Alcohols have been used as a fuel. The first four aliphatic alcohols (methanol, ethanol, propanol, and butanol) are of interest as fuels because they can be synthesized chemically or biologically, and they have characteristics which allow them to be used in internal combustion engines. The general chemical formula for alcohol fuel is CnH2n+1OH.
Most methanol is produced from natural gas, although it can be produced from biomass using very similar chemical processes. Ethanol is commonly produced from biological material through fermentation processes. Biobutanol has the advantage in combustion engines in that its energy density is closer to gasoline than the simpler alcohols (while still retaining over 25% higher octane rating); however, biobutanol is currently more difficult to produce than ethanol or methanol. When obtained from biological materials and/or biological processes, they are known as bioalcohols (e.g. “bioethanol”). There is no chemical difference between biologically produced and chemically produced alcohols.
One advantage shared by the four major alcohol fuels is their high octane rating. This tends to increase their fuel efficiency and largely offsets the lower energy density of vehicular alcohol fuels (as compared to petrol/gasoline and diesel fuels), thus resulting in comparable “fuel economy” in terms of distance per volume metrics, such as kilometers per liter, or miles per gallon.
Methanol and ethanol
Methanol and ethanol can both be derived from fossil fuels, biomass, or perhaps most simply, from carbon dioxide and water. Ethanol has most commonly been produced through fermentation of sugars, and methanol has most commonly been produced from synthesis gas, but there are more modern ways to obtain these fuels. Enzymes can be used instead of fermentation. Methanol is the simpler molecule, and ethanol can be made from methanol. Methanol can be produced industrially from nearly any biomass, including animal waste, or from carbon dioxide and water or steam by first converting the biomass to synthesis gas in a gasifier. It can also be produced in a laboratory using electrolysis or enzymes.
As a fuel, methanol and ethanol both have advantages and disadvantages over fuels such as petrol (gasoline) and diesel fuel. In spark ignition engines, both alcohols can run at a much higher exhaust gas recirculation rates and with higher compression ratios. Both alcohols have a high octane rating, with ethanol at 109 RON (Research Octane Number), 90 MON (Motor Octane Number), (which equates to 99.5 AKI) and methanol at 109 RON, 89 MON (which equates to 99 AKI). Note that AKI refers to ‘Anti-Knock Index’ which averages the RON and MON ratings (RON+MON)/2, and is used on U.S. gas station pumps. Ordinary European petrol is typically 95 RON, 85 MON, equal to 90 AKI. As a compression ignition engine fuel, both alcohols create very little particulates, but their low cetane number means that an ignition improver like glycol must be mixed into the fuel with approx. 5%.
When used in spark ignition engines alcohols have the potential to reduce NOx, CO, HC and particulates. A test with E85 fueled Chevrolet Luminas showed that NMHC went down by 20-22%, NOx by 25-32% and CO by 12-24% compared to reformulated gasoline. Toxic emissions of benzene and 1,3 Butadiene also decreased while aldehyde emissions increased (acetaldehyde in particular).
Tailpipe emissions of CO2 also decrease due to the lower carbon-to-hydrogen ratio of these alcohols, and the improved engine efficiency.
Methanol and ethanol fuels contain soluble and insoluble contaminants. Halide ions, which are soluble contaminants, such as chloride ions, have a large effect on the corrosivity of alcohol fuels. Halide ions increase corrosion in two ways: they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electrical, galvanic and ordinary corrosion in the fuel system. Soluble contaminants such as aluminum hydroxide, itself a product of corrosion by halide ions, clogs the fuel system over time.
To prevent corrosion the fuel system must be made of suitable materials, electrical wires must be properly insulated and the fuel level sensor must be of pulse and hold type, magneto resistive or other similar non-contact type. In addition, high quality alcohol should have a low concentration of contaminants and have a suitable corrosion inhibitor added. Scientific evidence reveals that also water is an inhibitor for corrosion by ethanol.
The experiments are done with E50, which is more aggressive & speeds up the corrosion effect. It is very clear that by increasing the amount of water in fuel ethanol one can reduce the corrosion. At 2% or 20,000 ppm water in the fuel ethanol the corrosion stopped. The observations in Japan are in line with the fact that hydrous ethanol is known for being less corrosive than anhydrous ethanol. The reaction mechanism is 3 EtOH + Al -> Al(OEt)3 + 3⁄2 H2 will be the same at lower-mid blends. When enough water is present in the fuel, the aluminum will react preferably with water to produce Al2O3, repairing the protective aluminum oxide layer. The aluminum alkoxide does not make a tight oxide layer; water is essential to repair the holes in the oxide layer.
