Second-generation biofuels, also known as advanced biofuels, are fuels that can be manufactured from various types of non-food
biomass. Biomass in this context means plant materials and animal waste used especially as a source of fuel.
First-generation
biofuels are made from sugar-starch feedstocks (e.g.,
sugarcane and
corn) and edible oil feedstocks (e.g.,
rapeseed
Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains a ...
and
soybean
The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.
Traditional unfermented food uses of soybeans include soy milk, from which tofu a ...
oil), which are generally converted into
bioethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hyd ...
and
biodiesel
Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat ( tallow), soybean oil, or some other vegetable oil ...
, respectively.
Second-generation biofuels are made from different feedstocks and therefore may require different technology to extract useful energy from them. Second generation feedstocks include
lignocellulosic biomass
Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels. It is composed of two kinds of carbohydrate polymers, cellulose a ...
or woody crops, agricultural residues or waste, as well as dedicated non-food energy crops grown on marginal land unsuitable for food production.
The term second-generation biofuels is used loosely to describe both the 'advanced' technology used to process feedstocks into biofuel, but also the use of non-food crops, biomass and wastes as feedstocks in 'standard' biofuels processing technologies if suitable. This causes some considerable confusion. Therefore it is important to distinguish between second-generation feedstocks and second-generation biofuel processing technologies.
The development of second-generation biofuels has seen a stimulus since the
food vs. fuel dilemma regarding the risk of diverting farmland or crops for
biofuels production to the detriment of
food supply
Food security speaks to the availability of food in a country (or geography) and the ability of individuals within that country (geography) to access, afford, and source adequate foodstuffs. According to the United Nations' Committee on World Fo ...
. The biofuel and
food price
Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices have an impact on producers and consumers of food.
Price levels depend on the food production process, including food marketing and ...
debate involves wide-ranging views, and is a long-standing, controversial one in the literature.
Introduction
Second-generation biofuel technologies have been developed to enable the use of non-food biofuel feedstocks because of concerns to food security caused by the use of food crops for the production of
first-generation biofuels. The diversion of edible food biomass to the production of biofuels could theoretically result in competition with food and land uses for food crops.
First-generation
bioethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hyd ...
is produced by
fermenting
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
plant-derived sugars to
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
, using a similar process to that used in
beer
Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
and wine-making (see
Ethanol fermentation
Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this ...
). This requires the use of food and fodder crops, such as
sugar cane
Sugarcane or sugar cane is a species of (often hybrid) tall, perennial grass (in the genus '' Saccharum'', tribe Andropogoneae) that is used for sugar production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fibrous stalk ...
,
corn,
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
, and
sugar beet. The concern is that if these food crops are used for biofuel production that food prices could rise and shortages might be experienced in some countries. Corn, wheat, and sugar beet can also require high
agricultural inputs in the form of
fertilizers
A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
, which limit the
greenhouse gas reductions that can be achieved.
Biodiesel
Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat ( tallow), soybean oil, or some other vegetable oil ...
produced by
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. The reaction ca ...
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
Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livin ...
by using biomass consisting of the residual
non-food parts of current crops, such as
stems,
leaves and
husks 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 crop
A nonfood crop, also known as industrial crop, is a crop grown to produce goods for manufacturing, for example fibre for clothing, rather than food for consumption.
Purpose
Industrial crops is a designation given to an enterprise that attempts ...
s), such as
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. Switchgrass is one of the ...
,
grass
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
,
jatropha
''Jatropha'' is a genus of flowering plants in the spurge family, Euphorbiaceae. The name is derived from the Greek words ἰατρός (''iatros''), meaning "physician", and τροφή (''trophe''), meaning "nutrition", hence the common name ...
, whole crop
maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
,
miscanthus
''Miscanthus'', or silvergrass, is a genus of African, Eurasian, and Pacific Island plants in the grass family, Poaceae.
; Species
* '' Miscanthus changii'' Y.N.Lee – Korea
* '' Miscanthus depauperatus'' Merr. – the Philippines
* '' Miscant ...
and cereals that bear little grain, and also industry waste such as
woodchips,
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different de ...
s and
pulp
Pulp may refer to:
* Pulp (fruit), the inner flesh of fruit
Engineering
* Dissolving pulp, highly purified cellulose used in fibre and film manufacture
* Pulp (paper), the fibrous material used to make paper
* Molded pulp, a packaging material
...
from fruit pressing, etc.
