Storing energy on the seabed

If Norway is to maintain its role as an energy supplier to Europe while meeting our climate targets, we must transition from exporting oil and gas to selling clean energy such as electricity and hydrogen within a relatively short period.

Deep Purple is a subsidiary of TechnipFMC, a global provider of infrastructure and services for the gas, oil and energy sectors. The company is now working on a large-scale, sustainable pilot project to store wind energy as green hydrogen. The pilot project, named Deep Purple, is being carried out in collaboration with several other companies, including Vattenfall Vindkraft, Repsol Norge, Nel Hydrogen Electrolyser, Umoe Advanced Composites, Slåttland, ABB, DNV and Sintef. The University of South-Eastern Norway, Energy Valley, Ocean Hyway Cluster and GCE Ocean Technologies are also key partners. The pilot is due to be ready as early as next year, in 2022.

‘Together, we have extensive core expertise in systems integration, automation, product development, safety and risk management that is valuable in a new technological arena,’ says Terje Andre Løver, Project Manager for Deep Purple.

The pilot project aims to achieve and document the effective operation of an entirely new energy system that can store large amounts of surplus wind energy.

‘One of the main challenges of generating electricity from clean energy sources such as wind is that these resources are intermittent and variable,’ Løver explains.

‘To make the most of the wind power we generate, we need to both store and retrieve the energy in the most technically and economically efficient way,’ he says.

And this is exactly the problem Deep Purple aims to solve.

The project simulates the energy produced by wind turbines to understand how variable power affects the energy system used to produce renewable hydrogen. The seawater must first be desalinated and then undergo electrolysis to separate the hydrogen and oxygen. The surplus wind energy is then converted into hydrogen and stored in large tanks.

When the wind turbines do not produce enough energy, the stored hydrogen can be converted back into electricity. This will help meet the end user's need for a stable power supply. As hydrogen is an environmentally friendly energy carrier, its only by-products are clean water, oxygen and salt.

‘Because of the way we can store electricity, the technology in the Deep Purple project can be compared to a giant industrial battery,’ says Løver.

However, the storage capacity will be far greater than that of today’s battery technology. By comparison, the world’s largest battery parks have a capacity of around 700 MWh. Deep Purple’s storage technology will have a capacity of 2,000 MWh. This provides much greater storage capacity without taking up large areas of land, as the tanks can be stored underwater.

Løver says that the funding they received from us played an important role in getting the project off the ground. It was also a symbolic recognition of the importance of developing renewable hydrogen, also known as green hydrogen.

Anders Melleby Fremmerlid at Innovation Norway is a financial advisor to Deep Purpble. He believes their work both inspires and lays the groundwork for other players – within Norwegian business and beyond – to move the industry in the same direction.

‘The transition from fossil fuels to a renewable energy system is both complex and resource-intensive. That is why it is important for Deep Purple to share information and knowledge about the project,’ says Fremmerlid.

‘The ability to store hydrogen will not only provide more consistent access to wind power as an energy source, but the storage technology and capacity will also make it possible to supply everything from island nations to cities with green energy,’ says Løver.

Combined with offshore wind power, the technology can provide a local electricity supply as an alternative to laying power cables from shore.

Clean energy from wind farms could also be used at large factories and oil platforms that are not connected to the power grid. Norwegian oil and gas production is known for its low CO2 emissions compared with other countries. Nevertheless, gas turbines on Norwegian oil platforms still account for a quarter of Norway's CO2 emissions.

Løver explains that this large-scale renewable energy initiative in the Deep Purple project represents a highly symbolic shift for Norway’s oil and gas industry. Developing and delivering new energy systems like this could create opportunities for substantial long-term growth in sustainable jobs in Norway.