Speargun-inspired device may make offshore wind farms cheaper

Australian engineers have built a speargun-inspired device that could cut the costs and time involved in planning offshore wind farms.

The device launches a probe into the seabed, which can tell surveyors what the ground is like.

Currently, surveying equipment for offshore wind farms involves inefficient, probes called penetrometers dropped or winched from a boat. More effective systems are available, but they can cost up to $200,000 per day, according to the researchers.

This device, according to the RMIT University team behind the technology,  is faster and better for the environment, because it has a retraction mechanism that can collect probes after they’ve been dropped.

The researchers have published a description of their probe in the Canadian Geotechnical Journal.

Lead author Junlin Rong, a PhD candidate at RMIT, tells Cosmos that the device  was developed from a spearfishing gun.“We all love sports – fishing is one of those,” he says.

“[When spear-fishing], we realise that how important protecting our environment is.”

This spurred Rong and colleagues to see if they could use a speargun for a geotechnical survey.

“The spear gun is designed for challenging underwater environments,” says Rong.

“That makes an ideal inspiration for a geotechnical tests device that needs to penetrate topsoil objects efficiently. And it is easy to access locally for us as researchers.”

The device would be easy to adapt to existing systems, and uses an elastic or pneumatic force to fire off its sensors.

So far, the researchers have tested the prototype device in labs – but not yet in the field. They trialled several different penetrometers with the spear gun.

“In laboratory environments, the device showed considerably greater penetration potential compared to free-falling probes on soil,” says Rong.

The device worked twice as well as free-falling probes in sandy soil.

While it’s difficult to tell how much this device would cost at this point in the research, Rong is confident it would be significantly cheaper.

“It is expected to substitute conventional tests by replacing portions of the drilling borehole. This can potentially cut down costs of a few days of surveys with large survey vessels.”

The researchers are now looking for industry support, and are hoping to take the device to field trials.

“The first stage [of field trials] is to test the prototype near shore beaches or in lake environments, which is not that dynamic compared to the ocean, to build up our confidence with a more sophisticated sensors,” says Rong.

Then, the researchers would aim to optimise the device further for full ocean trials. If they work, Rong expects industry to pick their design up quickly.

“The device at the moment is ready to go. So what we are looking for is future collaborators to actually bring it to life.”