What is the importance of ethanol

Ethanol can as fuel for gasoline engines, fuel cells and turbines. These can either be used in vehicles (e.g. motor vehicles or airplanes) or for stationary power generation. Pure ethanol (so-called E100) and mixtures of ethanol with gasoline or other alcohols (e.g. methanol) are used.

Ethanol is also increasingly used as an additive for standard gasoline as a substitute for methyl tert-butyl ether.

The gasoline-alcohol mixture is known as Gasohol in the US and as Gasolina Tipo C. designated. In the USA, the E10 and E85 blends, each containing 10% and 85% ethanol, are common. In Brazil, most blends contain 25% ethanol.

As Bioethanol (also agricultural alcohol) is the name given to ethanol that was produced exclusively from biomass (renewable carbon carriers). The starch contained in the biomass is enzymatically broken down into glucose, which is then fermented with yeast to make ethanol. If the ethanol is made from vegetable waste, wood, straw or whole plants, it is also known as cellulosic ethanol. From a chemical point of view, there is no difference between bioethanol and synthetically produced ethanol (from fossil carbon carriers).

In connection with the Kyoto Protocol, there is a lot of debate today about the production and use of biofuels. Ethanol obtained from biomass is a renewable energy source, although it has an advantage over fossil energy sources in terms of CO2-Emission, however, when cultivating energy crops, it is associated with high levels of climate-damaging gases such as nitrous oxide. Despite a positive energy balance, there is discussion about how environmentally friendly the production of ethanol actually is in view of the need for cultivation areas (monocultures).


Ethanol fuel is used as an energy carrier in internal combustion engines and fuel cells. In particular, the use as a gasoline substitute or additive in motor vehicles and recently also aircraft engines has gained in importance in recent years.

Mixtures of ethanol fuel

Common mixes come with E2, E5, E10, E15, E25, E50, E85 and E100 designated. The dem E. The attached number indicates how much volume percent ethanol was added to the gasoline. E85 consists of 85% anhydrous bioethanol and 15% conventional gasoline. Due to the higher knock resistance, the engine output with E85 can in part be significantly increased compared to conventional petrol. In the summer of 2002 the Federal Ministry of Finance passed a law on tax exemption, among other things. of ethanol as a biofuel for admixture with fossil fuels (based on EC regulation 92/81 / EEC Art.8.No.4.). In Sweden buses have also been tested with E95, using additives in addition to gasoline [1].

The DIN EN 228 standard allows up to 5% ethanol to be mixed with conventional gasoline (E5). This is already practiced today, but the proportion of ethanol in Germany is only around 2%. With a few exceptions, normal gasoline engines can be operated with E10 without modification. In some EU countries (e.g. Poland, the Czech Republic, Germany) compulsory addition of bioethanol is being tested.[2] Most of the E10 is already in use in the USA. Many vehicles with gasoline engines and regulated catalytic converters can also cope with E25 from a purely functional point of view; the generously dimensioned injection quantity correction control via lambda probe is used here. The fuel hoses (especially natural rubber) should be checked regularly for swelling in the case of an ethanol operation not approved by the manufacturer and, if necessary, replaced with more resistant materials (e.g. nitrile or thermoplastic). After the first 1000 km, the fuel filter must be replaced due to the dirt-dissolving effect of ethanol. In Brazil, 25% ethanol is mixed with regular gasoline. Half of all cars there already use the E85, 2% even use the E100. Engines that can be operated with pure alcohol have been sold there in the automotive industry since 1979 and for small aircraft since 2005. Japan plans to add up to 10% soon and is currently negotiating with Brazil over alcohol deliveries.

The first public bioethanol filling station for E85 in Germany opened in Bad Homburg on December 2nd, 2005. The price per liter is 92 cents and is therefore no more economical for the consumer than Eurosuper (1.35 €; Sep. 2007) in conventional petrol vehicles due to the 30% additional consumption. An additional consumption of ethanol is mainly due to the lower calorific value of the fuel compared to Eurosuper. One liter of E85 has a calorific value of approx. 22.6 MJ (normal gasoline approx. 30.5 MJ; premium gasoline approx. 30.8 MJ; super plus approx. 30.7 MJ). A petrol engine that has not been specially modified does not achieve any increase in efficiency through the use of ethanol. Increased performance or a reduction in additional consumption through higher compression is made possible by the higher knock resistance of the ethanol. There are currently around 60 filling stations that offer ethanol blends.[3]

