Going modular

Offshore structures for multiple uses were investigated by Mirco Busetto, head of basic design Offshore Business Unit, Fincantieri, at this year’s Offshore Mediterranean Conference (OMC) in Ravenna, Italy. Elaine Maslin reports.

A modular concept for Montecarlo.Images from Fincantieri.

Fincantieri has developed a modular concept, called floating modular platform technology (FMPT). It is based on a hexagonal semisubmersible structure (although there’s potential to make a gravity-based version), which could be scaled in size, both in terms of individual unit but also by linking multiple units together to create larger platforms or islands.

The firm’s research suggests such units could be used for conventional energy production, residential use, renewable energy, aquaculture, and as bases for deepsea mining. They could be used for short-term developments, for wind farms or other forms of power generation, and longer term, such as industrial or tourism uses. Medium-term uses could be aquaculture, marine energy, or artificial islands for logistic purpose.

FMPTs for a gas to power project offshore Mozambique.

A key part of the concept is that it could be built at “any shipyard” and that the design could be adapted to different uses, i.e. a base design could be customized to a variety of uses, says Busetto. “The modularity allows for different water depth and different distance from land,” he says. “It could be a fish farm or crew accommodation, a drilling and production platform or a base for mineral processing.”

At its narrowest and widest points, the hexagonal structure would be 50m by 60m – although Busetto says the size could be bigger. It would have a 12m-draft and would be 10m from the main deck to the water line.

Ideas Fincantieri has been looking into include a residential project just off Montecarlo. It would create a 6ha “artificial island,” the benefit of which would be having no contact with the seafloor, therefore limiting damage. Another application could be a wind generation platform. Fincantieri has called this concept “Seaflower.” It would have a mooring chain spread system in 50-200m water depths, a draft of 12m and 20-year design life for a North Sea site.

“Another application is offshore power generation, or offshore gas field, gas-to-power production.” This has been looked at for offshore Mozambique, where getting gas from deepwater (1000m) offshore gas fields to markets poses a challenge, while wave heights for a one-year average are 4.3m, or 6m for a 100-year storm.

Three FMPTs could be used, two for power generation (60MW each), with power transported to shore via electric export cables. The third unit would hold the crane, flare, living quarters and helideck. The concept could offer a first phase of development before full field development, Busetto says. Additional facilities could then be added over time. One of the critical points is that connections between the modules have to withstand environmental forces during a 100-year storm condition or during application, he says.

Fincantieri also sees synergies with wind and wave power, but also solar and microbial fuel cells, which could be added to projects to improve economics, Busetto says.