Repurposing Offshore Pipeline as Energy Storage Opens Market Segment

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 31703, “Repurpose Offshore Pipeline as Energy Storage (ROPES): Opening a New Market Segment Offshore,” by Azril Syazwan Hazim, SPE, Subsea 7, Daniel Buhagiar, FLASC, and Alasdair Gray, Xodus. The paper has not been peer reviewed. Copyright 2022 Offshore Technology Conference. Reproduced by permission. _ The repurposed offshore pipelines as energy storage (ROPES) solution repurposes aged offshore installations into energy storage systems based on proven hydropneumatic principles toward a cost-competitive, reliable system. Findings from a recent concept-assessment study show the cost competitiveness of the solution as a result of a low levelized cost of storage (LCOS) paired with the value of deferring full decommissioning of existing assets. The ROPES solution enables the storage of renewable power while allowing for the optimization of time and expenditure for decommissioning of infrastructure. Background Energy-storage technologies address a fundamental problem related to the integration of renewable energy production into conventional energy systems on a large scale: the mismatch between intermittent energy supply and consumer demand. Balancing supply and demand is quickly becoming the greatest obstacle to increased uptake of renewable energy. An emerging industrialized energy storage solution (ESS) technology uses mechanical power storage based on proven fluid-compression principles. Hydropneumatic energy storage (HPES) relies on a large pressure containment system (PCS) that acts as a pressurized liquid piston—potentially a pipeline system—with energy activated by a pump and recovered through a turbine. The solution is positioned to improve on economics for offshore wind farms either through remote units within each turbine or through the ROPES concept, with the energy conversion unit (ECU) on either the seabed or an adjacent decommissioned offshore platform. Overview of HPES Technology The proprietary HPES system stores energy by using it to pump seawater into a closed chamber to compress a fixed volume of precharged inert gas. The energy then can be recovered by allowing the compressed gas to push the water back out through a hydraulic turbine generator. The technology embodies a patented combination of two key features: - Pneumatic precharging allows the system to be installed in shallow water, making it suitable for both fixed-bottom and floating wind applications. - Using the ocean as a natural heatsink results in an efficient, isothermal system without the need for complex thermal-management systems.