Modification of internal combustion engines

The higher the proportion of ethanol in a gasoline-ethanol mixture, the less suitable it is for unmodified gasoline-powered engines. Pure ethanol reacts with or dissolves rubber and plastics (e.g. PVC) and must therefore not be used in unchanged vehicles. In addition, pure ethanol has a higher octane number than normal gasoline, which enables the ignition timing to be changed. Because of the lower calorific value, the delivery rate of the injection nozzles must be adapted. Pure ethanol engines also require a cold start system in order to ensure complete evaporation of the fuel in the cold running phase at temperatures below 13 ° C. With 10 to 30% ethanol in gasoline, hardly any conversion work is usually necessary. Not all major car manufacturers guarantee trouble-free functioning of the engine up to a proportion of 10% ethanol, because, for example, uncoated aluminum components can be attacked. Since 1999, an increasing number of vehicles in the world have been equipped with engines that can run on any possible mixture of gasoline and ethanol from 0% ethanol to 100% ethanol without modification.

In Europe, Sweden is a pioneer when it comes to blending ethanol. Ford already sold 15,000 Flexible Fuel Vehicles (FFV) in Sweden (as of December 2005). The three millionth FFV was sold in Brazil in December 2005. These vehicles are specially designed for operation with the E85, which is already available at 220 filling stations in Sweden and nationwide in Brazil. When operated with the E85, the FFV consume approx. 35% more fuel by volume compared to the standard petrol model with performance increases of up to approx. 20% (manufacturer information). FFV can be operated with any ethanol-gasoline mixture from 0 to 85% ethanol. Due to the (combustion) properties of ethanol that differ from gasoline, these engines are manufactured with different materials. Using the example of the Saab 9-5, an FFV costs 1000 euros extra compared to the petrol model (as of 2/2007). A special sensor continuously determines the mixing ratio during operation and regulates the combustion process.

Ethanol engines are not new: Henry Ford designed the Ford Model T, the "Tin Lizzy", based on the use of ethanol as a fuel and already had visions of the sustainable inclusion of agriculture as a fuel supplier. Only after pressure from the rapidly growing petroleum industry did Ford later convert the engines.

In Brazil, almost all manufacturers offer ethanol-compatible vehicles. At Volkswagen they have the addition Totalflex or at Chevrolet (Opel / GM) Flexpower and some have very economical engines (1.0 City Totalflex or 1.0 VHC Flexpower).

ETBE additive

(Bio) ethanol is the raw material for the production of ethyl tert-butyl ether (ETBE). ETBE can be mixed with normal petrol at a proportion of 15% and increases the knock resistance of the fuel.

Fuel cells

  Main Products:Fuel cell, hydrogen

Hydrogen is also seen as an alternative fuel for internal combustion engines and fuel cells. However, hydrogen is difficult to transport and store. One possible solution is to use ethanol for transport, then catalytically separate it into hydrogen and carbon dioxide, and transfer the hydrogen to a fuel cell. Alternatively, some fuel cells can be operated directly with ethanol or methanol.

In early 2004, researchers from the University of Minnesota showed a simple ethanol reactor that converts ethanol into hydrogen with the help of catalysts. The device uses a rhodium-cerium catalyst for the first reaction, which takes place at a temperature of around 700 ° C. In this reaction, ethanol, water vapor and oxygen are mixed and large amounts of hydrogen are produced. Unfortunately, this also produces toxic carbon monoxide, which is a nuisance for most fuel cells. Another catalyst oxidizes the carbon monoxide to carbon dioxide.

See also:Biohydrogen, hydrogen propulsion, solar hydrogen economy


Main Products:Ethanol

Like conventional alcohol, bioethanol is obtained through fermentation (alcoholic fermentation) from sugars with the help of microorganisms and then purified using thermal separation processes. For use as a fuel additive, bioethanol is also "dried" to a purity of more than 99%. Alternatively, synthetic routes are also available that start from fossil carbon carriers (see main article ethanol). However, this would hardly make sense for fuel use, since the intended purpose here is a substitution of fossil energy raw materials.

Process steps

In order to extract the sugar (glucose) from the raw material, it must be processed depending on the type:

  • Starchy raw materials such as grain are ground. The starch is converted into sugar in the liquefaction / saccharification process through enzymatic breakdown.
  • Sugary raw materials such as molasses can be fermented directly.
  • Cellulose-containing raw materials such as straw also have to be broken down by acids and enzymes.

The product of the raw material processing is a sugary mash to which yeast (Saccharomyces cerevisiae) is added during fermentation. The result is an alcoholic mash with around 12% ethanol content. This is purified in the distillation / rectification up to a concentration of 94.6% to so-called raw alcohol (an azeotrope that can no longer be separated by distillation). In the dehydration, the remaining water content of around 5% is removed in an adsorption process using a molecular sieve. The end product has a purity of up to 99.95%.

