Note that the article applies to the addition of very fine (1um) olivine 
powder direct to oceans. This requires a huger energy input, 10^4 times 
greater than that of creating the 100um granules suitable for spreading 
to land (grinding energy ~ surface area).

Yes, the volume of olivine required is large - but then so is the 
problem. By rule of thumb, you need the same weight of olivine as of the 
CO2 you want to sequester. So 1Gt of olivine for 1Gt of CO2 sequestered. 
And yes, it has to come from somewhere. Fortunately it is abundant and 
there are already huge volumes of it at existing and former mines as 
dumped overburden. For example, at nickel mines, and diamond mines. 
Maybe even at coal mines! Digging it up and moving it about will still 
have an impact, but a much smaller one than allowing global warming to 
let rip.

BTW the preferential fertilisation of diatoms would not be an altogether 
bad thing. They are good at sequestering carbon to ocean depths in their 
own right. Also they are good at feeding ocean food chains leading to 
fish. But obviously impacts would need to be closely monitored - on top 
of everything else we are doing to oceans, like wiping out top level 
predators, over-fishing, filling up with waste plastic, etc. Also you 
need to consider the benefits of restoring alkalinity to the oceans 
which olivine application would do (whether applied to land or sea, the 
bicarbonate and silicic acid would tend to end up the oceans).

Oliver.

On 22/01/2013 07:06, Kevin Coleman wrote:
> To All,
>   The article linked to below answers a few of my questions from last year regarding the efficiency of Olivine as a geoengineered solution to carbon emissions.
>
> As I said at the time the apparent benefits had hidden costs in terms of energy required to extract, transport, process and deliver to the ocean. The issue of global quantities required to absorb the carbon compared to what is globally available which I also asked to be clarified with no response has been only partially answered in this particular piece.
>
> In this respect they do say that the amount required to facilitate the absorption of about 9% carbon dioxide is substantial (3 billion tonnes) and would require an industry equivalent to the current coal mining industry and therefore equally destructive to ecosystems. You cannot dig a hole without digging up some natural habitat be it a lush rainforest or a desert. Each has its role and function in the greater scheme of things. Neither is in plentiful supply.
>
> When I challenged the idea last year no-one from the AMEG cartel, who were promoting geoengineering the planet, was willing to come forward with the necessary details to answer my legitimate questions.
>
> It was only when I received an article from a friend in the US that some of those questions were answered. The article relates to some serious research into Olivine as a solution to carbon capture in the oceans. Despite previous claims it appears to be yet another dead end.
>
> But what I also find interesting is the last two paragraphs references to two other solutions. They too are now being also deemed equally doubtful. One of them being cloud seeding.
>
> Kev C
> http://www.terradaily.com/m/reports/Climate_Rock_fix_for_oceans_is_badly_flawed_study_999.html
>