Storage of natural gas by adsorption on activated carbon

TLDR

Natural gas can be stored by liquefaction, compression, or adsorption, but liquefaction is impractical for transport and compression requires high pressure, whereas adsorbed natural gas at 3–4 MPa offers comparable capacity to compressed natural gas. The authors used Monte Carlo simulations of methane adsorbed between parallel graphite planes separated by 11.4 Å to model activated‑carbon storage of natural gas. The simulations show delivered energy densities of 0.25 kWh kg⁻¹ for monolithic carbon and 0.17 kWh kg⁻¹ for pelletized carbon, lower than 0.29 kWh kg⁻¹ for CNG and far below 1.0 kWh kg⁻¹ for gasoline.

Abstract

Natural gas may be stored by liquefaction, compression, or adsorption. For use as a transportation fuel, liquefaction is impractical and compression requires high pressure (20 MPa) and an expensive multi-stage compression facility. At relatively low pressure (3–4 MPa) achievable by single-stage compression, adsorbed natural gas (ANG) has nearly the capacity of compressed natural gas (CNG). Monte Carlo calculations were performed to simulate the adsorption of natural gas on activated carbon. The model is pure methane intercalated between parallel planes of graphite at a slit of width 11.4 Å, optimized for ANG storage. The simulations predict that the maximum delivered energy density of ANG is 0.25 for monolithic carbon and 0.17 for pelletized carbon, compared to 0.29 for CNG and 1.0 for gasoline.