Virgin Earth Challenge
The Virgin Earth Challenge is a competition offering a $25 million prize for the first person or organization to come up with a way of scrubbing greenhouse gases out of the Earth's atmosphere to avoid global warming. The prize was conceived and financed by Sir Richard Branson, a successful British entrepreneur, and was announced in London on February 9, 2007]] by Branson and former US Vice President and Al Gore. 
The Virgin Earth Challenge is similar in concept to other high technology competitions, such as the Orteig Prize for flying across the Atlantic, and the Ansari X Prize for spaceflight. The prize will be awarded to the first scheme that is capable of removing one billion metric tons (= 1 gigaton) of carbon dioxide from the atmosphere per year for 10 years (at present, fossil fuel emissions are around 6.3 gigatons per year). $5 million of the prize will be paid at the start of removal operations, with the remaining $20 million paid after the successful completion of the scheme at the end of the 10 year period.
The prize will initially only be open for five years, with ideas assessed by a panel of judges including Richard Branson, Al Gore and Crispin Tickell (British Diplomat), as well as climate scientists James Hansen, James Lovelock and Tim Flannery. If the prize remains unclaimed at the end of five years the panel may elect to extend the period.
Around two hundred billion metric tons of carbon dioxide have accumulated in the atmosphere since the beginning of the industrial revolution, raising concentrations by more than 100 parts per million (ppm), from 280 to more than 380 ppm. The Virgin Earth Challenge is intended to inspire inventors to find ways of bringing that back down again to avoid the dangerous levels of global warming and sea level rise predicted by scientific organisations such as the Intergovernmental Panel on Climate Change.
A Possible Contender: GRT Air Capture Device
According to the Earth Institute at Columbia University, Global Research Technologies, LLC has demonstrated a prototype device capable of capturing 10 tons of carbon dioxide per square meter per year; a device of 10 meters by 10 meters would be able to capture 1,000 tons per year. It is estimated that 1 million such devices would be needed to capture the 1 billion tons per year stipulated in the conditions of the prize offered by Mr. Branson. The process uses proprietary sorbents to capture carbon dioxide molecules from free-flowing air and release those molecules as a pure stream of carbon dioxide for carbon capture and storage. According to GRT, one major advantage of this new technology is that it is not necessary to site the devices in immediate proximity to a major carbon source (such as a power station); for example, the CO2 emitted by traffic in Bangkok could be sequestered in Iceland by CO2 towers running on geothermal energy. Of course, the power source for the towers must not be a net CO2 producer, as this would partially offset the beneficial effects of the device. Source: physorg.com