Marine Electrification is the Future: A Tugboat Case Study

Abstract

Increased emissions regulations, global volatility of petroleum supply chains, and a significant push to source energy from renewable and sustainable sources encourages companies and governments to move away from petroleum-based products. Research was conducted on the efficiencies and optimal operating parameters of internal combustion engines and electric motors, exposing situations where each would be best utilized given current energy infrastructure. To support the claim of partially electrified solutions for inland waterway vessels, an in-depth analysis was conducted for an inland waterway tugboat with a rated engine of 1800 kW. The unique operating parameters for tugboats make them prime candidates for plug-in-hybrid propulsion solutions. In this case, the 1800 kW rated tugboat operates at 360 kW or less 87% of the time. This means that most of the operating profile requires a very large engine to be running at low loads, wasting fuel. Proposing electric propulsion for operating modes that require 360 kW or less yields a 62% decrease in fuel consumption. Plug-in hybrid propulsion solutions allow for vessels to plug-in to charging stations after the completion of each voyage. Renewable sources like wind and solar, among others, directly feed the grid, permitting more flexibility in the move for sustainability. New developments in battery technology, require regulatory oversight to maintain safety compliance, specifically regarding the standardization of charging plugs and fire suppression systems for lithium-ion batteries. Implementing charging stations at frequented mooring locations will open the door for sustainable technology, like electrified propulsion solutions, to permeate the inland waterway infrastructure.