The most commonly used fuel in commercial scale applications is diesel, which gives a good fuel efficiency, reliability and longevity. For commercial scale projects, natural gas is a common alternative to diesel. Petrol (gasoline) is commonly used for domestic scale installations.
Biodiesel is similar to conventional diesel, but is produced from vegetable oil, animal oil/fats or waste cooking oil. The main source of biodiesel is from oil crops such as rapeseed, palm or soybean. Biodiesel can either be run in a biodiesel specific generator, or it can be blended with conventional diesel (up to 20% biodiesel), so that it can run in a conventional diesel generator. Biodiesel can have a similar price to conventional diesel, offers lower harmful emissions, but can be hard to source.
The use of emulsified diesel, produced by mixing a small percentage of water with the diesel, will give reduced emissions.
Gas engine driven generators operate on a similar principle to diesel generators, but utilise natural gas as a fuel source. These generators will require a connection to a natural gas supply, and therefore power is dependent on the availability of gas, although where it is available the running time is unlimited. Gas driven generators tend to have higher capital cost, but remove the need for fuel storage and have lower emissions than diesel generators.