A
biofuel is a
fuel that contains energy from geologically recent
carbon fixation, such as plants. These fuels are produced from
living organisms. Examples of this
carbon fixation occur in
plants and
microalgae. These fuels are made by a
biomass conversion (biomass refers to recently living organisms, most often referring to
plants
or plant-derived materials). This biomass can be converted to
convenient energy containing substances in three different ways: thermal
conversion, chemical conversion, and biochemical conversion. This
biomass conversion can result in fuel in
solid,
liquid, or
gas form. This new biomass can be used for biofuels. Biofuels have increased in popularity because of rising
oil prices and the need for
energy security.
Bioethanol is an
alcohol made by
fermentation, mostly from
carbohydrates produced in
sugar or
starch crops such as
corn,
sugarcane, or
sweet sorghum.
Cellulosic biomass, derived from non-food sources, such as trees and grasses, is also being developed as a
feedstock for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a
gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the
USA and in
Brazil. Current plant design does not provide for converting the
lignin portion of plant raw materials to fuel components by fermentation.
Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a
diesel additive to reduce levels of particulates,
carbon monoxide, and
hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using
transesterification and is the most common biofuel in Europe.
In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009,
[1] and biofuels provided 2.7% of the world's fuels for road transport, a contribution largely made up of ethanol and biodiesel.
[citation needed] Global
ethanol fuel
production reached 86 billion liters (23 billion gallons US) in 2010,
with the United States and Brazil as the world's top producers,
accounting together for 90% of global production. The world's largest
biodiesel producer is the
European Union, accounting for 53% of all biodiesel production in 2010.
[1] As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces.
[2] The
International Energy Agency
has a goal for biofuels to meet more than a quarter of world demand for
transportation fuels by 2050 to reduce dependence on petroleum and
coal.
[3]
The production of biofuels also led into a flourishing automotive
industry, where by 2010, 79% of all cars produced in Brazil were made
with a hybrid fuel system of bioethanol and gasoline.
[4]
There are various social, economic, environmental and technical
issues relating to biofuels
production and use, which have been debated in the popular media and
scientific journals. These include: the effect of moderating
oil prices, the "
food vs fuel" debate,
poverty reduction potential,
carbon emissions levels,
sustainable biofuel production,
deforestation and
soil erosion, loss of
biodiversity, impact on
water resources, rural social exclusion and injustice, shantytown migration, rural unskilled unemployment, and nitrous oxide (NO2) emissions.
Liquid fuels for transportation
Most transportation fuels are liquids, because vehicles usually require high
energy density. This occurs naturally in liquids and solids. High energy density can also be provided by an
internal combustion engine.
These engines require clean-burning fuels. The fuels that are easiest
to burn cleanly are typically liquids and gases. Thus, liquids meet the
requirements of being both energy-dense and clean-burning. In addition,
liquids (and gases) can be pumped, which means handling is easily
mechanized, and thus less laborious.
First-generation biofuels
'First-generation' or conventional biofuels are made from sugar, starch, or vegetable oil.
Ethanol
Main article:
Ethanol fuel
Biologically produced
alcohols, most commonly
ethanol, and less commonly
propanol and
butanol, are produced by the action of
microorganisms and
enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult).
Biobutanol
(also called biogasoline) is often claimed to provide a direct
replacement for gasoline, because it can be used directly in a gasoline
engines.
Ethanol fuel is the most common biofuel worldwide, particularly
in Brazil.
Alcohol fuels are produced by fermentation of sugars derived from
wheat,
corn,
sugar beets,
sugar cane,
molasses and any sugar or starch from which
alcoholic beverages such as
whiskey, can be made (such as
potato and
fruit waste, etc.). The ethanol production methods used are
enzyme digestion (to release sugars from stored starches), fermentation of the sugars,
distillation and drying. The distillation process requires significant energy input for heat (sometimes unsustainable
natural gas fossil fuel, but cellulosic biomass such as
bagasse,
the waste left after sugar cane is pressed to extract its juice, is the
most common fuel in Brazil, while pellets, wood chips and also waste
heat are more common in Europe
Waste steam fuels ethanol factory- where waste heat from the factories also is used in the district heating grid.
