Kurt House's idea to bolster the oceans' ability to sequester carbon dioxide sounds straightforward enough. Because higher atmospheric levels of the greenhouse gas have blunted the oceans' ability to act as a carbon sink by making them more acidic, House - a graduate student in Harvard's Earth and Sciences department - contends, pumping in more basic solutions should help reverse that trend.
Arguing that it would take much too long - several thousand years - for the oceans to return to their equilibrium state naturally , House's proposal, known as electrochemical weathering, would accelerate a normal process that dissolves rocks on land to form alkaline solutions. The reactions that form the solutions, which eventually find their way to the sea, would be sped up by using a much stronger acid to dissolve the rocks.
To do so, an electric current would first be passed through seawater to separate out chlorine and hydrogen gas. The gases would be combined in fuel cells to produce hydrochloric acid, which would then be used in industrial-scale plants to dissolve silicate rocks. The overall outcome, House predicts, would be the stabilization of the oceans' pH - and thus a strengthening of the oceans' ability to sequester carbon dioxide.
As with other geo-engineering schemes we've covered, however, the devil is in the details: though the plants could eventually finance their operations by selling carbon credits under a cap-and-trade regime, it would cost $100 - at the very least - to remove just one ton of carbon dioxide. In addition, electrochemical weathering is an extremely energy demanding process; by some estimates, the same carbon reducing objectives could be achieved by replacing one coal-burning power plant for one powered by clean energy. Perhaps more worryingly, the byproducts contained in the plant's basic solutions could harm local marine life.
Though he acknowledges its downsides, House argues that the development of more efficient fuel cells and electrolysis technologies, as well as the use of geothermal energy to power the plants, would validate his plan. An intriguing plan, no doubt, yet one which will have a hard time gaining traction given its obvious faults.
Via ::Environmental Science & Technology: Speeding up earth's natural climate control (news website), ::Green Car Congress: Researchers Develop New Method for Ocean Sequestration of Carbon Dioxide Through Accelerated Weathering of Volcanic Rocks (blog)