Methanol

Q: What is methanol?

A: Methanol is a fuel alcohol with a similar chemical and physical makeup to ethanol. Chemically, it is methane with a hydroxyl radical (OH) replacing one hydrogen molecule. Methanol is used as a fuel additive for gasoline in the form of methyl tertiary butyl ether (MTBE), an oxygenate that reduces ground-level ozone emissions. Methanol is also used in a variety of industrial processes, both as a fuel and as a chemical catalyst.

Q: How is methanol produced?

A: Methanol is primarily produced from natural gas, although it can be produced from other non-petroleum sources such as coal and biomass (albeit at a higher cost). Researchers are currently focusing on how to lower the cost of methanol production from these renewable alternative sources. Specifically, methanol is produced by steam reforming natural gas to create a synthesis gas (syngas), which is a combination of carbon monoxide (CO) and hydrogen (H2). This gas is then reacted with a catalyst to produce methanol and water vapor. Because the same syngas is used in ammonia production, methanol-producing facilities are often attached to ammonia plants.

Q: What are pros and cons of methanol?

Pros: When used as an automotive fuel, methanol reduces many harmful emissions, offers high fuel performance, and is not as flammable as gasoline. Methanol can be produced from many organic and waste-stream substances, and it can also be used to produce hydrogen power, especially in the form of hydrogen fuel cells. Research is currently underway to tap methanol for large-scale hydrogen production.

Cons: Combustion of methanol in the form of MTBE releases large quantities of harmful formaldehyde in its emissions. Also, MTBE is known to pollute ground and surface water and so is being phased out as a gasoline additive in favor of other oxygenates, including ethanol.

P-Series (MeTHF and Ethanol)

Q: What is the P-Series?

A: The fuel group known as the "P-Series" is a collection of cleaner gasoline additives developed by Dr. Stephen Paul of Princeton University. The fuel family comprises ethanol, methyltetrahydrofuran (MeTHF) and various other light hydrocarbon liquids derived from natural gas called "pentanes plus."

Q: How are P-Series fuels produced?

A: As stated in the "Ethanol" section, ethanol (CH3CH2OH) is produced by breaking down any type of plant matter into simple sugars and starches and then fermenting them in a similar fashion to produce alcohol. This process either uses microbe fermentation (with a byproduct of CO2) or a wet-milling procedure that also yields high-fructose corn sweetener. It is easier and less expensive using currently available technology to turn the seeds and fruits of plants, such corn kernels, into ethanol than it is to ferment more complex fibrous stocks, but it will soon be economically feasible to produce ethanol from these sources.

In the United States, ethanol is largely produced from corn, usually from surplus stocks. However, it can be made from any starch or sugar, and other common sources are sugar cane (Brazil's main source), milo, cheese whey, and potato waste. MeTHF is produced from cellulosic and hemicellulosic biomass. Cellulosic biomass includes waste products derived from agriculture, paper mills (sludge and wood waste), and the food service industry. Hemicellulosic waste includes bagasse from corncobs and sugarcane, as well as corn stover (husks, stalks, and other residues). After ethanol was adopted as a gasoline additive on a broad scale throughout various regions in the United States (particularly where corn is an important crop), several researchers raised the issue that when crops are grown solely to produce fuel, they typically require more energy to grow than they provide, for a net energy loss. For this reason, the United States is currently looking into producing MeTHF at a cost-effective rate. At present it is more costly and difficult to produce the latter type of ethanol, but in the coming years fuel additives will likely be produced inexpensively and in larger quantities from agricultural residues.

Fischer-Tropsch Fuels

Q: What are Fischer-Tropsch fuels?

A: The Fischer-Tropsch method has been in use since the 1920s to convert coal, natural gas, and other "low-value" fossil fuel products into a fuel that is high in quality and clean-burning. Whereas traditional fuels emit environmentally harmful particulates and chemicals, namely sulfur compounds, Fischer-Tropsch fuels combust with no soot or odors and emit only low levels of toxins. Fischer-Tropsch fuels can also be blended with traditional transportation fuels with little equipment modification, as they use the same engine and equipment technology as traditional fuels. Currently all of South Africa's vehicles run on Fischer-Tropsch fuels as supplied by the refining company Sasol.

Q: How are Fischer-Tropsch fuels produced?

A: The process for producing Fischer-Tropsch fuels was patented by two German scientists, Franz Fischer and Hans Tropsch, circa World War I. However, not until the 1930s did the idea become popular in Germany. The Fischer-Tropsch method uses carbon monoxide and hydrogen (the same synthesis gas used to produce hydrogen fuel) to convert coal and other hydrocarbons to high-value liquid fuels in a similar process to hydrogenation, another method for hydrocarbon conversion. The process uses a catalyst, usually iron or cobalt, and incorporates steam reforming to give off the byproducts of carbon dioxide, hydrogen, and carbon monoxide.

Q: Pros and cons of Fischer-Tropsch:

Pros: As stated above, Fischer-Tropsch fuels are cleaner than traditional hydrocarbons. In terms of transportation, engine emissions are greatly reduced with the combustion of Fischer-Tropsch fuels. Emissions of nitrogen oxides (NOx) are reduced because of Fischer-Tropsch fuels' high cetane number, and as the fuels contain a very low sulfur and aromatic content, they produce virtually no particulate emissions. Researchers also expect reductions in hydrocarbon and carbon monoxide emissions. Fischer-Tropsch fuels do not differ in fuel performance from hydrocarbons (such as gasoline and diesel), and in many cases their higher cetane number results in improved combustion.

Cons: At present, Fischer-Tropsch fuels are very expensive to produce on a large scale, although research is underway to lower processing costs.