Methanol and ethanol are also incompatible with some polymers. The alcohol reacts with the polymers causing swelling, and over time the oxygen breaks down the carbon-carbon bonds in the polymer causing a reduction in tensile strength. For the past few decades though, most cars have been designed to tolerate up to 10% ethanol (E10) without problem. This includes both fuel system compatibility and lambda compensation[clarification needed] of fuel delivery with fuel injection engines featuring closed loop lambda control. In some engines ethanol may degrade some compositions of plastic or rubber fuel delivery components designed for conventional petrol, and also be unable to lambda compensate the fuel properly.
“FlexFuel” vehicles have upgraded fuel system and engine components which are designed for long life using E85 or M85, and the ECU can adapt to any fuel blend between gasoline and E85 or M85. Typical upgrades include modifications to: fuel tanks, fuel tank electrical wiring, fuel pumps, fuel filters, fuel lines, filler tubes, fuel level sensors, fuel injectors, seals, fuel rails, fuel pressure regulators, valve seats and inlet valves. “Total Flex” Autos destined for the Brazilian market can use E100 (100% Ethanol).
One liter of ethanol contain 21.1 MJ, a liter of methanol 15.8 MJ and a liter of gasoline approximately 32.6 MJ. In other words, for the same energy content as one liter or one gallon of gasoline, one needs 1.6 liters/gallons of ethanol and 2.1 liters/gallons of methanol. The raw energy-per-volume numbers produce misleading fuel consumption numbers however, because alcohol-fueled engines can be made substantially more energy-efficient. A larger percentage of the energy available in a liter of alcohol fuel can be converted to useful work. This difference in efficiency can partially or totally balance out the energy density difference, depending on the particular engines being compared.
Methanol fuel has been proposed as a future biofuel, often as an alternative to the hydrogen economy. Methanol has a long history as a racing fuel. Early Grand Prix Racing used blended mixtures as well as pure methanol. The use of the fuel was primarily used in North America after the war.[clarification needed] However, methanol for racing purposes has largely been based on methanol produced from syngas derived from natural gas and therefore this methanol would not be considered a biofuel. Methanol is a possible biofuel, however when the syngas is derived from biomass.
In theory, methanol can also be produced from carbon dioxide and hydrogen using nuclear power or any renewable energy source, although this is not likely to be economically viable on an industrial scale (see methanol economy).Compared to bioethanol, the primary advantage of methanol biofuel is its much greater well-to-wheel efficiency. This is particularly relevant in temperate climates where fertilizers are needed to grow sugar or starch crops to make ethanol, whereas methanol can be produced from lignocellulose (woody) biomass.
Ethanol is already being used extensively as a fuel additive, and the use of ethanol fuel alone or as part of a mix with gasoline is increasing. Compared to methanol its primary advantage is that it is less corrosive and additionally the fuel is non-toxic, although the fuel will produce some toxic exhaust emissions. Since 2007, the Indy Racing League has used ethanol as its exclusive fuel, after 40 years of using methanol. Since September 2007 petrol stations in NSW, Australia are mandated to supply all their petrol with 2% Ethanol content
Butanol and propanol
Propanol and butanol are considerably less toxic and less volatile than methanol. In particular, butanol has a high flash point of 35 °C, which is a benefit for fire safety, but may be a difficulty for starting engines in cold weather. The concept of flash point is however not directly applicable to engines as the compression of the air in the cylinder means that the temperature is several hundred degrees Celsius before ignition takes place.
The fermentation processes to produce propanol and butanol from cellulose are fairly tricky to execute, and the Weizmann organism (Clostridium acetobutylicum) currently used to perform these conversions produces an extremely unpleasant smell, and this must be taken into consideration when designing and locating a fermentation plant. This organism also dies when the butanol content of whatever it is fermenting rises to 7%. For comparison, yeast dies when the ethanol content of its feedstock hits 14%. Specialized strains can tolerate even greater ethanol concentrations – so-called turbo yeast can withstand up to 16% ethanol. However, if ordinary Saccharomyces yeast can be modified to improve its ethanol resistance, scientists may yet one day produce a strain of the Weizmann organism with a butanol resistance higher than the natural boundary of 7%. This would be useful because butanol has a higher energy density than ethanol, and because waste fibre left over from sugar crops used to make ethanol could be made into butanol, raising the alcohol yield of fuel crops without there being a need for more crops to be planted.
