FEBRUARY 24, 2016—Eastern Shipbuilding Group, Panama City, FL, recently delivered the H. Douglas M, the first of a series of four Z-Tech 2400 Escort & Terminal Tugs for Bay-Houston Towing Co., Houston,
FEBRUARY 22, 2016 — The Royal Netherlands Navy brought the 29 m hybrid tug Noordsee into Den Helder this past Saturday. The Damen ASD tug 2810 is the first in a series
FEBRUARY 9, 2016 — IJmuiden, Netherlands, based OSD (Offshore Ship Designers) has designed a new series of high-performance tractor tugs that can be used for a wide range of functions, including escort
JANUARY 22, 2016—The 5,150 hp Neptune, the second in a series of four Z-Tech 2400 class escort tugs for Suderman & Young, was recently launched at the Nelson Street facility of the Eastern Shipbuilding Group,
JANUARY 18, 2016 — Eastern Shipbuilding Group, Inc., Panama City, FL, recently delivered the reverse tractor tug Archie T. Higgins to Bisso Offshore, LLC (E.N. Bisso & Son, Inc.). On arrival in
DECEMBER 30, 2015 — Eastern Shipbuilding, Panama City, FL, reports that it delivered the escort tug Triton to Suderman & Young Towing Company earlier this month. The vessel is one of a
Call me Ishmael. Melville’s famous opening line in his novel Moby Dick refers to an outcast and could once have been the motto of the hybrid and electric marine industry. There were a number of projects where hybrid and full electric drivetrains were prototyped and they worked well…for a while. The limitation was always the battery technology, where lead acid batteries were just not suited to this type of application. As a result, these projects and technologies were “interesting” with “lots of potential” but not a serious technology for the mainstream marine industry.
The advent of lithium ion batteries has fundamentally changed the value proposition for the hybrid and electric drivetrain. These batteries are smart, durable and have a lifetime that will ensure the customer is able to achieve their targeted Return on Investment (ROI). As a result, the hybrid and electric drivetrain has come of age.
To date, Corvus Energy has deployed over 30 MWh of its Lithium Polymer battery-based Energy Storage Systems (ESS) on over 45 projects. These vessels include large and small ferries, offshore supply vessels (OSVs), tugboats, research vessels, luxury superyachts and port cranes. Only two of these applications are for full electric ferries, the remainder are all hybrid vessels, but a common element is that both types of drivetrains make the vessel more efficient, as well as more environmentally sustainable.
Of course an ESS cannot create energy, but only stores it. The ESS therefore enables the vessel to use the cheapest energy available and shift it in time to the point where it is most cost effective. For a full electric this means the ESS is charged from shore using low cost energy and eliminates completely energy generated by costlier, on-board generators. For hybrids, it moves energy from the efficient portion of the generator’s load curve and replaces energy that would have been generated on the less efficient portion of the generator’s load curve.
Full Electric Drivetrains
At one time the round trip efficiency of an ESS was at 70% or less and the energy density was also not very high. This meant an ESS required a LOT of space on a vessel and did not actually store that much energy. The round trip efficiency on the Corvus ESS is now over 95% and the energy density is high enough that a space the size of a 20-foot container can store 650 kWh. This means that an ESS can now deliver enough power and energy to make a full electric drivetrain cost effective. Even with these improvements, full electric drivetrains still work best for applications where the duty cycle is relatively short such as a ferry with a route that is less than an hour between charging points. The 120-car Ampere ferry in Norway, for example, has a route which crosses Sognefjord between Lavik and Oppedal in 20 minutes and then recharges for 8 minutes from a shore-based charging station which uses the grid and another, smaller Corvus ESS to deliver a large amount of power into the vessel’s ESS in a short period of time. The shore-based charging station then recharges from the grid for about 48 minutes until the ferry returns.
The ferry operator, Norled, has other, diesel-fueled vessels on this route and based on a comparison has estimated that the Ampere is saving over 1 million liters of expensive, ultra-low sulfur diesel fuel per year. It is also saving 90% of the maintenance cost of the diesel engines and 100% of the cost of the NOx emissions, which are taxed in Norway. Norled is now looking at expanding the operating hours of the Ampere each day and is examining other routes it operates to determine if they could benefit from a fully electric ferry.
Hybrid Drivetrains
A hybrid drivetrain consists of a either a diesel or LNG engine as the prime generator for the vessel and supplements this engine with an ESS. The ESS is able to charge with energy produced when the engine generator is operating in its most efficient range and then, when the engine generator would be operating in its inefficient range, the engine is shut off and energy is extracted from the ESS to operate the vessel.
A harbor tug is a good application for a hybrid drivetrain. It will typically spend up to 25% of its time sitting and waiting for a call to push a ship. While in this mode, the vessel needs to maintain its position and run its hotel load. The engine is too large to idle and provide power just to the hotel load and so the engine drives its thrusters in opposite directions, thereby keeping the vessel in position but “boiling water” and wasting fuel. With a hybrid system, the engine is turned off and the ESS is used to periodically operate the thrusters to keep the vessel in position, and also serving the hotel load. When the ESS gets to the minimum state-of-charge, the engine is started to charge the batteries, serve the hotel load and run the thrusters. Depending on the hybrid drivetrain configuration, the ESS can also be used to supplement the engine when the tug is pushing or pulling a vessel to get it into position. When the batteries are charged the engine is turned off. An ESS on a tug can save up to 25% on fuel and emissions, as well as reducing maintenance on the engine(s).
