In this June 7, 2009, file photo, a Casco Bay Lines ferry leaves Peaks Island on its way to Portland. Credit: Robert F. Bukaty / AP

A Portland-based ferry service is slated to receive more than $3.5 million for a vessel that will be propelled by a low-emission system.

Casco Bay Island Transit District provides ferry service to islands and island communities off Portland. The district said it is receiving the federal funding to replace an aging vessel in its fleet.

The district said it plans to replace the Maquoit II, which takes passengers and freight almost 50 miles every day and also delivers mail. It said the replacement vessel will use a diesel electric hybrid propulsion system instead of a conventional diesel mechanical propulsion system.

The new type of propulsion system will eliminate more than 1,000 metric tons of carbon dioxide emissions over the span of the vessel’s 30-year expected lifespan, the district said. It will also reduce exhaust fumes and excessive engine noise, it said.

The district also secured funding to replace another vessel, the Machigonne II, previously.