Despite these drawbacks, DuPont and BP have recently announced that they are jointly to build a small scale butanol fuel demonstration plant alongside the large bioethanol plant they are jointly developing with Associated British Foods.
The company Energy Environment International developed a method for producing butanol from biomass, which involves the use of two separate micro-organisms in sequence to minimize production of acetone and ethanol byproducts.
The Swiss company Butalco GmbH uses a special technology to modify yeasts in order to produce butanol instead of ethanol. Yeasts as production organisms for butanol have decisive advantages compared to bacteria.
Butanol combustion is: C4H9OH + 6O2 → 4CO2 + 5H2O + heat
Propanol combustion is: 2C3H7OH + 9O2 → 6 CO2 + 8H2O + heat
The 3-carbon alcohol, propanol (C3H7OH), is not often used as a direct fuel source for petrol engines(unlike ethanol, methanol and butanol), with most being directed into use as a solvent. However, it is used as a source of hydrogen in some types of fuel cell; it can generate a higher voltage than methanol, which is the fuel of choice for most alcohol-based fuel cells. However, since propanol is harder to produce than methanol (biologically OR from oil), methanol-utilising fuel cells are preferred over those that utilise propanol.
Fuel alcohol supply
Fuel alcohol is produced from various crops such as sugar cane, sugar beet, corn, barley, potato, and the like. There is ethanol from Brazilian sugar cane as an important bio-alcohol plan. Alcohols can also be obtained synthetically from ethane or acetylene, calcium carbide, coal, petroleum gas or other resources.
Once said, “Farm alcohol production by agriculture requires a considerable amount of land that can be cultivated with rich soil and water, and therefore it is said that it is not as effective as an option in areas with high population density and industrialization like Western Europe” It was. Even if all of Germany is covered with sugar cane big plantation, it can supply only about half of the current energy demand of Germany (including fuel and electricity). Also, in agricultural lands with enough rainfall to produce cereals / luxury goods crops that can be sold at relatively high prices (as an exception for palm oil with extremely high yields per area) It is not always appropriate to cultivate energy crops Can not say
Since it is becoming possible to economically produce ethanol from cellulose by the RITE-HONDA method, it is said that the range of ethanol production materials such as seaweed, cornstalk, switchgrass, thinned timber and the like widely spread.
Widespread desert / semi-desert is unused as a wasteland from the viewpoint of the whole earth, and water cost is important instead of being able to use expansive land at low cost in such places. It is said that it is becoming possible to increase energy ethanol production by cultivating plants which are resistant to drying such as switchgrass and cactus in arid lands
In addition, algae have oil yields per hectare of arable land of several tens of tons, and it is expected that only paddy fields in the Kanto plain can cover the demand for transportation oil for Japan, and algae that does not require agricultural land Ethanol production is also being considered.
Considering them, even if there is an increase in demand for large fuel in future, if there is adequate irrigation etc. agricultural investment, running after the battery of the plug-in hybrid car runs out, running over the non-electrified section of the overhead wire type hybrid, power peak in daytime It is thought that it is possible to supply enough fuel to cover the cogeneration fuel
Iron gas co-production · · Methanol production by effective use of iron-making exhaust gas
Latent methanol producible amount by effective utilization of steel exhaust gas
Ironmaking is the reduction of iron ore, which is iron oxide. The steel industry consumes 100 million tons of coal every year in Japan and reduces iron ore by making a large amount of carbon monoxide every year, but if you synthesize methanol from its carbon monoxide as raw material, Ten thousand meters of methanol will be obtained as iron-made byproducts and should be of great help in saving oil imports.
Chemically, if a mixed gas (synthesis gas) of hydrogen, carbon monoxide and carbon dioxide is made by blowing steam into the carbon monoxide exhaust gas after the reduction of iron ore and by a water gas shift reaction, it is determined by methanol synthesis and the Fischer-Tropsch method It becomes a raw material for automobile fuel synthesis. (See C1 chemistry)
In the “2007 Energy Saving Technology Strategy”, the Agency for Natural Resources and Energy stated that “Cooperation among industries, coproduction, various fuels manufacturing from syngas, etc., covers production processes of chemistry, steelmaking, etc. and energy conversion processes such as power generation It is a system aiming at reducing the total amount of fossil fuel consumption to the limit by drastically reducing the amount of CO2 emissions by constructing a new complex system that simultaneously performs both material production and energy production “It is positioned.
In addition, in the technology strategy map of the steel industry, it became possible to list “up-gas co-production technology” for upstream / environment-friendly technology and global environmental conservation.
