U.S. Navy’s Great Green Fleet

Named to honor President Theodore Roosevelt’s Great White Fleet, the Great Green Fleet is a U.S. Navy initiative highlighting how the Navy and Marine Corps are using energy efficiency and alternative energy/fuels to increase combat capability and operational flexibility.

Stockdale became the first naval ship to use the fuel blend for regular operations when it departed for deployment from San Diego, Jan. 20. Mobile Bay and the other destroyers received the biofuel during replenishments-at-sea from Military Sealift Command (MSC) ships.

The alternative fuel is made from 10 percent beef tallow provided from farmers in the Midwest and 90 percent marine diesel, and is cost competitive with traditional fuels. It is used as a drop-in alternative, meaning no modifications to engines or operational procedures are required.

A centerpiece of this yearlong initiative is John C. Stennis Strike Group (JCSSG), which departed on a regularly scheduled Western Pacific deployment in January and is scheduled to join the Rim of the Pacific (RIMPAC) exercise later this month.

“As a whole, these energy saving measures allow us to be on station longer and to do our job better,” said Cmdr. Walter C. Mainor, commanding officer, USS William P. Lawrence (DDG 110). “The Navy has been at the forefront of energy innovation [for generations]. From coal to steam to oil, this is just another measure that the Navy is taking on and leaning forward for energy innovation.”

Guided-missile cruiser USS Mobile Bay (CG 53), and guided-missile destroyers USS Chung-Hoon (DDG 93), USS Stockdale (DDG 106) and William P. Lawrence are all operating in the Indo-Asia-Pacific using alternative fuel.

The U.S. Navy’s carrier fleet, including USS John C. Stennis (CVN 74) has operated using only an alternative fuel source, nuclear energy, since 2009. Nuclear power eliminates large-volume storage requirements for fuel, increasing capacity for other consumables and improving sustainability.

There’s more to the Great Green Fleet than alternative fuel. JCSSG uses various ECMs including energy-efficient systems, and operational procedures to operate farther, stay on station longer and deliver more firepower.

Chung-Hoon’s crew implemented a temperature control initiative in May, adjusting the settings of thermostats, ensuring that they are in proper working parameters, and finding and replacing faulty parts in the chill water cooling system.

Sailors replaced legacy lighting fixtures aboard all JCSSG ships with solid state lighting (SSL) lamps that use light-emitting diodes (LEDs). The new bulbs are rated for 100,000 hours of service life, compared to the 100 hours of use of an incandescent bulb.

The cruisers and destroyers of the strike group all have stern flaps installed. These modify the flow of water under the ship’s hull to reduce drag and resistance. Mobile Bay has a fouling release hull coating, which makes it harder for barnacles and other organisms to attach to the hull. Both of these ECMs reduce resistance through the water, thereby increasing fuel efficiency.

In March, William P. Lawrence separated from the strike group for its Oceania Maritime Security Initiative (OMSI) tasking in the Western Pacific, but continued practicing energy-efficient operational procedures as part of the Great Green Fleet.

During OMSI tasking, William P. Lawrence burned an average of 20,159 gallons of fuel per day, 4.4 percent of its total fuel capacity and 40 percent less than its average fuel burn rate in 2015.

When operational tasking allowed, the strike group conducted trail shaft and drift operations, which are both operational procedures U.S. Navy ships use to conserve energy use. Trail shaft means driving a ship with one of two propellers while the other remains out of use with a pitch angle set to minimize drag. Drift operations are just what they sound like, drifting with ocean currents.

Great Green Fleet ships recently participated in a ‘green’ replenishment maneuver with ships from the Italian Navy which also works on developing fuel efficiency measures.

 

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