Using High Wind’s Boom Lock tool to increase the wind speed limit for turbine component lifts from 11m/s to 16m/s leads to an average of 1.3% decrease in the levelised cost of energy (LCOE), a study carried out by BVG Associates on a representative 500MW wind farm has shown.
An increase in the wind speed limit for turbine component lifts lowers the LCOE by reducing the time on site for vessels during installation, interest cost by reducing the time between investment and first generation, cost of capital by lowering the project risk, construction insurance by lowering weather-related project risk, and yield losses from quicker blade replacements during operation, according to the study commissioned by High Wind, a consortium of GeoSea (DEME Group), G&G International, SBE and Sarens.
For the purpose of the study, titled ”Impact of the Boom Lock tool on offshore wind cost of energy,” BVG Associates ran 12 scenarios on the representative wind farm comprising 63 8MW turbines that were on average 20 nautical miles from the installation port.
The scenarios are distinguished by the start date, 1 April and 1 October, and maximum wind speed for turbine lifts, 11m/s (baseline) to 16m/s. The baseline of 11m/s is an average figure reported by developers as part of the quantitative assessment of the Cost Reduction Monitoring Framework in 2015.
A time breakdown of vessel activities for a programme start date of 1 April with a maximum wind speed for lifts of 11m/s has shown that on the representative site chosen, weather downtime contributes 29% to total turbine installation cost.
By using BoomLock to increase the maximum wind speed for lifts from 11m/s to 16m/s, the vessel time is reduced by 23.7%, from 156 days to 119 days. For a 1 October start, Boom Lock reduces vessel time by 32.3%, from 252 days to 171 days, by raising the maximum wind speed for lifts from 11m/s to 16m/s.
At a working vessel day rate of EUR 165,000, including personnel, crew vessels, shore support and fuel, and a waiting day rate of EUR 155,000, this equates to savings of GBP 5.5 million and GBP 12.2 million for 1 April and 1 October starts respectively, according to the study.
The results have also shown that each day of earlier generation has a value of EUR 400,000 for the representative 500MW wind farm, equating to savings of GBP 14.8 million and GBP 32.6 million for 1 April and 1 October starts respectively.
However, the study has pointed out that for its widespread uptake, and therefore its greatest impact on industry LCOE, it is important that both the installation contractors and their customers benefit from the use of Boom Lock or equivalent technologies.
About 40% of the saving is achieved through lower vessel use. This will only be reflected in the LCOE if it leads to lower costs to the developer, however, which requires either the developer to take the weather risk or contractors to lower quotations in recognition of the reduced weather risks from using Boom Lock tool. If this is the case, installation contractors have less incentive to invest in Boom Lock for their vessels unless their competitors either use Boom Lock or an equivalent technology.
The industry can hasten the impact of Boom Lock on offshore wind LCOE if installation contractors are able to take enough of the benefit from lower vessel use to justify their investment in the tool, according to the study.
Source: High Wind/BVG Associates