Alcohol fuel
From Freepedia
The use of alcohol as a fuel for internal combustion engines, either alone or in combination with other fuels, has been given much attention mostly because of its possible environmental and long-term economical advantages over fossil fuel.
Both ethanol and methanol have been considered for this purpose. While both can be obtained from petroleum or natural gas, ethanol may be the most interesting because many believe it to be a renewable resource, easily obtained from sugar or starch in crops and other agricultural produce such as grain, sugarcane or even lactose. When 10% alcohol fuel is mixed into gasoline, the result is known as gasohol. When 85% alcohol fuel is mixed into gasoline, the result is known as E85. Other experiments involve butanol, which can also be produced by fermentation of plants.
Alcohol is also increasingly used as an oxygenate for gasoline, as a replacement for MTBE.
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Fuel alcohols
Proposals to use alcohol as a fuel are generally concerned with its use in transportation, chiefly as a total or partial replacement for gasoline in cars and other road vehicles. However, other less conventional approaches have been advanced, such as the use of alcohol in fuel cells, either directly or as a feedstock for hydrogen production.
Fuel alcohols can be produced from a variety of crops, such as hemp, kenaf, sugarcane, sugar beets, maize, barley, potatoes, cassava, sunflower, eucalyptus, etc. Two countries have developed significant bio-alcohol programs: Brazil (ethanol from sugarcane) and Russia (methanol from eucalyptus). Ethanol for industrial use is often made synthetically from petroleum feedstock, typically by the catalytic hydration of ethylene with sulfuric acid as the catalyst. This process is cheaper than the production by fermentation. It can also be obtained via ethene or acetylene, from calcium carbide, coal, oil gas, and other sources.
Agricultural alcohol for fuel requires substantial amounts of cultivable land with fertile soils and water. It is hardly an option for densely occupied and industrialized regions like Western Europe. For example, even if Germany were to be entirely covered with sugarcane plantations, it would get only half of its present energy needs (including fuel and electricity), and even that only if we assume that sugarcane would grow in Germany at all. However, if the fuel alcohol is made of the stalks, wastes, clippings, straw, corn cobs, and other crop field trash, then no additional land is needed. However using these sources for this purpose would require additional replacement animal feedstock, fertilizers and electric power plant fuels.
Ethanol
Ethanol can be derived from corn, wheat, potato wastes, cheese whey, rice straw, sawdust, urban wastes, paper mill wastes, yard clippings, molasses, sugar cane, seaweed, surplus food crops, and other cellulose waste. Petroleum is also used to make industrial ethanol.
Ethanol, which is the same chemical as the alcohol in alcoholic beverages, can reach 96% purity by volume by distillation, and is as clear as water. This is enough for straight-ethanol combustion. For blending with gasoline, purities of 99.5 to 99.9% are required, depending on temperature, to avoid separation. These purities are produced using additional industrial processes. Ethanol in water is an azeotropic mixture which cannot be purified beyond 96% by distillation. Today, the most widely used purification method is a physical adsorption process using molecular sieves. Ethanol is flammable and pure ethanol burns more cleanly than many other fuels. Assuming it is derived from biomass, the combustion of ethanol produces no net carbon dioxide. When fully combusted, its combustion products are only carbon dioxide and water which are also the by-products of regular cellulose waste decomposition. For this reason, it is favoured for environmentally conscious transport schemes and has been used to fuel public buses. However, pure ethanol reacts with or dissolves certain rubber and plastic materials and cannot be used in unmodified engines. Additionally, ethanol has a much higher octane rating (about 115) than ordinary gasoline, requiring changes to the compression ratio or spark timing to obtain maximum benefit. To change a gasoline-fueled car into an pure-ethanol-fueled car, larger carburetor jets (about 30-40% larger by area) are needed. (Methanol requires an even larger increase in area, to roughly 50% larger.) A cold starting system is also needed to ensure sufficient vaporization for temperatures below 15 degrees C (59 degrees F) to maximize combustion and minimize uncombusted nonvaporized ethanol. If 10 to 30% ethanol is mixed with gasoline, no engine modification is typically needed. Many modern cars can run on the mixture very reliably.
A mixture containing gasoline with approximately 10% ethanol is known as gasohol. It was introduced nationwide in Denmark, and in 1989, Brazil produced 12 billion litres of fuel ethanol from sugar cane, which was used to power 9.2 million cars. It is also commonly available in the Midwest of the United States and is the only automobile fuel allowed to be sold in the state of Minnesota. The most common gasohol variant is "E10", containing 10% ethanol and 90% gasoline. Other blends include E5 and E7. These concentrations are generally safe for recent, unmodified automobile engines, and some regions and municipalities mandate that the locally-sold fuels contain limited amounts of ethanol. One way to measure alternative fuels in the US is the "gasoline-equivalent gallons" (GEG). In 2002, the U.S. used as fuel an amount of ethanol equal to 137 petajoules (PJ), the energy of 1.13 billion US gallons (4,280,000 m³) of gasoline. This was less than 1% of the total fuel used that year.[1]
The term "E85" is used for a mixture of 15% (by volume) gasoline and 85% ethanol. This mixture has an octane rating of about 105. This is down significantly from pure ethanol but still much higher than normal gasoline. The addition of a small amount of gasoline helps the engine under cold start conditions. E85 does not always contain exactly 85% ethanol. In winter, especially in colder climates, additional gasoline is added (to facilitate cold start). E85 has traditionally been similar in cost to gasoline, but with the large oil prices seen during 2005 it has become common to see E85 sold for as much as $0.70 less per gallon than gasoline, making it highly attractive to the small but growing number of motorists with cars capable of burning it. With no real hope of large long-term reductions in oil prices, the long term cost-competitiveness (even without tax subsidies) of E85 seems assured.
