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article imageCapturing Carbon Dioxide — Could sea urchins provide the answer?

By Robert Myles     Feb 5, 2013 in Science
Newcastle-on-tyne - A natural process involving carbon capture has been discovered by accident by researchers at Newcastle University in the UK. Researchers found that sea urchins could process carbon dioxide from the oceans to grow their exoskeletons.
Scientists at Newcastle University, operating in the field of nanoscale technology, stumbled upon a process whereby sea urchins use particles of the metal Nickel to ‘anchor’ carbon dioxide from seawater. If the process can be replicated commercially, it has the potential to lock in tonnes of atmospheric CO2.
Scientists discovered how sea urchins, with the help of the element Nickel, process CO2 found in the sea, solidifying it into calcium carbonate to grow their exoskeleton (shell). Sea urchins are small sea animals which come in a variety of forms. To date over 950 different species of sea urchin have been found all over the oceans, sometimes at depths of up to 5000 metres.
Turning carbon dioxide to stone
Se aurchin photographed off Sardinia
Se aurchin photographed off Sardinia
Wikimedia Commons
The UK based researchers’ discovery is published today in the scientific journal Catalysis Science & Technology. Such is the potential for the process in the field of carbon capture and storage, the Newcastle researchers have patented the process. If it can be developed commercially, then it holds out the tantalising prospect of CO2 — a key greenhouse gas when it comes to global warming and climate change — literally being turned to stone.
Dr Lidija Šiller, a physicist and Reader in Nanoscale Technology at Newcastle University, confirmed it was a completely chance discovery. She commented,
“We had set out to understand in detail the carbonic acid reaction – which is what happens when CO2 reacts with water – and needed a catalyst to speed up the process,”
“At the same time, I was looking at how organisms absorb CO2 into their skeletons and in particular the sea urchin which converts the CO2 to calcium carbonate.
“When we analysed the surface of the urchin larvae we found a high concentration of Nickel on their exoskeleton. Taking Nickel nanoparticles which have a large surface area, we added them to our carbonic acid test and the result was the complete removal of CO2.”
Existing methods of carbon capture and storage (CCS) usually involve pumping the CO2 deep underground and leaving nature to take its course in slowly absorbing the CO2. This method is both costly and carries risks since there are few ways of knowing if the CO2 will leach out from its underground reservoirs and emerge back into the atmosphere, possibly miles away from any pumping and storage facilities.
Scientists envisage this new process of carbon capture, similar to that which the humble sea urchin has been engaged in for millions of years, would see excess CO2 in the atmosphere converted to calcium carbonate or magnesium carbonate. Calcium carbonate occurs naturally in nature in many forms from chalk to marble.
Said Gaurav Bhaduri, lead author on the paper and a PhD student in the University’s School of Chemical Engineering and Advanced Materials,
“One way to do this is to use an enzyme called carbonic anhydrase,”
“However, the enzyme is inactive in acid conditions and since one of the products of the reaction is carbonic acid, this means the enzyme is only effective for a very short time and also makes the process very expensive.
“The beauty of a Nickel catalyst is that it carries on working regardless of the pH and because of its magnetic properties it can be re-captured and re-used time and time again. It’s also very cheap – 1,000 times cheaper than the enzyme. And the by-product – the carbonate – is useful and not damaging to the environment.
“What our discovery offers is a real opportunity for industries such as power stations and chemical processing plants to capture all their waste CO2 before it ever reaches the atmosphere and store it as a safe, stable and useful product.”
It's estimated that each year, due to human activity, 33.4 billion metric tons of CO2 are released into the Earth’s atmosphere. Of that total, about 45% is estimated to remain in the atmosphere. An average petrol or diesel powered car will produce one tonne of CO2 every 4,000 miles.
Calcium carbonate ( CaCO3) operates as a storage facility for carbon. As a common constituent part of the Earth’s crust it is estimated to equate to account for 1.5 million billion metric tons of carbon dioxide. In mineral form it occurs as chalk, limestone and marble whilst in biological form it can be found in eggshells, snail-shells and shellfish. It is also an important component in building materials such as cement.
The catalytic process developed by the Newcastle scientists, replicating the natural process of the sea urchin, is a relatively simple one involving passing waste carbon dioxide from a chimney top, through a water column rich in Nickel nano-particles then recovering the solid calcium carbonate from the bottom.
The process would not work for all CO2 emissions, as Dr Šiller pointed out, “It couldn’t be fitted to the back of a car, for example.” But it does look as though the Newcastle researchers have happened upon a cheap and effective solution that could be applied to many industrial processes and some of the world’s most polluting industries.
The Newcastle team have now taken steps to patent the technology and are currently looking for investment partners to take their newly discovered carbon capture process forward.
More about Greenhouse gases, Global warming, Carbon emissions, CO2 Emissions, Carbon capture
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