Each Gauge in the calculator has a value for plausible expectation (where the amber zone begins) and an extremely unlikely value (where the red zone begins). The justification for these are outlined below.
Based on estimates of 2018 consumption, modified to maximise sustainable availability. Assumptions: no net additional land used for extracting biomass, ~10% increase in wood extraction intensity on intensively managed plantations are possible without affecting carbon stocks and mineral availability, global yield gap closes to with 75% of the full potential for 16 important crops, estimated by Foley et al. (2011) to increase production by 28%, yields increase by 15% between 2018 and 2050 (consistent with trend found by Foley et al., 2011), no potential for increased pasture use without additional environmental implications, crop and forest residue use are maximised while sustaining ecological functions (based on data from Daioglou et al., 2015; Koopmans et al., 1997; Bajželj et al. ,2014).
The German Advisory Council on Global Change (WBGU) estimated the technical sustainable potential of bioenergy to be 34-120 EJ/yr (from crops) and 50 EJ/yr from residues (totalling ~ 6-11 Gt) noting that the technical sustainable potential should be viewed as an upper limit (Schubert et al., 2009). They made a rough estimate that economic potential in 2050 may be approximately half of the technical sustainable potential. This means the sustainable economic potential is around 5 Gt. This is assumed to be additional to the 14 Gt of biomass for food production and wood materials (estimated in this project to be available in 2050). Although novel sources of biomass such as algae may have Gt scale potential (DeAngelo et al., 2023), a significant growth increase is not considered since their future role is “highly uncertain”(Chum et al., 2011).
Assuming solar and wind grow with an s-shape curve (fitted against historical generation growth data between 2010 and 2022, as a Gompertz fit, following the approach of Cherp et al. (2021)). Hydropower, nuclear and geothermal assumed to grow at linear rates, consistent with historical data and mid-point of the trajectories given by The International Atomic Energy Agency (IAEA, 2020).
Assume nuclear growth at the highest projection rate given by IAEA (2020) to provide 25 EJ/yr in 2050, and IEA's updated Net Zero Scenario is achievable for Solar and Wind (180 EJ/yr in 2050) is achievable (IEA NZE by 2050 updated report, 2023. Table 6.1)
Assuming an exponential growth fitted to historical carbon capture capacity from CCS and Enhanced Oil Recovery Projects, as found by Haszeldine et al. (2018) and a capacity factor (CF) of ~70%, an increase when considered against probable historical CF of around 60% estimated from data from Global CSS Intitute (Status of CCS, 2022), case studies by Robertson & Mousavian (2022), and various news articles from sources such as the Financial Times.
Assumes that the capacity factor described above increases to 90%.
Bajželj, B., Richards, K. S., Allwood, J. M., Smith, P., Dennis, J. S., Curmi, E., & Gilligan, C. A. (2014). Importance of food-demand management for climate mitigation. Nature Climate Change, 4(10), 924–929. https://doi.org/10.1038/nclimate2353
Cherp, A., Vinichenko, V., Tosun, J., Gordon, J. A., & Jewell, J. (2021). National growth dynamics of wind and solar power compared to the growth required for global climate targets. Nature Energy, 6(7), 742–754. https://doi.org/10.1038/s41560-021-00863-0
Daioglou, V., Stehfest, E., Wicke, B., Faaij, A., & van Vuuren, D. P. (2016). Projections of the availability and cost of residues from agriculture and forestry. GCB Bioenergy, 8(2), 456–470. https://doi.org/10.1111/GCBB.12285
Foley, J. A., Ramankutty, N., Brauman, K. A., Cassidy, E. S., Gerber, J. S., Johnston, M., Mueller, N. D., O’Connell, C., Ray, D. K., West, P. C., Balzer, C., Bennett, E. M., Carpenter, S. R., Hill, J., Monfreda, C., Polasky, S., Rockström, J., Sheehan, J., Siebert, S., … Zaks, D. P. M. (2011). Solutions for a cultivated planet. Nature, 478(7369), 337–342. https://doi.org/10.1038/nature10452
Global CSS Institute. (2022). Global Status of CCS 2022. https://status22.globalccsinstitute.com/wp-content/uploads/2022/12/Global-Status-of-CCS-2022_Download_1222.pdf
IAEA. (2020). Energy, electricity and nuclear power estimates for the period up to 2050. https://www.iaea.org/publications/14786/energy-electricity-and-nuclear-power-estimates-for-the-period-up-to-2050
IEA (2022), World Energy Outlook 2022, IEA, Paris https://www.iea.org/reports/world-energy-outlook-2022, Licence: CC BY 4.0 (report); CC BY NC SA 4.0 (Annex A)
Koopmans, A., & Koppejan, J. (1997). Agricultural and forest residues - generation, utilization and availability. In Regional Consultation on Modern Applications of Biomass Energy. https://www.fao.org/3/AD576E/ad576e00.pdf
Robertson, B., & Mousavian, M. (2022). The carbon capture crux: Lessons learned. https://ieefa.org/resources/carbon-capture-crux-lessons-learned
Schubert, R., Schellnhuber, H. J., Buchmann, N., Epiney, A., Grießhammer, R., Kulessa, M., Messner, D., Rahmstorf, S., & Schmid, J. (2009). Future bioenergy and sustainable land use. In Future Bioenergy and Sustainable Land Use. https://doi.org/10.4324/9781849774505
Smyth, J., & Sheppard, D. (2021). Monster problem: Gorgon project is a test case for carbon capture. Financial Times. https://www.ft.com/content/428e60ee-56cc-4e75-88d5-2b880a9b854a