ROPES Offers an Energy Transition Solution to Pipeline Decommissioning
Authors: Wright Blake 
Published: September 2022

Oil and gas companies around the world are repositioning themselves to face the energy transition—whether that means embracing the fact that the green economy of the future calls for less hydrocarbon use or something more radical, like Lundin Energy’s (now called Orrön Energy) recent move to sell off its oil and gas assets to become a pure renewables player.

One certainty is that as companies trend away from oil and gas and toward a lower-carbon frontier there will still be plenty of “cleanup” to do while players figure out exactly what to do with more than 100 years of oil and gas infrastructure. Offshore, decommissioning of platforms and pipelines is a capital-intensive business and one that is expected to grow in the coming years.

Last year, IHS Markit released a forecast predicting global offshore decommissioning spending to reach almost $100 billion for the 2021–2030 period, up by more than 200% compared to the previous 10-year period. According to the forecast, nearly 2,800 fixed platforms and 160 floating platforms could be decommissioned. That represents 33% of fixed platforms and 43% of floating platforms currently in operation. Additionally, more than 18,500 wellheads, 2,850 subsea trees, and 83000 km of offshore pipelines and umbilicals currently in operation are subject to decommissioning during the same period. More than 50% of the expected activity is spread across four countries: the UK, US, Brazil, and Norway.

The financial burden and safety liability of marine decommissioning have prompted some to look at the potential for repurposing the hardware and using it in moving toward the drive to net-zero emissions: platforms that could be used to host wind turbines, vessels that could be redesigned to collect hydroenergy, and pipelines that could be repurposed for potential battery storage.

Repurposing offshore pipeline as energy storage (ROPES) is a concept that is being investigated by a partnership of offshore projects and services specialists Subsea 7 and offshore energy storage startup Flasc. Flasc was founded as a spinoff from the University of Malta in 2019 and is based in the Netherlands. The concept was described in a paper presented at the 2022 Offshore Technology Conference in Houston (OTC 31703).

Subsea 7 and Flasc signed a cooperative exclusivity agreement in late 2020 to work toward the commercialization of Flasc’s patented hydro-pneumatic energy storage (HPES) concept offshore. HPES combines pressurized seawater with compressed air to create an efficient, large-scale energy storage device that can be applied across a wide range of offshore applications. Energy is stored by pumping seawater into a closed chamber to compress a fixed volume of precharged inert gas. The energy can be recovered by allowing the compressed gas to push the water back out through a hydraulic turbine generator (Fig. 1).

The technology leverages existing infrastructure and supply chains, along with the marine environment itself as a natural heatsink. The first working prototype was successfully tested in 2018, and DNV has granted the technology a Statement of Feasibility based on a technical and commercial assessment.

“The hydro-pneumatic technology is at the core of the ROPES concept, but can also be applied to other embodiments,” said Daniel Buhagiar, co-founder and chief executive of Flasc. “Within this collaboration, we’ve looked at doing some different designs and different products, and ROPES emerged as a very interesting opportunity. Typically, we’re looking at doing new infrastructure, [for instance] installing a bundle or a new piece of kit to store the pressurized fluids. ROPES, we thought, was really the low-hanging fruit because the pipeline infrastructure is already there, and we can create a use case for it beyond the typical applications, such as hydrogen and carbon capture, which are not always possible.”