The problem that second-generation biofuel processes are addressing is to extract useful feedstocks from this woody or fibrous biomass, which is predominantly composed of
plant cell walls. In all
vascular plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
the useful sugars of the cell wall are bound within the complex carbohydrates (
polymers
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic an ...
of sugar molecules) hemicellulose and cellulose, but made inaccessible for direct use by the phenolic polymer
lignin.
Lignocellulosic ethanol is made by extracting sugar molecules from the carbohydrates 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
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hyd ...
production. The by-product of this process is lignin. Lignin can be burned as a
carbon neutral
Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the "p ...
fuel to produce heat and power for the processing plant and possibly for surrounding homes and businesses. Thermochemical processes (liquefaction) in hydrothermal media can produce liquid oily products from a wide range of feedstock that has a potential to replace or augment fuels. However, these liquid products fall short of diesel or biodiesel standards. Upgrading liquefaction products through one or many physical or chemical processes may improve properties for use as fuel.
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 yield a mixture of gases including hydrogen, carbon monoxide, carbon dioxide, methane and other hydrocarbons, and water. Pyrolysis also produces a solid char. The gas can be fermented or chemically synthesised into a range of fuels, including ethanol, synthetic diesel, synthetic gasoline or jet fuel.
[ National Non-Food Crops Centre]
"NNFCC Newsletter – Issue 19. Advanced Biofuels"
Retrieved on 2011-06-27
There are also lower temperature processes in the region of 150–374 °C, that produce sugars by decomposing the biomass in water with or without additives.
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 liquor. Output is normally
syngas for further synthesis to e.g.
Fischer–Tropsch products including diesel fuel,
biomethanol,
BioDME (
dimethyl ether
Dimethyl ether (DME; also known as methoxymethane) is the organic compound with the formula CH3OCH3,
(sometimes ambiguously simplified to C2H6O as it is an isomer of ethanol). The simplest ether, it is a colorless gas that is a useful precursor ...
),
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...
via catalytic conversion of dimethyl ether, or
biomethane
Renewable natural gas (RNG), also known as sustainable natural gas (SNG) or biomethane, is a biogas which has been upgraded to a quality similar to fossil natural gas and having a methane concentration of 90% or greater. By increasing the concentr ...
(
synthetic natural gas
Substitute natural gas (SNG), or synthetic natural gas, is a fuel gas (predominantly methane, CH4) that can be produced from fossil fuels such as lignite coal, oil shale, or from biofuels (when it is named bio-SNG) or using electricity with power- ...
). Syngas can also be used in heat production and for generation of mechanical and electrical power via gas motors or
gas turbine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...
s.
Pyrolysis
Pyrolysis is a well established technique for
decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
of
organic material
Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
at elevated temperatures in the absence of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
. 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
Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about with subsequent cool ...
for fuel oil applications. Bio-oil typically requires significant additional treatment to render it suitable as a refinery feedstock to replace crude oil.
Torrefaction
Torrefaction is a form of pyrolysis at temperatures typically ranging between 200–320 °C. Feedstocks and output are the same as for
pyrolysis
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
.
Hydrothermal liquefaction
Hydrothermal liquefaction is a process similar to pyrolysis that can process wet materials. The process is typically at moderate temperatures up to 400 °C and higher than atmospheric pressures. The capability to handle a wide range of materials make hydrothermal liquefaction viable for producing fuel and chemical production feedstock.
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
sugars. Products include
alcohols (such as
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
and
butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a bu ...
) and other
hydrocarbons
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or e ...
for transportation use.
Types of biofuel
The following second-generation biofuels are under development, although 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-liquid
Biomass to liquid (BtL or BMtL) is a multi-step process of producing synthetic hydrocarbon fuels made from biomass via a thermochemical route.
Main processes
According to a study done by the U.S. Department of Agriculture and the Department of E ...
s (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.
