Sea water & scrap metal could sequester 850 million tons of carbon dioxide

by Steve Hanley, Clean Technica

People are beginning to understand that lowering carbon dioxide emissions will not save the planet from overheating. It will be necessary to actually remove much of the carbon dioxide already in the atmosphere to keep global temperatures from rocketing past the 2º Celsius mark considered critical by most climate scientists (at least those who are not being paid off by the petroleum industry).

Carbon sequestration schemes that range from the bizarre to the possible are beginning to make headlines. Now researchers at the University of York in the UK are putting forward an idea they say could capture almost a billion tons of carbon dioxide a year at relatively low cost and turn it into the mineral Dawsonite, known chemically as sodium aluminium carbonate hydroxide or NaAlCO3(OH)2. Sadly, Dawsonite has no known practical uses, but let’s not put the cart before the horse.

Professor Michael North of the chemistry department at University of York says,

“We wanted to look for methods of trapping the gas using environmentally friendly tools to produce a result that could be highly scalable to capture millions of tonnes of unwanted carbon dioxide. We started with the realization that using graphite — the material used in pencils — to line aluminium reactors results in the mineralization of carbon dioxide. We wanted to trap the gas at much higher levels, using low-energy processes, so we decided to look at waste materials, such as scrap metals, to see if this could be done without using chemical agents as a catalyst.”

The research he and his team did is published in the journal ChemSusChem. First, they filled an aluminium reactor with water from the nearby North Sea then added scraps of aluminum foil. Then, they passed electricity generated by solar panels through the mixture. Dawsonite was the result.

“Tens of millions of tonnes of waste aluminium are not recycled each year,” North says, “so why not put this to better use to improve our environment? The aluminium in this process can also be replaced by iron, another product that goes to waste in the millions of tonnes. Using two of the most abundant metals in the Earth’s crust means this process is highly sustainable.”

According to Science Daily, other mineralization schemes rely on hydrogen gas under high pressure, but the process North and his colleagues came up with eliminates the need for hydrogen, which lowers the cost of the procedure considerably. Instead, hydrogen gas is a by-product that can be sold for industrial uses.

Like all laboratory experiments, this one is not yet commercially viable, but North and his partners are continuing to refine and improve the process in hopes that it may be economically feasible in the future. It would help if they could find a commercial use for millions of tons of Dawsonite.

source: https://cleantechnica.com/2017/12/18/sea-water-scrap-metal-sequester-850-million-tons-carbon-dioxide/

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