Flue gas carbon removal: Skyonic’s approach

imagesCALD2L5JA new EPA ruling, just validated by the U.S. Supreme Court, is aimed at substantially reducing carbon dioxide emission in the flue gas from coal-fired power plants and other large coal-burning plants. In previous posts on this blog I have discussed different technologies designed to achieve this goal, including carbon capture. These include scrubbing flue gas with amines or other alkalis, using oxygen instead of air to burn the coal (both possible for retrofits) or gasifying (instead of burning) the coal to produce a “synthesis” gas for combined cycle operation, again with carbon dioxide recovery. In all cases, carbon dioxide is either sold (valuable for tertiary recovery of crude oil) or stored underground. The first was tested in a U.S. plant without great success and may shortly be tested in China, the second is starting to be used in  two (250KW and 100KW, respectively) power plants in Germany and Korea, and the last will be employed in a very costly government supported combined cycle-based plant fueled with lignite in Missouri. The “bottom line” is that no technology is currently available and economically justified to deal with carbon emission and capture.

This brings me to Skyonic, a private company, which is developing an entirely new technology with both private and public support. Its unique approach involves capturing the carbon dioxide with caustic soda (sodium hydroxide) and turning it into sodium bicarbonate, an article of commerce. The caustic soda is produced in a conventional adjacent chlor-alkali plant where the chlorine co-product is reacted with hydrogen co-product to make hydrochloric acid, another article of commerce, now needed in large quantities for the hydraulic fracturing “fracking” process, as well as for other industrial uses.

Skyonic’s so-called SkyMine process has been piloted and is now about to be demonstrated in a commercial-sized facility at a cement plant in San Antonio Texas, with startup slated for October 2014. A chlor-alkali plant was constructed adjacent to the cement plant and a substantial percentage of the flue gas will be fed into the SkyMine facility that also sits next to the plant. The economics for the technology look good, with offtakers for both the sodium bicarbonate and the hydrochloric acid.Skymine

The obvious drawback to the process is the need to sell the very substantial amounts of sodium bicarbonate produced. While there are a series of markets for this chemical ( baking soda, toothpaste, animal feed, etc) the amount of bicarbonate produced by several SkyMine plants would soon flood the market. Large-coal-based power plants would therefore not be a prime target. However, steel plants, which emit much less carbon dioxide and need hydrochloric acid for steel “pickling” would be a more logical place for the process. Other types of plants that will need to remove carbon dioxide from their flue gas would also evaluate SkyMine.

The company has two answers for the bicarbonate market issue. It plans to sell the technology in other countries where large bicarbonate markets exist and it is also looking at adapting the process to make sodium carbonate (a much larger market : glass, soap, paper) and calcium carbonate instead of bicarbonate.



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