Want to better understand first generation renewable fuels, such as corn ethanol and biodiesel and next-generation advanced biofuels? There are significant differences in the fuels, feedstocks and underlying process technologies, how well each fuel performs, and how much each fuel costs to produce.
One vital environmental aspect of all types of liquid fuels is their relative biodegradability.
Oil-based fuels float on water when spilled and pollute water, land, and the atmosphere when spilled or combusted, regardless of their origin (petroleum oil or biologically derived oils).
Alcohol fuels such as ethanol, methanol, butanol and higher mixed alcohols are water-, oil- and coal-soluble and completely biodegradable.
Fuel Types
Biodiesel: Made from oil crops or animal fats and trans-estrification processes: Converts greases and plant oils into a cleaner bio-oil which has thermal gelling problems in winter and is not highly biodegradable. Biodiesel floats on water just like petroleum oil does. Processes are difficult to scale, cost per gallon highest of all biofuels on the market today. Waste french fry grease and soy beans are the two most prevalent oil feedstocks used to produce biodiesel. There is growing support for cultivating hemp for producing oils which can be converted to usable fuels as well.
Biodiesel combusts cleaner than petroleum-derived diesel, and it can either substitute for petroleum diesel in warmer climates or be utilized as a volumetric blendstock to petroleum diesel, especially in colder climates. Biodiesel like other oils still floats on water and does not readily biodegrade, although biodiesel will break down in the natural environment faster than crude oil or petroleum-derived fuels.
Corn Ethanol: Currently produced via four-day batch fermentation from corn using acidic enzymes and yeasts while offgassing beer fizz CO2. Ethanol is a superb alcohol fuel, yet fermentation methods most commonly used to produce it are not very energy efficient. Domestic production of corn ethanol is currently near 14 billion gallons per year, and the volume of corn ethanol allowed in domestic fuel supplies is capped at 15 bgpy. Current volumes of ethanol production and blending with fuel stocks equate to about 10% of U.S. unleaded gasoline volume, consuming over 30% of the U.S. corn crop. Ethanol is water soluble, biodegradable, features a 107 octane rating and provides 2/3s of the BTUs per gallon when compared to gasoline.
Corn ethanol production capacity has increased nearly sevenfold since 2000, thanks to government mandates, subsidies, trade barriers and facility overbuilding. Now the ethanol industry wants regulators to increase the allowable blend of ethanol in gasoline from 10 percent to 15 percent, which would effectively boost ethanol sales by 50 percent.
Cellulosic Ethanol: Produced from ground biomass (corn cobs, corn stalks, wood chips) via a longer, seven-day batch fermentation process converting wood, stalks or cobs into sugars then using yeasts to further convert sugars into EtOH. Converting biomass cellulose into EtOH requires more acidic, more expensive enzymes plus traditional yeasts. Ligno-cellulosic ethanol fermentation produces only about 1/3 of the alcohol volumes per batch when compared to four-day batch fermentation of ground corn. Mother nature’s biobugs invade seven-day batch cooking processes and typically contaminate every third batch. Ligno-cellulosic ethanol fermentation is not likely to scale, it is far more expensive than batch fermenting ground corn. Two-carbon ligno-cellulosic Ethanol is water soluble and it easily biodegrades.
Synthetic Ethanol: Produced via thermal conversion (gasification) of solid biomass feedstocks, which generates an intermediate synthetic gas (CO and H2) which is then run through gas to liquid catalysis producing a blend of formula-patented C1 to C10 higher mixed alcohols. Ethanol then needs to be fractionalized and distilled out of this blend of alcohols after first removing the C1 methanol portion. It is very expensive to isolate EtOH in this manner. Synthetic ethanol (like fermented corn ethanol) features 75,500 BTUs per gallon, about 2/3rds the energy density of gasoline.
Methanol: Produced via thermal conversion (gasification) of solid carbonaceous feedstocks or steam reformation of methane natural gas. This GTL process first generates an intermediate synthetic gas (CO and H2) when solids are gasified or CO and H2, H2, H2 when methane gas is steam reformed. This intermediate syngas is then run through gas to liquid methanization catalysts in use worldwide since 1923. Synthesis of single carbon MeOH requires 10-12 passes of syngas across the catalyst which is somewhat process intensive. Methanol contains 56,000 BTU’s per gallon, about one-half the energy density of gasoline yet can be produced commercially from stranded sources of methane natural gas for about 25¢ per gallon. Methanol is the largest volume chemical produced on the planet (used to produce plastics, nylon, rayon, paints, varnishes, thinners, window washing solvent) yet MeOH has been purposefully kept out of the petroleum-derived fuel pool for the past 100 years. C1 Methanol (octane rating 107) was used as a neat, substitute fuel in Indy 500 race cars for 37 years until it was politically replaced about four years ago with C2 corn ethanol. Water soluble and oil soluble, Methanol is highly biodegradable in the natural environment.
