Diesel is the world's most efficient internal combustion engine. It has greater energy density and provides more power and fuel efficiency than alternatives such as gasoline, compressed natural gas or liquefied natural gas.
Diesel engines have dramatically evolved since their invention nearly 150 years ago. Today’s advanced diesel technology is a three-part system that includes engines with optimized components, controls, design, and combustion strategies; ultra-low sulfur diesel fuels and/or low-carbon renewable biodiesel fuels as well as state-of-the-art emissions control technology that taken together, virtually eliminate emissions from diesel engines.
Advanced diesel’s proven energy efficiency, and ability to use renewable fuels, position it as a key technology to help achieve cleaner air and lower greenhouse gas emissions for a sustainable environment.
Diesels are known as compression ignition engines. How the engine burns fuel is the main difference between gasoline and diesel engines. Gasoline engines ignite fuel with spark plugs. Diesels ignite fuel with compression instead. Inside a diesel engine, the combustion of air and fuel takes place under pressure. Heat is created by compressing the air-fuel mixture so intensely that it spontaneously combusts, releasing energy. That energy is transmitted to powering the vehicle’s wheels, the piston's motion and creating mechanical energy.
Advanced diesel is fuel efficient because of a combination of the energy-rich properties of the fuel and the completeness of its combustion which creates more useful mechanical energy than other fuels. Ultra-low sulfur diesel fuel (ULSD) is a petroleum-based fuel with the highest energy density among transportation fuels; about 10-12% more energy (btu’s) per gallon than gasoline. The U.S. Energy Information Administration states that few transportation fuels surpass the energy density of diesel. Even advanced biofuels including biodiesel and renewable diesel have energy densities far superior than other alternatives.