This high purity is required if ethanol is to be mixed with gasoline. This is because the water would settle in this mixture, with corresponding consequences in the engine. In vehicles that run on pure alcohol (as in the early days in Brazil), water-containing, i.e. not dehydrated, raw alcohol can also be used.


Mash is produced as a by-product, which contains the residues of the mash depending on the raw material. Grain stillage contains proteins and is marketed dried as animal feed (DDGS). In addition to animal feed, molasses mash is also used as a fertilizer or burned to generate steam for the ethanol plant.

raw materials

The raw materials in Latin America are sugar cane (produces e.g. cachaça) or sugar cane molasses (produces rum) - (molasses is a by-product of sugar production) - and in North America maize, because they provide high levels of sugar and starch, which after enzymatic breakdown are used as glucose for the production of ethanol by yeast. The fibers (bagasse) that arise from sugar cane use are difficult to dispose of. B. used as fodder and fertilizer, the stillage from corn use comes in dried form as corn gluten feed (dried distillers grains and solubles, DDGS) also on the European market. Maize as a raw material is of no interest for Europe, but sugar beet and sugar beet molasses, potatoes and the various types of grain are already being used.

The bagasse from sugar cane fermentation is not used directly as animal feed due to its low nutritional value. Often, however, the residual energy of the bagasse is fed back into the energy cycle of the distillery via a partially multi-stage methane fermentation, which reduces the costs per unit of ethanol produced. The development of technology is advancing rapidly in this area, so that in the future systems that deliver water of almost drinking water quality are conceivable. The weak point of this approach and also of the previously very competitive Latin American, sugar cane-based biofuel production is the sole focus on the amount of ethanol produced. Despite the lack of flexibility, the great advantage of using sugar cane lies in the cheaper raw material base, the clear location advantage and the lower capital expenditure due to the lack of large-volume drying systems. Currently, these types of ventures are the cheapest ethanol suppliers in the world and represent the model that newcomers like India and Thailand are choosing.

The production from starch and sugar cane will not be able to meet the long-term increasing demand for bioethanol. The only limited available agricultural cultivation areas, ecological problems with the necessary intensification of agriculture and the competition with the food market stand in the way of large-scale production of bioethanol in this conventional way. An inexpensive and environmentally friendly alternative would be to use plants or plant waste that are less interesting for humans as crops. These materials, consisting primarily of cellulose, hemicellulose and lignin, are abundant and inexpensive. The ideal would be a process in which the cellulose and hemicellulose are converted into fermentable sugars in so-called biorefineries and fermented directly by the yeast in ethanol. The lignin could be used as fuel to power the process. However, there are still some technical difficulties preventing the use of this process. On the one hand, the breakdown of cellulose and hemicellulose into fermentable sugars is difficult and slow due to the complex structure of these compounds, in contrast to the saccharification of starch. On the other hand, most of the microorganisms used to produce ethanol cannot ferment all the types of sugar released from the hemicellulose. However, this is an important prerequisite for an economically mature process. Researchers at the Goethe University in Frankfurt have made great progress in this direction by constructing a new yeast that is able to ferment almost all types of sugar found in plant waste, hexoses and pentoses, into ethanol.

History and use in selected countries


In 1860, Nikolaus August Otto used ethanol as fuel in the prototype of his internal combustion engine.

The auto industrialist Henry Ford designed his legendary T-model, with which he revolutionized the series production of cars, on the basis that ethanol was the actual fuel for this "people's car". Ford believed that ethanol was the fuel of the future, which at the same time would bring new growth impulses to agriculture: "The fuel of the future is going to come from fruit like that sumach out by the road, or from apples, weeds, sawdust - almost anything ".

Due to the supply situation with gasoline there was in Germany with the 1925 founded Reichskraftsprit (RKS) a manufacturer of "Spiritus" (potato schnapps for use as petrol. However, the use served less as a means to increase the knock resistance, but rather to support the growing agriculture. The RKS sold its gasoline mixture with an approx. 25 percent share of "alcohol" under the brand name Monopoline. In 1930 the ordinance on alcohol for fuel purposes came into force in Germany for all fuel companies. 2.5 percent by weight of the amount of fuel produced or imported was to be obtained from the Reich monopoly administration and added to the petrol. This quota increased gradually to 10% by October 1932.

In the decades that followed, oil became the primary source of energy. It was not until the oil crises of the 1970s that ethanol found new interest as a fuel. Starting in Brazil and the USA, the use of ethanol made from sugar cane and grain as fuel for cars was increasingly supported by government programs. A global expansion of these efforts came about as a result of the Kyoto Protocol.

