Sophisticated subsea battery storage

Louise Smyth

Paul Slorach introduces a new approach to subsea battery storage technology

Novel subsea battery storage technology has recently passed the final stages of testing, marking a major milestone for its creator, an Aberdeen-based clean energy system provider.

Halo is a modular and scalable Lithium-ion battery storage system designed specifically for the demanding subsea environment. Built around EC-OG’s in-house developed battery module, Halo can deliver to remote offshore locations an energy capacity range from 50kWh to over 2.5MWh, providing a reliable and uninterrupted power source on the seabed, directly at the point of use.

Power for subsea operations is an ever-present challenge for the blue economy, not least within the offshore oil & gas industry. Large capacity battery systems overcome many of the challenges presented by existing power solutions, such as integrity concerns and CAPEX costs of long distance umbilicals and the carbon emissions of diesel generators and gas turbines.

As an adaptable and configurable system, Halo places a large amount of energy on the seabed whilst providing the user with a flexible re-charging methodology, which can be optimised for the project budget.

 Existing subsea power distributions system can be prone to failure, such as umbilical insulation resistance or connector failure. Subsea intervention to remedy these issues is typically expensive and any periods of downtime can have significant impacts on operator revenue.

Halo offers an alternative solution to the field operator. By providing a quick to install temporary power source to the subsea production system, the technology safeguards hydrocarbon production and well integrity, which can rapidly degrade during extended periods of shut-in production.

Battery storage with clean energy in mind

The solution has been developed with clean energy systems in mind. Spun out from EC-OG’s Powerhub development, a seabed based tidal energy converter with integrated energy storage, the new battery storage technology has been specifically designed to integrate with marine and alternative energy converters, for example wave, tidal, floating solar and even hydrogen fuel cells.

The firm believes that renewable power systems for the blue economy will soon become mainstream technology. Within oil & gas, operators are looking to clean-up their operations and provide autonomy within IMR and production. Renewable power systems will do just that and are now one of the many field development options available to the operator.

The Halo technology can store power from a remote power generation system, such as a wave energy converter, to offer an uninterrupted power supply to subsea systems. This protects the operator from the intermittency of renewable power generation whilst also allowing peak power demands to be serviced, such as well start-up or valve function operations.The solution is not just for brownfield, but for new long-distance tie-backs, the adoption of all-electric systems and new field extensions, where access to the existing offshore power supplies might be limited.

Over-the-horizon operation of resident subsea vehicles is another focus for EC-OG, where the advancement of robotic technology and autonomous operations is marked by huge shifts in the supply chains approach to IMR.

There are countless autonomous and resident subsea and surface vehicles available or in development at the moment. Providing energy to this fleet of vehicles will be an important part of new field developments and for brownfield operations, extended operating durations can be limited by relatively small onboard batteries.

The Halo technology is equally adaptable for this application, providing an energy source for vehicle recharging in remote offshore locations and providing a gateway for information transfer. This has the potential to save an operator millions in inspection, maintenance and repair costs, by completely removing the need for expensive offshore vessels to be permanently on-station.

The solution is a modular system, built around standard building blocks and power electronics. The mechanical design allows different cell types to be easily integrated to the system, allowing optimal cell selection to suit the energy, power, duty and life cycle requirements of the application.

Complete battery storage system showcased

The July 2010 trials showcased all the building blocks of a complete Halo system in an underwater environment for the first time. Offshore trials are anticipated later in the year, which will include integrating the technology with marine renewable energy systems and demonstrating the system capabilities for full autonomous operation with subsea production systems, resident vehicles and various sensor packages.

In preparation for the expected growth in the use of large-scale subsea energy storage technology, EC-OG has recently undertaken a considerable upgrade of its battery manufacturing capabilities at its Aberdeen facility. CNC battery cell welding equipment and automated battery module test systems have been installed, enabling the company to reduce the lead time of the Halo energy system whilst maintaining high levels of quality and reliability. As a result, it can now offer a complete 500kWh Halo system in as little as eight weeks from order to delivery.

In April 2020, EC-OG received inward investment of £1.6m from an investment consortium led by Par Equity. Par Equity, a venture capital firm based in Edinburgh that specialises in investing in innovative technology companies, was joined by existing investors, Orchard Venture Capital and Scottish Investment Bank.

Paul Slorach is with EC-OG

Recent Issues