Second generation biofuels
Encyclopedia
Second generation biofuels - also known as advanced biofuels - can be manufactured from various types of biomass
.
Biomass is a wide-ranging term meaning any source of organic carbon that is renewed rapidly as part of the carbon cycle. Biomass is derived from plant materials but can also include animal materials.
First generation biofuels are made from the sugars and vegetable oils found in arable crops, which can be easily extracted using conventional technology. In comparison, second generation biofuels are made from lignocellulosic or woody crops, agricultural residues or waste, which makes it harder to extract the required fuel.
s such as oil, and some of them produce only limited greenhouse gas
emissions savings. When taking emissions from production and transport into account, life cycle assessment
from first generation biofuels frequently approach those of traditional fossil fuels.
Second generation biofuels can help solve these problems and can supply a larger proportion of our fuel supply sustainably, affordably, and with greater environmental benefits.
First generation bioethanol is produced by fermenting
plant-derived sugars to ethanol
, using a similar process to that used in beer
and wine-making (see Ethanol fermentation). This requires the use of 'food' crops such as sugar cane, corn
, wheat
, and sugar beet
. These crops are required for food, so if too much biofuel is made from them, food prices could rise and shortages might be experienced in some countries. Corn, wheat and sugar beet also require high agricultural inputs in the form of fertilizers, which limit the greenhouse gas
reductions that can be achieved. Biodiesel
produced by transesterification
from rapeseed oil, palm oil
or other plant oils is also considered a first generation biofuel.
The goal of second generation biofuel processes is to extend the amount of biofuel that can be produced sustainably by using biomass consisting of the residual non-food parts of current crops, such as stem
s, leaves
and husk
s that are left behind once the food crop has been extracted, as well as other crops that are not used for food purposes (non food crops), such as switchgrass
, grass
, jatropha
, whole crop maize
, miscanthus
and cereals that bear little grain, and also industry waste such as woodchips
, skin
s and pulp
from fruit pressing, etc.
The problem that second generation biofuel processes are addressing is to extract useful feedstocks from this woody or fibrous biomass, where the useful sugars are locked in by lignin, hemicellulose and cellulose. All plants contain lignin
, hemicellulose
and cellulose
. These are complex carbohydrates (molecules based on sugar). Lignocellulosic ethanol is made by freeing the sugar molecules from cellulose using enzymes, steam heating, or other pre-treatments. These sugars can then be fermented to produce ethanol in the same way as first generation bioethanol production. The by-product of this process is lignin. Lignin can be burned as a carbon neutral
fuel to produce heat and power for the processing plant and possibly for surrounding homes and businesses.
These thermochemical processes both yield a combustible gas and a solid char. The gas can be fermented or chemically synthesised into a range of fuels, including ethanol, synthetic diesel or jet fuel.
. Output is normally syngas
for further synthesis to e.g. Fischer-Tropsch products, biomethanol, BioDME or biomethane (synthetic natural gas). Syngas can also be used in heat production and for generation of mechanical and electrical power via gas motors or gas turbine
s.
of organic material at elevated temperatures in the absence of oxygen
. In second generation biofuels applications forest and agricultural residues, wood waste and energy crops can be used as feedstock to produce e.g. bio-oil for fuel oil applications.
Feedstocks are energy crops, agricultural and forest residues, food industry and municipal biowaste and other biomass containing sugar
s. Products include alcohol
s (such as ethanol
and butanol
) and other hydrocarbons for transportation use.
A process producing liquid fuels from gas (normally syngas) is called a Gas-to-Liquid (GtL) process. When biomass is the source of the gas production the process is also referred to as Biomass-To-Liquids (BTL).
is a Gas-to-Liquid (GtL) process. When biomass is the source of the gas production the process is also referred to as Biomass-To-Liquids (BTL).
A disadvantage of this process is the high energy investment for the FT synthesis and consequently, the process is not yet economic.
, hemicellulose
and cellulose
; second generation technology uses one, two or all of these components. Common lignocellulosic energy crops include wheat
straw, Miscanthus
, short rotation coppice poplar
and willow
. However, each offers different opportunities and no one crop can be considered 'best' or 'worst'.
or park
waste may be used to produce biofuel
via different routes. Examples include Biogas
captured from biodegradable green waste
, and gasification
or hydrolysis
to syngas
for further processing to biofuel
s via catalytic processes.
that contains concentrated lignin
and hemicellulose
, may be gasified
with very high conversion efficiency
and greenhouse gas
reduction potential to produce syngas
for further synthesis
to e.g. biomethanol or BioDME.
