October 31, 2017
Economics, Technology

Wind Energy Operations & Maintenance

Wind Energy Update

2010 report:

O&M costs for wind power are double or triple the figures originally projected; they are particularly high in the U.S.

There’s a −21% change in wind farm return on investment. This underperformance of wind assets is most likely attributable to both differences in power production and O&M costs over original estimates.

$0.027/kWh, or €0.019/kWh, is the average values of O&M costs obtained from report surveys. This compares to early estimates by one of the world’s dominant turbine suppliers of $0.005/kWh.

A significant amount of R&D is currently going into gearbox reliability. Many gearboxes, designed for a 20-year life, are failing after 6 to 8 years of operation.

Data suggests that O&M challenges for wind turbines peaked in 2007/2008.

At 2 cents/kWh, O&M costs are roughly equal to the federal production tax credit offered in the U.S. as a subsidy to make wind energy competitive.

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2012 report:

Engineers are still scratching their heads when it comes to gearboxes. Even though gearboxes are certified to operate for 20 years, none of them on today’s market lasts more than 8 years.

66% – the percentage of offshore O+M costs that are caused by unscheduled corrective maintenance

2-6 times higher – offshore wind turbines O+M costs compared with on-shore

10% – the loss in revenue due to the effect of spattered debris accumulation on the blade’s leading edge

€100,000 to €300,000 per year – the costs of keeping offshore turbines online vs. an allocation of €45,000 per turbine for onshore wind

2017 report:

As part of our research into failure rates, costs and downtime on US Wind Farms, we have built a model which estimates lifetime costs of scheduled maintenance for a wind farm in the US. The input data used to build this data pack is a 210MW wind farm made up of 105 2MW turbines of 80 metres in height. The tables below show component risk factors, periodic maintenance costs, failure scenarios and supply chain factors [all costs USD]. CMS [complete monitoring system] options play an increasingly important role in both mean time to repair and the time between failures. As a result they have a large impact on costs. These are also taken into account. Finally the data pack provides major component lifetime O&M cost for the wind farm.

Scheduled maintenance cost—
Frequency per year: 2
Cost per action per turbine: $6,000
Reduced cost: $5,100
Lifetime cost per farm: $21,420,000

Component risk factors—

Components	Replacement cost	Failure rate (%), failures per 100 parts by year 20	Total failures in 20 years (total farm)	Average downtime per failure, days	Average downtime losses per faiure	Total downtime losses for the rest of the	Labor cost per failure	Crane cost per failure
Gearbox	$220,000	8	8.4	5.2	$5,241.6	$44,029	$20,000	$150,000
Blades	$120,000	8	25.2	1.8	$1,814.4	$45,723	$25,000	$45,000
Generator	$130,000	10	10.5	4.2	$4,233.6	$44,453	$7,000	$61,000

Supply chain risk factors—

	Spare in stock / No spare		Distance to manufacturing facility (if no spare available)
	Available / No spare	Lead time, days	Close / Medium / Remote	Time for transportation, days
Gearbox	No spare	70	Remote	15
Blades	No spare	105	Remote	15
Generator	No spare	70	Remote	15

CMS factors (per turbine)—

	Capital Sensor Cost (including installation) per turbine			Annual cost (O&M) per turbine		Detectability	Efficiency
	Monitoring type	Cost	Reduced cost (economies of scale)	Fixed cost	Reduced cost (economies of scale)	Detectability	Efficiency
Gearbox	Oil+vibration+temperature	$20,000	$18,000	$1,000	$850	58	59
	Vibration+temperature	$10,000	$9,000			41	49
	Temperature	0	0			24	42
Blades	Optical	$15,500	$13,950			35	40
Generator	Temperature	0	0			—	40

	Preventive		Predictive
	Lifetime maintenance cost for the farm	Lifetime maintenance cost assuming secondary damage	Lifetime maintenance and CMS operation cost for the farm	Monitoring type
Gearbox	$3,420,829	$3,762,912	$3,910,603	Oil+vibration+temperature
			$3,444,192	Vibration+temperature
			$2,915,926	Temperature
Blades	$5,241,963	$5,504,061	$5,930,817	Optical
Generator	$2,224,253	$2,379,950	$1,909,027	Temperature

We have also looked at failure rates across different turbine technology types and designs. The graph below shows major component failure rates for all types of turbines in our dataset during the first ten years of operations. Different failure modes have different repair times, ultimately leading to different costs.

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URL to article: https://www.wind-watch.org/documents/wind-energy-operations-maintenance/

URLs in this post:

[1] Image: https://docs.wind-watch.org/downtime.png

[2] Image: https://docs.wind-watch.org/wind-maintenance-2017-failure-rate.png

[3] Image: https://docs.wind-watch.org/wind-maintenance-2017-repair-time.png

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