* Bio-derived
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...
can be produced from DME via high-pressure catalytic
condensation reaction
In organic chemistry, a condensation reaction is a type of chemical reaction in which two molecules are combined to form a single molecule, usually with the loss of a small molecule such as water. If water is lost, the reaction is also known as a ...
. Bio-derived gasoline is chemically indistinguishable from petroleum-derived gasoline and thus can be blended into the gasoline pool.
*
Biohydrogen
Biohydrogen is H2 that is produced biologically. Interest is high in this technology because H2 is a clean fuel and can be readily produced from certain kinds of biomass.
Many challenges characterize this technology, including those intrinsic to ...
can be used in
fuel cells to produce electricity.
* Mixed Alcohols (i.e., mixture of mostly
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
,
propanol
There are two isomers of propanol.
*1-Propanol, ''n''-propanol, or propan-1-ol : CH3CH2CH2OH, the most common meaning
*2-Propanol, Isopropyl alcohol
Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a c ...
, and
butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a bu ...
, with some
pentanol,
hexanol
Hexanol may refer to any of the following isomeric organic compounds with the formula C6H13OH:
:
See also
* Cyclohexanol
* Amyl alcohol
An amyl alcohol is any of eight alcohols with the formula C5H12O. A mixture of amyl alcohols (also called a ...
,
heptanol, and
octanol
Octanols are alcohols with the formula C8H17OH. A simple and important member is 1-octanol, with an unbranched chain of carbons. Other commercially important octanols are 2-octanol and 2-ethylhexanol.
There are 89 possible isomers
In che ...
). Mixed alcohols are produced from
syngas with several classes of catalysts. Some have employed catalysts similar to those used for methanol. Molybdenum sulfide catalysts were discovered at Dow Chemical
[Quarderer, George J., Rex R. Stevens, Gene A. Cochran, and Craig B. Murchison. "Preparation of ethanol and higher alcohols from lower carbon number alcohols." U.S. Patent 4,825,013, issued April 25, 1989.] and have received considerable attention. Addition of cobalt sulfide to the catalyst formulation was shown to enhance performance.
Molybdenum sulfide catalysts have been well studied but have yet to find widespread use. These catalysts have been a focus of efforts at the U.S. Department of Energy's Biomass Program in the Thermochemical Platform. Noble metal catalysts have also been shown to produce mixed alcohols. Most R&D in this area is concentrated in producing mostly ethanol. However, some fuels are marketed as mixed alcohols (see
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
The bioconversion of biomass to mixed alcohol fuels can be accomplished using the MixAlco process. Through bioconversion of biomass to a mixed alcohol fuel, more energy from the biomass will end up as liquid fuels than in converting biomass to etha ...
)
*
Biomethane
Renewable natural gas (RNG), also known as sustainable natural gas (SNG) or biomethane, is a biogas which has been upgraded to a quality similar to fossil natural gas and having a methane concentration of 90% or greater. By increasing the concentr ...
(or
Bio-SNG) via the
Sabatier reaction
The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures (perhaps 3 MPa ) in the presence of a nickel catalyst. It w ...
From syngas using Fischer–Tropsch
The
Fischer–Tropsch (FT) process 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
kerosene
Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
can be produced
Biocatalysis
*
Biohydrogen
Biohydrogen is H2 that is produced biologically. Interest is high in this technology because H2 is a clean fuel and can be readily produced from certain kinds of biomass.
Many challenges characterize this technology, including those intrinsic to ...
might be accomplished with some organisms that produce hydrogen directly under certain conditions. Biohydrogen can be used in
fuel cells to produce electricity.
*
Butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4 H9 O H, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a bu ...
and
Isobutanol
Isobutanol (IUPAC nomenclature: 2-methylpropan-1-ol) is an organic compound with the formula (CH3)2CHCH2OH (sometimes represented as ''i''-BuOH). This colorless, flammable liquid with a characteristic smell is mainly used as a solvent either dire ...
via recombinant pathways expressed in hosts such as
E. coli and
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
, butanol and isobutanol may be significant products of
fermentation using
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
as a
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
and energy source.
