Hi, I'm familiar with CQuestrate and Tim Kruger, but my understanding is that this is all about kilning CaCO3 to CaO + CO2, then hydrating CaO to Ca(OH)2, then putting that in ocean to react with CO2 to Ca++ + 2(HCO3)- - a net gain of one CO2. The problems are that this is energy intensive, and in alkaline conditions you get a high rate of CaCO3 precipitation which just takes you back where you started, and in the long term all the Ca / CO2 ends up as CaCO3 anyway. If CQuestrate is now taking silicates as their starting point, I can only be glad that colleagues such as Olaf Schuilling, and to some extent I, have managed to convince him that Mg silicate is a much better starting point than Ca carbonate. Oliver Tickell.
On Sep 23, 3:20 pm, Chris <[email protected]> wrote: > Oliver, > > In his reference to "Dumping lime or calcium or magnesium silicates > into > the sea...", George Monbiot was referring to the concept put forward > by Tim Kruger of Cquestrate - seewww.cquestrate.com. > > Chris Vivian. > > On Sep 23, 12:40 pm, Oliver Tickell <[email protected]> wrote: > > > > > > > > > Monbiot's real mistake here is to swallow the conclusion of the Royal > > Society report on the subject, whole and undigested, without critical > > scrutiny or attention to other sources of information - in particular > > as regards the weathering of magnesium silicate (not enough Ca > > silicate to bother with): > > > Monbiot reports: "Dumping lime or calcium or magnesium silicates into > > the sea, where they react with carbon dioxide. Fairly safe. Effective. > > Expensive. Has > > the advantage of potentially reversing ocean acidification, but the > > amount of quarrying required to produce enough ground-up rock is > > likely to be prohibitive. " > > > A) where does he get the idea that it's about dumping it in the sea? > > It is about spreading the rock powder on land, and in intertidal > > zones. > > B) So it's "fairly safe". Why only "fairly"? This is just to > > accelerate a natural process that is going on all the time anyway. > > C) "Expensive" - how much? People who have done the sums > > conservatively estimate $10-15 per tCO2. Making it one of the cheapest > > options around. > > D) It will only "potentially" reverse ocean acidification. Well, > > insofar as the science of chemistry "potentially" applies. He seems to > > be implying that maybe chemistry is "potentially" all wrong. George, > > tell us more! > > D) The amount of quarry is "likely to be prohibitive" - is it? Has he > > done the sums? Has he asked anyone who has done the sums? Or is this > > just his uniformed guess? For a start there are Gt of already mined > > rock that can be used, in mine tailings around the world. From then > > on, roughly 1t of rock sequesters 1t of CO2. So you need to mine an > > amount of rock comparable to the amount of fossil fuel we are burning. > > If it's not "prohibitive" to mine the coal, why's it "prohibitive" to > > mine the rock? > > > Oliver Tickell. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
