Table 1.
The expert appraisal of each of the CDR options’ ESG score as well as their expected CO2 sequestration timescale
| ESG Score (1–5) | Sequestration timescale (years) | “Quality”(ESG+sequestration timescale) | |
|---|---|---|---|
| Direct air carbon capture and sequestration(DACCS) | 4 | >1,000 | 9 |
| Wood for construction | 5 | <100 | 8.5 |
| Reforestation | 5 | <100 | 8.5 |
| Biochar | 4 | 100–1,000 | 8 |
| Mineral carbonation | 3 | >1,000 | 7.5 |
| Enhanced weathering | 3 | >1,000 | 7.5 |
| Direct ocean carbon capture and storage (DOCCS) | 3 | >1,000 | 7.5 |
| Afforestation | 4 | <100 | 7 |
| Soil carbon storage | 4 | <100 | 7 |
| Seaweed | 3 | 100–1,000 | 6.5 |
| Bio energy carbon capture and sequestration (BECCS) | 2 | >1,000 | 6 |
| Costal blue carbon | 3 | <100 | 5.5 |
| Ocean fertilization | 1 | 100–1,000 | 3.5 |
| Ocean upwelling | 1 | 100–1,000 | 3.5 |
| Ocean alkalinity enhancement | 1 | 100–1,000 | 3.5 |
| Crops | 1 | 100–1,000 | 3.5 |
Based on these two parameters, a “quality” measure is calculated given more weight to ESG as compared to CO2 sequestration timescale: “Quality” = ESG score ∗ 1.5 + CO2 timescale value (whereby a timescale value of 1 was given for a CDR options with an expected CO2 sequestration time <100 years, a value of 2 for a timescale between 100 and 1,000 years and a value of 3 for a timescale >1,000 years).