World production in 2006 was around 50 billion liters, and the trend is growing rapidly.


In Brazil, in the 1980s - as an alternative to foreign exchange-intensive oil imports - the so-called "Proàlcool" program established a distinctly indigenous industry for ethanol fuel based on the production and refining of sugar cane.Due to the high world market prices for sugar in the 1990s, ethanol production almost came to a standstill, but there has been an enormous upswing in recent years. In the beginning, pure ethanol was used, which requires its own motors. In the meantime, so-called flexible fuel vehicles are used almost exclusively, which are able to burn any mixture of gasoline and ethanol.

Brazil produces approximately 15 billion liters (4 billion gallons) of ethanol per year and was the world's largest producer and consumer of ethanol fuel until 2005 (now overtaken by the US). By burning the sugar-free residues of the sugar cane (bagasse) to generate electricity and process heat, the ethanol factories in Brazil have a positive energy balance. In Brazil, gasoline must contain at least 20 to 25% alcohol.

United States

In the USA, too, the oil shock in the mid-1970s led to a national fuel-ethanol program to reduce dependence on oil imports. Tax relief for fuel mixtures with ethanol from grain ("Gasohol" = E10) enabled the development of a fuel-ethanol industry.

Some US states from the so-called Grain Belt started to financially support the production of ethanol from corn after the Arab oil crisis in 1973. The so-called Energy Tax Act from 1978 allowed an exemption from excise tax on biofuels, mainly gasoline. The loss of revenue from excise tax exemption alone was estimated at $ 1.4 billion per year. Another US federal program guaranteed a loan to grow crops for ethanol production, and in 1986 the US even gave free grain to ethanol makers.

With the "Clean Air Act" in the 1990s came another aspect for the use of ethanol: improving the air quality in large cities by reducing emissions from road traffic. In August 2005, the American President George W. Bush signed a comprehensive energy law, which among other things would increase the production of ethanol and biodiesel from 14.8 to 27.8 billion liters (or from 4 to 7.5 billion US gallons). plans within the next ten years.

The production and demand of ethanol in the USA is growing steadily. Around 700 of a total of 165,000 petrol stations have petrol pumps with E85. Ethanol is mainly available in the Midwest and California, which is where most of the ethanol is refined. As of June 2006, the capacity has been 18 billion liters (4.8 billion gallons) of ethanol per year. Capacities to produce an additional 8 billion liters (2.2 billion gallons) per year are under construction.[4]


Colombia's ethanol fuel program began in 2002 when the government passed a law to fortify gasoline with oxygenated chemical compounds. Initially, the main intention was to reduce the emission of carbon monoxide from cars. Bioethanol was later exempted from petroleum tax, making ethanol cheaper than gasoline. This trend was exacerbated as gasoline prices have been rising since 2004, increasing interest in renewable fuels (at least for cars). In Colombia, gasoline and ethanol prices are controlled by the government. As a supplement to this ethanol program, a program for biodiesel is planned to enrich diesel fuel with oxygen-containing compounds and to produce renewable fuel from plants.

Initially, the Colombian sugar industry was particularly interested in ethanol production. The government's goal was to gradually switch car fuel to a mixture of 10% ethanol and 90% gasoline. Plantings for ethanol production are tax-subsidized.

The first plant for ethanol fuel started production in October 2005 in the Colombian region of Cauca with an output of 300,000 liters per day. Five plants with a total capacity of 1,050,000 liters per day have been in operation since March 2006 at the latest. In the Colombian Cauca Valley, sugar is harvested all year round and the new distilleries are regularly used. The total investment in these facilities amounts to approximately 100 million dollars. By 2007 at the latest, production should be 2.5 million liters per day in order to achieve the target of 10% ethanol in gasoline. The ethanol fuel produced is currently mainly used in the major cities near the Cauca Valley such as Bogota and Cali Pereira. There is not yet enough production for the rest of the country.

Bioetanol production (GWh)[5]
No Country 2006 2005
1 Germany 2,554 978
2 Spain 2,382 1,796
3 France 1,482 853
4 Sweden 830 907
5 Italy 759 47
6 Poland 711 379
7 Hungary 201 207
8 Lithuania 107 47
9 Netherlands 89 47
10 Czech Republic 89 0
11 Latvia 71 71
12 Finland 0 77
27 EU total 9,2745,411
100 l bioethanol = 79.62 kg,
1 ton of bioethanol = 0.64 toe
Bioethanol use (GWh)[5]
No Country 2006 2005
1 Germany 3,573 1,682
2 Sweden 1,895 1,681
3 France 1,747 871
4 Spain 1,332 1,314
5 Poland 611 329
6 UK 561 502
7 Netherlands 238 0
8 Hungary 125 28
9 Lithuania 99 10
10 Czech Republic 14 0
11 Finland 9 0
12 Ireland 8 0
13 Italy 0 59
14 Latvia 0 5
27 EU total 10,2106,481
toe = 11.63 MWh


Already in the 1980s in Europe there was largely unnoticed by the public the addition of 5% ethanol to gasoline to increase the octane number. Later, the production of ETBE from surplus wine began in France and Spain.

