Introduction

      Energy (from whatever the sources – fossil fuel sources or renewable sources, often referred to as alternate sources) appears in many different forms, including electricity, light, heat, chemical energy, and motional (or kinetic) energy. An important scientific discovery in the 19^th century was that energy is conserved, which means that energy can be converted from one form to another but that the total amount of energy must stay the same.

      Renewable energy can be derived from a variety of sources because the sources can be used and replaced without irreversibly depleting reserves or the sources (such as power from water systems, wind systems, and the sun) are consistently present in the Earth system, which makes these sources a valuable resource for the consistent production of energy. For this reason, renewable sources will continue to grow in importance as replacements for fossil materials used as fuels and as feedstocks for a range of products. Some renewable materials also have particular unique and beneficial properties which can be exploited in a range of products including pharmaceuticals and lubricants.

      The concept is centered around a long-term vision that a significant proportion of the demand for energy and raw materials should be met through the commercial exploitation of science from crops, in a way which stimulates biodiversity and reduces greenhouse gas emissions and waste – particularly biodegradable waste going to a landfill site – and slows depletion of finite natural resources.

      Fuels based on natural gas and crude oil are well-established products that have served industrial and domestic consumers for more than a hundred years. For the foreseeable future most of these fuels will still be largely based on liquid hydrocarbon derivatives. The specifications of such fuels will, however, continue to be adjusted as they have been and are still being adjusted to meet changing demands from consumers. Traditional refining of natural gas and crude oil underwent increasing levels of sophistication to produce fuels of appropriate specifications. Increasing operating costs continuously put pressure on refining margins but it remains problematic to convert all refinery streams into products with acceptable specifications at a reasonable return.

      However, time is running out and natural gas and crude oil, once considered inexhaustible, is now being depleted at a rapid rate – the gas and oil from tight formations notwithstanding. As the amount of available natural gas and crude oil decreases, the need for alternate technologies to produce liquid fuels that could potentially help prolong the liquid fuels culture and mitigate the forthcoming effects of the shortage of transportation fuels that has been suggested to occur under the Hubbert peak oil theory. To mitigate the influence of the oil peak and the subsequent depletion of supplies, unconventional (or non-gas and crude oil) fuels are becoming a major issue in the consciousness of oil-importing countries.

      In the near term, the ability of conventional fuel sources and technologies to support the global demand for energy will depend on how efficiently the energy sector can match available energy resources with the end user and how efficiently and cost effectively the energy can be delivered. These factors are related to the continuing evolution of a truly global energy market. In the long term, a sustainable energy future cannot be created by treating energy as an independent topic (Zatzman, 2012). Rather, the role of the energy and the interrelationship of the energy market with other markets and the various aspects of market infrastructure demand further attention and consideration. Greater energy efficiency will depend on the developing world market’s ability to integrate energy resources within a common structure.

However, the production of liquid fuels from sources other than natural gas crude oil (as well as coal and oil shale) has a checkered history. The on-again-off-again efforts that are the result of political maneuvering has seen to it that the race to secure self-sufficiency by the production of non-conventional fuels has never got much further than the starting gate! This is due in no small part to the price fluctuations in the price of natural gas and crude oil accompanied by the lack of foresight by various levels of government. It must be realized that for decades the price of natural gas and crude oil (and the resulting fuel products) has always been maintained at a level that was sufficiently low to discourage the establishment of an alternate fuels industry. However, it is close to the time when the lack of preparedness for the production of non-conventional fuels may set any national government on its heels.

      On the other hand, alternate fuels, such as gasoline and diesel fuel derived from non-fossil carbonaceous sources, are making headway into the fuel balance. For example, naphtha – the typical starting liquid for automotive fuels – and biodiesel from plant sources is similar to naphtha and kerosene but may have differences that include a different distribution of the constituents. At this time, the potential for liquid fuels from various types of biomass is also seeing considerable interest.

      Whatever the source of the fuels (gaseous, liquid, or solid) there is always the need for methods by which the fuels can be analyzed and specification derived. Typically, this aspect of non-fossil fuel technology is often omitted from many of the relevant works. In order to combat and mitigate such omissions, this encyclopedia contains articles related to product analysis that includes general descriptions of and references to the relevant text methods.

      In order to satisfy specific needs with regard to the type of feedstock to be processed, as well as to the nature of the product, the various standard test methods and specifications are a means of describing and/or recommending the rules and conditions for how materials and products should be manufactured, defined, measured, or tested. There are various standards organizations, such as the ASTM International (formerly known as American Society for Testing and Materials). Thus, it is appropriate that in any discussion of the physical properties of fuels from non-fossil fuel sources and, accordingly, where appropriate, the various ASTM test numbers have been cited in the text.

      However, although not mentioned in the text, several other countries have standard test methods for fuel identification – examples are Germany (identified by the prefix DIN), the European countries (intended to be used in the European