Renewable Natural Gas from Carbonaceous Wastes via Phase Transition CO2/O2 Sorbent Enhanced Chemical Looping Gasification

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With growing concerns over global climate change, increased utilization of renewable energy sources is preferred over use of carbon intensive fossil fuel feedstocks. Efficient conversion of these biomass wastes to renewable natural gas (RNG) represents a promising route to meet the challenges of global climate change, security of domestic energy supply, and cost-effective disposal of biomass waste. Although biogas or biofuels can be produced via conventional anaerobic digestion or pyrolysis approaches, the efficiency and product yields from these processes are limited due to incomplete feedstock conversion and low product quality.

The project aims to develop a significantly intensified, sorbent enhanced – chemical looping gasification (SE-CLG) process, which combines biomass gasification, air separation, and syngas conditioning and cleaning into a single circulating fluidized bed (CFB) gasifier to produce methanation ready syngas. Overall, SE-CLG can reduce the levelized cost of energy (LCOE) for pipeline quality RNG production by 35% compared to the baseline indirect steam gasification technology. The SE-CLG technology being developed by NC State’s Fanxing Li has excellent potential to produce cost-competitive renewable natural gas (RNG) to serve the domestic market. Since this project will address most of the technical uncertainties related to SE-CLG and provide high-fidelity validation of its economic attractiveness, successful completion of the project will potentially attract investments from the private sector for technology scale up and commercialization.

To bring the technology to the market, the project team aims to either enter a joint technology development agreement with commercial partners (candidates include Duke Energy and Aries Clean Energy) or license out the technology.  Prior to full-scale commercialization, another intermediate scale up step would likely be necessary to demonstrate auto-thermal, long term operation of the SE-CLG gasifier (4-7-year timeline). Dr. Li has recently been awarded a Department of Energy grant of $2,499,462 for this project.