Causes why fuel synthesis is not being carried out by the current blast furnace method and reasons for the construction stagnation of a new smelting reduction reactor
However, because the current blast furnace method is air blowing, the exhaust gas contains a large amount of nitrogen besides carbon monoxide, so it can not be used as a synthesis gas for synthesis of fuel, and only a wasteful use of fuel in steel works I can not do it. However, sintering furnaces and coke ovens are unnecessary in the case of melt reduction iron making method such as DIOS, high production efficiency, inexpensive general coal and fine ore can be used and oxygen is used to gasify coal so that the exhaust gas contains nitrogen Because there is no byproduct of synthesis fuel raw material gas, there is also the possibility of opening up the way to effective utilization of iron-making exhaust gas for synthesis of fuel and self-sufficiency production of synthetic fuel of tens of millions of tons. However, in the current single-plant methanol production, the natural gas reforming method is more advantageous in cost than the coal gasification method in many cases, and how much cost can be reduced by the use of iron-making exhaust gas is CNG, imported methanol It is said to be a branch point of cost competition with
Although the smelting reduction ironmaking method has many advantages, in 1995 when it was developed, steelmakers in Japan, Europe and the United States have built a blast furnace, a fine iron ore sintering furnace, and a coke oven sufficiently satisfying demand there were. In China and India, where demand is growing, the steels to be supplied by local companies are cheaper than the cold-rolled steel sheets and higher-grade steel products, and the steel companies that they supply are cheaper. Capital investment by Japanese steel companies is concentrated downstream, including galvanizing facilities, It was no longer an environment to invest capital investment in pig iron making process. However, in recent years, such as buying raw material coal mines of resource measures, raising the price of coking coal more than twice as much in a single year, starting the operation of smelting reduction furnace in Korea POSCO, cooking oven has reached the end of its useful life of 40 years in 2015, The environmental conditions of construction of the smelting reduction reactor are being aligned.
Sugarcane grows in the southern part of the United States (it is not a cold climate like an area where maize is the main crop). On the other hand, many areas where maize is currently grown are also suitable areas for cultivating sugar beets. Several studies have shown that ethanol production in the United States is a considerably more efficient way of using these sugar beets than using maize.
In Brazil in the 1980 ‘s, staple food crops, a method to produce ethanol from cassava that can take a large amount of starch from the root was seriously examined. However, the ethanol yield was lower than that of sugar cane, and the treatment of cassava to convert from starch to fermentable sugar was complicated. And the possibility of plant residues as ethanol source was investigated.
Attention has focused on using biomass as an ethanol source or other type of fuel source. This is a widespread idea, as well as industrial waste and livestock sewage, use a variety of organic materials including cultivated crops and wood.
At the moment, the process of converting biomass to ethanol or other fuels is nothing more complicated and less efficient. Thermal depolymerization (produced by process products such as light heavy oil) may be a topic.
See also Biomass ethanol
Net fuel energy balance
In order to continue to exist, the alcohol-based fuel economy should have a net surplus in fuel energy balance. That is, all the fuel energy spent to produce alcohol, including not only fuels spent on cultivating, harvesting, transporting, fermenting, distilling, and delivering raw material plants, as well as building farms and farming equipment Although the fuel spent to produce the fuel is included, for the total it should not exceed the amount of energy that the produced fuel contains. For example, saying “to consume 2 gallons of fuel before making and using one gallon of fuel” means that there is no point.
Switching the system with fuel energy balance in the deficit state will end simply with increasing non-alcohol fuel consumption. Such a system would not have a value more than a detour for utilizing non-alcoholic fuels that are not suitable for transport, such as coal, natural gas or crop residue biofuels (indeed, many US The proposal assumes the use of natural gas for distillation). And the environmental contribution of alcohol fuel and the superiority of sustainability can not be realized if the fuel balance of the system is in the red.
If the surplus width of energy balance is small, the problem still arises. If the net fuel energy balance is 50%, in order to stop using non-alcohol fuel, 2 gallon alcohol production is required to deliver 1 gallon alcohol to consumers.
Geopolitics is a deciding factor for this problem. The persistence of ethanol produced from sugarcane in the tropical provinces with abundant water and land resources such as Brazil has no doubt. Indeed, by burning sugar cane residue (bagasse) it produces more energy than operating an ethanol plant, and many of the plants now sell surplus electricity to the public. Also, since it is a country with abundant hydropower stations, there is room for improvement in the energy balance circulation by improving the use of electricity for production, for example by improving powder grinding and distillation.