Beginning with the model year 1999, an increasing number of vehicles in the world are manufactured with engines which can run on any gasoline from 0% ethanol up to 85% ethanol without modification. Many light trucks (a class containing minivans, SUVs and pickup trucks) are designed to be dual fuel or flexible fuel vehicles, since they can automatically detect the type of fuel and change the engine's behavior, principally air-to-fuel ratio and ignition timing to compensate for the different octane levels of the fuel in the engine cylinders.
In the past, when farmers distilled their own ethanol, they sometimes used radiators as part of the still. The radiators often contained lead, which would get into the ethanol. Lead entered the air during the burning of contaminated fuel, possibly leading to neural damage. However this was a minor source of lead since tetraethyl lead was used as a gasoline additive. Today, ethanol for fuel use is produced almost exclusively from purpose built plants eliminating any use of lead.
In Brazil and the United States, the use of ethanol from sugar cane and grain as car fuel has been promoted by government programs. Some individual U.S. states in the corn belt began subsidizing ethanol from corn (maize) after the Arab oil embargo of 1973. The Energy Tax Act of 1978 authorized an excise tax exemption for biofuels, chiefly gasohol. The excise tax exemption alone has been estimated as worth US$1.4 billion per year. Another U.S. federal program guaranteed loans for the construction of ethanol plants, and in 1986 the U.S. even gave ethanol producers free corn.
In August 2005, President Bush signed a comprehensive energy bill which included a requirement to increase the production of ethanol and biodiesel from 4 to 7.5 billion US gallons (15,000,000 to 28,000,000 m³) within the next ten years. It is expected that in the short term the majority of this increase will come from ethanol produced from corn.
Methanol
Methanol, too, has been considered as a fuel, mainly in combination with gasoline. It has received less attention than ethanol, however, because it has a number of problems of its own. Its main advantage is that it can be easily manufactured from methane (the chief constituent of natural gas) as well as by pyrolysis of many organic materials. The only issue with pyrolysis is that it is only economically-feasible on an industrial scale, so it is not advisable to try and produce methanol from renewable resources like wood on a small (personal use) scale. Regardless, high temperatures are involved; and methanol is extremely toxic, so great care should be taken at all times not to ingest methanol or spill it onto exposed skin.
Since 1965, pure methanol was used in United States Auto Club competition for its series, and today used by many short track organisations, especially midget and sprint cars, Champ Car, and until 2005, Indy cars, primarily for safety reasons.
A seven-car crash on the second lap of the 1964 Indianapolis 500 resulted in USAC's decision to mandate methanol. Eddie Sachs and Dave McDonald died in the crash when their gasoline-fueled cars exploded. Johnny Rutherford was also involved, in a methanol-fueled car which also leaked following the crash, and while burned from the impact of the first fireball, the car did not turn into the inferno the gasoline cars did. That testimony and pressure from the Indianapolis Star writer George Moore, led to the 1965 alcohol fuel mandate.
Currently, the Indy Racing League uses pure methanol (M100.) But the IRL will switch to a 10% ethanol / 90% methanol (M90 or E10) mix in 2006, before switching to an all-ethanol mix (E100) in 2007.
However, unlike ethanol, methanol is a toxic product; extensive exposure to it could lead to permanent health damage, including blindness. US maximum allowed exposure in air (40 h/week) are 1900 mg/m³ for ethanol, 900 mg/m³ for gasoline, and 260 mg/m³ for methanol. It is also quite volatile and therefore would increase the risk of fires and explosions. Besides the increased fire and explosion risks, though, higher volatility often means more evaporative emissions. In the case of methanol, that means rapidly-intoxicating levels of two highly-potent toxins - formaldehyde (used as a preservative for dead organic matter in laboratories), and formic acid (the poison found in ant stings). Catalytic converters would usually break down these two toxins in a manner similar to the sulfur, nitrogen, or carbon monoxide molecules which they normally dispose of if it were not for the fact that catalytic converters operate below the required temperature until the vehicle has gone 5 to 10 miles (10 to 15 km).
It is possible to overcome this environmental issue in two ways. Firstly, there is the very expensive option of adding more catalyst to the converter's aluminium honeycomb. But the catalysts themselves just happen to be the metals platinum, palladium, and rhodium - all of which are very rare and expensive to purchase. As an example, palladium costs about $200 per ounce - the equivalent of $3,200 per pound or £4,000 (€5,500) per kilogram. Also, platinum costs even more - it $935 per ounce! (That's up to $15,000 per pound or £18,700 - €26,200 - per kilo!) That's why catalytic converters contain so little catalyst - the catalysts themselves are too expensive to be used generously enough to be as effective as they were meant to be!
