Flue-Gas Carbon Capture on Carbonaceous Sorbents: Toward a Low-Cost Multifunctional Carbon Filter for “Green” Energy Producers

Abstract

A low-pressure Carbon Filter Process (patent pending) is proposed to capture carbon dioxide (CO 2 ) from flue gas. This filter is filled with a low-cost carbonaceous sorbent, such as activated carbon or charcoal, which has a high affinity (and, hence, high capacity) to CO 2 but not to nitrogen (N 2 ). This, in turn, leads to a high CO 2 /N 2 selectivity, especially at low pressures. The Carbon Filter Process proposed in this work can recover at least 90% of flue-gas CO 2 of 90%+ purity at a fraction of the cost normally associated with the conventional amine absorption process. The Carbon Filter Process requires neither expensive materials nor flue-gas compression or refrigeration, and it is easy to heat integrate with an existing or grassroots power plant without affecting the cost of the produced electricity too much. An abundant supply of low-cost CO 2 from electricity producers is good news for enhanced oil recovery (EOR) and enhanced coal-bed methane recovery (ECBMR) operators, because it will lead to higher oil and gas recovery rates in an environmentally sensitive manner. A CO 2 -rich mixture that contains some nitrogen is much less expensive to separate from flue-gas than pure CO 2; therefore, mixed CO 2 /N 2 -EOR and CO 2 /N 2 -ECBMR methods are proposed to maximize the overall carbon capture and utilization efficiency.