LafargeHolcim Marseille Cement Plant
Methodology
Step 1: Calculate the quantity of CO2 emissions that were delayed on each day of the action.
The LafargeHolcim Marseille Cement Plant emits 403,211 tonnes of CO2 per year ^{1}. To estimate the tCO2/d, we’ll divide the annual emissions of the facility by the number of days in a year.
Step 2: Calculate the benefit of delaying (temporarily storing) these emissions for the period of the action.
After the date of the shutdown, the cement plant was projected to be inoperative for several weeks ^{1}. To calculate the tCO2 lost per day, a conservative range of two, four, and eight weeks was factored in to estimate the tCO2/day: 14 days, 28 days, and 56 days.
Assuming that the factory was shut down for two weeks, halting cement production on day 1 of the action prevents the resultant CO2 from being released for the full 14 days. This can be thought of as storing this CO2 for this entire period. Halting the production on day 2 can be thought of as storing the CO2 for 13 days. Halting production on day 3 means 12 days of stored CO2, and so on. The sequence of days between 14 and 1 must be multiplied by the CO2 emissions that are delayed for each daily batch of cement that is held up at the facility. The same logic was applied to calculate for four and eight weeks as a potential range of emissions.
Step 3: Calculate the offset.
We then use an equivalence factor of 128 which was calculated using the Lashof method with a discount rate of 0 and a time horizon of 100 years ^{4} ^{5}. This equivalence factor posits that the effects of the release of 1 tonne of CO2 emissions is offset by the storage of 128 tonnes of CO2 for 100 years. From the range identified, the most conservative tonnage of carbon dioxide emissions was chosen to represent the final offset.

https://theatlasnews.co/conflict/2022/12/12/200frenchenvironmentalactivistssabotagelafargeholcimmarseillecementplant ↩↩

https://www.cevreadaleti.org/conflict/holcimlafargequarryswitzerland ↩

https://ground.news/article/environmentalistsattackoneoffrenchcementgiantlafargesfactories_59c55a ↩

Chay et. al. calculate this equivalence factor using Lashof here: https://carbonplan.org/research/tonyearexplainer ↩

Fearnside et. al. (2000) Accounting for time in mitigating global warming through landuse change and forestry. Mitigation and adaptation strategies for global change ↩