Adding lime to seawater

Shell Oil is funding a project that is studying the potential of adding lime to seawater to store carbon dioxide (CO2) in the sea.

Due to increased CO2 levels, the oceans have become more acid. Adding lime (calcium hydroxide) to seawater will increase the alkalinity of the water, making the water absorb more CO2 and reducing the release of CO2 from the water into the atmosphere.

Tim Kruger, a management consultant at London-based Corven, believes that this can be done most economically where there's plenty of limestone, and plenty of energy that is too remote to exploit for conventional 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.

"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."

Sources and Links:

Shell Oil funds "open source" geoengineering project to fight global warming, at:
Mongabay.com

'Turning back the clock on climate change' - A technology to reverse climate change? To reduce ocean acidification? And that also promises to increase food production? Cath O’Driscoll investigates, at:
Chemistry & Industry Magazine

Adding lime to seawater feasibility study, funded by Shell, at: 

www.cquestrate.com

Pipes in the oceans to pump up water

Science Museum head Chris Rapley and Gaia theorist James Lovelock are suggesting to install flotillas of vertical pipes in the tropical seas. Free-floating or tethered vertical pipes could pump up nutrient-rich waters from below the thermocline in order to mix them with the relatively barren waters at the ocean surface.

Such pipes could be 100 to 200 metres long, 10 metres in diameter and with a one-way flap valve at the lower end in order to pump water upwards powered by by wave movement. The water pumped up this way could fertilize algae in the surface waters and stimulate them to bloom. More specifically, pumping up water through such pipes would result in an increased presence in the surface waters of the salp, a tiny tube-like species that excretes carbon in its solid faecal pellets. This carbon would subsequently descend to the ocean floor. The hope is that this could store carbon away for millennia on the ocean floor. 

An additional effect would be that the algae produced an abundance of dimethyl sulphide (DMS), a chemical that acts as the precursor of nuclei that form sunlight-reflecting clouds. As more clouds would form above the ocean, more sunlight would be reflected away from the Earth's surface, resulting in relative cooling of the ocean underneath. 

US company Atmocean has in fact already started trials with this type of technology, using pipes that bring cold water to the surface from a depth of 200m. 

References: 

- Mixing the oceans proposed to reduce global warming 

http://www.nature.com/news/2007/070924/full/news070924-8.html 

- Ocean pipes could help the Earth to cure itself 

http://www.nature.com/nature/journal/v449/n7161/full/449403a.html 

- Lovelock urges ocean climate fix 

http://news.bbc.co.uk/1/hi/sci/tech/7014503.stm

Covering parts of oceans with snow-like material

To combat global warming, William (Bill) Johns, of Chemcept Ltd, suggests to cover part of the surface of the oceans with a material as reflective as snow. The materials could be made from conventional polymers, using facilities that currently produce (excessive) packaging for retail products. 

 Bill notes that the reflective capacity of such material depends on where it will be positioned in the oceans. The closer to the equator, the more effective it will be. Snow is now predominantly located close to the poles and appears from the sun as two small rims on the edges of Earth that receive less sunshine than any other area on Earth. Yet, this relatively small snow-covered area accounts for a cooling of Earth of about three degrees Celsius, Bill estimates, because snow reflects nearly 90% of the solar radiation that falls on it. Positioning the material closer to the equator will therefore require less surface than the areas of the poles currently covered by snow -- the closer to the equator, the less surface will be needed, in order to achieve the same amount of cooling. 

For more, see: 

Chemcept on Global Warming

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Planktos - seeding the oceans with iron

Planktos plans to fertilize the oceans with iron to stimulate growth of phytoplankton, microscopic marine plants that soak up carbon dioxide. Their ship plans to dissolve tons of iron over a 10,000-square-km patch.

https://www.youtube.com/v/Qe1fOxQSUKs

For more details, see: Planktos.com The Independent NY Times

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