Alternative fuels and their application to combustion engines

Alternative fuels for both spark ignition (SI) and compression ignition (CI) engines have become very important owing to increased environmental protection concern, the need to reduce dependency on petroleum and even socioeconomic aspects. In the paper a review of alternative fuels for combustion engines has been performed, including physicochemical properties of these fuels, their sources and technological aspects of production, as well as recent data on R&D work and application. Fuels that are most used at present are natural gas, liquefied petroleum gas (LPG) and biofuels, such as transesterified vegetable oils and alcohols (bioethanol). Some species cannot be directly applied as neat fuels, but may be used as additives, e.g. dimethyl ether (DME), alcohols and oxygenates.