*
DMF (2,5-Dimethylfuran). Recent advances in producing DMF from
fructose and
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
using
catalytic
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
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 diesel
Wood diesel is a new biofuel developed by the University of Georgia from woodchips. In the process, oil is extracted and then added to unmodified diesel engines. In the process, either new plants are grown to be used in the process, or a new crop ...
. A new biofuel was developed by the
University of Georgia
, mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things."
, establ ...
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. 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.
Second Generation Feedstocks
To qualify as a second generation feedstock, a source must not be suitable for human consumption. Second-generation biofuel feedstocks include specifically grown inedible energy crops, cultivated inedible oils, agricultural and municipal wastes, waste oils, and algae.
[ National Non-Food Crops Centre]
"Pathways to UK Biofuels: A Guide to Existing and Future Options for Transport, NNFCC 10-035"
Retrieved on 2011-06-27 Nevertheless, cereal and sugar crops are also used as feedstocks to second-generation processing technologies. Land use, existing biomass industries and relevant conversion technologies must be considered when evaluating suitability of developing biomass as feedstock for energy.
Energy crops
Plants are made from
lignin,
hemicellulose
A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls.Scheller HV, Ulvskov Hemicelluloses.// Annu Rev ...
and
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell w ...
; second-generation technology uses one, two or all of these components. Common lignocellulosic energy crops include
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
straw, ''
Arundo donax
''Arundo donax'' is a tall perennial cane. It is one of several so-called reed species. It has several common names including giant cane, elephant grass, carrizo, arundo, Spanish cane, Colorado river reed, wild cane, and giant reed. ''Arundo'' a ...
'', ''
Miscanthus
''Miscanthus'', or silvergrass, is a genus of African, Eurasian, and Pacific Island plants in the grass family, Poaceae.
; Species
* '' Miscanthus changii'' Y.N.Lee – Korea
* '' Miscanthus depauperatus'' Merr. – the Philippines
* '' Miscant ...
'' spp., short rotation coppice
poplar and
willow
Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...
. However, each offers different opportunities and no one crop can be considered 'best' or 'worst'.
[ National Non-Food Crops Centre]
"Advanced Biofuels: The Potential for a UK Industry, NNFCC 11-011"
, Retrieved on 2011-11-17
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.
[ National Non-Food Crops Centre]
"Evaluation of Opportunities for Converting Indigenous UK Wastes to Fuels and Energy (Report), NNFCC 09-012"
, Retrieved on 2011-06-27
Green waste
Green waste such as forest residues or
garden
A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...
or
park waste may be used to produce
biofuel via different routes. Examples include
Biogas
Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste and food waste. It is a ...
captured from
biodegradable green waste, and
gasification or
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolys ...
to
syngas for further processing to
biofuels via
catalytic
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
processes.
Black liquor
Black liquor, the spent cooking liquor from the
kraft process that contains concentrated
lignin and
hemicellulose
A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls.Scheller HV, Ulvskov Hemicelluloses.// Annu Rev ...
, 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.
The yield of crude tall oil from process is in the range of 30 – 50 kg / ton pulp.
Greenhouse gas emissions
Lignocellulosic biofuels reduces
greenhouse gas emissions
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...
by 60–90% when compared with fossil petroleum (Börjesson.P. et al. 2013. Dagens och framtidens hållbara biodrivmedel), which is on par with the better of current biofuels of the first-generation, where typical best values currently is 60–80%. In 2010, average savings of biofuels used within EU was 60% (Hamelinck.C. et al. 2013 Renewable energy progress and biofuels sustainability, Report for the European Commission). In 2013, 70% of the biofuels used in Sweden reduced emissions with 66% or higher. (Energimyndigheten 2014. Hållbara biodrivmedel och flytande biobränslen 2013).
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
Swedish or ' may refer to:
Anything from or related to Sweden, a country in Northern Europe. Or, specifically:
* Swedish language, a North Germanic language spoken primarily in Sweden and Finland
** Swedish alphabet, the official alphabet used by ...
specialty
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell w ...
mill
Domsjö Fabriker
Domsjö Fabriker is a Swedish biorefinery located in Örnsköldsvik that converts raw forest materials into specialty cellulose, lignin, and bio-ethanol. In 2000 it was spun off from the forest company Mo och Domsjö AB (MoDo), of which it had ...
in
Örnsköldsvik
Örnsköldsvik (, ) is a locality and the seat of Örnsköldsvik Municipality in Västernorrland County, Sweden, with 32,953 inhabitants in 2017.