With the EC directive 2003/30 / EC [6] The European Community is pursuing the goal of promoting the use of biofuels or other renewable fuels as a substitute for petrol and diesel fuels in the transport sector. The biofuel guideline gives - based on the energy content - guideline values ​​for the Share of biofuels as a replacement for conventional fuels in traffic by:

  • 2% by 2005
  • 5.75% by 2010

In March 2007 the European Council agreed an additional objective:

Note: These values ​​do not represent the admixture to gasoline or diesel, but rather indicate the desired proportion of renewable fuels (i.e. bioethanol, biodiesel, biogas, biomethanol, ...) in the total fuel requirement.

The implementation in the member states is voluntary. The target for 2005 was not achieved[7]. In addition, the Energy Tax Directive (2003/96 / EC) allows the member states to waive the mineral oil tax for biofuels up to 100%.

In Germany Bioethanol in the form of E85 is currently not taxed like fossil mineral oil, but is completely tax-free. For lower mixing ratios, the legislator has the Biofuel Quota Act[8] a regulatory instrument created to ensure that bioethanol is mixed with petrol. The mineral oil industry is obliged to add bioethanol to gasoline that is increasing every year (1.2% in 2007 to 3.6% in 2010). These shares are then fully subject to energy tax (bioethanol 65.4 cents). With this combination measure, the Federal Government aims to support the mostly medium-sized biofuel industry by securing a sales market. The currently largest European plant is in Zeitz (Saxony-Anhalt). Here CropEnergies (formerly Südzucker Bioethanol GmbH) produces 260,000 m³ / a of bioethanol from wheat, barley, triticale and corn. In the second largest German plant, Verbio in Schwedt, Brandenburg, produces 180,000 t of bioethanol annually from 500,000 t of rye.

Austria has set itself ambitious goals for the implementation of the biofuels directive, which are above the EU requirements (2.5% by 2005 | 4.3% by 2007 | 5.75% by 2008). With changes to the Fuel Ordinance and the Mineral Oil Tax Act, a substitution obligation was even introduced. With the start of production of the Agrana bioethanol plant in Lower Austria based on wheat, corn and sugar beet (2008), the Austrian market for E5 should be covered.

In Sweden Flexible Fuel Vehicles (FFV) have been marketed since 2001. The ethanol is produced in Sweden from grain, sugar cane and also from waste from local wood processing. E85 is available at more than 140 public filling stations. Sweden's goal is to become completely oil independent by 2020.

Great Britain has a policy to increase the use of biofuels, including ethanol, even though the taxation on alternative fuels such as biodiesel is almost as high as on conventional fossil fuels. Spain is the largest producer of bioethanol in Europe. Mainly barley and wheat are fermented here.

Environmental impact

Energy balance

Bioethanol is a renewable energy source, but its production is also dependent on fossil fuels. For example, pesticides and fertilizers are needed for intensive cultivation, some of which require petroleum for their production.

In order for ethanol fuel to make a meaningful contribution to the energy industry, production must have a positive energy balance. This is possible with today's technology.

A number of factors are decisive for determining the energy balance:

  • the energy contained in the ethanol
  • the energy of the by-products generated during ethanol production
  • the energy that is lost in ethanol production
  • the energy for growing the biomass (e.g. diesel for tractors, or nitrogen fertilizers)
  • Process energy for the distillation

The higher knock resistance of ethanol can enable a higher degree of efficiency in the gasoline engine conversion of chemical energy into mechanical energy.

