Lime In Seawater May Reduce CO2 To Pre-Industrial Days - Study
    By News Staff | July 20th 2008 04:01 PM | 1 comment | Print | E-mail | Track Comments
    Scientists say they have found a workable way of reducing CO2 levels in the atmosphere by adding lime to seawater. And they think it has the potential to dramatically reverse CO2 accumulation in the atmosphere, reports Cath O’Driscoll in SCI’s Chemistry & Industry magazine published today.

    Shell is so impressed with the new approach that it is funding an investigation into its economic feasibility. ‘We think it’s a promising idea,’ says Shell’s Gilles Bertherin, a coordinator on the project. ‘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.’

    Adding lime to seawater increases alkalinity, boosting seawater’s ability to absorb CO2 from air and reducing the tendency to release it back again.

    However, the idea, which has been bandied about for years, was thought unworkable because of the expense of obtaining lime from limestone and the amount of CO2 released in the process.

    Tim Kruger, a management consultant at London firm Corven is the brains behind the plan to resurrect the lime process. He argues that it could be made workable by locating it in regions that have a combination of low-cost ‘stranded’ energy considered too remote to be economically viable to exploit – like flared natural gas or solar energy in deserts – and that are rich in limestone, making it feasible for calcination to take place on site.

    Kruger says: ‘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.’

    The process of making lime generates CO2, but adding the lime to seawater absorbs almost twice as much CO2. The overall 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,’ Kruger says.

    And Professor Klaus Lackner, a researcher in the field from Columbia University, says: ‘The theoretical CO2 balance is roughly right…it is certainly worth thinking through carefully.’

    The oceans are already the world’s largest carbon sink, absorbing 2bn tonnes of carbon every year. Increasing absorption ability by just a few percent could dramatically increase CO2 uptake from the atmosphere.

    This project is being developed in an open source manner. To find out more, please go to, a new website, launched today.


    So we are supposed to dig up 10,000 km3 of limestone in Australia? That sounds pretty environmentally devastating. What is the safe rate to add all that to Southern Ocean? You have to give it time to dissipate if you don't want it to kill off local sealife. If you can safely dump only a few cubic kilometers a year in one area then it won't be effective rapidly enough and/or you have to expend large amounts of energy to ship this stuff around the world to spread it dilutely enough.

    I think this idea may form a very small part of the solution to climate change but it should not be thought of as an easy fix that doesn't require us to do the much harder (and far more effective) job of conserving energy, switching to carbon-free energy sources, and restoring our ecosystems instead of strip mining the planet in an effort to remain lazy while buying the all latest toys.