In a region other than the tropics, it becomes a completely different composition. The climate there is too cold for sugarcane. In the United States, agricultural alcohol is generally obtained from cereals, mainly maize. And the net fuel budget is the state that the road is still steep.
The future of alcohol fuel
Alcohol and hydrogen
Current demand for fossil fuels is thought to shift to hydrogen as fuel and is forming a situation that is also called hydrogen economy. According to a theory, hydrogen itself should not be regarded as a fuel resource. According to this theory, hydrogen is a temporary energy storage medium that exists between energy sources and places where energy is used (such as photovoltaic, biomass, or fossil fuels). In fact, when hydrogen is in a gaseous state, it occupies a huge volume compared to other fuels, which is a very difficult problem in terms of energy delivery. One solution is to deliver hydrogen using ethanol. It is a method of releasing it from the carbon bonding the hydrogen by hydrogen reform at the delivery destination and supplying it to the fuel cell. Another method is to supply ethanol directly as fuel for fuel cells.
In early 2004, researchers at the University of Minnesota announced that they developed a simple structured ethanol fuel cell. That is, ethanol permeates the catalyst layer and supplies necessary hydrogen to the fuel cell. The apparatus uses a rhodium-cerium catalyst for the first step reaction, at which the reaction temperature reaches approximately 700 ° C. In the first step, a mixture of ethanol and water vapor is reacted with oxygen to generate a sufficient amount of hydrogen. Unfortunately, carbon monoxide is generated as a by-product, which clogs the fuel cell. So it passes through another catalyst and converts it to carbon dioxide. Ultimately, this simple device produces a gas consisting of approximately 50% hydrogen and 30% nitrogen. The remaining 20% is carbon dioxide as the main component. Mixed gas of inert nitrogen and hydrogen together with carbon dioxide is pumped to the appropriate fuel cell. After that, carbon dioxide is released into the atmosphere and is reabsorbed by the plant.
One of the advantages of converting to an alcohol fuel economy would probably be a reduction in total emissions of carbon dioxide, which is a greenhouse gas, perhaps most important. Even if CO2 is released by the production and consumption of ethanol, the plant will absorb it. In contrast, the combustion of fossil fuels releases a huge amount of “new” CO 2 into the atmosphere without a saucer like an alcohol fuel.
Needless to say, this advantage occurs only for ethanol produced in agriculture, not in the case of ethanol converted from petroleum. And because it is only a small but the cost is low, it is alcohol derived from natural gas that accounts for most of the industrially consumed alcohol. This point should be included in the evaluation when aggregating the costs for converting to agricultural production ethanol.
Effective use of petroleum / coal / renewable energy
The advantage of one of the alcohol of agricultural production can be said to be a renewable energy source never exhausted. Along with the soaring price of crude oil,
High-cost oil fields with poor mining conditions are profitable and supply increases.
Oil shale, mining of oil sands begins.
Application of natural gas spreads to automobile fuels such as alcohol and compressed natural gas.
The sharing ratio of railway / water shipping in transportation is increased, the share ratio of container train, piggyback transport, dual mode vehicle, container ship, RO – RO ship increases.
Coal liquefaction, which synthesizes methanol and jet fuel from coal, will take profit even if it is not using oxygen-made iron exhaust gas.
Coal is said to have hundreds of years, but after the coal residue has become low it depends on methane hydrate and brewed ethanol.
It is thought that the alternative energy for oil gradually spreads gradually from now on.
However, due to the popularization of automobiles in China and India with a population of more than 1 billion, the explosive increase in oil consumption is two or three times, and for soft landing 2) Advance early development of alternative energy of 3) 5) Otherwise it is likely to cause a surge in crude oil prices
Among the petroleum applications, power generation is nuclear power, industrial fuel is coal, heating kerosene is natural gas, automobile fuel can be substituted with alcohol or compressed natural gas, but ship fuel heavy oil / aviation fuel jet oil is liquefied It is expensive to make, and if synthetic resin is made from coal raw material it becomes very expensive. In other words, precious petroleum should be saved for petrochemical, marine diesel fuel, aviation jet fuel, and it should be used for applications such as power generation that can be replaced by nuclear power and automobile fuel that can be substituted with alcohol It can be said that it is a wasteful resource. However, if alcohol use to automobile fuel in China and India is delayed, valuable petroleum to be used for chemical industry will be burned out for automobile fuel and power generation. In that sense oil “noble youth” is a problem, alcohol for automobile fuel is expected.
Source from Wikipedia