FLOATING WIND POWER AT SHALLOW AND DEEP WATERS
Offshore wind is today on an upward trend as more and more entities see the benefit of setting out wind turbines out at sea. The sea offers steady winds, but at the same time also continues wave heave. This unwanted heaving can over time cause more stress on the blades and nacelle of the wind turbine resulting in higher maintenance frequencies and shorter life spans.
Stationmar has completed the engineering of their new concept called Sakayan, up to scantling design, including verification of structural integrity, structural masses, hydrodynamic properties and stability (intact and damage). The Sakayan is a three-column assymmetric
semi-submersible platform. The name derives from a Philippino fishing boat with two outriggers used for stabilization.
The Sakayan concept has a main column carrying the wind turbine assembly and two outriggers with smaller columns.
All columns are fitted with the Stationmar Heave Motion Neutralization system (HMN), while the two outriggers also contain the Energy Neutral Predicative Advanced Control system (ENPAC), which shall ensure that heave neutralization also can be achieved with short high frequency waves, when such occur. The system shall neutralize both heave motion and pitch and roll.
In addition to the above mentioned features the following can also be mentioned:
Minimized motion dynamics extends lifetime and up-time for the WTG
Floats fully outfitted with very shallow draft
No heavy offshore crane operations
Saves mooring costs
Simplified entrance for service personnel
Can be retrieved and towed to yard for heavy overhaul of the WTG
In addition to the patent-pending systems for achieving motion neutralization of the foundation, the company has also recently filed a patent application for a "complementary" system called WALET, which is short for "Wave Artificial Lift Energy Turbine". The purpose of WALET is to generate energy also from the wave power, in addition to the wind power, so that total energy production can be increased considerably, and probably doubled, while at the same time obtaining more stable and predictable electricity production. This is done by using well-known technology that is currently used for a number of hydropower installations on land. The principle of Walet is relatively simple. The bobber (bobber, slang for bob) – the ring barge – heaves with the waves (as much as possible), and the risers to which it is attached gulp water into a water magazine/basin, which balances the gulps into a steady stream in pipes inside the column. When the bobber goes up, water is sucked into the feed tanks at the bottom of the column, when the bobber goes down, new water is pressed into the riser pipes, and the water is gulp out into the basin. From this basin, the water is led down into the column to drive a turbine similar to that used in small power plants on land, for which Norwegian industry has considerable experience. Here, a drop height of 20m is achieved to drive the turbine, which is installed in the "dead volume" inside the column. The turbine is effectively regulated for varying amounts of water, as is done with e.g. all Kaplan turbines in use in small power plants in operation today. The turbine has a fixed head, but can be regulated for varying amounts, as is done on all similar turbines used for hydropower installations in operation on land today.
With WALET, technology from land-based small power plants, can be combined with Stationmar's heave neutralization technology developed from the oil industry, to double the energy production from floating offshore wind turbines, seen in relation to existing concepts. Or you can simply use WALET for bottom-fixed solutions, without combining this with the Stationmar heave neutralization technology, and double the energy production also for such offshore wind turbines.
The following animations shows the main principles of WALET, and WALET applied for a bottom fixed monopile turbine, a bottom fixed tripod turbine and for the Sakayan floating wind turbine.
-> Floating wind power at shallow waters (20m - 100m)
Fully outfitted deployment from yard
Eliminate expensive offshore operations
Stationmar is developing a range of structure concepts to compensate for the numerous issues related to shallow water foundations. All of our structures are non-piling where we instead rely on suction caisson design. This allows for floating both out and in if needed for maintenance. This again will eliminate the need for large purpose-built cranes and surface vessels on standby. Suction caissons have been used in the offshore industry successfully for more than 30 years.
WindJACK Patent pending
Floating structure with sea-bed fixed foundation
Releasable quick connections for periodic maintenance
WindBUOY Deployment Patent pending
Simplicity of spar buoy without costly offshore operations
WindSTAR Patent pending
Preset suction anchors
Two-level pre-tensioned taut mooring
-> Floating wind power at deep waters (100m and beyond)
Shallow water construction
Deep water deployment
Telescopic wind turbine foundation
Stationmar has developed a telescopic wind turbine foundation (Patent Pending).
This is a Telescopic Spar Buoy that allows to be loaded at a quay side with only 30 meters water depth. We call this telescopic Spar Buoy “Floating Wind Station (FWS). The FWS will after deployment be telescoped down to 100-meter water depth.
We have also developed a Dual Service and Support Vessel (DSSV) that can load and transport two sets of (12MW) complete wind turbines and its foundations onto the operational field and install them to operational draft. All is done with no vertical movement to either the FWS or the DSSV. The two entities operate as one unit.
Both the FWS and the DSSV are fitted with Wave Motion Neutralization technology.
OIL AND GAS
Oil and gas semi-submersible rigs
Remove the need for costly heave compensation on deck
A drilling rig without any heave (vertical) movement from waves may be taut moored using fiber ropes.
The list of benefits with this new technology is long.
StationMar Semi Submersible redefined
For drilling operations, you don't need a sub-sea BOP. A smaller and lighter dry BOP placed on-board the rig saves time and money. A simpler mooring system that is faster and cheaper to lay out. No need for heave compensation equipment that are heavy and costs a lot of money. No need for slip-joint and marine riser.
For work-over rigs that perform light or heavy interventions the benefits are many. In rough sea areas you may extend the operational window from today being 3-4 months of the year to a year round operation. That alone represents enormous savings for the oil company as well as the contractor. The safety of the rig will also be increased when helicopters may land in any type of weather condition due to the fact that the rig is not moving.
For a Dynamically Position semi-submersible rig with no mooring we have a special system built into the rig that allows the Dynamically Position rig not only to be horizontally kept in place, but also be vertically kept in place due to the Heave Neutralization system. This will be very beneficial for deep water drilling and interventions. As the rig will be kept in place in a 3D perspective. This has never been done before.
FLOATING SEABED MINING
Extraction of seabed minerals
The extraction of minerals from the seabed is a tremendous future opportunity. Large areas of the seabed have not yet been mapped, and there is now a lack of many minerals that have previously been found with traditional mining. Large amounts of cobalt, copper, manganese, silver, gold and zinc are found under the seabed. A stable and completely rigid platform is needed to extract these valuable minerals.
Floating cities can solve space shortages and climate crises. Such cities are now planned in several locations around the world. The "zero heave" technology means cities are as stable as on land since there are no vertical movements. The city is anchored with fiber rope and becomes completely rigid in the horizontal direction.
Floating bridges and submersed tunnels
Stationary beams provide stable bridges and tunnels since the system holds a fixed vertical position.
The structures are cost saving since all dynamics are reduced.
Offshore waver power generation
Power generation by the means of exploiting the continuous heave is a field that has been studied and developed and prototyped for years. Our technology should help to open up new avenues of interest due to its ability to cancel out the wave heave impact on structure. This will allow different technologies to use said structure to again take out the power of the waves in a multitude of ways.