To subscribe to the ORE seminar mailing list, click here.
For a (working draft) list of upcoming seminars, click here.
If you are interested in giving an ORE seminar, please contact us at nosal [at] hawaii [dot] edu.
- This event has passed.
MS Plan A Defense: A fatigue analysis of the No-WEC mooring system at the U.S. Navy Wave Energy Test Site off Oʻahu, Hawaiʻi
1 December 2020 @ 9:00 am - 10:00 am
Cameron Morrow
Graduate Student
Department of Ocean and Resources Engineering
University of Hawai’i
In order to reduce carbon emissions, there is a pressing need to look for alternative fuel sources. Energy created by renewable sources is the way of the future. One of the emerging renewable energy technologies is wave energy. The theoretical gross power generated from waves is 3.7 TW, but the estimated total net power is 3 TW.
The Wave Energy Test Site (WETS), off the coast of Marine Corps Base Hawaiʻi, provides a unique location for the full-scale validation of Wave Energy Conversion (WEC) devices in the USA. WETS has three separate berths, allowing for the simultaneous testing of three WEC devices with up to 1MW power transmission to shore. Two WEC devices have been tested at WETS (two deployments each), and many other devices are planned to be deployed in the coming years.
The mooring system at the two deeper WETS berths is a 3-point spread catenary system consisting of 2.75″ ground chain and 4” (60m berth)/3.5” (80m berth) riser chains, leading from the anchors to three separate surface buoys. From the surface buoys, hawsers connect a WEC device to the rest of the mooring system. When no WEC is deployed, a no-WEC hawser system keeps the system in tension to reduce long-term fatigue and wear on the moorings.
This study focuses on understanding the fatigue damage to the mooring chain when in this no-WEC configuration. This analysis is desirable for understanding how changes to this system might improve system fatigue life during these extended WETS idle periods. For the fatigue damage analysis, typical sea states are identified based on analyzing a 41-year wave hindcast and validated with 20 years of buoy data. The fatigue damage analysis is based on a frequency-domain analysis of the no-WEC mooring system’s responses to typical sea states. The long-term fatigue damage calculation is performed by considering the probability of occurrence of these typical short-term sea states.
Zoom Meeting Link
Meeting ID: 821 9497 6549
Passcode: f8BKDj