Methanol is a synthetic fuel which is produced from reactants which provide carbon, hydrogen and oxygen. There are various sources of each of these molecules. For example, the requisite carbon may be obtained from coal (see for example U.S. Pat. No. 4,476,249 Avery), natural gas (see for example U.S. Pat. No. 5,496,589 Fong et al.) and heavy hydrocarbons such as pitch and atmospheric and vacuum residues (see for example Canadian Patent Application No. 2,060,108 Naber). Similarly, the oxygen and hydrogen, which are combined with the carbon during the synthesis step to form methanol, may be obtained from various sources. These include electrolysis, as well as the water gas shift reaction. For example, Avery and U.S. Pat. No. 5,416,245 (McGregor et al.) disclosed the use of electrolysis to provide hydrogen and oxygen. In the case of Avery, the oxygen is added together with steam to a gasifier to produce carbon monoxide and hydrogen for synthesis (column 4, lines 46-50).
Methanol is advantageous as a substitute fuel for gasoline as well as diesel fuel since it is a cleaner burning fuel (i.e. the fuel is converted to carbon dioxide and water with fewer by-products being produced). The reduced emissions associated with methanol will not favor its production unless methanol can be produced in a cost effective manner. In the retail marketplace, methanol must be priced competitively with gasoline and diesel fuel to be a commercial alternative fuel.
The advantage of methanol being a low polluting fuel will be reduced, or potentially lost, if the process for producing methanol has substantial emissions of greenhouse gases. Typical commercial processes, which are in operation to date, produce about 600 to 1200 pounds of carbon dioxide per ton of methanol produced. Therefore, while the methanol produced by these processes may be relatively non-polluting compared to gasoline and diesel fuel when it is combusted, when considered with the manufacturing process, the production and use of methanol may in fact be a substantial source of greenhouse gases.
USPTO Backgrounds
USPTO Backgrounds