Ethanol can be used in petrol engines as a replacement for gasoline;
it can be mixed with gasoline to any percentage. Most existing car
petrol engines can run on blends of up to 15% bioethanol with
petroleum/gasoline. Ethanol has a smaller
energy density
than that of gasoline; this means it takes more fuel (volume and mass)
to produce the same amount of work. An advantage of ethanol (
CH
3CH
2OH) is that it has a higher
octane rating than ethanol-free gasoline available at roadside gas stations, which allows an increase of an engine's
compression ratio for increased
thermal efficiency. In high-altitude (thin air) locations, some states mandate a mix of gasoline and ethanol as a winter
oxidizer to reduce atmospheric pollution emissions.
Ethanol is also used to fuel bioethanol
fireplaces. As they do not require a chimney and are "flueless", bioethanol fires
[5]
are extremely useful for newly built homes and apartments without a
flue. The downsides to these fireplaces is that their heat output is
slightly less than electric heat or gas fires, and precautions must be
taken to avoid carbon monoxide poisoning.
In the current
corn-to-ethanol production model in the United States, considering the total energy consumed by
farm equipment, cultivation, planting,
fertilizers,
pesticides,
herbicides, and
fungicides made from petroleum,
irrigation
systems, harvesting, transport of feedstock to processing plants,
fermentation, distillation, drying, transport to fuel terminals and
retail pumps, the net energy content value added and delivered to
consumers is about 1.3 - 2 times higher than the total energy input. The
net climate benefit (all things considered) was in the early 2000s
between 15 and 30% net savings,
[6]
but have since improved and is now approaching the European wheat and
corn-based ethanol with typical values of 65-67 % reduction of climate
gasses. The best European production lines are however reducing climate
emissions with 90-95 %.
[7]
Corn-to-ethanol and other food stocks has led to the development of
cellulosic ethanol. According to a joint research agenda conducted through the US Department of Energy,
[8] the fossil energy ratios (
FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3, 1.36, and 0.81, respectively.
[9][10][11]
Ethanol has roughly one-third lower energy content per unit of volume
compared to gasoline. This is partly counteracted by the better
efficiency when using ethanol (in a long-term test of more than 2,1
million km, the BEST project found FFV vehicles to be 1-26 % more energy
efficient than petrol cars
The BEST project),
but the volumetric consumption increases by approximately 30%, so more
fuel stops are required. For practical terms this has no big
implications as the typical driver does not use up a full tank in one
trip. (E.g. European citizens drive on average less than 20 km/day).
With current subsidies, ethanol fuel is slightly cheaper per distance traveled in the United States.
[12]
Biodiesel
In some countries, biodiesel is less expensive than conventional diesel.
Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using
transesterification
and is a liquid similar in composition to fossil/mineral diesel.
Chemically, it consists mostly of fatty acid methyl (or ethyl) esters (
FAMEs). Feedstocks for biodiesel include animal fats, vegetable oils,
soy,
rapeseed,
jatropha,
mahua,
mustard,
flax,
sunflower,
palm oil,
hemp,
field pennycress,
Pongamia pinnata and
algae. Pure biodiesel (B100) currently reduces emissions with up to 60% compared to diesel
Second generation B100.
Biodiesel can be used in any
diesel engine
when mixed with mineral diesel. In some countries, manufacturers cover
their diesel engines under warranty for B100 use, although
Volkswagen of
Germany,
for example, asks drivers to check by telephone with the VW
environmental services department before switching to B100. B100 may
become more
viscous
at lower temperatures, depending on the feedstock used. In most cases,
biodiesel is compatible with diesel engines from 1994 onwards, which use
'
Viton' (by
DuPont) synthetic rubber in their mechanical
fuel injection
systems. Note however, that no vehicles are certified for using neat
biodiesel before 2014, as there was no emission control protocol
available for biodiesel before this date.