The net energy balance of alcohol production has not always been clearly positive, but the industry has made some major breakthroughs in the past 10 years. At the “Institute for Brewing and Distilling” in Lexington (Kentucky), for example, the natural selection of an extremely thermostable yeast that allows fermentation at far higher temperatures than usual and achieves alcohol contents of up to 23% in the fermentation of corn under laboratory conditions; a clear step compared to the usual 13 to 14%. The high fermentation temperature means considerable energy savings in terms of cooling and the duration of the fermentation process. It enables a more complete fermentation of the mash. The enzymes that are added to raw materials to break down starch and release glucose (-amylases, glucoamylases) have also experienced a revolution. The rediscovery of the millennia-old process of dry fermentation (Koji) produces more powerful and temperature-tolerant enzyme complexes that break down not only starch and sugar, but also celluloses and hemicelluloses. But not only the biological side of fermentation, but also the plant technology has experienced significant advances. The water consumption has been significantly reduced, infections of the system can be avoided thanks to a new hygiene management system and almost pure ethanol can be achieved after distillation by removing water using molecular sieves (zeolites). The concern about a negative energy balance is justified, but can be overtaken by new technologies and the economic challenges can be overcome by considering the overall concept of "fermentation of grain".

With a view to the balances of energy, greenhouse gas and economic efficiency, grain comes off best if the feed value of the by-products is calculated. The frequently raised question of whether, in view of the unresolved hunger problem in the world, the use of food crops to power cars can be ethically justified remains unaffected, as does the question of whether the high and growing procurement pressure on the productivity of the soil is not already affecting the productivity of the soil relatively quickly could have a negative impact. Bottlenecks in Germany could be overcome by using the abandoned agricultural land for energy crops.

Thermal efficiency

The thermal efficiency in fuel production is heavily dependent on the raw material used. In the case of maize it is only up to 15%, in the case of manufacture from wood up to 20% and in the case of manufacture from sugar cane up to 35%. The significantly better efficiency when using sugar cane (and the ban on diesel fuels for private individuals) also explains the widespread use of ethanol as a fuel in Brazil.

Carbon footprint

When the raw materials are fermented and the bioethanol is burned, the greenhouse gas carbon dioxide is released; However, since the same amount of carbon dioxide from the atmosphere was bound by photosynthesis during the growth of the raw material plants, these chemical processes (photosynthesis, fermentation, combustion) are CO2-neutral in addition. The manufacturing process as a whole is not CO2-neutral or even climate-neutral.

According to an international study conducted by the Nobel laureate in chemistry, Paul Crutzen, in 2007, the cultivation of energy crops, especially fertilization, produces nitrous oxide that is highly harmful to the climate. According to the results, rapeseed fuel causes 1.7 times the relative warming compared to fossil fuel. For the energy crop maize, the relative warming was increased by a factor of 1.5, for sugar cane by 0.5. [9][10]

However, the publication of the study by Crutzen was rejected by renowned scientific magazines. On the one hand, the study is based only on its own model calculation for nitrous oxide emissions, i.e. H. the mathematically determined values ​​have not been confirmed by tests. On the other hand, the relevance of nitrous oxide emissions is overstated. For reasons of cost, nitrogen fertilization is becoming increasingly rare in agriculture. [11][12]

Air pollution

Compared to conventional unleaded gasoline, ethanol burns cleaner to carbon dioxide and water. In the United States, the Clean Air Act requires the addition of oxygen-rich compounds to reduce carbon monoxide emissions. The use of the additive MTBE, which is hazardous to groundwater, is reduced and replaced by ethanol.

By using pure ethanol (E100) instead of gasoline, the measured carbon dioxide emissions are reduced by around 13%. However, the photosynthesis cycle actually reduces emissions by over 80%.

The advantages are offset by the environmental pollution caused by the production of ethanol. In addition, the future possible production volume of bioethanol is limited by the limited agricultural area or new arable land would have to be created. This could reactivate fallow land, but also endanger forests or other biotopes.

Effects on Agriculture

If the demand for bioethanol continues to rise, intensive cultivation methods will be necessary. The disadvantages of monocultures are known. In Europe, instead of being set aside with subsidies, arable land could be used to produce bioethanol or diesel. In developing and emerging countries, the demand for bioethanol on the world market could lead to a relocation of the crops grown. Growing food could be neglected in favor of ethanol crops that generate foreign currency. "The grain that is needed to fill a 120-liter tank of an off-road vehicle with ethanol is enough to feed a person for a year."[13] Irresponsible cultivation methods could also lead to increased clearing of rainforests.

Agriculture and Economics

Bio-ethanol is obtained from grain, sugar beet, etc. The yield in l / ha depends on the respective plant (i.e. the table only refers to ???). The yield of sugar beet is, for example, significantly higher than that of wheat. Grains, oats, rye, barley, wheat and triticale produce, depending on the process, far higher quality feed than corn, potatoes and sugar beet have previously allowed. With protein contents of 40% and higher, these fermented grain feeds may potentially reach larger markets than just their use in concentrated feed for dairy cattle as before. When it comes to the price of ethanol, however, the burners have to compete with the world market, because fuel alcohol, as a freely tradable commodity, does not come under the regulatory measures of the spirits monopoly - an uphill battle.

