Shell Oil funds "open source" geoengineering project to fight global warming
July 21, 2008

Shell Oil is funding a project that seeks to test the potential of adding lime to seawater as a cost-effective way to fight global warming by sequestering large amounts of carbon dioxide in the world's oceans, reports Chemistry & Industry magazine.

Adding lime (calcium hydroxide) to seawater increases its alkalinity, thereby increasing the ocean's capacity to absorb CO2 and reducing its tendency to the greenhouse gas back into the atmosphere. The process could also help counter acid acidification, which biologists say is increasingly a threat to marine life, including coral reefs and plankton.

While the concept has been discussed for years, it has been believed to be too expensive to be carried out on a scale necessary to affect ocean chemistry. Now Tim Kruger, a management consultant at Corven, a London-based firm, think he has figured out a way to make the idea economical by locating in regions that are rich with limestone and have substantial energy resources that are too remote to exploit for commercial purposes.

"There are many such places — for example, Australia's Nullarbor Plain would be a prime location for this process, as it has 10 000km3 of limestone and soaks up roughly 20MJ/m2 of solar irradiation every day," said Kruger.

Although the process generates CO2 emissions, on paper it sequesters twice as much of the warming gas than it produces. Kruger says the process is therefore 'carbon negative'.

'This process has the potential to reverse the accumulation of CO2 in the atmosphere. It would be possible to reduce CO2 to pre-industrial levels,' he explained.

Shell is funding an economic feasibility study of the concept, which is detailed at Like other oil companies facing a future with caps on greenhouse gas emissions, Shell is increasingly keen on technologies that can reduce its carbon footprint.

"We think it's a promising idea," says Shell's Gilles Bertherin, a coordinator on the project, which is being developed in an "open source" manner. "There are potentially huge environmental benefits from addressing climate change — and adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification, so it should have a positive impact on the marine environment."

The project isn't the first to try to exploit the capacity of the oceans — the planet's largest carbon sink — to sequester CO2 from the atmosphere. Earlier this year Planktos, a California-based firm, attempted to conduct a large-scale iron-fertilization experiment in the equatorial Pacific. It argued that artificial iron fertilization would trigger massive blooms of phytoplankton that would absorb carbon dioxide from the atmosphere and help fight global warming. The firm would then sell the carbon credits to individuals and companies looking to offset their greenhouse gas emissions. But the scheme was widely opposed by environmental groups who said it could harm marine life. Some scientists — including researchers at Stanford and Oregon State Universities — said that any bloom of phytoplankton induced by Planktos would be accompanied by a bloom in bacteria as phytoplankton die. These bacteria may produce gases--like nitrous oxide, a powerful greenhouse gas--that counteract the effects of carbon sequestration by phytoplankton. Further, bacterial decay consumes oxygen, which alters water chemistry.

In any case, Planktos failed to attract sufficient funding to conduct its experiments. Investors were apparently put off by criticism of its plan, which relied on the use of foreign vessels to skirt the U.S. Ocean Dumping Act.

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CITATION: (July 21, 2008).

Shell Oil funds "open source" geoengineering project to fight global warming.