Secondly, you could install an electric heater (or a glow plug from an old diesel engine) to preheat the converter a bit more rapidly than it would if a car's engine was just left to idle for 5 or 10 minutes. It would still take time, but pollution levels would face yet more dramatic cuts, and could help the UK achieve the promises it made under the Kyoto Protocol, as cars are a major source of net CO2 emissions there, just as they are in most other countries as well. NOTE: Electric vehicles (EVs) won't have as much of a problem with this approach because they already have the necessary voltages for heating the catalyst up to a sufficient level, whereas normal cars need to have higher-voltage electrical systems installed to make this work properly.
So that is how we should go about solving the toxic emissions generated by burning methanol. But besides the issue of toxicity and flammability, methanol has other problems. Notably, its energy content is only 45% that of gasoline (75% of ethanol) so you would need methanol with an octane rating of minimum AKI 200 or so (methanol's regular octane rating is just 107) in an accordingly-adjusted and rebuilt engine for this to work. Yet the only chemicals that can achieve this are ones like benzene, toluene, xylene and tetraethyl lead. But these are expensive, and cause even more pollution than methanol, hence the alternative fuels movement.
Nevertheless, a drive to add a significant percentage of methanol to gasoline got very close to implementation in Brazil, following a pilot test set up by a group of scientists involving adding adulterating gasoline with methanol between 1989 and 1992. The larger-scale pilot experiment that was to be conducted in São Paulo was vetoed at the last minute by the city's mayor, out of concern for the health of gas station workers (who are mostly illiterate and could not be expected to follow safety precautions). The idea has not been heard of since.
See also the Methanol economy article.
Other alcohols: butanol and propanol
Although not as common as ethanol and methanol, there are other fuel alcohols in existence, notably butanol and propanol. Like methanol though, these alcohols are toxic, and butanol has a high flashpoint of 35 °C. Besides this, the fermentation process of butanol is fairly tricky to execute. Also, the smell produced by the cellulose-eating Weizmann organism during butanol production is simply revolting. Ethanol has a flashpoint of 13 °C, methanol has a flashpoint of 11 °C, and propanol has a flashpoint of 15 °C. One advantage shared by all four alcohols is octane rating; coupled with a cold-start system running a fuel with high volatility. Butanol fuel could be an excellent replacement since it has energy almost identical to petrol, with over 25% higher octane rating. Recent discoveries have made bio-synthesis of butanol much more economic, although butanol derived from fossil fuels is still much cheaper - but then, that's no surprise, seeing as it's cheaper to produce any form of alcohol from fossil fuels than it is to ferment them.
Alcohol and hydrogen
There is an emerging view that current consumers of fossil fuels should move to using hydrogen as a fuel, creating a new so-called hydrogen economy. However, hydrogen is not a fuel source in and of itself. Rather, it is merely an intermediate energy storage medium existing between an energy source (be it solar power, biofuels, and nuclear power) and the place where the energy will be used. Because hydrogen in its gaseous state takes up a very large volume when compared to other fuels, logistics becomes a very difficult problem. One possible solution is to use ethanol to transport the hydrogen, then liberate the hydrogen from its associated carbon in a hydrogen reformer and feed the hydrogen into a fuel cell. Alternatively, some fuel cells can be directly fed by ethanol.
By comparison, ethanol is a less efficient fuel in a fuel cell compared with methanol. Each molecule of methanol produces 6 electrons in a three-step anode reaction, while ethanol would only produce 2 electrons in a single step.
In early 2004, researchers at the University of Minnesota announced that they had invented a simple ethanol reactor that would take ethanol, feed it through a stack of catalysts, and output hydrogen suitable for a fuel cell. The device uses a rhodium-cerium catalyst for the initial reaction, which occurs at a temperature of about 700 °C. This initial reaction mixes ethanol, water vapor, and oxygen and produces good quantities of hydrogen. Unfortunately, it also results in the formation of carbon monoxide, a substance that "chokes" most fuel cells and must be passed through another catalyst to be converted into carbon dioxide. The ultimate products of the simple device are roughly 50% hydrogen gas and 30% nitrogen, with the remaining 20% mostly composed of carbon dioxide. Both the nitrogen and carbon dioxide are fairly inert when the mixture is pumped into an appropriate fuel cell. Once the carbon dioxide is released back into the atmosphere, where it can be reabsorbed by plant life. No net carbon dioxide is released, though it could be argued that while it is in the atmosphere, it does act as a greenhouse gas.
EEI has developed a new method for producing butanol from biomass. This process involves the use of two separate micro-organisms in sequence to minimize production of acetone and ethanol byproducts. Interstingly, this process produces hydrogen as well as butyl alcohol. [2][3]
Alternate sources
Sugar cane grows in the extreme southern United States, but not in the cooler climates where corn is dominant. However, many regions that currently grow corn are also appropriate areas for growing sugar beets. Some studies indicate that using these sugar beets would be a much more efficient method for making ethanol in the U.S. than using corn.
