Hydrates Based Carbon Capture System in Texas: a Techno-Economic Perspective

Abstract

Abstract This work analyzes the techno-economic factors associated with the production of blue H2, and hydrates-based capturing of CO2 produced by sorption-enhanced steam methane reforming (SESMR) of methane from landfill gas (LFG) across various counties in Texas. The SESMR system is coupled with a hydrates-based carbon capture system, and the energy and cost of setting up and running such a hydrates-centered capture facility have been estimated. In doing so, the amount of water and energy required to compress and refrigerate the gas down to hydrate-forming conditions and the capital and operating costs involved in setting up and running such a facility are evaluated in detail. The cost of producing hydrogen (without the carbon capture system) from this analysis is estimated at $0.5/kg of H2. The total cost (CAPEX+OPEX) for capturing one metric ton of CO2 ranges from $96 (Harris County) to $145 (Brazoria County). Notably, adding a thermodynamic promoter such as Tetrabutylammonium bromide (TBAB) to the hydrate precursor mixture to achieve favorable thermodynamic formation conditions increases the overall cost ($107–$137/metric ton of CO2 captured). This can be attributed to the increased water requirement necessitating a higher number of reactors, higher refrigeration capacity, and labor costs. The minimum hydrogen cost required for a positive combined net present value (NPV) for a coupled SESMR + hydrate-based carbon capture system for a 30-year project duration is estimated at $0.9/kg and $2.4/kg of H2 for Harris and Brazoria counties, respectively. Furthermore, a 5-year payback period would require a minimum cost corresponding to $1.35/kg (Harris) and $4.95/kg (Brazoria) of H2, demonstrating that the coupled system would be economical only for counties that have a significant hydrogen production potential.