An ESS is also very effective to replace the operation of a second engine that is running in spinning reserve to provide emergency power in the event the prime mover generator fails during a critical operation. On the Scandlines ferries in Denmark and Germany they only operate one generator during crossing and use their ESS for spinning reserve. Scandlines have identified 13% reduction in fuel and emissions and a 45% reduction in generator maintenance.
Likewise, Offshore Supply Vessels (OSVs) in the North Sea can use an ESS for spinning reserve during Dynamic Positioning (DP) operation, where the vessels have to be kept stationary when servicing floating oil and gas platforms. DNV-GL has now approved ESS for DP operations. Eliminating the operation of an additional generator used in spinning reserve has the potential to save fuel, emissions, maintenance and even the capital cost of the additional generator.
Key Benefits
The key benefits from an ESS include:
The Future is Now
No longer the elusive white whale, cost effective and proven hybrid electric propulsion has arrived and is here to stay with early adopters now reaping the benefits. An ESS helps owners make their vessels more efficient by helping them manage the operating and capital costs of their vessels, while also making these vessels more reliable and environmentally sustainable. No longer outcasts like Ishmael, the electric and hybrid marine industry has proven the value proposition for electric drivetrains and energy storage. Corvus Energy’s ESS is a key piece of these innovative hybridization projects for commercial vessels, which are fundamentally changing these marine markets. Where once there was only a potential for these benefits, Corvus Energy has the ESS technology, people and experience to make them real.
Designed by Robert Allan Ltd., Vancouver, BC, Canada, the Triton is the result of the successful operation of the first two Z-Tech 2400 tugs, Chloe K and Zeus, which were built for G & H Towing. The Triton also incorporates the lessons learned during 5 years of operation of eight previously built larger Z-Tech 7500 class tugs, starting with Thor in 2007. Those tugs are all operate by G&H Towing. The Triton is expected to be delivered before the end of 2015.
Joseph D’Isernia, Eastern Shipbuilding’s President, hosted the launching ceremony. Lisa Nigro, wife of Mike Nigro, VP of G & H Towing, christened the vessel, breaking the traditional bottle of champagne on the tug’s hull.
The Triton has an overall length of 80 feet, beam of 38 feet 3 in., depth of 15 feet 9 in., and operating draft of 16 feet 10 in. The propulsion power for the tug is supplied by two Caterpillar 3516C Tier 3-compliant diesel engines, each rated at 2,575 hp at 1,600 rev/min. The Triton has two Schottel SRP 1215 fixed pitch Z-drives for propulsion, with an expected bollard pull of 66 tonnes. Other equipment includes a Markey Machinery Fairleader 50-hp electric hawser winch. The tug is classed ABS +A1, Towing Vessel, AMS and Escort Service ABS Loadline (SoC), Statement of Compliance.
G&H Towing Company is the owners’ onsite representative and agent during the engineering, construction and delivery of the eight tugs for both Suderman & Young and Bay Houston. G&H Towing Company will operate the vessels after delivery.
The two, 120-foot long, 35-foot wide tugboats, which will be used for tow operations, will be powered by two Caterpillar 3516C, 2447 BHP at 1600 rpm main engines with Reintjes reduction gears turning two NautiCAN fixed-pitch propellers with fixed nozzles.
The vessels will also have two C7.1 Caterpillar generators for electrical service, one TESD-34 Markey tow winch, one CEW-60 Markey electric capstan and one Smith Berger Town Pin.
“Jensen is proud to have been chosen as the design firm on this project and looks forward to seeing the vessels through from concept to completion,” said Johan Sperling, vice president, Jensen Maritime. “We will embed a full-time Jensen designer in the shipyard for the duration of this project to help with system design and to ensure that the tugboats are built to exacting specifications.”
Keels will be laid for both vessels this fall with complete vessel delivery scheduled for May and November 2017. Both vessels will be fully classed by ABS and compliant with U.S. Coast Guard, as required, at delivery.
The two tugs just ordered will each be powered by twin Caterpillar 3516C engines delivering 2,447 bhp at 1,600 rpm with Reintjes reduction gears turning two NautiCAN fixed pitched propellers with fixed nozzles. The vessels will also have two C7.1 Caterpillar generators for electrical service.
Deck machinery includes one TESD-34 Markey tow winch, one CEW-60 Markey electric capstan, and one Smith Berger Tow Pin.
Keels will be laid for both vessels this fall with delivery of the first vessel from the shipyard scheduled for May 2017 and the second vessel scheduled for delivery in November 2017.
The tugboats will carry an ABS loadline, and will be compliant with USCG regulationsJensen Maritime Consultants of Seattle WA, will provide the ABS Class and functional design for the tugboats. , as required at delivery.