Lignocellulosic biofuels can reduce greenhouse gas emissions by around 90% when compared with fossil petroleum, in contrast first generation biofuels offer savings of only 20-70%
The Swedish
specialty cellulose
mill Domsjö Fabriker
in Örnsköldsvik
, Sweden
develops a biorefinery
using Chemrec's
black liquor
gasification
technology. When commissioned in 2015 the biorefinery will produce 140,000 tons of biomethanol or 100,000 tons of BioDME per year, replacing 2% of Sweden's imports of diesel fuel for transportation purposes.
In the UK comapnies like INEOS
Bio and British Airways
are developing advanced biofuel refineries, which are due to be built by 2013 and 2014 respectively. Under favourable economic conditions and strong improvements in policy support, NNFCC projections suggest advanced biofuels could meet up to 4.3 per cent of the UK's transport fuel by 2020 and save 3.2 million tonnes of CO2 each year, equivalent to taking nearly a million cars off the road.
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
.
Biomass is a wide-ranging term meaning any source of organic carbon that is renewed rapidly as part of the carbon cycle. Biomass is derived from plant materials but can also include animal materials.
First generation biofuels are made from the sugars and vegetable oils found in arable crops, which can be easily extracted using conventional technology. In comparison, second generation biofuels are made from lignocellulosic or woody crops, agricultural residues or waste, which makes it harder to extract the required fuel.
Introduction
Second generation biofuel technologies have been developed because first generation biofuels manufacture has important limitations. First generation biofuel processes are useful, but limited in most cases: there is a threshold above which they cannot produce enough biofuel without threatening food supplies and biodiversity. Many first generation biofuels are dependent of subsidies and are not cost competitive with existing fossil fuelFossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s such as oil, and some of them produce only limited greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions savings. When taking emissions from production and transport into account, life cycle assessment
Life cycle assessment
A life-cycle assessment is a technique to assess environmental impacts associated with all the stages of a product's life from-cradle-to-grave A life-cycle assessment (LCA, also known as life-cycle analysis, ecobalance, and cradle-to-grave analysis) is a technique to assess environmental impacts...
from first generation biofuels frequently approach those of traditional fossil fuels.
Second generation biofuels can help solve these problems and can supply a larger proportion of our fuel supply sustainably, affordably, and with greater environmental benefits.
First generation bioethanol is produced by fermenting
Ethanol fermentation
Ethanol fermentation, also referred to as alcoholic fermentation, is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products...
plant-derived sugars to ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, using a similar process to that used in beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
and wine-making (see Ethanol fermentation). This requires the use of 'food' crops such as sugar cane, corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, and sugar beet
Sugar beet
Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B...
. These crops are required for food, so if too much biofuel is made from them, food prices could rise and shortages might be experienced in some countries. Corn, wheat and sugar beet also require high agricultural inputs in the form of fertilizers, which limit the greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
reductions that can be achieved. Biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
produced by transesterification
Transesterification
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R′ of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst...
from rapeseed oil, palm oil
Palm oil
Palm oil, coconut oil and palm kernel oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the fruit of the oil palm Elaeis guineensis; palm kernel oil is derived from the kernel of the oil palm and coconut oil is derived from the kernel of the...
or other plant oils is also considered a first generation biofuel.
The goal of second generation biofuel processes is to extend the amount of biofuel that can be produced sustainably by using biomass consisting of the residual non-food parts of current crops, such as stem
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
s, leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
and husk
Husk
Husk in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit or vegetable...
s that are left behind once the food crop has been extracted, as well as other crops that are not used for food purposes (non food crops), such as switchgrass
Switchgrass
Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico...
, grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
, jatropha
Jatropha
Jatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female...
, whole crop maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, miscanthus
Miscanthus
Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one species Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one...
and cereals that bear little grain, and also industry waste such as woodchips
Woodchips
Woodchips are a medium-sized solid material made by cutting, or chipping, larger pieces of wood. Woodchips may be used as a biomass solid fuel. They may also be used as an organic mulch in gardening, landscaping, restoration ecology and mushroom cultivation...
, skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
s and pulp
Juice vesicles
The juice vesicles of a citrus fruit are the membranous content of the fruit’s endocarp. The vesicles contain the juice of the fruit. The pulp is usually removed from the juice by filtering it out...
from fruit pressing, etc.