In the 1980s, Brazil seriously considered producing ethanol from cassava, a major food crop with massive starchy roots. However yields were lower than sugarcane, and the processing of cassava was considerably more complex, as it would require cooking the root to turn the starch into fermentable sugar. The babaçu plant was also investigated as a possible source of alcohol.
There is also growing interest in the use of waste biomass as a source for alcohol other types of fuel. New technologies such as cellulose to ethanol production could provide much higher positive energy ratios of 2 to 3 times more energy in ethanol produced than input. Cellulose to ethanol production could also run on any cellulose source from farm waste, hay/grass, basically any plant matter including wood, cardboard and paper. Theoretically farms could produce fuel without sacrificing food production, because all that is needed is the left over plant matter after harvesting. Cellulose to ethanol production is still in development and has seen limited use in industrial ethanol production. The biggest challenges in using cellulose as a feedstock is the treatment and disposal of process waste and the conversion of C5 sugars (these are typically unconverted adding to the waste treatment demand). Unlike grain based processes which produce a by-product known as distillers grain with minimal waste treatment needs, cellulosic processes are typically effluent and waste treatment intensive. Distiller grain is a protein enriched animal feed with much higher nutritional value than natural grain and is typically priced at less than half that of natural grain. It therefore tends to be a desirable product for animal feeders. Approximately one-third of grain usage in the production of ethanol in modern plants is recovered as distillers grain.[4] [5] [6]
At this time, most of the different processes for converting biomass into ethanol and other fuels are very complicated and not particularly efficient. A few processes have seen increasing buzz, including thermal depolymerization (though that process produces what is described as light crude oil).
Economics of corn ethanol in the U.S.
While the energy balance of ethanol production is controversial and estimates vary widely, the economics are more certain. Ethanol production from corn costs $1.10 per US gallon (290 $/m²). [7] This figure takes into account a government subsidy of $0.214 per US gallon (57 $/m²). Additionally, corn farmers receive subsidies equivalent to about $0.61 per US gallon (161 $/m²) of ethanol. Finally, the government subsidizes $0.54 per US gallon (143 $/m²) of ethanol sold as fuel. Totaling these subsidies and including the $1.10 cost of production gives $2.464 per US gallon (651 $/m²) of ethanol.
The national trade deficit (USA) has risen to an all time high of $686 billion. Most of this rise has been attributed to the record high prices of crude oil ($67/barrel). [8] Domestic production of ethanol for fuel has the potential to ease this deficit.
Net fuel energy balance
To be viable, an alcohol-based fuel economy should have positive net fuel energy balance. Namely, the total fuel energy expended in producing the alcohol — including fertilizing, farming, harvesting, transport, fermentation, distillation, and distribution, as well as the fuel used in building the farm and fuel plant equipment — should not exceed the energy contents of the product.
This is a controversial subject charged with potential bias. Much of it depends on what is included and what is excluded from the calculation, particularly when compared with the energy balance of the production of gasoline itself. Analyses are greatly complicated by various methods of accounting for the energy value coproducts and consideration of alternate uses of the feedstock. Not surprisingly, this debate has been at best inconclusive to date.
Switching to a system with negative fuel energy balance would only increase the consumption of non-alcohol fuels. Such a system would only be worth considering as a way of exploiting non-alcohol fuels that may not be suitable for transportation use, such as coal, natural gas, or biofuel from crop residues. (Indeed, many U.S. proposals assume the use of natural gas for distillation.) However, many of the expected environmental and sustainability advantages of alcohol fuels would not be realized in a system with negative fuel balance.
Even a positive but small energy balance would be problematic: if the net fuel energy balance is 50%, then, in order to eliminate the use of non-alcohol fuels, it would be necessary to produce two units of alcohol for each unit of alcohol delivered to the consumer.
In this regard, geography is the decisive factor. In tropical regions with abundant water and land resources, such as Brazil, the viability of production of ethanol from sugarcane is no longer in question; in fact, the burning of sugarcane residues (bagasse) generates far more energy than needed to operate the ethanol plants, and many of them are now selling electric energy to the utilities. Also, in countries with abundant hydroelectric power, the net fuel energy balance of the cycle could be improved to some extent by using electricity in the production, e.g. for milling and distillation.
The picture is quite different for other regions, such as the United States, where the climate is too cool for sugarcane. In the U.S., agricultural ethanol is generally obtained from grain, chiefly maize, and the net fuel energy balance of that route is still critical.
Energy balance in the United States
One study has concluded that the use of corn ethanol for fuel would have a negative net energy balance. Namely, the total energy needed to produce ethanol from grain — including fermentation, fertilizing, fuel for farm tractors, harvesting and transporting the grain, building and operating an ethanol plant, and the natural gas used to distill corn sugars into alcohol — exceeds the energy content of ethanol. However, all subsequent studies have concluded that ethanol production yields more energy than it consumes (most agree on a ratio of 1.34:1) This is remarkable when one considers that the two primary sources of fuel for transportation (diesel and gasoline) have a negative energy balance. Both consume about 20% more energy than they yield. [9]
Using old data greatly affects the outcome in these studies. According to the USDA, farms have become more energy efficient since 1978 due in large part to replacing gasoline powered equipment with more fuel-efficient diesel engines. Total farm energy use peaked in 1978 at 2,244 trillion Btu (2.368 EJ), but by 2000 had dropped to about 1,600 trillion Btu (1.7 EJ). In the meantime, corn production rose from an average of 110 bushels per acre (6.9 Mg/ha) in 1980 to 140 bushels per acre (8.8 Mg/ha) in 2000.
