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The trouble with negative emissions


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In December 2015, member states of the United Nations Framework Convention on Climate Change (UNFCCC) adopted the Paris Agreement, which aims to hold the increase in the global average temperature to below 2°C and to pursue efforts to limit the temperature increase to 1.5°C. The Paris Agreement requires that anthropogenic greenhouse gas emission sources and sinks are balanced by the second half of this century. Because some nonzero sources are unavoidable, this leads to the abstract concept of “negative emissions,” the removal of carbon dioxide (CO2) from the atmosphere through technical means. The Integrated Assessment Models (IAMs) informing policy-makers assume the large-scale use of negative-emission technologies. If we rely on these and they are not deployed or are unsuccessful at removing CO2 from the atmosphere at the levels assumed, society will be locked into a high-temperature pathway.

Published in: Environment
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The trouble with negative emissions

  1. 1. The trouble with negative emissions Glen Peters (CICERO) 9th Trondheim Conference on CO2 Capture, Transport, & Storage (TCCS9), 13/06/2017
  2. 2. Source: MCC 2016 Alternative negative emissions
  3. 3. The future is uncertain, and we use scenarios to explore these future uncertainties Emission scenarios
  4. 4. IPCC assessed about 1200 scenarios, and about 120 different “2°C scenarios” Different scenarios cover different models, policy start dates, technology portfolios, etc Light lines: The IPCC Fifth Assessment Report assessed about 1200 scenarios using Integrated Assessment Models (IAMs) Dark lines: Detailed climate modelling was done on four Representative Concentration Pathways (RCPs) Source: Fuss et al 2014; CDIAC; IIASA AR5 Scenario Database; Global Carbon Budget 2016 There are many options to stay below 2°C External to the IAM community, lack of understanding of negative emissions and their consequences…
  5. 5. Net emissions = CO2 emissions from fossil fuels, industrial processes, land-use change, and bioenergy with CCS Source: Anderson & Peters (2016) The trouble with negative emissions
  6. 6. Net emissions = CO2 emissions from fossil fuels, industrial processes, land-use change, and bioenergy with CCS Source: Anderson & Peters (2016) The trouble with negative emissions
  7. 7. CO2 removal starts in 2020-2030 and rises to 15 billion tonnes CO2 per year in 2100 Source: Anderson & Peters (2016) The trouble with negative emissions
  8. 8. Less CO2 removal requires more rapid reductions in fossil fuel and industry emissions Source: Anderson & Peters (2016) Are negative emissions a moral hazard? With BECCS Without BECCS
  9. 9. Carbon Capture and Storage (CCS) and “Negative Emissions” allows the budget to be exceeded Note: Totals are not always consistent because medians are not additive, and some columns have different numbers of scenarios Source: Peters (2016) The carbon budget and CCS
  10. 10. BECCS is not just for 2°C, but whenever there is mitigation BECCS is used in scenarios To stabalise temperature at any given level, likely we need to have negative emissions Source: IIASA AR5 Scenario Database (own calculations) BECCS by forcing level in 2100 ~1.6°C ~2.0°C ~2.6°C ~3.4°C Median temperature
  11. 11. • Even if BECCS is a “moral hazard”, we still need research, development, deployment, ... – …but we need to act as if BECCS will not work at scale – …treat “Plan A (high BECCS)” as a pleasant surprise • We can’t just accept model results, we have to challenge them, make sure they are robust • No matter at what temperature we stabilize, we need negative emissions A few clarifications…
  12. 12. The trouble with carbon, capture & storage
  13. 13. A typical CCS facility today is about 1MtCO2/yr storage (e.g., Sleipner) → 1000 facilities per 1GtCO2 We can build 10’s of CCS facilities, but can we scale up to 10,000s over the next decades? Today, there is capture capacity of 28MtCO2/yr, but only about 7.5MtCO2/yr is verified as stored (IEA). Source: Based on IIASA AR5 Scenario Database Carbon Capture and Storage
  14. 14. • Deployment rates consistent with historical examples – Nuclear in Europe, coal in China • Energy system optimization models: – Short-term reductions more expensive than cost of negative emissions in the long-term (given constraints, model structure) • Comparisons of CCS deployment in IAMs – Large variation in results not explained by model assumptions – CCS complex interplay of several factors in each model Sources: van Sluisveld et al (2015); van Vuuren et al (2015); Koelbl et al (2014) Why do models love CCS?
  15. 15. Today, robust scientific debate over 1EJ/yr, scenarios are 100-300EJ/yr between 2050 and 2100 Need to have a clear and accessible narrative on why 100-300EJ/yr is carbon neutral Source: Based on IIASA AR5 Scenario Database Bioenergy use
  16. 16. • Bioenergy ranges are broad, generalizations are elusive • Results determined by a combination of assumptions: – Biomass feedstock supplies – Bioenergy options and costs – Other technology options and costs – Integrated systems modeling – Baselines • Elucidating & assessing this requires a dedicated effort… Bioenergy potential Source: Rose et al (2014)
  17. 17. Research needs
  18. 18. • Engineers will solve the plant-level problems, but … – What are the engineering limits to rapid deployment? – Is the scale of BECCS in models technically feasible? • Incentivizing negative emissions – Basic ingredients missing (e.g., accounting systems) – What policy structures and business models (may) work? • Boutique-scale CCS not useful, we need gigatonne-scale! • BECCS may be your saviour, we need BECCS at scale Research needs
  19. 19. Peters_Glen cicerosenterforklimaforskning Glen Peters