The analysis has highlighted the main design, economical and technical issues related to the XL monopile technology, which are summarized below:

XL monopiles offer a considerable design and cost advantage when deployed with higher capacity turbines.

Usage of the higher capacity turbines supported on XL monopiles results in lower material usage and therefore foundation cost, in comparison with lower capacity OWTs supported on monopiles.

LCOE for wind farms using high capacity OWTs may be lower than for low capacity OWTs supported on monopiles (over full operational life).

Design limitations impose a highly constrained operating envelope for XL monopiles (localized buckling, natural frequency, toe-kick deflection).

8.0MW turbines achieve the same ratio of weight per MW of rated power at deeper waters as 3.3MW OWTs, which indicates the possibility of future developments at great water depths.

The breaking point for XL monopiles, using higher capacity OWTs, is 40 m. Over 40m jacket foundations become more competitive.

Storage, manufacturing, transport and installation bottlenecks have delayed the wider usage of the technology.

Transport and installation cost will be the determining factors in any future XL monopile deployment.

XL monopiles have several cost related limitations that could be potentially lifted during the next 15-20 years.

New emerging foundation technologies could potentially challenge the design benefits obtained with XL monopiles.