The term \u201ccarbon capture and storage\u201d seems only to appear when shortly followed by \u201cnot commercially proven\u201d or \u201cin development\u201d. But construction has now begun on what will be the world\u2019s first commercial carbon dioxide mineralisation plant, in which carbon dioxide greenhouse gas is transformed into baking soda.<\/p>\n
Skyonic<\/a> has been developing its patent-backed carbon capture process since 2004. The principle is to turn gaseous waste products including CO2<\/sub> into valuable industrial chemicals that can be sold. The technology, Skymine, is a self-contained unit about the size of an articulated lorry, set up at power stations or industrial installations such as steelworks or petrochemical plants. Construction of the first commercial Skymine plant began this week alongside the Capital Aggregates<\/a> cement works in San Antonio, Texas. When completed in 2014, it will capture around 83,000 tons of direct CO2<\/sub> emissions and create around 160,000 tons of bicarbonate, preventing 300,000 tons of emissions in total.<\/p>\n The process is powered by using the heat in waste gases from industrial chimneys to generate electricity. First the carbon dioxide, sulphur dioxide, nitrogen oxides, and heavy metals like mercury are scrubbed from the waste gases. The latter are stored, and the CO2<\/sub> enters absorption chambers where it is treated with sodium hydroxide \u2013 caustic soda \u2013 made from salt (sodium chloride, or NaCl) and water (H2<\/sub>O). The chemical reaction that occurs is:<\/p>\n CO2<\/sub> + H2<\/sub>O + NaCl \u2014> NaHCO3<\/sub> + H2<\/sub> + Cl2<\/sub><\/p><\/blockquote>\n Put another way, carbon dioxide, water and salt react to produce sodium bicarbonate (baking soda), hydrogen gas and chlorine gas. Hydrogen and chlorine gas have commercial uses themselves, or both can be easily dissolved in water to create hydrochloric acid (HCl), an important industrial solvent. Even the poisonous extracted mercury has value. \u201cA few kilos of mercuric oxides in solid form is much better than spreading it about far and wide as aerosols in the air,\u201d Skyonic CEO and founder, Joe Jones said. \u201cAnd we will sell that to other people who will mine it for rare earth minerals like yttrium, niobium, vanadium, many of which are highly prized per microgram.\u201d<\/p>\n The market for these products, and the products which they are used to manufacture, is enormous. \u201cIn North America alone the market for carbonates, soaps, limestone products used in making paper, cement, or fine chalks is with US$7.5 billion,\u201d Jones said. \u201cEven if only about half of that is lucrative, we\u2019ll be able to drive down the price of carbon sequestration process to around US$20 per tonne. The market will deliver the most sequestration at the least cost to society.\u201d<\/p>\n Also acting in Skyonic\u2019s favour are regulations that already require polluters to scrub out sulphur and nitrous dioxides that cause acid rain. Jones says his process can do it cheaper than the current commercial scrubbers that cost hundreds of millions of dollars, and millions more on annual maintenance. Even the baking soda, lime, and acid products can be created more cheaply from the carbon dioxide stream through Skymine than from traditional methods. New, tighter EPA regulations on power station emissions enacted recently may also drive interest in his technology \u2013 energy firms such as BP, ConocoPhilips, Luminant and Cenovus have already backed Skyonic to the tune of US$128m.<\/p>\n The question is, can this baking soda process save the planet from runaway climate change? Jones, himself a chemist, is realistic. \u201cSkymine by itself cannot save the world, because the sodium-based product market by itself could only support 200-250 plants worldwide,\u201d he said. But a second design, codenamed Skycycle, that will manufacture calcium-based products like chalks and limestones, might be able to.<\/p>\n \u201cIn this county alone there are more than a pentillion<\/a> tonnes of limestone, that contain more CO2<\/sub> than has or could be generated by all fossil fuels for all time,\u201d Jones said. \u201cDisposing of CO2<\/sub> as solids has already been proven to work over very long, geological periods of time.\u201d<\/p>\n Despite the straightforward chemistry, it\u2019s the first attempt at mineralising carbon in a way that is commercially viable and carbon negative. The method seen as more mainstream is to capture the CO2<\/sub>, transport and inject it in gaseous form into subterranean geological formations. The UK has a great number of these, Michelle Bentham, senior geoscientist at the British Geological Survey. \u201cWe have lots of suitable formations offshore, and lots of oil and gas fields, in which the gas and oil collects in the same way the CO2<\/sub> would.\u201d<\/p>\n The so-called reservoir rocks such as sandstone are filled with tiny holes known as porespaces which are microns in size, into which the CO2<\/sub> is forced, eventually bonding to the rock. While the technology required at each stage \u2013 scrub, capture, transport and inject \u2013 are well-established, commercial schemes have been held up by economic, not technical questions.<\/p>\n \u201cThere are still unanswered questions until we actually do it, but I have no doubt that carbon dioxide can be stored in that fashion,\u201d said Bentham. A Norwegian drilling firm has been carrying out a similar process<\/a> since the 1990s \u2013 stripping CO2<\/sub> from oil and gas as it is extracted and then injecting millions of tons of it every year back under the North Sea.<\/p>\n