Forecasts for European production show an annual output of 7 million tons of dried, fermented feed, of which one million tons in Germany alone, for which German distilleries buy up to 3 million tons of grain from agriculture. But in addition to a few small-scale pilot projects, these systems in Germany have only existed on paper so far and now it is important not to repeat the mistakes of the American ethanol industry. There are only two big ones left of over 250 companies that got into this business 20 years ago. The downfall of these projects is largely due to a major flaw: a lack of understanding of the potential of the by-product produced as animal feed. The resulting stillage was mostly given to agriculture free of charge or only to cover costs. This is practiced in a similar way by German schnapps distillers today, but these companies earn money from their own branded product or from higher-quality neutral alcohol in beverage quality.For ethanol as a biofuel, however, the price is fixed. There is therefore economic flexibility in purchasing raw materials and in the marketing of by-products.

A high price for the feed produced on the market is realistic, because a European product assessed according to QS criteria, manufactured using a natural fermentation process, taking into account all feed law regulations, is exactly what the market openly welcomes today.

Across the Atlantic one sees these lines of thought with concern, because around a fifth of the corn gluten feed produced there is exported to Europe by the North American ethanol industry. Great efforts are now being made to find further applications for “DDGS” (distillers dry grain solubles). The development becomes clear in the biorefinery in Springfield, Kentucky, which opened in 2002 and is the only facility of its kind in the world. There, Alltech Inc. develops downstream fermentation processes for the ethanol and feed industry to produce higher quality feed and new food additives, as well as new cellulose complexes as feed additives.

Lester R. Brown, President of the Earth Institute (Columbia University) says: "The stage is clear for the conflict between the 800 million car owners and the world's two billion poorest people who just want to survive."

Agriculture and ecology

  • Soil consumption by arable farming: erosion, compaction
  • Influence of groundwater and surface water through agriculture: nutrient discharge, e.g. nitrogen and phosphorus
  • Influence of groundwater and surface water through arable farming: extraction and consumption in the case of irrigated arable farming
  • Greenhouse gases in addition to CO2, e.g. nitrous oxide as a result of agricultural activity
  • Use of pesticides
  • Usage pressure on the "landscape" in general (intensive agriculture), e.g. from the point of view of biodiversity

A perception of the classic points of criticism of agriculture carried out with industrial methods must also be emphatically demanded from the perspective of renewable raw materials, in order to include them in the weighing of the goods.

economic aspects

Some economists argue that bioethanol as a gasoline substitute is only profitable for farmers and industry through government subsidies. According to the US Department of Energy, for every unit of energy used to make ethanol from corn, 1.3 units are returned. With other plants (sugar cane, China grass) the efficiency is better.

More intensive agriculture, higher yields and possibly genetically modified plants could make ethanol production more profitable from an economic point of view. Research is being carried out on special breeds and genetic manipulations. A high price of crude oil also makes the use of other biomass (e.g. straw) economically interesting.

Since the demand for the limited resource crude oil - also due to the economic development in China - will continue to rise, high oil prices are to be expected. The political goal of some countries is to make themselves less dependent on oil imports and to strive for an energy mix. Since in regions like the USA or Europe it is not possible to produce as much bioethanol as would be necessary to replace crude oil, a new dependency on imports from countries with corresponding cultivation and production possibilities could arise.


In Brazil, sugar cane is planted on 5.6 million hectares. Half of this is processed into 15 million m³ of bioethanol. According to Embrapa[14] (the Brazilian state agricultural research company) there is a potential of 90 million hectares for bioethanol production. With the same ethanol yield (which is significantly higher than the yield given in the adjacent table for Germany) this area would be 480 million m3 Bring bioethanol per year. With an energy equivalent of 6.4 million barrels of oil per day, this corresponds to only 7.5% of current world oil production (85 million barrels per day). Biofuelwatch[15] doubts that a corresponding expansion of the cultivation area in Brazil would be possible without the destruction of irreplaceable habitats.

Bioethanol production in Brazil is increasing by around 5 million m annually3 (25 million barrels of petroleum equivalent). However, global oil demand will rise by 776 million barrels (2.5% annually) over the same period. In view of this fact, bioethanol will not be able to make a relevant contribution in the near future. Production would have to be massively expanded worldwide. An incentive for this can only be promotional measures or very high oil prices.