A study by Cornell University ecology professor David Pimentel seemed to confirm this conclusion. Pimentel's study was disputed by other specialists, forcing him to revise his figures. Still, in August 2003 (and again in March 2005), he stated in a Cornell bulletin that production of ethanol from corn takes 29% more energy than it produces, ethanol from switch grass requires 45% more energy and ethanol from wood biomass requires 57% more energy that it produces [10]. However, he concluded yield was 218 US gallons per acre (204 m³/km²) of gasoline equivalent, due to the energy in ethanol being only 66% that of gasoline.
Pimentel also calculated it corn (maize) production requires about 115 US gallons per acre (108 m³/km²) of gasoline equivalent. Thus, he calculated a net energy production of 103 US gallons per acre (96 m³/km²), while his studies somehow all concluded a net energy loss in producing ethanol. Critics of Pimentel's study cite questionable deductions, for example; 1,000,000 Btu per acre (260 kJ/m²) for labor, 5,656,000 Btu per acre (1474 kJ/m²) for machinery, as well as additional deductions for steel and concrete production and construction of ethanol refineries, while not saying from where these numbers were derived. (Shapouri, Hosein, James A. Duffield, Michael Wang. The Energy Balance of Corn Ethanol: An Update. USDA: Office of the Chief Economist; Office of Energy Policy and New Uses. Washington, DC. July, 2002) Pimentel’s work has been largely criticized and discredited by subsequent studies.
It is only fair to hold gasoline to the same standard that ethanol is being put through. The focus of the USDA report, and others, was on ethanol and the energy balance equation, but according to a report by the Minnesota Department of Agriculture, when taking into account the energy needed to extract, transport and refine crude oil into gasoline, the final energy product of gasoline has an energy ratio of 0.805. That means ethanol production is 81% more energy efficient than gasoline. (Groschen <http://www.mda.state.mn.us/Ethanol/balance.html>)
Continuous refinements to ethanol production procedures have much improved the benefit/cost ratio, and most studies of modern systems indicate that they now have a positive net energy balance. Also, when ethanol is mixed with water vapor and converted into hydrogen, it does not need to be as pure as when it is used in a combustion engine, making the process more efficient. (see source below)
Many other studies of corn ethanol production have been conducted, with greatly varied net energy estimates. Most indicate that production requires energy equivalent to 1/2, 2/3, or more of the fuel produced to run the process. A 2002 report by the United States Department of Agriculture concluded that corn ethanol production in the U.S. has a net energy value of 1.34, meaning 34% more energy was produced than what went in. This means that 75% (1/1.34) of each unit produced is required to replace the energy used in production. The study also concluded that the energy used to produce and convert the ethanol was from abundant domestic sources, with only 17% of the energy used coming from liquid fuels, therefore, for every 1 unit of energy from of liquid fuel used, such as gasoline or diesel fuel, there was a gain of 6.34 units of energy. MSU Ethanol Energy Balance Study: Michigan State University, May 2002. This comprehensive, independent study funded by MSU shows that there is 56% more energy per unit volume of ethanol than it takes to produce it.
Arguments and criticisms
The use of alcohol as fuel is advocated with various arguments, mainly relating to its beneficial effects on the local and global environment, its independence from foreign oil, and its economic advantages. Critics generally dispute those arguments, claim that the switch would be expensive, and object to perceived need for increased government subsidies, taxes, and regulations.
Air pollution
There has long been widespread acknowledgement that ethanol is a cleaner-burning fuel than gasoline. Ethanol has far fewer standard regulated pollutants such as carbon monoxide and hydrocarbons, compared with plain gasoline in equivalent tests. See, for example, the air pollution and environmental studies listed at the Renewable Fuels Association website http://www.ethanolrfa.org/pubs.shtml
There has been concern about increased evaporative smog-forming hydrocarbon emissions. For example, the conservative organization RPPI claims that "adding ethanol to gasoline will at best have no effect on air quality and could even make it worse. Studies show ethanol could even increase emissions of nitrogen oxides and volatile organic compounds, which are major ingredients of smog." [11] Other critics have argued that the beneficial effects of ethanol can be achieved with other cheaper additives made from petroleum.
It is important to distinguish the issues. Ethanol in a blend with gasoline replaces tetra ethyl lead, benzene and MTBE -- all of which are additives that are meant to raise octane levels. Ethanol, with an octane rating of 110, far surpasses regular gasoline and precludes needs for other dangerous additives. However, ethanol can increase vapor pressure of gasoline causing increased evaporative emissions which, on balance, are far less serious than lead, benzene or MTBE.
