I entered this contest some time ago, but no check yet.  Branson was offering  25 mill for a process that would actually remove CO2 from the atmosphere.  My new plan.

Make steel with solar power and substitute CO2 for the coal as a carbon source.  Extract the CO2 from the atmosphere with waste heat from the solar furnace powered smelting.

http://gristmill.grist.org/story/2008/3/6/72549/02694#17

We may see energy intensive industries moving to very sunny regions for the cheap solar furnace process power.  Smelting with solar power?

Using CO2 collected from from biogas grid backup power plants) to substitue for the coal and oxygen in steel making?

That would even cause steel manufacturing to take some CO2 back out of the atmosphere if there was a shortage of CO2 from biogas.

All other industries that have high heat processes would want solar furnace power too.  This would also produce titanic amounts of cogenerated waste heat, that couldf be turned into very cheap clean kwhs after the sun goes down..  all night long.