The problem that second generation biofuel processes are addressing is to extract useful feedstocks from this woody or fibrous biomass, where the useful sugars are locked in by lignin, hemicellulose and cellulose. All plants contain lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
, hemicellulose
Hemicellulose
A hemicellulose is any of several heteropolymers , such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
and cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
. These are complex carbohydrates (molecules based on sugar). Lignocellulosic ethanol is made by freeing the sugar molecules from cellulose using enzymes, steam heating, or other pre-treatments. These sugars can then be fermented to produce ethanol in the same way as first generation bioethanol production. The by-product of this process is lignin. Lignin can be burned as a carbon neutral
Carbon neutral
Carbon neutrality, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount sequestered or offset, or buying enough carbon credits to make up the difference...
fuel to produce heat and power for the processing plant and possibly for surrounding homes and businesses.
Second generation technology
The following subsections describe the main second generation routes currently under development.Thermochemical routes
Carbon-based materials can be heated at high temperatures in the absence (pyrolysis) or presence of oxygen, air and/or steam (gasification).These thermochemical processes both yield a combustible gas and a solid char. The gas can be fermented or chemically synthesised into a range of fuels, including ethanol, synthetic diesel or jet fuel.
Gasification
Gasification technologies are well established for conventional feedstocks such as coal and crude oil. Second generation gasification technologies include gasification of forest and agricultural residues, waste wood, energy crops and black liquorBlack liquor
Black liquor is the spent cooking liquor from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers....
. Output is normally syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
for further synthesis to e.g. Fischer-Tropsch products, biomethanol, BioDME or biomethane (synthetic natural gas). Syngas can also be used in heat production and for generation of mechanical and electrical power via gas motors or gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....
s.
Pyrolysis
Pyrolysis is a well established technique for decompositionDecomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
of organic material at elevated temperatures in the absence of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. In second generation biofuels applications forest and agricultural residues, wood waste and energy crops can be used as feedstock to produce e.g. bio-oil for fuel oil applications.
Torrefaction
Torrefaction is a form of pyrolysis at temperatures typically ranging between 200-320°C. Feedstocks and output are the same as for pyrolysis.Biochemical routes
Chemical and biological processes that are currently used in other applications are being adapted for second generation biofuels. Biochemical processes typically employ pre-treatment to accelerate the hydrolysis process, which separates out the lignin, hemicellulose and cellulose. Once these ingredients are separated, the cellulose fractions can be fermented into alcohols.Feedstocks are energy crops, agricultural and forest residues, food industry and municipal biowaste and other biomass containing sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s. Products include alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s (such as ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
and butanol
Butanol
Butanol or butyl alcohol can refer to any of the four isomeric alcohols of formula C4H9OH:*n-Butanol, butan-1-ol, 1-butanol, n-butyl alcohol;*Isobutanol, 2-methylpropan-1-ol, isobutyl alcohol;...
) and other hydrocarbons for transportation use.
Types of biofuel
The following second generation biofuels are under development, although it must be noted that most or all of these biofuels are synthesized from intermediary products such as syngas using methods that are identical in processes involving conventional feedstocks, first generation and second generation biofuels. The distinguishing feature is the technology involved in producing the intermediary product, rather than the ultimate off-take.A process producing liquid fuels from gas (normally syngas) is called a Gas-to-Liquid (GtL) process. When biomass is the source of the gas production the process is also referred to as Biomass-To-Liquids (BTL).
From syngas using catalysis
- Biomethanol can be used in methanol motors or blended with petrol up to 10-20% without any infrastructure changes.
- BioDME can be produced from Biomethanol using catalytic dehydration or it can be produced directly from syngas using direct DME synthesis. DME can be used in the compression ignition engine.
- BiohydrogenBiohydrogenBiohydrogen is defined as hydrogen produced biologically, most commonly by algae and bacteria. Biohydrogen is a potential biofuel obtainable from both cultivation and waste organic materials.-Introduction:...
can be used in fuel cells to produce electricity. - Mixed Alcohols (i.e., mixture of mostly ethanol, propanol and butanol, with some pentanol, hexanol, heptanol and octanol). Mixed alcohols are produced from syngasSyngasSyngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
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 (see EcaleneEcaleneEcalene is the trade mark name given to a mixture of alcohols, which may be used as fuel or as a fuel additive. The typical composition of Ecalene is as follows: Composition of Ecalene...
and E4 Envirolene) 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. (For another method for producing mixed alcohols from biomass see bioconversion of biomass to mixed alcohol fuels) - BiomethaneMethaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
(or Bio-SNG) via the Sabatier reactionSabatier reactionThe Sabatier reaction or Sabatier process involves the reaction of hydrogen with carbon dioxide at elevated temperatures and pressures in the presence of a nickel catalyst to produce methane and water. Optionally ruthenium on alumina makes a more efficient catalyst...
From syngas using Fischer-Tropsch
The Fischer-Tropsch (FT) processFischer-Tropsch process
The Fischer–Tropsch process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas to liquids technology, produces a petroleum substitute, typically from coal, natural gas, or biomass for use as synthetic...
is a Gas-to-Liquid (GtL) process. When biomass is the source of the gas production the process is also referred to as Biomass-To-Liquids (BTL).
