Coverting CO2: The world's first commercial carbon dioxide mineralization plant can capture 83,000 tons of direct CO2 emissions and create around 160,000 tons of bicarbonate. Image: Vattenfall/The Conversation
Editor's note: The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
By Michael Parker, Environment and Energy Editor, The Conversation
The term “carbon capture and storage” seems only to appear when shortly followed by “not commercially proven” or “in development”. But construction has now begun on what will be the world’s first commercial carbon dioxide mineralization plant, in which carbon dioxide greenhouse gas is transformed into baking soda.
Skyonic has been developing its patent-backed carbon capture process since 2004. The principle is to turn gaseous waste products including CO2 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 cement works in San Antonio, Texas. When completed in 2014, it will capture around 83,000 tons of direct CO2 emissions and create around 160,000 tons of bicarbonate, preventing 300,000 tons of emissions in total.
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 enters absorption chambers where it is treated with sodium hydroxide – caustic soda – made from salt (sodium chloride, or NaCl) and water (H2O). The chemical reaction that occurs is:
CO2 + H2O + NaCl —> NaHCO3 + H2 + Cl2
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. “A few kilos of mercuric oxides in solid form is much better than spreading it about far and wide as aerosols in the air,” Skyonic CEO and founder, Joe Jones said. “And 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.”
The market for these products, and the products which they are used to manufacture, is enormous. “In North America alone the market for carbonates, soaps, limestone products used in making paper, cement, or fine chalks is with US$7.5 billion,” Jones said. “Even if only about half of that is lucrative, we’ll be able to drive down the price of carbon sequestration process to around US$20 per ton. The market will deliver the most sequestration at the least cost to society.”
Also acting in Skyonic’s favor 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 – energy firms such as BP, ConocoPhilips, Luminant and Cenovus have already backed Skyonic to the tune of US$128m.