I honestly don't think there are any.
I did read a post from .... Trevor??? ... that advocated burying CO2.
However, I don't think that will work for the amounts we need to deal with.
Twice in the past few decades, burying waste water has caused earthquakes,
and the process had to be stopped.
I think that the same would happen with CO2.
And, there would be the risk of leaks that couldn't be capped.
I think I've seen someone suggest burying CO2 in the deep ocean.
I don't like that idea either.
Putting one's waste where one can't see it is rarely a good solution.
Changing the chemistry of the ocean, where we'll likely continue to get much of our food from is also a bad idea.
I honestly think that the only solution is to stop burning carbon.
It's not going to happen in my lifetime, but it is the right thing to do for our grandchildren.
There aren't any that can match the scale of CO2 we are adding from almost 1 billion cars to ships, aircraft factories, power stations (using coal or oil), frankly I think a number of these schemes are being put in place by denier groups as the next level ploy, when claiming it's not happening falls apart as it is going to in the next decade. The best solution to any unwanted additional of pollution is usually not to create a new problem like vast amounts of lye for Carbon scrubbing or adding vast amounts of iron to the worlds oceans, the simple solution is to reduce the amount of CO2 we are adding to the atmosphere.
It is not a coincidence that the two main groups who would take great profit losses if action where taken of CO2 emissions are the oil and energy sector and these are the very same groups that are funding the denial movement.
Ocean plant life. The world's oceans are huge yet largely unused except for commercial fishing just recently we have started usiing fish farms although using the ocean for vegetation I beleive is the next step and one that can change the world. Ocean vegetation is the basis for life in the ocean so seeding areas with it would not only help decrease CO2 but would also help fish populations. Although this isn't done because people are against changing anything that might have consequence in other ways.
The best option to the problem is to stop the source. If we at least maintain the size of our forests, decrease pollution being put into the atmosphere and generally try to clean things up, CO2 will go away with plant life thriving.
http://en.wikipedia.org/wiki/Carbon_dioxide_air_capture
