Last week’s post on Permable Pavement reminded me of another sustainable paving material: cement made from carbon dioxide and seawater. This technology has been pioneered by a Northern California company called Calera, situated near the Moss Landing gas-fired power plant. Their process involves capturing the “stack gas” created by the power plant, running it through fresh seawater, and adding the resulting calcium carbonate to a concrete mix for commercial use. Calera claims that they can use up to 90% of Moss Landing’s carbon dioxide emissions for such processes, but it has not yet been fully approved by the construction industry or relevant building authorities, which are generally slow to accept changes.
More research needs to be done on the impacts of seawater intake/outtake and cost-effectiveness of this technique, but it offers a benefit that few other building materials do: it actually sequesters carbon dioxide, not by storing it in leaky underground reservoirs like other CCS techniques suggest, but by creating useful and necessary new materials from it. In all likelihood, CCS-cement won’t be available in time for the Green Dorm, but it’s an interesting technology to be aware of as we move forward, looking for both sustainable materials and emissions-reduction strategies.