Technical FAQs
- What water depth is the Power Buoy System suitable for?
The Power Buoy System is designed for 147 metres but could go considerably deeper (2000 metres plus). This will depend upon weather conditions, especially survival wave heights and other factors -site-specific details will require to be considered.
- What environmental conditions will apply?
The Power Buoy System is designed for a wave height of 26 metres with a typical North Sea spectrum - so is likely to be suitable for most sites. The Power Buoy System can accommodate different conditions but if its function is significantly changed then this will need to be revisited.
- What is the normal routine maintenance interval?
The Power Buoy System is designed on the basis of a minimum maintenance interval of 3 months. It is anticipated that in the light of operating experience it will be possible to extend this to 4 months plus.
- What happens if communications are lost for any reason?
Total communications failure on the Power Buoy System is considered to be an unlikely scenario. It should be noted that there are alternative communication paths and the systems are configured to provide very high reliability so this is considered to be an unlikely event.
However, in the unlikely event of a total communications failure, the Power Buoy System will continue to operate provided that its operation remains within preset parameters. The on-board control systems can be pre-programmed to shut down in a controlled fashion after a pre-determined interval or if these parameters are exceeded.
- What happens if a tether breaks?
The tethers are designed to have a very high factor of safety compatible with appropriate codes. However, a tether break will not cause the loss of the Power Buoy System as it is designed to withstand a 1 year storm in this eventuality.
- Can the Power Buoy System be relocated if a field life is relatively short?
Yes. The Power Buoy System is designed to be re-useable and it is anticipated that it could be relocated several times throughout its design life. The design is deliberately flexible and can accommodate differing conditions (water depth, wave parameters etc.) at different sites.
- At what distance from the host platform will the Power Buoy System operate?
The Power Buoy System can be controlled from and hence can operate at any distance. We have examined in detail Power Buoy Systems located up to 175 kilometers from its host station (in this case on-shore). The great advantage of this system is that it is independent of distance which will be governed by other factors. It is worth noting that most other means of delivering power or control to remote offshore locations attracts costs that are directly related to distance. The Power Buoy System is not.
- Is fuel supply likely to be an issue?
No. Fuel for the diesel-driven generators can be supplied via a small (50mm) umbilical or local storage can be provided up to any practicable level (say 6 months supply). At maximum output the Power Buoy System consumes approximately 20 cubic metres of diesel oil per day. It can also store up to 200 cubic metres on-board for emergency operation.
- What about other consumables?
There is storage on-board for 6 months supply of lubricating oil and engine cooling water.
- In what wave conditions can the facility be boarded for maintenance or intervention?
This depends on the boarding system used. If a RIB (Rigid Inflatable Boat) or FRC (Fast Rescue Craft) is used then it will be the coxan's decision depending on wave height, wave direction and relative motion between the service boat and the Power Buoy System. As a guide only, statistical boarding can be estimated on a significant wave height of 2.5 metres. There are alternative boarding techniques available which may increase the significant wave height during which boarding can occur. These systems can be accommodated.
