CO₂ use and re-use efforts focus on pathways and novel approaches for reducing CO₂ emissions by developing beneficial uses for the CO₂, such as the conversion of CO₂ to useable products and fuels and other breakthrough concepts that will mitigate CO₂ emissions in areas where geologic storage may not be an optimal solution.

CO₂ can be used in applications that could generate significant benefits and by using and re-using CO₂, the emission of CO₂ into the atmosphere is reduced.  Use and re-use is a very important component in carbon sequestration and below are a few applicable approaches:

• Conversion of CO₂ – use CO₂ as one of the feedstock to produce chemicals (including fuels and polymers) and find applications for the end products.
• Non-Geologic Storage of CO₂ – Use CO₂ from an effluent stream to immobilize the CO₂ permanently by producing stable solid materials that are either useful products with economic value or a low cost produced material.  This approach could be viewed as an effective carbon storage method.
• Indirect Storage – Promote indirect carbon storage by removing CO₂ in the air (such as enhanced photosynthesis) or by enhancing carbon intakes in terrestrial vegetations and soils where the biomass could be used in coal fired systems to produce power, liquid fuels, or synthetic natural gas.
• Beneficial Use of Produced Water – For produced water from CO₂ storage in saline formations, develop novel methods to use CO₂ to react with metallic ions to form less soluble carbonates that can be removed – and then find useful applications for the desalinated water.
• Breakthrough Concepts – Develop novel applications of CO₂ that would limit its emissions into the air novel approaches using microbes that consume CO₂ and other materials to produce useful products or fuels.

Processes or concepts that undertake this CO₂ reduction must take into account the life cycle of the process to ensure that additional CO₂ is not produced beyond what is already being removed from or going into the atmosphere.  A compilation of some examples of research found in the literature shows progress is being made in this area by a variety of groups.  The examples found (note: not all DOE funded) include reuse of CO₂ for fuels to chemicals.  CO₂ derived from flue gas has been used to grow algae that can later be used as a fuel or feedstock for other materials. Studies have also been conducted in using CO₂ injection for enhancing methanol production in which CO₂ is used as one of the reactants.  Similarly, studies on using CO₂ to make polycarbonates or other polymers have shown some success.  Research efforts are also continuing to enhance the rate of photosynthesis and increase the net fixation of atmospheric carbon dioxide indirectly.  Further, CO₂ is being considered as a working medium for enhanced geothermal systems that would facilitate CO₂ storage in underground formations. Finally, genetic studies are being conducted on microbes that consume CO₂ and other ingredients and then produce methane.