WHETHER streaming from the tailpipes of cars or the smokestacks of so many power plants and factories, carbon dioxide emissions keep growing around the globe.

Now a Canadian company has developed a cleansing technology that may one day capture and remove some of this heat-trapping gas directly from the sky. And it is even possible that the gas could then be sold for industrial use.

Carbon Engineering, formed in 2009 with $3.5 million from Bill Gates and others, created prototypes for parts of its cleanup system in 2011 and 2012 at its plant in Calgary, Alberta. The company, which recently closed a $3 million second round of financing, plans to build a complete pilot plant by the end of 2014 for capturing carbon dioxide from the atmosphere, said David Keith, its president and a Harvard professor who has long been interested in climate issues.

The carbon-capturing tools that Carbon Engineering and other companies are designing have made great strides in the last two years, said Timothy A. Fox, head of energy and environment at the Institution of Mechanical Engineers in London.