crossfuel

Crossfuel is an engineering concept describing the use of two or more fuels in a single propulsion or power-generation system delivered in coordinated, cross-fed streams. The aim is to blend the favorable properties of each fuel to improve efficiency, reduce emissions, and increase fuel flexibility. The term is used particularly in internal combustion engines and gas-turbine systems where fuel volatility, energy density, or combustion characteristics differ between fuels.

In a crossfuel system, a primary fuel provides most of the energy, while a secondary fuel is introduced through an independent port or manifold. The engine control unit adjusts the relative flow and timing to maintain stable ignition and desired combustion phasing. This allows lean-burn operation with a secondary fuel that promotes ignition or aids combustion at part load, or enables rapid fueling switches to adapt to fuel availability or price.

Applications include stationary power plants, marine engines, and heavy-duty transportation where diesel can be supplemented with natural gas, hydrogen, or ethanol. Crossfuel strategies can lower specific fuel consumption and enable use of low-cost or low-carbon fuels, contributing to emissions reductions when managed properly.

Advantages include fuel flexibility, potential emissions reductions, and resilience to supply disruptions. Limitations involve increased system complexity, higher capital costs, and the need for robust control strategies to prevent adverse combustion phenomena such as knock or NOx formation.

Related concepts include dual-fuel engines, blended fuels, and multi-fuel systems.