A disadvantage of this process is the high energy investment for the FT synthesis and consequently, the process is not yet economic.
- FT diesel can be mixed with fossil diesel at any percentage without need for infrastructure change and moreover, synthetic keroseneKeroseneKerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
can be produced
Biocatalysis
- BiohydrogenBiohydrogenBiohydrogen is defined as hydrogen produced biologically, most commonly by algae and bacteria. Biohydrogen is a potential biofuel obtainable from both cultivation and waste organic materials.-Introduction:...
might be accomplished with some organisms that produce hydrogen directly under certain conditions. Biohydrogen can be used in fuel cells to produce electricity. - ButanolButanol fuelButanol may be used as a fuel in an internal combustion engine. Because its longer hydrocarbon chain causes it to be fairly non-polar, it is more similar to gasoline than it is to ethanol...
and IsobutanolIsobutanolIsobutanol is an organic compound with the formula 2CHCH2OH. This colorless, flammable liquid with a characteristic smell is mainly used as a solvent. Its isomers include n-butanol, 2-butanol, and tert-butanol, all of which are more important industrially.-Production:Isobutanol is produced by the...
via recombinant pathways expressed in hosts such as E. coli and yeastYeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
, butanol and isobutanol may be significant products of fermentationFermentationFermentation may refer to:* Fermentation , the use of fermentation in food preparation* Fermentation , a metabolic process whereby electrons released from nutrients are ultimately transferred to molecules obtained from the breakdown of those same nutrients* Fermentation , the process of...
using glucoseGlucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
as a carbonCarbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and energy source. - DMF2,5-Dimethylfuran2,5-Dimethylfuran is a heterocyclic compound with the formula 2C4H2O. Although often abbreviated DMF, it should not be confused with dimethylformamide. A derivative of furan, this simple compound is a potential biofuel, being derivable from cellulose.-Production:Fructose can be converted into...
(2,5-Dimethylfuran). Recent advances in producing DMF from fructoseFructoseFructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
and glucoseGlucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
using catalyticCatalysisCatalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....
biomass-to-liquid process have increased its attractiveness.
Other processes
- HTU (Hydro Thermal Upgrading) diesel is produced from wet biomass. It can be mixed with fossil diesel in any percentage without need for infrastructure.
- Wood dieselWood dieselWood diesel A new biofuel which was developed by the University of Georgia from woodchips. The oil is extracted and then added to unmodified diesel engines. Either new plants are used or planted to replace the old plants. The charcoal byproduct is put back into the soil as a fertilizer...
. A new biofuel was developed by the University of GeorgiaUniversity of GeorgiaThe University of Georgia is a public research university located in Athens, Georgia, United States. Founded in 1785, it is the oldest and largest of the state's institutions of higher learning and is one of multiple schools to claim the title of the oldest public university in the United States...
from woodchipsWoodchipsWoodchips are a medium-sized solid material made by cutting, or chipping, larger pieces of wood. Woodchips may be used as a biomass solid fuel. They may also be used as an organic mulch in gardening, landscaping, restoration ecology and mushroom cultivation...
. The oil is extracted and then added to unmodified diesel engines. Either new plants are used or planted to replace the old plants. The charcoal byproduct is put back into the soil as a fertilizer. According to the director Tom Adams since carbon is put back into the soil, this biofuel can actually be carbon negative not just carbon neutral. Carbon negative decreases carbon dioxide in the air reversing the greenhouse effect not just reducing it.
Feedstocks
Second generation biofuel feedstocks include cereal and sugar crops, specifically grown energy crops, agricultural and municipal wastes, cultivated and waste oils, and algae.Energy crops
Plants are made from ligninLignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
, hemicellulose
Hemicellulose
A hemicellulose is any of several heteropolymers , such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
and cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
; second generation technology uses one, two or all of these components. Common lignocellulosic energy crops include wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
straw, Miscanthus
Miscanthus
Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one species Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and southern Asia, with one...
, short rotation coppice poplar
Poplar
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar , aspen, and cottonwood....
and willow
Willow
Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...
. However, each offers different opportunities and no one crop can be considered 'best' or 'worst'.