Electronically controlled '
common rail' and '
unit injector'
type systems from the late 1990s onwards may only use biodiesel blended
with conventional diesel fuel. These engines have finely metered and
atomized multiple-stage injection systems that are very sensitive to the
viscosity of the fuel. Many current-generation diesel engines are made
so that they can run on B100 without altering the engine itself,
although this depends on the
fuel rail design. Since biodiesel is an effective
solvent and cleans residues deposited by mineral diesel,
engine filters
may need to be replaced more often, as the biofuel dissolves old
deposits in the fuel tank and pipes. It also effectively cleans the
engine
combustion chamber
of carbon deposits, helping to maintain efficiency. In many European
countries, a 5% biodiesel blend is widely used and is available at
thousands of gas stations.
[13][14] Biodiesel is also an
oxygenated fuel, meaning it contains a reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel. This improves the
combustion
of biodiesel and reduces the particulate emissions from unburnt carbon.
However, using neat biodiesel may increase NOx-emissions
Nylund.N-O
& Koponen.K. 2013. Fuel and Technology Alternatives for Buses.
Overall Energy Efficiency and Emission Performance. IEA Bioenergy Task
46. Possibly the new emission standards Euro VI/EPA 10 will lead to reduced NOx-levels also when using B100.
Biodiesel is also safe to handle and transport because it is non-toxic and
biodegradable, and has a high
flash point of about 300 °F (148 °C) compared to petroleum diesel fuel, which has a flash point of 125 °F (52 °C).
[15]
In the USA, more than 80% of commercial trucks and city buses run on
diesel. The emerging US biodiesel market is estimated to have grown 200%
from 2004 to 2005. "By the end of 2006 biodiesel production was
estimated to increase fourfold [from 2004] to more than" 1 billion US
gallons (3,800,000 m
3).
[16]
Other bioalcohols
Methanol is currently produced from
natural gas, a non
renewable fossil fuel. In the future it is hoped to be produced from biomass as
biomethanol. This is technically feasible, but the economic viability is still pending
[17] The
methanol economy is an alternative to the
hydrogen economy, compared to today's
hydrogen production from natural gas.
Butanol (
C
4H
9OH) 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 and allegedly can be burned "straight" in existing gasoline
engines (without modification to the engine or car),
[18] and is less corrosive and less water-soluble than ethanol, and could be distributed via existing infrastructures.
DuPont and
BP are working together to help develop butanol.
E. coli strains have also been successfully engineered to produce butanol by modifying their
amino acid metabolism.
[19]
Green diesel
Green diesel is produced through
hydrocracking biological oil feedstocks, such as vegetable oils and animal fats.
[20][21]
Hydrocracking is a refinery method that uses elevated temperatures and
pressure in the presence of a catalyst to break down larger
molecules, such as those found in
vegetable oils, into shorter
hydrocarbon chains used in
diesel engines.
[22] It may also be called renewable diesel, hydrotreated vegetable oil
[22] or hydrogen-derived renewable diesel.
[21] Green diesel has the same chemical properties as petroleum-based diesel.
[22]
It does not require new engines, pipelines or infrastructure to
distribute and use, but has not been produced at a cost that is
competitive with
petroleum.
[21] Gasoline versions are also being developed.
[23] Green diesel is being developed in
Louisiana and
Singapore by
ConocoPhillips,
Neste Oil,
Valero, Dynamic Fuels, and
Honeywell UOP.
[21][24] and also by Preem in Gothenburg, Sweden
Evolution Diesel
Biofuel gasoline
In 2013 UK researchers developed a genetically modified strain of
Escherichia coli which could transform glucose into biofuel gasoline that does not need to be blended.
