Cutting the cost of energy
Research so far using conservative cost estimates shows that the use of the SENSE System on a shallow water site will reduce the lifetime cost of energy (LCoE) by around 4%. This cost benefit is expected to increase to 9% or higher as the design is refined. The predicted cost savings for a deep water site (>70m), farther away from land and with larger (10MW) turbines are even greater.
Capital expenditure savings derive in part from the use of more readily available construction vessels at competitive prices that can be mobilised at shorter notice compared to crane vessels. The concept easily scales to projected 10MW + turbines, while the market may not so quickly provide large crane vessels to keep pace with this development curve.
In addition conventional installation methods average around 24 hours per turbine but using SENSE turbines can be installed in parallel by multiple SENSE equipped vessels leading to a shorter construction programme. Rapid installation rates significantly reduce the construction finance risk profile and interest costs of large wind farms by generating early revenue.
In turn weather-critical operations are shorter duration so can take advantage of narrow weather windows. Only one short "lift" operation is needed to transfer the rotor nacelle assembly onto the tower base rails, which can be completed quickly with minimal vessel time on station. The rotor nacelle assembly can remain at the base of the tower if necessary until a suitable weather window is available.
Operating costs (OpEx) also see significant savings as large crane vessels are not needed for major component replacements, leading to lower refurbishment costs mid-life and lower OpEx costs in the later years of operation. In the event of a major failure, rather than replacing the individual major component the complete nacelle and rotor assembly can be "swapped out" getting the turbine back up and working in one weather window.
During the operations phase, SENSE can be used to improve access for external inspections of the turbine. In particular it can provide a mounting for a secure platform for blade inspection and repair.
By reducing overall O&M costs and increasing the turbine availability to levels now normal for onshore wind farms, SENSE will help offshore projects move towards a "least cost €/MWhr sweet spot".