Municipal solid waste
Municipal Solid Waste comprises a very large range of materials, and total waste arisings are increasing. In the UK, recycling initiatives decrease the proportion of waste going straight for disposal, and the level of recycling is increasing each year. However, there remains significant opportunities to convert this waste to fuel via gasification or pyrolysis.Green waste
Green waste such as forest residues or gardenGarden
A garden is a planned space, usually outdoors, set aside for the display, cultivation, and enjoyment of plants and other forms of nature. The garden can incorporate both natural and man-made materials. The most common form today is known as a residential garden, but the term garden has...
or park
Park
A park is a protected area, in its natural or semi-natural state, or planted, and set aside for human recreation and enjoyment, or for the protection of wildlife or natural habitats. It may consist of rocks, soil, water, flora and fauna and grass areas. Many parks are legally protected by...
waste may be used to produce biofuel
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
via different routes. Examples include Biogas
Biogas
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung, and kitchen waste can be converted into a gaseous fuel called biogas...
captured from biodegradable green waste
Biodegradable waste
Biodegradable waste is a type of waste, typically originating from plant or animal sources, which may be degraded by other living organisms. Waste that cannot be broken down by other living organisms are called non-biodegradable....
, and gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...
or hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
to syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
for further processing to biofuel
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
s via catalytic processes.
Black liquor
Black liquor, the spent cooking liquor from the kraft processKraft process
The kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
that contains concentrated lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
and hemicellulose
Hemicellulose
A hemicellulose is any of several heteropolymers , such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
, may be gasified
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...
with very high conversion efficiency
Energy conversion efficiency
Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.-Overview:...
and greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
reduction potential to produce syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
for further synthesis
Chemical synthesis
In chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...
to e.g. biomethanol or BioDME.
Greenhouse gas emissions
Producing second generation biofuels offers greater greenhouse gas emissions savings than those obtained by first generation biofuels.Lignocellulosic biofuels can reduce greenhouse gas emissions by around 90% when compared with fossil petroleum, in contrast first generation biofuels offer savings of only 20-70%
Commercial development
An operating lignocellulosic ethanol production plant is located in Canada, run by IOGEN Corporation. The demonstration-scale plant produces around 700,000 litres of bioethanol each year. A commercial plant is under construction. Many further lignocellulosic ethanol plants have been proposed in North America and around the world.The Swedish
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
specialty cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
mill Domsjö Fabriker
Domsjö Fabriker
Domsjö Fabriker is a Swedish refinery located in Örnsköldsvik, specializing in refining forest raw materials into specialty cellulose, lignin and bio-ethanol. In 2000 it was spun off from the forest company Mo och Domsjö AB , of which it had been a part since the early 20th century, and sold to a...
in Örnsköldsvik
Örnsköldsvik
Örnsköldsvik is a locality and the seat of Örnsköldsvik Municipality in Västernorrland County, Sweden with 28,617 inhabitants in 2005.Its natural harbour and archipelago is in the Gulf of Bothnia and the northern boundaries of the High Coast area. It is well known as an exporter of paper products...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
develops a biorefinery
Biorefinery
A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, heat, and value-added chemicals from biomass...
using Chemrec's
Chemrec
Chemrec is a Stockholm, Sweden corporation that develops technology for entrained flow gasification of black liquor and certain types brown liquor for production of biofuels from the resulting syngas....
black liquor
Black liquor
Black liquor is the spent cooking liquor from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers....
gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...
technology. When commissioned in 2015 the biorefinery will produce 140,000 tons of biomethanol or 100,000 tons of BioDME per year, replacing 2% of Sweden's imports of diesel fuel for transportation purposes.
In the UK comapnies like INEOS
Ineos
INEOS Group Limited is a privately owned multinational chemicals company headquartered in Lausanne, Switzerland and with its registered office in Lyndhurst, United Kingdom...
Bio and British Airways
British Airways
British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...
are developing advanced biofuel refineries, which are due to be built by 2013 and 2014 respectively. Under favourable economic conditions and strong improvements in policy support, NNFCC projections suggest advanced biofuels could meet up to 4.3 per cent of the UK's transport fuel by 2020 and save 3.2 million tonnes of CO2 each year, equivalent to taking nearly a million cars off the road.
See also
- Algae fuelAlgae fuelAlgae fuel might be an alternative to fossil fuel and uses algae as its source of natural deposits. Several companies and government agencies are funding efforts to reduce capital and operating costs and make algae fuel production commercially viable...
- Cellulosic ethanol commercializationCellulosic ethanol commercializationCellulosic ethanol commercialization is the process of building an industry out of methods of turning cellulose-containing organic matter into fuel...
- Food vs fuelFood vs fuelFood vs. fuel is the dilemma regarding the risk of diverting farmland or crops for biofuels production in detriment of the food supply on a global scale. The "food vs. fuel" or "food or fuel" debate is international in scope, with good and valid arguments on all sides of this issue...
- JatrophaJatrophaJatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female...