Pacific Maritime Magazine - Marine Business for the Operations Sector

Hybrid Tugs Evolve To Meet Power Demands, Emission Targets


April 1, 2019

Foss Maritime's Carolyn Dorothy was the first hybrid tugboat on the West Coast in 2009. Photo courtesy of Foss.

The first hybrid tugboat on the west coast was introduced by Foss Maritime in 2009. Three years later, Foss followed up with a similar boat, for operation at the ports of Los Angeles and Long Beach.

Last month, another hybrid, built by Nichols Brothers Boat Builders for Bay Delta, launched in the San Francisco Bay. However, the new Delta Teresa tugboat features a different design from the previous two Foss tugs and offers enhanced power capabilities.

The boat demonstrates how hybrids, like other tugs, have evolved in the past decade to accommodate the changing ship-assist requirements of the maritime industry. For operators, finding a hybrid model that offers adequate power and meets environmental standards has become increasingly necessary, as ports and government bodies move to reduce emissions.

Delta Teresa's Capabilities

The 100- by 40-foot Delta Class Hybrid Z-Drive Tractor Tug offers more than 90 tons of bollard pull, according to Matt Nichols, executive vice president of Nichols Brothers Boat Builders. By contrast, the Carolyn Dorothy and Campbell Foss boats that launched in the past decade, provide 65 tons of bollard pull ahead and 69 tons astern.

San Francisco-based Baydelta Maritime plans to use the Delta Teresa to assist and dock containerships, oil tankers and other vessels that call at the Port of San Francisco, said Jonathan Parrott of Jensen Maritime Consultants.

Although the number of ship-assist tugs at major west coast ports has remained fairly static in the past decade, Charles Costanzo, Pacific regional vice president for the American Waterways Operators, also said that some ports have started to see larger ships. This has created a need for more powerful tugs.

"You have seen a need for larger tugs, more powerful tugs either that the oil industry is interested in for docking tankers or that the pilots are asking for because they do have 12,000-, 14,000-, 18,000-TEU ships," Constanzo said.

But Constanzo added that operators also see a great need to maintain a flexible fleet of tugboats that complies with environmental standards.

The Delta Teresa is the seventh 100-foot tractor tug Jensen has designed for Baydelta, according to Parrott.

Its propulsion system, designed by Rolls-Royce, received class approval from the American Bureau of Shipping (ABS) in late 2018. Unlike the Foss models that launched in 2009 and 2012, it does not utilize lithium ion batteries. Instead, the Delta Teresa uses three 480-volt main generators, each supplying 300 kW of power. The generators power two Rolls-Royce electric motors, according to specifications published by Nichols Brothers Boat Builders.

"Operating on just the motors and two or three generators, they'll be able to run and loiter, they'll probably be able to run at 7 to 8 knots depending on the weather conditions...they'll be able to do that without having to turn on their main engines, so right there, they're looking at a maximum of 1,000 kilowatts online instead of idling a pair of 2,000 kilowatt engines." Parrott said.

Although the tug also has two 1,995-kW Caterpillar diesel engines, it will only need to use them when operating near full power.

"We just boosted the size of our generators and went through an electrical panel to run electric motors on the Z-drives themselves. So you're not even running on the main engines, probably 75 percent of the time you're running on your generators which are much more quiet, they burn less fuel," Nichols said of the Delta Teresa.

He added that tractor tugs have a lot of idle run time, and not using the main engines during these periods can help reduce emissions.

Tug operators, especially in California, have grown more conscious of emissions standards, and maintaining compliance can bring significant benefits.

"It's a big market and if you can solve the regulatory puzzle piece, then you have a leg up on your competitors who haven't invested that money and haven't gone on that journey," Costanzo said.

Emissions Considerations

California state regulators are encouraging ports to move toward zero emissions. Regional air quality management districts, each with the authority to set their own emissions targets, have also encouraged the use of clean energy. Organized by the state, these management districts cover metropolitan regions from San Francisco to San Diego.

In 2017, the ports of Los Angeles and Long Beach adopted a Clean Air Action Plan (CAAP), approved by the South Coast Air Quality Management District (SCAQMD). According to the Los Angeles Times, the plan offers a framework for transforming freight-moving trucks and ships to cleaner technologies by 2035.

It requires terminal operators to start deploying zero-emissions cargo handling equipment by next year. CAAP also calls for reductions in the wait time and slow-speed movements of tugboats waiting to assist vessels.

In its 2016-2021 strategic plan, the Port of San Francisco published its own sustainability objectives, which include implementing policies that will convert port operations to 100 percent renewable energy.

Financial incentives from state regulatory bodies are also helping ports reduce their emissions. With help from a $9.7 million grant from the California Energy Commission, the Port of Long Beach is electrifying nine gantry cranes and purchasing 12 battery-electric yard tractors, CityLab has reported.

Last year, the port received $50 million from the California Air Resources Board for the Sustainable Terminals Accelerating Regional Transformation (START) project, World Maritime News has reported. One of the project's goals is the development of a near-zero-emissions tugboat.

Costanzo said that progressive jurisdictions with large port complexes, like Seattle-Tacoma, Vancouver and Prince Rupert, British Columbia, will likely follow California's lead.

"These are places that are comparing talking points and comparing pointers and figuring out (that) where we want to get to is a zero-emission, super-green port, and they're actually building that into their marketing," he said.

Cranes, forklifts, ocean-going vessels and Harbor craft all have their own slice of the pie when it comes to emissions. To achieve the necessary reduction, Costanzo added that tug operators have switched fuels and upgraded to more efficient engines.

The six Delta Class tugboats built before the Delta Teresa were designed to meet Environmental Protection Agency (EPA) Tier 4 standards, the strictest emissions criteria for diesel engines. According to Nichols, any tug over 805 horsepower must now be built with a Tier 4 engine.

But for operators, upgrading to higher tiers brings diminishing marginal returns, from a fuel consumption standpoint.

"You're using more fuel to generate the horsepower you need and actually getting less emissions at the stack, but you're putting much more fuel into the engine, and you're just not burning it as efficiently," said Costanzo.

With a move to zero emissions happening "down the line," according to Parrott, Baydelta in particular was interested in seeing how hybrid technology fits into its operations.

The Delta Teresa's two Rolls-Royce 424-kW electric motors. Photo courtesy of Nichols Brothers Boat Builders.

"This is kind of a first step in checking technology with Baydelta (to) see how they can accomplish an emissions reduction," he added.

Although upgrading to Tier 4 has successfully reduced emissions, it challenges the limits of the internal combustion engine. The last step – getting to zero emissions – will be the hardest and the most technologically sophisticated, Costanzo said.

The Jensen-designed hybrid model is a step in that direction. But whether or not it can be replicated depends on how well the vessel performs.

If Baydelta can do better than Tier 4 from an emissions reduction standpoint and avoid technical breakdowns with its new hybrid, "then they have achieved a smashing success that will probably be a model for the industry on the West Coast," Costanzo said.


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