Heat to Power Feasibility Study on Oil and Gas Offshore Installations Using Organic Rankine Cycle (ORC)

Abstract

The North Sea Transition Deal (NSTD) agreed in 2021 between the UK government and the offshore oil and gas industry placed a strong emphasis on emission reduction. Amongst various enhancement options, immediate reductions in production related emissions from improved production efficiency, energy efficiency, operational process change, consideration of fuel usage and equipment upgrades was recommended. In this study, the feasibility of retrofitting an Organic Rankine Cycle (ORC) unit was assessed by determining the power generated from heat on the power generator turbines on Serica Energy's Bruce platform. The modification proposes using the heat generated, to generate sufficient power to meet platform's demand. The study's findings show that a 40% increase in energy efficiency is achievable. The study also indicates that using the ORC reduced fuel usage by 0.5 – 1.6 kg/s and CO2emissions by 96.86 – 310 metric tonnes of Carbon Dioxide (CO2) equivalent per day. Economic analysis also demonstrates that the added benefits of ORC such as increased revenue from additional gas sales and savings from lower carbon tax outweigh the investment capital cost of £20 million. This maturity of this technology which has been successfully demonstrated in other environments has not yet been implemented on offshore oil and gas installations makes this an attractive option for companies. Given the relatively small impact on plant layout and weight, this study also discusses the wider benefits that using ORC could have on the running of aging offshore platforms especially if redundant equipment can be decommissioned, reducing abandonment expenditure (ABEX) scope in advance of the cessation of production (CoP).