Because of technical challenges and limited infrastructure, carbon dioxide, used for years to force crude oil out of old wells, likely will not replace water in hydraulic fracturing (fracking) anytime soon, says General Electric (GE).

GE is cooperating with Norway's Statoil to study the issue as part of the ecomagination program, which also focuses on gas turbine efficiency, wind blade design and other energy projects.

The delay means that energy companies will continue to use more than 2 million gallons of water for each fracked well, putting additional pressure water supplies in arid American states and likely delaying fracking's expansion to western China and other water-stressed regions.

The "ecomagination" project, formed in 2005 to broadly focus on sustainability and other environmental issues, has cost nearly $15 billion to date. It had been set to expire next year but is being extended to 2020 with an additional $10 billion input.

The energy industry's copious use of water has put it into conflict with some residents in Texas, New Mexico and other arid U.S. states. Many companies have been trying to find ways to curb fracking's use of water, looking at using CO2 and even propane.

While CO2 fracking is not economical today, the ecomagination project hopes to find a way to collect CO2 at the wellhead, recycle it, use it to frack again, then collect the CO2 and repeat the process, said Mark Little, GE's chief technology officer and head of global research.

GE's researchers are also trying to find the best viscosity, or thickness, for the CO2 at its chilled state to carry proppant, a type of sand that holds open cracks in rock so oil and natural gas can escape, much like water does in current methods.

Separately, the energy giant is cooperating with the U.S. Department of Energy to study how coal-fired power plants could best capture CO2 emissions and use the gas in fracking and other uses. GE and Statoil currently get CO2 from industrial gas suppliers such as Linde and Air Liquide.

Collecting CO2 as a power generation byproduct and using it to frack would reduce greenhouse gas emissions. But fracking would turn CO2 from a chilled fluid into a gas, and GE says it needs to devise a way to trap that gas back at the wellhead.