Carbon dioxide (CO2) use and reuse efforts focus on the conversion of CO2 to useable products and fuels that will reduce CO2 emissions in areas where geologic storage may not be an optimal solution. These include:
- Enhanced Oil/Gas Recovery – Injecting CO2 into depleting oil or gas bearing fields to maximize the amount of CO2 that could be stored as well as maximize hydrocarbon production.
- CO2 as Feedstock - Use CO2 as a 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 material 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.
- 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; then find useful applications for the desalinated water.
- Breakthrough Concepts – Develop novel applications of CO2 that would limit its emissions into the air and 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 processes to ensure that additional CO2 is not produced beyond what is already being removed from or going into the atmosphere. Several other challenges exist in using/reusing CO2. One involves determining how best to tap energy sources, since turning CO2 into fuels and chemicals would require energy input. In photosynthesis, solar energy is the obvious energy source. However, for solar applications as well as other approaches such as chemical processes or the use of microbes, consideration has to be given as to how best to tap solar or other energy sources, Another challenge is to find new reaction paths, including new catalysts and enzymes. This is important for many approaches in using CO2 to make new products, such as polymers. For some of these reactions, especially those involved in biological systems, the rate of reactions need to be improved.