Matching Power to Need
Hybrid technology minimizes fuel consumption by using a specialized power management system to match required power to the most efficient combination of batteries, generators, and main engines at whatever power level is needed.
If a tug is idling or docked, a lower amount of power will be provided. For escorting or moving a ship, the full horsepower of the tug will be available immediately. There are several different modes of operation for the tugs:
- minimal emissions, with a 0-5% load when idling or stopped;
- eco-cruise, with a 6-19% load during slow transit;
- mid-range, carrying a 20-65% load at faster speeds or while assisting ships;
- full power, carrying a 66% to full load at full-power ship assist speeds.
The Payoff
Tugboats often spend time idling in a harbor or doing tasks less strenuous than full-powered ship assists. When that power is supplied only by diesel engines, resources are spent and unnecessary emissions are created. The hybrid tug will rely on battery power, supplemented by diesel generators and main engines.
We expect the hybrid tug will demonstrate benefits beyond using less fuel and having fewer emissions, such as fuel and lube savings, reduced life cycle costs, and the possibility of the hybrid tug acting as a mobile power generating station.
Also, by using battery power in standby mode and only bringing generators and main engines online when higher power is required, the hybrid tug will be generally quieter than traditional tugs.
For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.
Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.
Online survey available at: http://www.uscg.mil/proceedings/survey.asp.
Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil
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