Ethanol as a straight fuel is far cleaner than gasoline in its own right and this has been recognized from the dawn of the automotive age. See, for instance, Kovarik's "Fuel of the Future" http://www.radford.edu/~wkovarik/lead
Fire safety
Ethanol appears to be less of a fire hazard than gasoline; while methanol, being more volatile, is somewhat more prone to fire and explosions. However, since ethanol and methanol dissolve in water (rather than floating on it like gasoline) their fires can be extinguished with ordinary water hoses.
One of the problems with accidental combustion of pure ethanol is that it burns with a dim, blue flame, with invisible smoke. Methanol flames are dim enough to be considered invisible in daylight. Blending significant amounts of gasoline produces a highly visible flame; small quantities of dye can also produce this effect.
Greenhouse gases
A separate (and perhaps more important) benefit of switching to an ethanol fuel economy would be the decreased net output of the greenhouse gas carbon dioxide (CO2), since all the CO2 that would be liberated in the manufacture and consumption of ethanol would have to be absorbed by the plantations. In constrast, the burning of fossil fuels injects massive amounts of "new" CO2 into the atmosphere, without creating a corresponding sink.
Needless to say, this advantage will be accrued only with agricultural ethanol, not with ethanol derived from petroleum — which, due to its much smaller cost, presently accounts for most of the alcohol produced for industrial consumption. This point must be taken into account when estimating the cost of the switch.
However, this assumes processes such as distillation of ethanol and production of fertiliser which require large amounts of energy would be done without using fossil fuels.
Renewable resource
According to its proponents, another advantage of (agricultural) alcohol as a fuel is that it is a renewable energy source that will never be exhausted; whereas an economy based on fossil fuels will sooner or later collapse when the world runs out of oil.
However, David Pimentel disputes that "ethanol production from corn" is a renewable energy source. However, Pimentel's studies have been widely discredited, and also fails to compare other viable sources of ethanol such as Sugar_beets and Sugarcane.
Dependency on foreign oil and international crime
A somewhat related (but more compelling) argument is that developed regions like the United States and Europe consume much more fossil fuels than they can extract from their territory, therefore becoming dependant upon foreign suppliers as a result. As such, this dependency has become a major cause of oil wars and coups d'etat initiated by Western powers, and attendant misery and human rights violations in certain oil-producing countries allied with the West. Even if the energy balance is negative, US production involves mostly domestic fuels such as natural gas and coal, so the impact on oil importation is still positive.
Statism
Some critics, mainly on ideological grounds, dislike the idea of an ethanol economy because they see it as leading to increased government subsidy for corn-growing agribusiness, and statism. The Archer Daniels Midland Corporation of Decatur, Illinois, better known as ADM, the world's largest grain processor, produces 40% of the ethanol used to make gasohol in the U.S. The company and its officers have been eloquent in their defense of ethanol and generous in contributing to both political parties.
Tax Incentives for ethanol and petroleum: U.S. General Accounting Office, September 2000. This study examines subsidies historically given to the oil industry and to the ethanol industry and finds that the amounts of those to the oil industry are far higher. At the same time, this study applies only to historical subsidies and doesn't investigate the question of what the case would be if petroleum fuels were substantially replaced by ethanol.
Cost
Some economists have argued that using bioalcohol as a petroleum substitute is economically infeasible because the energy required to grow the corn and other crops used as fuel is greater than the amount ultimately produced. They argue that government programs that mandate the use of bioalcohol are simply agricultural subsidies enacted to gain votes from heavily agricultural states, especially Iowa. However, this reflects a lack of understanding of the motor fuel industry; production of gasoline also requires more energy input than the fuel itself provides, but the trade-off is worthwhile because it converts less portable forms of energy (electricity for pumps, burning off crude oil for heat at refineries, etc.) into a high-value (portable, easily used) form of energy. As of 2005, ethanol production has actually become much more energy-efficient than gasoline production, with energy inputs as low as 70% of the energy value of the ethanol produced.
The Brazilian experiment
In Brazil, ethanol is produced from sugar cane which is a more efficient source of fermentable carbohydrates than corn as well as much easier to grow and process. Brazil has the largest sugarcane crop in the world, which, besides ethanol, also yields sugar, electricity, and industrial heating. Sugar cane growing requires little labor, and government tax and pricing policies have made ethanol production a very lucrative business for big farms. As a consequence, over the last 25 years sugarcane has become one of the main crops grown in the country.
Ethanol production basics
Sugarcane is harvested manually or mechanically and shipped to the distillery (usina) in huge specially built trucks. There are several hundred distilleries throughout the country; they are typically owned and run by big farms or farm consortia and located near the producing fields. At the mill the cane is roller-pressed to extract the juice (garapa), leaving behind a fibrous residue (bagasse). The juice is fermented by yeasts which break down the sucrose into CO2 and ethanol. The resulting "wine" is distilled, yielding hydrated ethanol (5% water by volume) and "fusel oil". The acidic residue of the distillation (vinhoto) is neutralized with lime and sold as fertilizer. The hydrated ethanol may be sold as is (for ethanol cars) or be dehydrated and used as a gasoline additive (for gasohol cars). In either case, the bulk product was sold until 1996 at regulated prices to the state oil company (Petrobras). Today it is no longer regulated.
