Waste Heat to Power: Araz presents to Topside UK

Presented by Araz R. Khojasteh

The North Sea Transition Deal agreed upon in 2021 between the UK government and the offshore oil and gas industry placed a strong emphasis on energy efficiency. Amongst various enhancement options, waste heat recovery was recommended.

Organic Rankine Cycle (ORC) diagram
Simple diagram of the Organic Rankine Cycle (ORC)

In this study, the feasibility of retrofitting an organic Rankine cycle (ORC) unit was assessed. The modification proposes using the heat generated on the power generator turbines to generate power to meet demand.

Energy Efficiency

The results show that a ~40% increase in energy efficiency is achievable. Our study also shows that using ORC reduced fuel usage by 0.5 - 1.6 kg/s and CO2 emissions by 121 – 387 Metric tons of Carbon Dioxide (CO2) equivalent.

Economic Benefits

The economic analysis also demonstrates that the benefits of ORC increased revenue from additional gas sales combined with savings from lower carbon tax outweigh the investment capital cost of ~£20 million.

Ageing Asset Lifecycle Extension

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 ageing offshore platforms especially if redundant can be removed from topsides.