GHGT-16: Panel 6C on ‘Upstream emissions and the limits to emissions reductions from CCS’


By Jasmin Kemper

26 October 2022

This panel session was jointly moderated by Sean McCoy (University of Calgary) and Susan Hovorka (University of Texas). The panellists included Gaelle Cauchois (Carbon Limits), Rachael Moore (IEA), Jose Benitez (USDOE), and Jon Gibbins (University of Sheffield). The panels used a very interactive format, posing questions to the attendees, which were then used as starting points for further elaboration by the panellists.

Some attendees were probably surprised to learn that, assuming a 1% CH4 leakage rate, a pulverized coal power plant equipped with CCS (PC-CCS) has lower LCA carbon emissions than a natural gas combined cycle plant with CCS (NGCC-CCS). There is a lot of variability and uncertainty in the CH4 emissions estimates though, especially for the upstream emissions parts, and the resolution of the collected data is quite course currently.

The CH4 leakage rate for oil and gas productions in the Permian Basin can be anywhere between 2-6%. This range is due to the different technologies used for production/extraction and measurement of the emissions. It is also often not clear how much of the leaked CH4 is attributed to oil or to gas production. Another issue to keep in mind is the dynamics of emission factors, e.g. over time, as the age of infrastructure increases, so will the amount of leaks.

Next, there was a discussion of ‘blue H2 vs NG with CCS /DACCS’. It is unclear yet, which pathway will be more cost effective and sustainable, especially after infrastructure investments etc for a change from NG to H2 are taken into account.

Panellists agreed that using either a GWP20 or a GWP100 approach are correct and the selection for one over the other (you could of course also decide to calculate both) will depend on the context and the research questions asked.

Currently, about 15% of global energy sector emissions are from indirect upstream emissions, which is equivalent to a loss of 180 bn m3, and CH4 emissions in the energy sector rebounded in 2021. Russia and the USA emit the most in total terms but they are also the main producers, so the emissions intensity is actually relative low. Norway has the lowest emissions intensity, due to very strict regulations. It was also pointed out that implementing tried and tested policies could easily halve CH4 emissions. This all means that even NGCC-CCS with 99% CO2 capture rate can overall only be as good as the amount upstream emissions.

What can be done now in absence of better data collection/measurement is to reduce venting and fix leaks in a timely manner. This is usually low cost (e.g. addressing emissions related to bleed valves comes at about $10/tCO2).

The session concluded with the following key messages:

  • Choices cannot be made purely on economics.
  • We need to identify the appropriate tools to answer the specific research questions.
  • We need a portfolio, not a single option, and a holistic systems point-of-view.
  • Both CO2 and CH4 abatement are required. If the process involves NG, then CO2 mitigation alone is not enough.
  • Following from the previous point, we need to get to net zero greenhouse gas (GHG) emissions and we need to clarify what the implications are for this. 
The panel at Panel Session 6C at GHGT-16

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