Engineers develop air-powered propeller to replace diesel engines in ferries

Researchers have developed an innovative propeller system to replace the electric and diesel engines currently powering ferries on fixed sea routes.

The system is powered by an air motor-mounted propeller fed by an onboard compressed air tank(s).

According to the researchers from the University of Sharjah, while waiting for passengers to board, the compressed air tanks on board can be filled with air at the conclusion of the voyage. These tanks power an air motor, which turns the propeller.

The team said in a statement that in addition to being friendly to the environment, “the pneumatic system would prove more feasible both economically and from an energy efficiency perspective.”

Cleaner maritime solutions

Maritime transportation is vital to global trade, handling over 90 percent of goods by quantity and 70 percent by value. However, fossil fuel-powered ships contribute significantly to marine pollution, emitting harmful substances like sulfur dioxide and carbon dioxide, which degrade air quality, harm ecosystems, and accelerate climate change.

To address these issues, cleaner propulsion alternatives, such as electric and hybrid systems, are being researched. Electric propulsion offers zero emissions at the point of use, greater efficiency, and reduced noise, but challenges include low battery power density and environmental concerns regarding battery disposal.

Hybrid systems combine conventional fuels with renewable energy sources to offer improved performance. Studies show that, depending on the technology used, hybrid systems can reduce fuel consumption and emissions by 2 percent to 45 percent.

According to researchers, pneumatic propulsion systems use compressed air to generate thrust, offering key advantages for short-trip maritime transport. These systems provide clean, low-emission alternatives to fossil fuels, helping protect marine ecosystems.

Their simplicity leads to lower maintenance costs and greater reliability, crucial in harsh marine environments. Additionally, pneumatic systems deliver instant power and acceleration, making them ideal for situations requiring rapid speed. Compressed air’s environmental benefits also extend to applications like energy storage and cogeneration.

Pneumatic ferry innovation

Researchers at the University of Sharjah developed a novel maritime propulsion approach, focusing on pneumatic systems for ferry boats.

Unlike conventional research on electric or hybrid systems, it highlights the advantages of pneumatic motors, known for their rapid response, durability, and ease of integration into existing vessels.

An experimental rig was built to compare the thrust forces of pneumatic propulsion and electric systems powered by lead-acid batteries, using a load cell for measurement.

The study examines how pressurized air tank capacity, pressure, and discharge rate affect thrust force. Additionally, a lifecycle analysis was conducted to assess the environmental impact and energy consumption of both systems, focusing on reductions in carbon dioxide emissions achieved by the pneumatic system compared to its electric counterpart.

“The experimental results proved that compressed air is an effective alternative to electrical motors in terms of eco-friendliness, effectiveness, and sustainability. The pneumatic system provided a 6 percent extra propulsion force and a carbon footprint saving of 307 kgCO2/year over their electrical counterparts,” said the team.

To industrialize their project, the team is now working with two establishments in the United Arab Emirates. The Road and Transportation Authority in Dubai, as well as the boat manufacturing facility-equipped Sharjah Water Sports Club, have already been introduced to their pneumatic propeller.

The details of the team’s research were published in the journal Ocean Engineering .