One ton (1,000 kg) of harvested sugarcane, as shipped to the processing plant, contains about 145 kg of dry fiber (bagasse) and 138 kg of sucrose. Of that, 112 kg can be extracted as sugar, leaving 23 kg in low-valued molasses. If the cane is processed for alcohol, all the sucrose is used, yielding 72 liters of ethanol. Burning the bagasse produces heat for distillation and drying, and (through low-pressure boilers and turbines) about 288 MJ of electricity, of which 180 MJ is used by the plant itself and 108 MJ sold to utilities.
The average cost of production, including farming, transportation and distribution, is US$0.63 per US gallon (US$0.17/L); gasoline prices in the world market is about US$ 1.05 per US gallon (US$0.28/L). The alcohol industry, entirely private, was invested heavily in crop improvement and agricultural techniques. As a result, average yearly ethanol yield increased steadily from 300 to 550 m³/km² between 1978 and 2000, or about 3.5% per year.
Electricity from bagasse
Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant; 35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in the fibrous material (bagasse) left over from pressing.
Part of the bagasse is currently burned at the mill to provide heat for distillation and electricity to run the machinery. This allows ethanol plants to be energetically self-sufficient and even sell surplus electricity to utilities; current production is 600 MW for self-use and 100 MW for sale. This secondary activity is expected to boom now that utilities have been convinced to pay fair price (about US$10/GJ) for 10 year contracts. The energy is especially valuable to utilities because it is produced mainly in the dry season when hydroelectric dams are running low. Estimates of potential power generation from bagasse range from 1,000 to 9,000 MW, depending on technology. Higher estimates assume gasification of biomass, replacement of current low-pressure steam boilers and turbines by high-pressure ones, and use of harvest trash currently left behind in the fields. For comparison, Brazil's Angra I nuclear plant generates 600 MW (and it is often off line).
Presently, it is economically viable to extract about 288 MJ of electricity from the residues of one ton of sugarcane, of which about 180 MJ are used in the plant itself. Thus a medium-size distillery processing 1 million tons of sugarcane per year could sell about 5 MW of surplus electricity. At current prices, it would earn US$ 18 million from sugar and ethanol sales, and about US$ 1 million from surplus electricity sales. With advanced boiler and turbine technology, the electricity yield could be increased to 648 MJ per ton of sugarcane, but current electricity prices do not justify the necessary investment. (According to one report, the World bank would only finance investments in bagasse power generation if the price were at least US$19/GJ.)
Bagasse burning is environmentally friendly compared to other fuels like oil and coal. Its ash content is only 2.5% (against 30-50% of coal), and it contains no sulfur. Since it burns at relatively low temperatures, it produces little nitrous oxides. Moreover, bagasse is being sold for use as a fuel (replacing heavy fuel oil) in various industries, including citrus juice concentrate, vegetable oil, ceramics, and tyre recycling. The state of São Paulo alone used 2 million tons, saving about US$ 35 million in fuel oil imports.
Program statistics
Except where noted, the following data apply to the 2003/2004 season.
| land use: | 45,000 km² in 2000 |
| labor: | 1 million jobs (50% farming, 50% processing) |
| sugarcane: | 344 million metric tons (50% sugar, 50% alcohol) |
| sugar: | 23 million tons (30% is exported) |
| ethanol: | 14 million m³ (7.5 anhydrous, 6.5 hydrated; 2.4% is exported) |
| dry bagasse: | 50 million tons |
| electricity: | 1350 MW (1200 for self use, 150 sold to utilities) in 2001 |
The labor figures are industry estimates, and do not take into account the loss of jobs due to replacement of other crops by sugarcane.
Effect on oil consumption
Most cars in Brazil run either on alcohol or on gasohol; only recently dual-fuel ("Flex Fuel") engines have become available. Most gas stations sell both fuels. The market share of the two car types has varied a lot over the last decades, in response to fuel price changes. Ethanol-only cars were sold in Brazil in significant numbers between 1980 and 1995; between 1983 and 1988, they accounted for over 90% of the sales. They have been available again since 2001, but still account for only a few percent of the total sales.
Ethanol-fuelled small planes for farm use have been developed by giant Embraer and by a small Brazilian firm (Aeroálcool), and are currently undergoing certification.
Domestic demand for alcohol grew between 1982 and 1998 from 11,000 to 33,000 cubic metres per day, and has remained roughly constant since then. In 1989 more than 90% of the production was used by ethanol-only cars; today that has reduced to about 40%, the remaining 60% being used with gasoline in gasohol-only cars. Both the total consumption of ethanol and the ethanol/gasohol ratio are expected to increase again with deployment of dual-fuel cars.
Presently the use of ethanol as fuel by Brazilian cars - as pure ethanol and in gasohol - replaces gasoline at the rate of about 27,000 cubic metres per day, or about 40% of the fuel that would be needed to run the fleet on gasoline alone. However, the effect on the country's oil consumption was much smaller than that. Although Brazil is a major oil producer and now exports gasoline (19,000 m³/day), it still must import oil because of internal demand for other oil byproducts, chiefly diesel fuel (which cannot be easily replaced by ethanol).
