Offshore Power Generation Floater and Gravity Based Structure with Integrated CO2 Capture

Abstract

Abstract This paper presents two novel concepts of combined cycle power generation floater and Gravity Based Structure (GBS) with a Post Combustion CO2 Capture (PCC) system integrated in the hull structure. Decarbonizing offshore power generation based on simple cycle gas turbines and using conventional post combustion CO2 capture technology is challenging due to the high flow rate of flue gas with carbon content as low as 3.5 vol%. The use of a compact combined cycle power generation with a back pressure steam turbine optimized for offshore space and weight constraints and with the carbon capture system integrated within the hull structure of a floater or a GBS allows significant cost reduction compared to a conventional design. A conceptual level engineering study was carried out to assess the technical feasibility and the economic viability of these two concepts. The following two cases studied are each based on a centralized power generation facility able to supply up to 100 MWe (Net export) of low carbon electricity to several offshore fields and where CO2 can be stored locally underground: Centralized power generation floater with CO2 capture in a West African deep-water sectorCentralized power generation GBS with CO2 capture in a shallow water sector of the North Sea The carbon capture system is based on a generic mono ethanol amine (MEA) solvent. Process simulations, 3D models, stability studies and structural modelling were also carried out using industry's leading software. Capital cost estimates were developed for each concept. The largest parts of this capture system (direct contact cooler, absorption and water wash columns) are directly integrated into the concrete or steel structure (shell & bulkheads) to benefit from the naval architecture requirement for hull structure partitioning (watertight compartments) which thus reduces the impact on topside weight and layout. This novel design can substantially help to overcome the challenges due to the cost and complexity to implement CO2 capture at existing or newbuild offshore facilities which are too remote for electrification from shore or to use offshore renewable sources, in order to decarbonize a significant part of the oil & gas production.