced from lignocellulosic biomass. The emission factors of BECCS vary considerably depending on the implementation. For carbon to be sequestered from BECCS, emission factors must be negative. Emission factors are most likely to be negative in land use scenarios that have high crop growth yield, low existing carbon stocks, and minimal emissions associated with changing the land use to BECCS. It is estimated that BECCS would have nontrivial, positive emissions factors over a 30-year time frame if implemented on much of the industrialized landmass across the global north. The greatest potential for nearer-term mitigation with BECCS is found in abandoned landmass sites with subtropical, warmer temperate climates. The 30-year time frame (from today) extends to 2050—the Paris Agreement target for net zero emissions. Climate targets for limiting global warming are set to the year 2100. The second half of the 21st century will, under ideal circumstances, be five decades of negative global emissions. Expanding the emission factor analysis of BECCS to 2100, an 80-year time frame, gives an estimate of the total sequestration potential of the technology till these target dates. A span of 80 years means the initial greenhouse gas emissions and natural vegetation sequestration losses amortized over a longer period. It was found that over this time frame, most of the global landmass has negative BECCS emission factors. The total worldwide potential for electricity production from negative-emissions BECCS was estimated at 28 EJ pear year, sequestering 2.5 GtCO2 annually over 30 years, or 220 EJ per year, sequestering 40 GtCO2 annually over 80 years. The total global BECCS sequestration potential was estimated to be less than what is presently found in proposed IPCC 1.5°C mitigation pathways S2 (middle-of-the-road) and S5 (fossil fuel and high energy demand). The uncertainty of crop yield over long time periods, changes in local crop feedstock life cycle emissions, and potential variations in soil quality over time all influence such projections. Still, the work by Hanssen and co-authors is part of a growing body of evidence that BECCS offers a biophysical route to meaningful emissions sequestration throughout the century. The evolving sustainability agendas (or lack thereof) of governments and the uphill economic battle to implement NETs still loom as a major challenge. As is shown here, the earlier NETs such as BECCS are implemented, the greater the payback by end-of-century climate target dates. Continued work demonstrating the urgency of scaling NETs from today and the payoffs for doing so will hopefully set new sustainability agendas for global agents of change.