Environmental effect
The improvement in air quality in big cities in the 1980s, following the widespread use of ethanol as car fuel, was evident to everyone; as was the degradation that followed the partial return to gasoline in the 1990s.
However, the ethanol program also brought a host of environmental and social problems of its own. Sugarcane fields are traditionally burned just before harvest, in order to remove the leaves and kill snakes. Therefore, in sugarcane-growing parts of the country, the smoke from burning fields turns the sky gray throughout the harvesting season. As winds carry the smoke into nearby towns, air pollution goes critical and respiratory problems soar. Thus, the air pollution which was removed from big cities was merely transferred to the rural areas (and multiplied). This practice has been decreasing of late, due to pressure from the public and health authorities. In Brazil, a recent law has been created in order to ban the burning of sugarcane fields, and machines will be used to harvest the cane instead of people. This not only solves the problem of pollution from burning fields, but such machines have a higher productivity than people.
Many nations have produced alcohol fuel with no destruction to the environment. Advancements in fertilizers and natural pesticides have eliminated the need to burn fields. With condensed agriculture, like hydroponics and greenhouses, less land is used to grow more crops.
Social implications
The ethanol program also led to widespread replacement of small farms and varied agriculture by vast seas of sugarcane monoculture. This led to a decrease in biodiversity and further shrinkage of the residual native forests (not only from deforestation but also through fires caused by the burning of adjoining fields). The replacement of food crops by the more lucrative sugarcane has also led to a sharp increase in food prices over the last decade.
Since sugarcane only requires hand labor at harvest time, this shift also created a large population of destitute migrant workers who can only find temporary employment as cane cutters (at about US$3 to 5 per day) for one or two months every year. This huge social problem has contributed to political unrest and violence in rural areas, which are now plagued by recurrent farm invasions, vandalism, armed confrontations, and assassinations.
Politics
The Brazilian alcohol program has been often criticized for many motives, including excessive land use, environmental damage, displacement of food crops, reliance on misery-wage temporary labor, statism and dependency on government subsidies, etc..
Until 1996, the Brazilian oil company (Petrobras) was forced to buy ethanol from the private distilleries and sell it to gas station chains, both as pure (hydrated) ethanol and gasohol. Nowadays Petrobras only buy ethanol as a anti-knocking additive. However, for lack of internal demand, Petrobras is virtually forced to sell its surplus gasoline in the international market at a rather low price, US$ 0.13/liter. Since the domestic market price is about US$ 0.50/liter, Petrobras could increase its revenue by over 1 billion US$ per year if the ethanol program were cancelled. Petrobras also produces methyl-tert-butyl ether (MTBE), a compound that could replace ethanol in gasohol as an anti-knocking and anti-pollution additive. However, it is unlikely that this replacement will happen as although MTBE is cheaper than ethanol, it is also mostly derived from methanol that is a byproduct of the natural gas industry; therefore, apart from being carcinogenic, MTBE is also non-renewable (since it is made from crude oil-derived methane.)
On the other hand, the sugarcane agribusiness sector is politically powerful and so far it has successfully defended the program from its critics. The positive effect of the program on Brazil's overstrained foreign trade speaks louder than all its environmental and social problems.
U.S. National security
It is believed by some (including former CIA director James Woolsey and Frank Gaffney, President Reagan's undersecretary of defense [12]) that oil consumption in the U.S. contributes in a large way to the funding of terrorism. Oil is the primary source of revenue for many mid-east countries. Many of these countries are thought to harbor and/or fund terrorist organizations. The use of alternative fuels would divert money away from these nations. Ideally, instead of funding terrorism, this money would then be used to fuel the U.S. economy.
See also
- Landless Movement (Movimento dos Sem-Terra) under Politics of Brazil
External links
- Ethanol Facts, provided by the National Corn Growers Association.
- U.S. Department of Energy: Biomass Program.
- U.S. Department of Energy: Clean Cities. Includes info on flexible fuel vehicles.
- Ethanol as Fuel - Documentation that Ethanol consumes more energy to make than is derived from its burning.
- American Coalition for Ethanol: www.ethanol.org. Advocacy group.
- Methanol Institute: [13] Article about methanol in race cars.
- How To Run Your Car On Alcohol Fuel - A 1982 book, now published online, with information on converting gasoline cars to use ethanol.
- Farm Industry News: Hydrogen Corn Economy. Article about converting ethanol to hydrogen.
- Making Alcohol Fuel - A website that covers the use and production of ethanol as a fuel.
- Cogeneration in Ethanol Plants by P. M. Nastari
- CDM Potential in Brazil, by S. Meyers, J. Sathaye et al.
- Brazilian Ethanol program (in Portuguese) and its machine translation
- UNICA - Brazilian Sugarcane growers assoc. (in Portuguese) and its machine translation
- Renewable Fuel Association [14]
- National Ethanol Vehicle Coalition [15] Shows locations of E85 fuel pumps in the USA
- Clean Fuels Development Coalition [16]
- Pimentel: Ethanol - Inefficient Fuel
- Debunking Pimentel: Ethanol - Efficient Fuel
- Ethanol Fuel News and Discussion
