The problem is on the scale we are talking about you are not just reversing ocean acidification, you are making it basic. (This is from GreyFalcon's link.) At the same time, on a global scale you are not affecting acidity.

Another point from GreyFalcon's first link: none of the articles link compare putting up high voltage line and feeding the energy to do this into the grid with this. Also in terms of costs, you not only have to compare costs of doing this with the costs of putting putting the power into the grid, but the cost of the fossil fuel that would be displaced by putting the power into the grid. We need the hard figures, but I'd bet:

You get more sequestration via limestone than via putting the power into the grid

you get higher costs via limestone than putting power into the grid

the cost per unit of reductions is about the same, but you are better off putting in place renewable infrastructure faster. You can do limestone if that turns out to be a good idea, after we stop putting garbage into the atmosphere. The first rule of holes is: if you are in one, stop digging. The second rule of holes (which I just made up) is don't start filling the hole you are in until you are out of it.

I'm not against it in principle. Maybe dumping limestone in the ocean really would be harmless. Maybe the even when all costs are counted this is a really cheap way to get garbage out of the atmosphere. I'm all for a full evaluation being done. Also an ocean acidfied via Co2 and then with acidity reduced via limestone is not the same as an the state it started out with. Maybe this is better than the status quo, but I'd be really suspicious of unexpected consequences.

Also on one of my earlier points: they think this makes sense only using "stranded power". That implies that "unstranding" it might be more productive that producing limestone.

Or basic in it's light/dark cycle.  This might be employed in floating algae/energy farming to manipulate PH, if that is all that is needed for greater CO2 absorption.

Flush the basic water and replace it with ocean water at the right time.  It would filter pollutants from fertilizer run off and aereate the water as well.

Maybe using solar furnaces to convert the limestone would help, but it still sounds like a huge dangerous trip mining, species killing effort.  A better use of the solar energy and land area would be solar for energy production that halts GHG intensive power generation.

I still think waste biodigestion/organic fertilizer energy production is the key to reversing GHG concentration.  Along with renewable/conservation energy policy in general.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

....... then it must be a bad idea right? The truth is, a fair amount of people in the green movement oppose sequestering because their objective has nothing to do with climate change, but social change. They just aren't honest about it.

Victory in Pattani

Even if this has the potential to economically counteract global warming, think about the potential to royally screw up the oceans and thus the entire world.  MUCH more study is needed in order to even possibly consider doing this on a massive scale.  

By over 20 times in terms of GHG balancing effect, with organic fertilizer production it returns nutrients to the soil too.  Biochar sends nutrients into the astmosphere as pollution.  If the char is added to soil it doesn't work as a sequestration tactic at all, it increases the break down of soil organic matter.

Fertilizer from a biodigestor builds the soil eco-system and restores the sequestration ability of the crop land tuned into inert agrichem poisoned dustbowl ready to blow away in the next drought/wind storm event.  Toxic dust in every lung.  That can't be a good cost effective situation.

The char would have to be used for filtration or some other use, like combustion, where it doesn't get turned back into CO2.

I suspect if the valuable charcoal was produced it would inevitably be burned for profit when government regulator's backs were turned.  Hear no GHG, see no GHG...  let industry regulate itself, yeah that's the (GOP) ticket to big bribes (campaign contributions).

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

Emissions reduction and sequestration must go hand in hand.

As far as I understand, biodigestion is emissions reduction (and a very serious one), whilst charcoal is sequestration.

Soil organic matter breaks down anyway. Charcoal takes significantly longer to break down (if ever, for all practical purpose). Plus: It stores/fixes nutritients (e.g. those delivered from your biodigestor), significantly reducing run off and nitro outgassing. That's why Amazonian char coal soil is still extremely fertile, after 500y.

So, forget about that Swedish study (or look at Folke Günther's blog for explanation) and have a look at terra preta instead.

Of course, just producing char coal from anything would be no help. You should 1) produce from biomass that would decay soon anyway 2) capture the pyrolysis gas for energy production.

Ceterum censeo: I'm still awaiting for the invention of a c21st wood gas car, driving carbon negative.

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.

The environment in Australia is already devastated. Most of it is one, big crappy desert. Who cares about the "eco systems" there? Certainly not me. There's not much you can do to a desert to make it worse. I've lived in them before, and they suck.

Victory in Pattani