Its natural harbour and archipelago is in the Gulf of Bothnia and the northern boundaries of the Hig ...
,
Sweden develops a
biorefinery
A biorefinery is a refinery that converts biomass to energy and other beneficial byproducts (such as chemicals). The International Energy Agency Bioenergy Task 42 defined biorefining as "the sustainable processing of biomass into a spectrum of bio ...
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 May 2012 it was revealed that Domsjö pulled out of the project, effectively killing the effort.
In the UK, companies like
INEOS
INEOS Group Limited is a British multinational chemicals company headquartered and registered in London. , it is the fourth largest chemical company in the world.
Ineos is organised into about 20 standalone business units, each with its own b ...
Bio and
British Airways
British Airways (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London, England, near its main hub at Heathrow Airport.
The airline is the second largest UK-based carrier, based on fleet size and passengers ...
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
NNFCC is a consultancy company specialising in bioenergy, biofuels and bio-based products.
History
Established by the UK Government in 2003 as the National Non-Food Crops Centre (NNFCC) to help extend the competitive non-food uses of crops, ...
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 each year, equivalent to taking nearly a million cars off the road.
Helsinki, Finland, 1 February 2012 – UPM is to invest in a biorefinery producing biofuels from crude tall oil in Lappeenranta, Finland. The industrial scale investment is the first of its kind globally. The biorefinery will produce annually approximately 100,000 tonnes of advanced second-generation biodiesel for transport. Construction of the biorefinery will begin in the summer of 2012 at UPM’s Kaukas mill site and be completed in 2014. UPM's total investment will amount to approximately EUR 150 million.
Calgary, Alberta, 30 April 2012 – Iogen Energy Corporation has agreed to a new plan with its joint owners Royal Dutch Shell and Iogen Corporation to refocus its strategy and activities. Shell continues to explore multiple pathways to find a commercial solution for the production of advanced biofuels on an industrial scale, but the company will NOT pursue the project it has had under development to build a larger scale cellulosic ethanol facility in southern Manitoba.
In India, Indian Oil Companies have agreed to build seven second generation refineries across the country. The companies who will be participating in building of 2G biofuel plants are Indian Oil Corporation (IOCL), HPCL and BPCL. In May 2018, the Government of India unveiled a biofuel policy wherein a sum of INR 5,000 crores was allocated to set-up 2G biorefineries. Indian oil marketing companies were in a process of constructing 12 refineries with a capex of INR 10,000 crores.
See also
*
Algae fuel
Algae fuel, algal biofuel, or algal oil is an alternative to liquid fossil fuels that uses algae as its source of energy-rich oils. Also, algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane. When made fr ...
*
Cellulosic ethanol commercialization
Cellulosic ethanol is ethanol (ethyl alcohol) produced from cellulose (the stringy fiber of a plant) rather than from the plant's seeds or fruit. It can be produced from grasses, wood, algae, or other plants. It is generally discussed for use as a ...
*
Food vs fuel
Food versus fuel is the dilemma regarding the risk of diverting farmland or crops for biofuels production to the detriment of the food supply. The biofuel and food price debate involves wide-ranging views, and is a long-standing, controversial ...
*
IEA Bioenergy
*''
Jatropha
''Jatropha'' is a genus of flowering plants in the spurge family, Euphorbiaceae. The name is derived from the Greek words ἰατρός (''iatros''), meaning "physician", and τροφή (''trophe''), meaning "nutrition", hence the common name ...
''
*
Renewable Fuel Standard
The Renewable Fuel Standard (RFS) is an American federal program that requires transportation fuel sold in the United States to contain a minimum volume of renewable fuels. It originated with the Energy Policy Act of 2005 and was expanded and exte ...
References
External links
The National Non-Food Crops Centre
{{DEFAULTSORT:Second Generation Biofuels
Biofuels
Renewable fuels