Viability of Technologies for CO2 Capture and Reuse in a FPSO: Technical, Economic and Environmental Analysis

The recent discoveries of Pre-Salt layers in Brazil require process developments for enhanced sustainability as these reservoirs have oil with associated natural gas exhibiting an expressive amount of CO2. Monetization of CO2 by offshore production of methanol in a dedicated FPSO - MFPSO - is a potential alternative to sustainable E&P. Two process alternatives for an MPFSO were previously investigated by the authors, consisting of physical absorption of CO2 with propylene carbonate and its conversion to yield methanol. Alternative 1 combines dry and steam reforming in one reactor (Bi-Reforming), while Alternative 2 segregates the two reactions - dry reforming occurs in one reactor and water gas-shift reaction in a subsequent reactor. Both alternatives considered Enhanced Oil Recovery (EOR) as a parallel path for CO2 destination. The economic evaluation employed the software Capital Cost Estimation (CAPCOST) for calculations of CAPEX and OPEX. The software Waste Reduction Algorithm (WAR, EPA) was used to evaluate the potential environmental impacts. The analysis indicated that the performance of Alternative 1 was superior to the performance of Alternative 2: (a) methanol production (17.9 t/h) 4 times higher, (b) lower CAPEX, (c) sales revenue 181% greater, and (d) the potential environmental impact (PEI) 47.7% lower (868 PEI/h). In the present work, Alternative 1was modified by eliminating the EOR step, resulting in enhancement of methanol production as CO2 was integrally designated to chemical conversion. The modified process (Alternative 3) inherits the environmental feasibility of Alternative 1 and, through elimination of the EOR compression train, has the potential of positive impacts on CAPEX.