Dimethyl Ether: Made via thermal conversion (gasification) of feedstocks, which generates an intermediate synthetic gas (CO and H2) which is then run through gas to liquid catalysis. Dimethyl Ether or DME (formula CH3OCH3) is a pressurized, gaseous fuel (similar to propane) which combusts cleaner than C3 hydrocarbon propane does because the ether molecule contains a missing Oxygen atom. Dimethyl ether is a two-carbon, oxygenated gas which provides less BTU strength than does propane yet it combusts much cleaner than does propane. The use of DME in transport would require tanks of 125 psi pressurized gas to be retrofitted to truck and buses. Conventional autos are presently not being converted to combust pressurized DME.
Butanol: Butanol may be used as a fuel in an internal combustion engine. Because its longer hydrocarbon chain causes it to be fairly non-polar, it is more similar to gasoline than it is to ethanol. Butanol has been demonstrated to work in vehicles designed for use with gasoline without modification. It can be produced from biomass (as “biobutanol”) as well as fossil fuels (as “petrobutanol”); but biobutanol and petrobutanol have the same chemical properties.
Biobutanol can be produced by fermentation of biomass by the A.B.E. process, which uses the bacterium Clostridium acetobutylicum, also known as the Weizmann organism. It was Chaim Weizmann who first used this bacteria for the production of acetone from starch (with the main use of acetone being the making of Cordite) in 1916. The butanol was a by-product of this fermentation (twice as much butanol was produced). The process also creates a recoverable amount of H2 and a number of other byproducts: acetic, lactic and propionic acids, acetone, isopropanol and ethanol.
The difference from ethanol production is primarily in the fermentation of the feedstock and minor changes in distillation. The feedstocks are the same as for ethanol: energy crops such as sugar beets, sugar cane, corn grain, wheat and cassava as well as agricultural byproducts such as straw and corn stalks.
Higher Mixed Alcohol Fuel: This formulated blend of synthetically-produced alcohols includes methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nananol and 10-carbon decanol. Higher mixed alcohol fuel features a 120+ octane rating and 96,000 BTUs per gallon, which is 20% stronger BTU energy content than ethanol. In larger commercial GTL facilities higher mixed alcohols can be produced for less than $1.00 per gallon using a process similar to the methanol chemistry set used worldwide since 1923. Like methanol and ethanol, the blend of higher mixed alcohols is both water soluble and oil soluble, plus it is coal soluble and easily biodegrades in the natural environment.
Higher mixed alcohols can be combusted as a neat fuel as a complete substitute for gasoline via a widely available FFV computer chip which adjusts air/fuel ratios (like E-85 ethanol) and advances spark ignition timing. Alternatively, higher mixed alcohols can be blended with gasoline, diesel, jet fuel, locomotive diesel, home heating oil, and even the bunker oils combusted in large ships. No engine modifications are necessary when using higher mixed alcohol fuel as a blendstock to petroleum-derived fuels.
Additionally, higher mixed alcohols are also coal soluble and work to clean, beneficiate and transport via slurry ground coal instead of unit-training coal by railroad. Alcohol-cleaned coal functions to improve combustion efficiencies, provide more BTUs and greatly reduce smokestack pollutants just like this blend of synthetic alcohols slashes tailpipe emissions from auto and truck engines or in motorboats, motorcycles and small engines.
Mixed Alcohols are produced via two “front end” methods:
Synthesis method 1. Clean, thermal conversion (gasification) of solid and liquid feedstocks, which generates an intermediate synthetic gas (CO and H2) or;
Synthesis method 2. Steam reformation of methane and CO2 greenhouse gas which produces an intermediate synthetic gas containing CO and H2, H2, H2.
With either method, the intermediate syngas is run through a gas-to-liquid catalyst, efficiently generating a blend of C1-C6 or C1-C8 or C1-C10 higher mixed alcohols.
Further Advantages of Higher Mixed Alcohol Fuel
In addition to direct economic benefits, mixed alcohol fuel use will reduce industry and social costs by:
- Reducing volatile organic compounds (VOCs), particulate exhaust, carbon monoxide, Benzene, 1,3 Butadiene and other harmful emissions.
- Reduce problematic cost-consuming waste by turning it into a high-value biodegradable fuel.
- Utilize carbon dioxide as a low-cost carbon feedstock rather than venting it as a costly pollutant.
- Production of mixed alcohol fuel will be near zero emissions, unlike oil refineries and ethanol plants which generate large volumes of air pollutants.
- If ignited, mixed alcohol fuel can be immediately quenched with water. Spills of this fuel in waterways will feed living phytoplankton at the base of the planet’s food chain. Thus mixed alcohol fuel is very attractive in reducing environmental liabilities.
- Allows countries to build self-reliance using existing resources, improving infrastructure, creating jobs and reducing imports of foreign energy sources.