Motion control technology first developed for Formula 1 racing cars and then successfully used in tall buildings could help lower costs in fixed-bottom offshore wind and extend its range into deeper waters, claimed a senior academic.
Applying novel inertial mass dampers in conjunction with design optimisation of foundations and masts has the potential to make fixed-bottom structures more robust while slashing their weight, and therefore cost, Agathoklis Giaralis, associate professor in structural dynamics at City, University of London, told Recharge.
Successfully designing-in the ‘inerters’ – which have cut by 30% the amount of structural steel in 15-storey buildings – could make deployment of fixed-bottom foundations viable beyond the roughly 70-metre depths that are the current limit and make projects in shallower waters more competitive, said Giaralis, who will lead a project with sector partners under an industrial research fellowship with the UK’s Royal Academy of Engineering (RAE).
Giaralis told Recharge that optimised design using inerters – “a relatively new concept of devices that can supply the inertia that a big mast would provide to a structure without the dead weight” – would aim to bring about a step-change in the existing concepts of jacket and monopile foundation “without reinventing the wheel”.
“We want to see to what extent these vibration absorbers, by optimising them together with the structure, could overall reduce the weight.”
The inerter technology was pioneered on the suspension systems of Formula 1 cars and then successfully migrated by Giaralis and his colleagues to tall buildings. Now they believe it can perform the same function of delivering robustness without adding weight to offshore wind structures – also potentially a major benefit when deploying in harsh weather environments such as typhoon regions.
Giaralis will work on the RAE project with energy and marine engineering specialist ABL Group and its companies including OWC and Innosea.
“Currently, the application of the very mature bottom-fixed offshore wind turbines is limited to 60-70 metres water depth, as the required dimensions and the self-weight of offshore wind turbine supporting structures to safely resist dynamic loads due to wind and wave loads, become uneconomical for deeper waters installation,” Giaralis said.
While floating wind is a fast-developing option for deeper waters, “we feel it’s going to take quite some time for floating to become mainstream.
“We want to see whether with current mainstream foundations we can go to higher depths or reduce costs.” Giaralis added: “We want something that will not take five or 10 years to develop.”
The academic said it was too early to say how far further the viable range of fixed-foundation technology could be pushed by successful use of the inerter technology, but “if we can get even another 10 or 15 metres that would be a substantial gain.”