Advantages Of Electric And Hybrid Diesel/Electric Engine Systems Are Growing

Joshua Sebastian, an engineering manager at the vessel-design firm The Shearer Group Inc., says that advances in battery design, size and weight have made the advantages of electric and hybrid diesel-electric engines increasingly attractive across most segments of the marine industry.

The Shearer Group was formed in 2010 when Greg Beers, P.E. and Cory Wood of Bristol Harbor Group Inc. bought the assets of Shearer & Assoc. Inc. from Ed Shearer, P.E., President of Shearer & Assoc. It provides naval architecture, marine engineering, marine surveying and professional engineering services to clients in the inland and offshore marine industries.

“The biggest change has been in the cost of batteries,” Sebastian told The Waterways Journal. Innovation has been gathering speed, as investment in battery development has spread and smaller companies enter the market, driving up competition and lowering prices.

“As the batteries and electric motors have gotten cheaper, Tier 4 [diesel] engines have gotten more expensive,” he said. “So there’s a cost convergence.” The switch gears and other components that integrate battery power into a power train have also gotten less expensive and more reliable.

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The speed of innovation has been helped by the fact that the technologies are being developed for many industries, driven by the need to reduce emissions. The marine sector benefits from innovations developed elsewhere. “The battery manufacturing process is getting better and cheaper,” said Sebastian. “Instead of one or two ‘big boys’ like Siemens driving research, you have five or six companies in the market now.”

For one thing, being able to switch to battery power will reduce wear and tear on a diesel engine, reducing maintenance costs and extending its working life.

The cost advantages to a vessel of being able to switch from diesel to battery power will likely favor smaller towboats first, Sebastian believes, like harbor boats and fleet boats that stay in one area, or lower-horsepower towboats that have to spend a lot of time in lock queues. Those lower-horsepower boats—between 1,200 and 1,800 hp.—represent a large portion of the inland marine market, he said. “Running your engine for fewer hours reduces and spreads out its maintenance costs anywhere from 25 to 50 percent,” he said.

Then there are the green advantages.  “Many ports are beginning to require ‘cold-ironing’ operations,” Sebastian said. “Cold-ironing” is a term from the days of coal-fired marine engines, when a vessel would turn off its engines while in port.  While marine engines are powered by diesel or bunker fuel today, many ports are requiring blue-water vessels to “cold-iron” while in port, and to switch either to shore-based power or to battery power to reduce emissions.

Sebastian notes that the upcoming International Marine Organization rules requiring deep-sea commercial vessels to switch to low-sulfur fuels—known as IMO 2020—won’t directly affect what inland vessels burn, since their low-sulfur fuels are already IMO-compliant.

But the new regulations have already sharply driven up demand for low-sulfur fuels. A series of articles in energy and business publications have questioned whether refineries are switching to enough production of low-sulfur fuels to avoid a shortfall when the deadline hits next year. If IMO drives up the cost of low-sulfur fuels substantially, that would increase the fuel savings of electric and hybrid propulsion systems for inland towboats.

The bottom line, said Sebastian, is that a number of trends are converging to increase the benefits and lower the costs, of springing for a backup battery and/or installing a hybrid diesel-electric engine. Further, many of those trends, like emissions restrictions in port, will only increase.

“It can be a big capital expenditure, but we’ve found that the ROI [return on investment] can often be measured in months rather than years.”

The Shearer Group will have a booth at the Inland Marine Expo (Booth 1040) with a presentation on electric and hybrid engines that provides more details.