Biomass

Biomass is living and recently dead biological material that can be used as fuel or for production of fibers, chemicals, plastics, building materials, and heat.   These products are mostly biodegradable, so they do not pollute the biosphere.   However, bioplastics will not remain in service as long as petroplastics.   Sources of biomass energy are crop residues, energy plantations, and municipal, animal, and industrial wastes.   Biomass is grown from several plants, including miscanthus, switchgrass, hemp, corn, poplar, willow and sugarcane.   The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material.   Production of biomass is a growing industry as interest in sustainable fuel sources is growing.   Biomass is part of the carbon cycle.   Carbon from the atmosphere is converted into biological matter by photosynthesis.   On decay or combustion the carbon goes back into the atmosphere or soil.   This happens over a relatively short time and plant matter used as a fuel can be constantly replaced by planting for new growth.   Therefore a reasonably stable level of atmospheric carbon results from its use as a fuel.   It is commonly accepted that the amount of carbon stored in biomass is approximately 50% of the biomass by weight.   Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been 'out' of the carbon cycle for a very long time.   Their combustion therefore disturbs the carbon dioxide content in the atmosphere. ^{Wiki n.p.}

Biofuel is fuel derived from biomass.   Solid biomass fuels such as wood or dried waste have been used since man learned to control fire.   Liquid biofuels for industrial applications have been used since the early days of the car industry.   Nikolaus August Otto, the German inventor of the internal combustion engine, expected his invention to run on ethanol.   Rudolf Diesel, the German inventor of the Diesel engine, expected it to run on peanut oil.   Other inventors used turpentine distilled from pine resin.   However, crude oil proved to provide the most energy per unit volume and price. ^{Wiki n.p.}

Conventional ("First Generation") biofuels in engines.

Vegetable oil

Vegetable oil used as a fuel is produced using the same methods as vegetable oil used for consumption, but its quality oil may be a lot lower for fuel use.   The oils come from plants ("straight" or SVO) or from businesses ("waste" or WVO).   Vegetable oil can be used in many older diesel engines equipped with indirect injection systems, but only in the warmest climates when its viscosity is low to allow for proper atomization of fuel; otherwise incomplete combustion and carbon build up will ultimately damage the engine.   Usually vegetable oil is turned into biodiesel instead. ^{Wiki n.p.}

The first known use of vegetable oil as fuel for a diesel engine was a demonstration of an engine built by the Otto company and designed to burn mineral oil.   The engine was run on pure peanut oil at the 1900 World's Fair.   When Rudolf Diesel invented the diesel engine, he designed it to run on peanut oil after coal dust was determined to be unsuitable as a fuel, but it was soon discovered that it would operate on cheaper petroleum oil.   Periodic petroleum shortages spurred research into vegetable oil as a diesel substitute during the 30s and 40s, and again in the 70s and early 80s when straight vegetable oil enjoyed its highest level of scientific interest.   The 1970s also saw the formation of the first commercial enterprise to allow consumers to run straight vegetable oil in their automobiles, Elsbett of Germany.   Coconut oil has also been usede as fuel.   Academic research into straight vegetable oil fell off sharply in the 80s with falling petroleum prices and greater interest in biodiesel as an option that did not require extensive vehicle modifications. ^{Wiki n.p.}

Biodiesel

Biodiesel, an alkyl ester, is the most common biofuel in Europe.   It is produced from any oil or fat using transesterification by which triglycerides (fats & oils) are reacted with methyl or ethyl alcohol, to get methyl or ethyl esters (biodiesel), which has combustion characteristics similar to mineral diesel (petrodiesel).   It can be used in any diesel engine and can be mixed with mineral diesel in any percentage, although 20% biodiesel with 80% petrodiesel (B20) is common.   In some countries, manufacturers cover many of their diesel engines under warranty for 100% biodiesel use.   Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel (B100).   In many European countries, 5% biodiesel blend (B5) is widely used and is available at thousands of gas stations.   In the U.S., more than 80% of all commercial trucks and city buses run on diesel gas, using from 25 million gallons per year in 2004 to 78 million gallons by the beginning of 2005 of biodiesel instead of petroleum diesel.   Because biodiesel becomes more viscous at colder temperatures, B20 and higher may cause clogged engine filters and parts, many car manufacturers warn against using them. ^{Wiki n.p.}

Ethanol

Ethanol (ethyl alcohol), C₂H₆O, is the most common biofuel worldwide.   It is produced from wheat, corn and sugar cane and many other biomass stocks.   The production methods used are fermentation of the sugars, distillation and drying.   Ethanol can be used in the petrol engine as a replacement to gasoline.   it can be mixed with gasoline to any percentage.   However, until the recent introduction of new engines, cars would need to have their engines modified in order to run with 100% alcohol. ^{Wiki n.p.}   As is the case of all alcohol fuels, they are partially oxidized, so they need to be run at much richer mixtures than hydrocarbon fuels.

Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene from petroleum and other sources.   Current interest in ethanol mainly lies in bio-ethanol, produced from the starch or sugar in a wide variety of crops, but there has been considerable debate about how useful bio-ethanol will be in replacing fossil fuels in vehicles.   Concerns relate to the large amount of arable land required for crops.   Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants.   Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be produced in many regions of the United States. ^{Wiki n.p.}

The basic steps for large scale production of ethanol are: microbial (yeast) fermentation of sugars, distillation, dehydration (required unless distillation is done repeatedly), and denaturing (optional).   Prior to fermentation, some crops require saccharification or hydrolysis into carbohydrates.   Saccharification of cellulose is called cellulolysis.   Other pre-production steps can be necessary for certain crops like corn that requires refinement into starch and liquification. ^{Wiki n.p.}

Cellulosic ethanol or cellanol is a general term for ethanol fuel produced from lignocellulose, a structural material that comprises much of the mass of plants.   It is composed mainly of cellulose, hemicellulose and lignin.   Cellulosic ethanol is chemically identical to ethanol from other sources, such as corn starch or sugar, but has the advantage that the lignocellulose raw material is available in a great diversity of biomass including waste from urban, agricultural, and forestry sources.   It differs in that it requires a greater amount of processing to make the sugar monomers available to the microorganisms that are typically used to produce ethanol by fermentation. ^{Wiki n.p.}

The largest single use of ethanol is as a motor fuel and fuel additive.   The largest national fuel ethanol industries exist in Brazil (gasoline sold in Brazil contains at least 20% ethanol and hydrous ethanol is also used as fuel).   In order for ethanol to be suitable for use as a replacement to petrol in its pure form, it must be distilled to at least 70-80% purity by volume before use.   For use as an additive to gasoline, almost all water must be removed; otherwise, it will separate from the mixture and settle to the bottom of the fuel tank, causing the fuel pump to draw water into the engine, which will cause the engine to stall.   Flex fuel engines are able to work with all ethanol, all gasoline or any mixture of both, giving the buyer a choice for a perfect balance between price and performance.   That is made possible by efficient sugar cane production.   Sugar cane not only has a greater concentration of sucrose (about 30% more than corn), but is also much easier to extract.   The bagasse generated by the process is not wasted, for it is utilized in power plants becoming a surprisingly efficient source of electricity.   One method of production is through fermentation of sugar.   Ethanol creates very little pollution when burned.   Millions more acres of land are needed if ethanol is to be used to replace gasoline.   Pure ethanol has a lower energy content than gasoline (about 30% less energy per unit volume).   Where available at gas stations, ethanol is contained in a mix of ethanol and gasoline, known as gasohol.   Blends of up to 10% per cent are normally regarded as the safe maximum for a vehicle designed to operate on petroleum.   However, ethanol blends can run at up to 85% or higher in specially designed flexible fueled vehicles.   The volume of consumption will increase with increasing ethanol consumption.   Growth in fuel ethanol in the United States is largely being driven by financial incentives that naturally exist when oil prices are over a certain level, as ethanol typically costs under $1.50 per gallon to manufacture and is exempt from the federal gasoline tax. ^{Wiki n.p.}

The energy returned on energy invested (EROEI) for ethanol made from corn in the U.S. is 1.34 (it yields 34 percent more energy than it takes to produce it).   Input energy includes natural gas based fertilizers, farm equipment, transformation from corn or other materials, and transportation.   Oil has historically had a much higher EROEI, especially on land in areas with pressure support, but also under the sea, which only offshore drilling rigs can reach.   Apart from this, the amount of ethanol needed to run the United States, for example, is greater than its own farmland could produce, even if fields used for food were converted into cornfields.   It is for these reasons that ethanol alone is generally not seen as a solution to replacing conventional oil. ^{Wiki n.p.}

Butanol

Butanol (butyl alcohol), C₄H₁₀O, is claimed as a direct replacement for gasoline.   It is not in widespread production at this time, and engine manufacturers have not made statements about its use.   Theretically, it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists.   Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product.   Butanol will produce more energy than ethanol, allegedly can be burned "straight" in existing gasoline engines without modification to the engine, is less corrosive and less water soluble than ethanol, and can be distributed via existing infrastructures. ^{Wiki n.p.}   As is the case of all alcohol fuels, they are partially oxidized, so they need to be run at much richer mixtures than hydrocarbon fuels.

