Feb 25, 2021Clean Energy Future

The fake reefs where fish flourish

What is a an ‘artificial reef’, and how do these fake formations become magnets for marine life and a destination for divers?

Australian gas companies are involved with the creation of these reefs, which involves repurposing offshore platforms once they are no longer needed for their original purpose. These towering platforms extract oil and gas from large, resource-rich regions called ‘basins’.

The oldest platform in Australia started operations in the Bass Strait in the 60s. Named ‘Barracouta’, the platform is still in service, but other platforms from the same vintage are entering retirement.

These old men of the sea, large and bulky, take considerable effort to dismantle, and the oil and gas industry has proposed several solutions on how to effectively decommission retired platforms with minimal disruption to surrounding sea life.

One solution: Repurpose the platforms’ support structures to create artificial reefs.

The submerged legs that support the platforms attract marine life. Over time, they spawn ecosystems that become dependent on them in a similar fashion to naturally occurring reefs. Other parts of the platforms can also be reused in this fashion.

This intentional leaving of submerged support structures and parts is referred to by the industry as a Rigs-to Reefs (RTR) procedure. This produces visually stunning habitats conducive to the growth of marine life. It is not unique to the oil and gas industry, either – everything from decommissioned ships and vehicles through to underwater art installations have been created for a similar purpose.

The benefits aren’t just for the marine life who inhabit the structures. Local fisheries, marine scientists, and tourists all win, turning the platforms into destinations for recreational divers.

Decommissioned platforms have also been reused in other ways that encourage the flourishing of marine life. One of the largest examples of this in Australia is King Reef, located approximately six nautical miles off the coast of Exmouth, Western Australia. The largest and fastest developing purpose-built artificial reef in the Southern Hemisphere, it is primarily composed of six giant steel structures repurposed from BHP’s Griffin offshore facility, which was decommissioned in 2018.

These structures were repurposed and returned to the ocean along with 49 concrete modules to a two-acre segment of seabed around 10 minutes from Exmouth Marina.

These structures helped form a reef that now boasts more than 27,000 cubic metres of underwater habitat, giving birth to a lively, diverse and carefully monitored marine system in the Exmouth community. This monitoring even extended to implementing a citizen science program, Reef Vision, which allows locals access to the reefs to capture footage of local fish species that can be collected and catalogued.

Another method that has been proposed for dealing with older platforms is not to decommission them at all, but to convert them into electricity stations that draw on natural geothermal energy from beneath the surface of the earth. Geothermal energy is the planet’s natural heat – it’s what makes geysers gush and hot springs bubble. It provides an abundant, clean, and renewable energy source that won’t run out.

Reusing old platforms for this purpose could help the environment not only because of the non-emitting nature of geothermal energy, but because it could also potentially cut down the need to produce new geothermal wells on the land, which is where they are more commonly found.

Decommissioning offshore platforms is an important environmental topic for Australia. It presents tremendous opportunities for the science and engineering communities, which will continue to come up with innovative solutions as the nation progresses towards a low-carbon future.