Quantification of ERW: Suggesting the concept of “stages” for MRV (Update)

Based on Feedback we have changes the word "scope" to "stage" in our concept

In July we had posted a blog article that suggested a “scope” model for MRV of enhanced weathering. Since then a few readers gave feedback that they would recommend to use the word “stage” instead of “scope”.

After some consideration we agree. So we have updated the article.

Here is also another approach to explain the graph:

The graph's metric is "CDR Potential in t of CO2", either “per ton of rock” or “per hectare”. The last two can be converted by multiplying with the number of tons/ha amended.

• Stage 1: 

  • We start with 100% of stoichiometric CDR potential per ton of rock. 

  • Metric at exit of the stage: "t of CO2" = rock's lifetime max CDR potential per ton of rock (eventually related to tons of rock/hectare)

  • minus "t CO2" for required emissions (rock is mined, ground, transported, spread) per ton of rock

  • At the end of stage 1 (line between light blue and dark blue) we already have less than 100% of the rock's potential left 

  • Let's assume it's 80%, that the CO2 costs of mining, grinding, transport, distribution is about 20%

• Stage 2: 

  • The initial CDR potential (max CDR potential of rock – CO2 cost of project set up) is now slowly sliced into time-slices, some x% of rock is dissolved every year 

  • Metric at exit of stage: "dissolved % of amended rock per time" can be converted into "t of CO2/ha/year of dissolved rock's CDR potential"

  • When rock dust is dissolved we need to diversify by type of acid, e.g. carbonic or nitric, and subtract the latter

  • At the end of stage 2, at the dark blue line, we have time-sliced the 80% from stage 1 into 100 chunks over up to 100 or so years

• Stage 3: 

  • In this stage the time-dilated CDR potential can be further delayed or it is even lost

  • Metric at exit of stage: "% of CDR potential that reached the leachate" which can be converted from/to "tons of carbon as TA in leachate" per time and field area 

• Stage 4:

  • Now we transport the TA in rivers and into the sea.

  • Again we have losses during things that happen far away from the field, e.g. transport or in the ocean itself over time

  • Metric at exit of stage: "% of CDR potential that reached the Ocean" over time and per field surface area

• Finally we know what we have done for the climate!