The more modern perspective sees the production of a high quality feed with ethanol as a by-product. Regardless of which production goal the operators focus on, biological and technical progress favors the profitability of all products, because more efficient mash preparation leads to more efficient fermentation but also to reduced water consumption, lower drying costs and fewer fiber components in the end product. More efficient fermentation also enables higher levels of more valuable protein. Advances in distillation and alcohol separation mean higher alcohol yields, and advances in drying facility design mean lower cost production of feed. An efficiently running system also produces feed of the same quality as the compound feed industry is looking for. When 8 to 9% ethanol from fermentation was standard, the 14% discussion was utopian. Good plants in North America already run 17 to 18%, even 19% ethanol, and Prof. Ingledew from the University of Saskatchewan in Canada is discussing ethanol yields above 20% as the future standard in fermentation. An increase in the efficiency of the entire system is also important for the public's assessment of ethanol as an ecologically balanced source of energy. Previous ecological reports based on outdated data tended to favor the use of biogas or wood.

The fermentation of cereals essentially means a reduction in anti-nutritional effects, an increase in the digestibility of minerals (phosphorus), a partial breakdown of the fiber fractions and a significant increase in the protein content with improved rumen stability. Since the fermentation process essentially leads to a concentration of the ingredients, this process also harbors risks that can only be managed through careful purchasing and plant management. Because the concentrations of some undesirable substances such as heavy metals and mycotoxins also increase in the end product.

Historically, this has always been the great advantage in the purity of the alcoholic products from distillation processes, because undesirable components remained in the stillage. Fusarium toxins are not broken down by the mash preparations and the fermentation process and are present in the end product in up to twice the concentration relative to the raw material. This phenomenon also means that toxins such as fusaric acid that have hitherto occurred in the background can reach a critical level. For the fermentation process itself, the toxin concentration is of minor importance, since the sensitivity of the yeast cultures used affects far higher concentrations than is discussed in animal nutrition.

The purchase of raw materials from future distilleries that want to produce feed must therefore enforce very high quality requirements, similar to those of the brewing industry, in agriculture and use these arguments when selling feed. In addition to the purity, the price is not determined by the protein content and falling number, but by starch and moisture, as slight fluctuations in the starch and moisture content of the raw materials correlate directly with the alcohol yield. The hope that biofuel systems would offer an ideal medium for marketing third-class goods or that they could even be used to dispose of non-marketable grain is quickly dashed. New or simply different quality criteria determine the market and this is precisely where the great opportunity for domestic goods over imports lies.

Europe is now looking to fuel alcohol in terms of compliance with the Kyoto Protocol and potential new markets for agriculture. After the introduction of biodiesel with the promotion of the cultivation of renewable raw materials, this approach is not new for agriculture, but it soon became clear that diesel is not interesting for all energy markets and the public is keeping an eye on the energy balance of the overall concept. The question of whether, after including the expenses for cultivation, refining, further processing and disposal, more energy is generated net than was expended and whether the process leads to a net reduction in CO2- Eliminations are always up for discussion. There is also the unresolved question of whether the public would like to accept genetically modified plants to achieve higher yields in this context.

See also

  • Bioethanol as a fuel - status and prospects
  • Information collection of the German bioethanol association LAB e.V.
  • With coal and biofuel into the greenhouse - Telepolis article
  • List of European bioethanol plants
  • Conversion of mono-jet petrol vehicles to E85
  • The "biofuel lie": regrowing madness
  • 20 years of experience in the production of bioethanol


  1. http://www.greenfleet.info
  2. Germany: Biofuel Quota Act BioKraftQuG of December 18, 2006
  3. http://www.ethanol-tanken.com/index.php?dat=2&show=5&list=1&cat=1
  4. http://www.ethanolproducer.com/plant-list.jsp List of US bioethanol plants
  5. ab Biofuels barometer 2007 - EurObserv’ER Systèmes solaires Le journal des énergies renouvelables n ° 179, p. 63-75, 5/2007
  6. see Official Journal link
  7. Country reports under [1]
  8. http://www.bgblportal.de/BGBL/bgbl1f/bgbl106s3180.pdf
  9. Jeanne Rubner: Climate killer from the field Sueddeutsche Zeitung, September 26, 2007
  10. Marlies Uken: Sobering carbon footprint Die Zeit, September 26, 2007
  11. Ruth Weinkopf: [2] Mannheim Morning, November 21, 2007
  12. Julia Langensiepen: [3] taz.de, September 27, 2007
  13. spiegel.de: Fuel for the world: "Cars, not people, consume most of the grain that was additionally processed in 2006 compared to the previous year. (...)"
  14. Luiz Fernando Furlan: Ethanol and Renewable Fuels: The Brazilian Experience
  15. [4]

Categories: Flammable Substance | Petroleum product