By Lura Schmoyer and Miranda Intrator, West Main Consultants
The Cool Climate Concrete (C3) program is an innovative monitored and verified greenhouse gas (GHG) offset program that offers financial incentive to concrete producers to replace portland cement with supplementary cementitious materials (SCMs) in mix designs. The program is sponsored by The Climate Trust, which also funded the program’s first phase completed in 2008. During the first phase, C3 paid $125,000 to participants for verifying 250,000 metric tons of avoided carbon dioxide (CO2) emissions due to portland cement reductions. The Climate Trust has since committed an additional $1.25 million to West Main Consultants, a sustainable materials consulting firm, to manage a second phase. Up to $800,000 in participant incentives is available during the second phase, paid at $4 per metric ton, to verify an additional 200,000 metric tons of avoided CO2 emissions.
Companies that purchase portland cement and SCMs from suppliers to blend their own cement when mixing concrete are eligible to participate in the C3 program, including precast concrete products manufacturers and ready-mix concrete manufacturers. Under the program, when a producer reduces the portland cement used in their concrete production beyond established baselines by substituting SCMs, CO2 emissions are avoided and offsets are generated (one metric ton of avoided CO2 emissions is equal to one offset). This program methodology evolved due to the majority of emissions related to concrete arising from portland cement production. For every metric ton of portland cement produced, nearly one metric ton of CO2 is produced.
While several SCMs may be acceptable for use in concrete production, only five are eligible for portland cement substitution in the program: ASTM C618 Fly Ash; ASTM C989 Grade 100 or 120 Ground-Granulated-Blast-Furnace Slag (GGBFS); ASTM C1240 Silica Fume; Rice Hull Ash; and Cement Kiln Dust. These SCMs qualify for use under C3 because they are byproducts of other processes and do not represent a net increase in GHG emissions (except in the case of GG BFS, where associated emissions are accounted for under the program).
To ensure that high-quality offsets are generated through the program, a Monitoring and Verification plan outlines program details and addresses the issue of “additionality,” or the fact that offsets created under the program must result from company practices that go beyond business as usual. For the purposes of the C3 program, business as usual is represented both by an industry-wide norm of portland cement use and by a participant’s own baseline (historical) portland cement use. The baseline is updated annually to incorporate the most recent year of participation. The employment of this sliding baseline encourages continual improvement by participating companies and ensures that SCMs replace portland cement at progressively higher percentages than business as usual practices. Offsets generated through the C3 program are verified by an independent third party.
Example: Consider a manufacturer with a baseline cement-to-concrete ratio for the first calendar quarter of 14.79 percent. At the close of the first quarter of this year, the manufacturer produced 27,000 cubic yards of concrete using 6,048 tons of portland cement. This manufacturer’s current cement-to-concrete ratio is 11.2 percent (converting both figures to pounds, the calculation is (6,048 tons x 2,000 lbs/ton)/(27,000 cy x 4,000 lbs/cy)). This decrease of the current ratio below the baseline results in avoided emissions of 1,425 metric tons, yielding an incentive payment of $6,700.
To help companies capitalize on participation, West Main Consultants analyzes a producer’s baseline data to determine potential offsets that could be verified under the program at various portland cement reduction levels, and estimates incentives for each level. This analysis, together with a potential offsets calculator (a tool developed by West Main Consultants that estimates potential offsets and incentives based on user inputs), is provided to companies after enrollment in C3, and can be used to investigate and set cement-reduction target. As companies strive to improve sustainability, this tool can be used to better understand the correlation between cement reduction and offset generation, and may prove useful in establishing and documenting sustainability goals.
Additional program documentation includes quarterly monitoring reports for each program participant, which track baseline portland cement use, actual cement reductions and CO2 emissions avoided. These third-party-verified, performance-based reports can monitor progress toward corporate sustainability goals and may provide quantifiable milestones for companies interested in reducing their carbon footprint.
By capitalizing on the use of SCMs through participation in the C3 program, producers can help further both the economic and environmental sustainability goals of the concrete industry through mix ingredient optimization, program incentives and the use of industrial byproducts as a portland cement replacement strategy. As each program participant reduces production costs and carbon emissions, the entire concrete industry may benefit similarly.