Wolfgang Beez, Sr. Business Portfolio Manager – Wind, Maxwell Technologies Inc.
Wind turbine owners and operators face a number of challenges maintaining battery based blade-pitch systems. For example, replacing the battery every two to five years comes with high maintenance costs, a revenue loss from downtime, safety concerns regarding leaking battery acid, working in confined spaces, and operational safety with battery failure in cold weather conditions.
Maxwell Technologies suggests that a better way to power pitch drives is with its reliable ultracapacitor-based retrofit modules. These help reduce safety concerns and maximize turbine uptime. This article examines the operational benefits and cost savings for retrofitting blade pitch systems with two particular ultracapacitor solutions: the Energy Storage Module Pitch Backup System GE 1.5 MW and the Clipper Turbine 2.5 MW modules.
For the GE turbine, there is one ultracapacitor module per turbine blade which replaces the battery and a charger. Although a site assessment is required, the ultracapacitor is available now and has been prototype tested since October 2015.
For the Clipper turbine, the ultracapacitor is a drop-in replacement for batteries. Typically 18 modules replace the batteries on one turbine blade. The design of the ultracapacitor module maintains the same form and fit as batteries. This unit began prototype testing in July 2015 and is available now. The ultracapacitor advantage provides a thumbnail sketch of their plusses.
The table Operational benefits of ultracapacitors lists several retrofit advantages. The listed costs, retrofit advantages and benefits are based on site-specific assessment of a Clipper turbine. Similar savings can be realized with the GE 1.5 MW module.*
Retrofit advantages and benefits are based on Clipper C9X operational costs with a Maxwell customer (confidential).
Of course, results may vary and depend on the site conditions (hot/cold weather condition). A few factors, notably site procedures and installation architectures, may either reduce or increase the advantages and benefits listed above. See the warranty details and datasheet for applicable operating and use requirements.
Cost for parts and labor provides a 20-year scenario of cost data collected from selected wind farm operators relating to battery-related services, revenue loss, replacements costs, and cumulative costs over turbine life. All calculated cost savings are site-specific and are influenced by the local Power Purchase Agreement, operating conditions, and the battery related issues and service times. The actual numbers may vary depending on the aforementioned variables.
The table suggests that up to $60,000 in total savings are possible per turbine using ultracapacitors instead of batteries. Results, of course, may vary depending on the site, equipment, and operations.
The table above highlights a few noteworthy periods. For example, in a scenario where ultracapacitors replaced batteries in the eighth year of operation, the wind farm operator has already spent $38,000 in battery-related costs. Consider that a turbine typically lasts 20 years and the operator could save nearly $60,000 by replacing batteries with ultracapacitors. Of course, results may vary. Factors including site procedures and installation architecture may either reduce or increase the figures in the table. See the warranty details and datasheet for applicable operating and use requirements.
To sum up
Ultracapacitors from our company have been installed in over 46,000 wind turbines worldwide providing numerous benefits for their operators since 1999. Retrofitting battery pitch systems with ultracapacitors offers:
- Significant cost savings
- Reduced safety concerns
- Operational reliability
- Installation requires minimal to no modifications to the existing Emergency Power Unit (EPU)
- Simple and easy to install or retrofit in an existing EPU
- Can be fully discharged, eliminating exposure when working in high voltage, confined space environments
And taking all monetary and operational safety improvements aside, reducing the number of climbs in a turbine also reduces the risk of personnel injuries climbing turbines as well as working in a high voltage confined space environment.
With two module solutions designed to fit existing configurations in battery pitch systems in the field, Maxwell ultracapacitors significantly reduce turbine O&M costs, eliminate battery-related downtime issues and safety concerns, and operate reliably in a temperatures ranging from –40 to 65°C.
For further reading
Hennchen, Norbert. Freqcon Pitch System Design with Ultracapacitors. Drawing. March 2014.
Filed Under: News, O&M