Liquid fuels are those combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. Most liquid fuels, in widespread use, are or derived from fossil fuels; however, there are several types, such as hydrogen fuel (for automotive uses), which are also categorized as a liquid fuel. It is the fumes of Liquid fuels that are flammable instead of the fluid.

This article deals primarily with the concept of liquid fuels in relation to ground transport. However, others such as rocket fuel also play an important role in the economy.

Most liquid fuels used currently are produced from petroleum. The most notable of these is gasoline. Scientists generally accept that petroleum formed from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth's crust.

Gasoline is the most widely used liquid fuel. Gasoline, as it is known in United States and Canada, or petrol in India, Britain, Australia, New Zealand, South Africa and many other Commonwealth countries, is made of hydrocarbon molecules forming aliphatic compounds, or chains of carbons with hydrogen atoms attached. However, many aromatic compounds (carbon chains forming rings) such as benzene are found naturally in gasoline and cause the health risks associated with prolonged exposure to the fuel.

William Blaine "Bill" Richardson III (born November 15, 1947) is an American politician, who served as the 30th Governor of New Mexico from 2003 to 2011. Before being elected governor, Richardson served in the Clinton administration as U.S. Ambassador to the United Nations and Energy Secretary. Richardson has also served as a U.S. Congressman, chairman of the 2004 Democratic National Convention, and chairman of the Democratic Governors Association. On December 3, 2008, then-President-elect Barack Obama designated Richardson for appointment to the cabinet-level position of Commerce Secretary. On January 4, 2009, Richardson announced his decision to withdraw his nomination because of an investigation into possibly improper business dealings in New Mexico. In August 2009, federal prosecutors dropped the pending investigation against the governor, and there was speculation in the media regarding Richardson's career, as his second and final term as New Mexico governor concluded.

Klaus Lackner is a professor in the Department of Earth and Environmental Engineering at Columbia University and co-founder of Global Research Technologies in Tucson, AZ. Lackner pioneered the concept of carbon dioxide air capture as a means for climate change mitigation, i.e. abating emissions of greenhouse gases into the atmosphere. Trained as a theoretical physicist, he has made a number of contributions to the field of Carbon Capture and Storage since 1995, including early work on the sequestration of carbon dioxide in silicate minerals and zero emission power plant design. His current work includes the use of tracers in geological carbon storage, power plant modeling, carbon capture membranes for use at high temperatures, gravitational carbon storage, advanced fossil fuel technologies, scaling and automation, among others. Lackner is currently the director of the Lenfest Center for Sustainable Energy at the Earth Institute.

He is also known for a self-replicating machine scheme, joint work with Christopher Wendt .