DualFuel

Dualfuel refers to engines or propulsion systems designed to operate on two distinct fuels, typically a gaseous fuel such as natural gas or biogas and a liquid fuel such as diesel. In dualfuel operation, the gaseous fuel provides the majority of the energy, while a smaller diesel pilot initiates ignition and helps stabilize combustion. This arrangement aims to combine the efficiency and reliability of a diesel-based system with the fuel flexibility and potential emissions benefits of gas.

Most dualfuel engines are used in marine propulsion and stationary power generation, though land-based applications exist. Gas is usually premixed with air and burned lean, with the diesel pilot controlling ignition, peak pressure, and burn duration. The energy split between gas and diesel depends on design and load, but gas typically supplies a large share of the power, enabling cost savings and reduced soot formation compared with diesel-only operation. The systems require gas conditioning, fuel metering, and careful control to maintain performance and safety.

Advantages include fuel flexibility, potential reductions in particulate emissions and some pollutants, and compatibility with existing diesel-engine platforms. Disadvantages include greater system complexity and cost, the risk of methane slip, and limits on maximum power at certain operating points. Operation depends on reliable gas supply, robust safety systems, and appropriate shutdown procedures.

Applications include large container ships, ferries, and stationary power plants that can run on natural gas, biogas, or LPG as the primary fuel with a diesel pilot. Manufacturers such as Wärtsilä, MAN Energy Solutions, and Caterpillar offer dualfuel configurations or engines designed to switch between fuels or run on gas-rich mixtures.