A dash of lime...for CO2 reduction?
Seema Singh -
Monday, July 21, 2008 6:00 AM
A dash of lime can make your drink; lift a bland pudding or make
idlis fluffy; but a dash of lime for carbon sequestration?
Yes, that's what scientists are proposing in today's issue of Chemistry & Industry, journal of Society of Chemical Industry. A dash of lime in seawater has the potential to dramatically reverse CO2 accumulation in the atmosphere, they say. Of course, they don't mean the green citrus that we squeeze in our cups and glasses but lime from limestone.
Oil major Shell seems to be pretty impressed with the idea and is funding further research 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."
The way it works is-adding lime to seawater increases alkalinity, enhancing seawater's ability to absorb CO2 from atmosphere and reducing the tendency to release it back again. The idea has been around for some time but didn't seem feasible due to the expense of getting lime from limestone, which also releases large amounts of CO2 released in the process.
Now, a management consultant at a UK firm Corven, says it can be made workable by locating it in regions that that have a combination of low-cost "stranded" energy that are often not economically viable for regular use -- such as flared natural gas or solar energy in deserts -- and that are also rich in limestone. This combination, it is argued, can make calcination (a method using heat to drive off carbon dioxide from limestone to obtain lime) possible on site.
Some researchers in the field say the idea is "certainly worth thinking through carefully"; others might call it preposterous. But the scientific world is full of such ideas.
Way back in 1989, oceanographer John Martin published an astounding theory of ‘iron fertilization' in Nature and famously said: "Give me half a tanker of iron and I'll give you the next ice age."
He believed if iron was sprinkled on the anemic zones of the oceans (20% of the world's waters lack nutrient for plant life and are called "high nutrient/low chlorophyll" zones) they would cause marine plants (phtoyplanktons) to bloom and soak up CO2. Martin believed that HNLC zones worldwide could lock up to billions of tons of CO2.
He died a few months before his planned expedition to test this theory but researchers have since carried out at least half a dozen such experiments, including IronEx I and IronEx II, and have reported noticeable plant growth on water surface.
The idea's audacity, of course, halted it and now there's a resurgence of sorts. Who knows what the future of CO2 control holds?