Because its long hydrocarbon chains cause it to be fairly nonpolar, butanol is more similar to gasoline than ethanol.   Butanol has been demonstrated to work in some vehicles designed for use with gasoline without any modification.   It can be produced from biomass (biobutanol) as well as fossil fuels (petrobutanol).   Some call this biofuel biobutanol to reflect its origin, although it has the same chemical properties as butanol produced from petroleum.   Butanol can be produced by fermentation of biomass by the A.B.E. process.   The difference from ethanol production is primarily in the fermentation of the feedstock — producing butanol rather than ethanol like primary fermentation product and minor changes in distillation.   The feedstocks are the same as for ethanol — sugar beets, sugar cane, corn grain, wheat and cassava as well as agricultural byproducts such as straw and corn stalks. ^{Wiki n.p.}

Methanol

Methanol (methyl alcohol, wood alcohol), CH₄O, which is now produced from natural gas, can also be produced from biomass, although this is not economically viable at present. ^{Wiki n.p.}   Its application is limited due to its toxicity.   Small amounts are used in some gasolines to increase the octane rating.   Methanol-based fuels are used in some race cars and model airplanes. ^{Wiki n.p.}   As is the case of all alcohol fuels, they are partially oxidized, so they need to be run at much richer mixtures than hydrocarbon fuels.

Biogas

Biogas (swamp gas, marsh gas, landfill gas, digester gas) is produced by the process of anaerobic digestion of organic material by anaerobes.   It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields.   The solid byproduct, digestate, can also be used as a biofuel.   Biogas contains methane and can be recovered in industrial anaerobic digesters and mechanical biological treatment systems.   Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion.   If it escapes into the atmosphere it is a potent greenhouse gas. ^{Wiki n.p.}

Advanced ("Second generation") biofuels in engines.

Bio-DME

Bio-DME (dimethyl ether) is the same as DME, but is produced from a bio-sources.   Bio-DME can be produced from biomethanol using catalytic dehydration or it can be produced from syngas using DME synthesis. DME can be used in IC engines. ^{Wiki n.p.}

Biomethanol

Biomethanol is the same as methanol but it is produced from biomass.   Biomethanol can be blended with gasoline up to 10-20% without any harmful effects to the IC engine. ^{Wiki n.p.}

Bio-DMF

Bio-DMF (2,5-Dimethylfuran) is the same as DMF, but made from fructose and glucose. ^{Wiki n.p.}

HTU diesel HTU (HydroThermalUpgrading) diesel is produced from wet biomass, e.g., sewage sludge.   It can be mixed with fossil (petro) diesel in any percentage without harmful effects to the IC engine. ^{Wiki n.p.}

Fischer-Tropsch diesel

Fischer-Tropsch (FT) diesel is produced from coal and natural gas. First, syngas, a mixture of carbon monoxide and hydrogen, is produced, and then higher-order hydrocarbons.   FT diesel can be mixed with fossil diesel at any percentage without any harmful effects on the IC engine. ^{Wiki n.p.}   The process also can be used to produce many other hydrocarbons. ^{Wiki n.p.}

Mixed Alcohols Mixed alcohols, i.e., mixture of mostly ethanol, propanol and butanol, with some pentanol, hexanol, heptanol and octanol, are produced from synthetic gas (syngas), a mixture of carbon monoxide and hydrogen, with catalysts similar to those used for methanol.   Most R&D in this area is concentrated in producing mostly ethanol.   However, some fuels are marketed as mixed alcohols.   Mixed alcohols are superior to pure methanol or ethanol in that the higher alcohols have higher energy content.   Also, when blending, the higher alcohols increase compatibility of gasoline and ethanol, which increases water tolerance and decreases evaporative emissions.   In addition, higher alcohols have also lower heat of vaporization than ethanol, which is important for cold starts. ^{Wiki n.p.}

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