[25] Later in 2013
UCLA researchers engineered a new metabolic pathway to bypass
glycolysis and increase the rate of conversion of sugars into biofuel,
[26] while
KAIST
researchers developed a strain capable of producing short-chain
alkanes, free fatty acids, fatty esters and fatty alcohols through the
fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA
pathway
in vivo.
[27] It is believed that in the future it will be possible to "tweak" the genes to make gasoline from straw or animal manure.
Vegetable oil
Filtered waste vegetable oil
Walmart's truck fleet logs millions of miles each year, and the company planned to double the fleet's efficiency between 2005 and 2015.
[28] This truck is one of 15 based at Walmart's
Buckeye, Arizona
distribution center that was converted to run on a biofuel made from
reclaimed cooking grease produced during food preparation at Walmart
stores.
[29]
Straight unmodified
edible
vegetable oil is generally not used as fuel, but lower-quality oil can
and has been used for this purpose. Used vegetable oil is increasingly
being processed into biodiesel, or (more rarely) cleaned of water and
particulates and used as a fuel.
As with 100% biodiesel (B100), to ensure the
fuel injectors atomize the vegetable oil in the correct pattern for efficient combustion,
vegetable oil fuel must be heated to reduce its
viscosity
to that of diesel, either by electric coils or heat exchangers. This is
easier in warm or temperate climates. Big corporations like
MAN B&W Diesel,
Wärtsilä, and
Deutz AG, as well as a number of smaller companies, such as
Elsbett, offer engines that are compatible with straight vegetable oil, without the need for after-market modifications.
Vegetable oil can also be used in many older diesel engines that do not use
common rail or
unit injection electronic diesel injection systems. Due to the design of the combustion chambers in
indirect injection
engines, these are the best engines for use with vegetable oil. This
system allows the relatively larger oil molecules more time to burn.
Some older engines, especially Mercedes, are driven experimentally by
enthusiasts without any conversion, a handful of drivers have
experienced limited success with earlier pre-"Pumpe Duse"
VW TDI engines and other similar engines with
direct injection. Several companies, such as
Elsbett or Wolf, have developed professional conversion kits and successfully installed hundreds of them over the last decades.
Oils and fats can be
hydrogenated to give a diesel substitute. The resulting product is a straight-chain hydrocarbon with a high
cetane number, low in
aromatics and
sulfur and does not contain oxygen.
Hydrogenated oils
can be blended with diesel in all proportions. They have several
advantages over biodiesel, including good performance at low
temperatures, no storage stability problems and no susceptibility to
microbial attack.
[30]
Bioethers
Bio
ethers (also referred to as fuel ethers or
oxygenated fuels) are cost-effective
compounds that act as
octane rating enhancers."Bioethers are produced by the reaction of reactive iso-olefins, such as iso-butylene, with bioethanol."
[31] Bioethers are created by wheat or sugar beet.
[32] They also enhance
engine performance, whilst significantly reducing engine wear and
toxic exhaust emissions.
Though bioethers are likely to replace petroethers in the UK, it is
highly unlikely they will become a fuel in and of itself due to the low
energy density.
[33] Greatly reducing the amount of ground-level
ozone emissions, they contribute to air quality.
[34][35]
When it comes to transportation fuel there are six ether additives-
1. Dimethyl Ether (DME) 2. Diethyl Ether (DEE) 3. Methyl Teritiary-Butyl
Ether (MTBE) 4. Ethyl
ter-butyl ether (ETBE) 5. T
er-amyl methyl ether (TAME) 6.
Ter-amyl ethyl Ether (TAEE)
[36]
The European Fuel Oxygenates Association (aka EFOA) credits Methyl
Tertiary-Butyl Ether (MTBE) and Ethyl ter-butyl ether (ETBE) as the most
commonly used ethers in fuel to replace lead. Ethers were brought into
fuels in Europe in the 1970s to replace the highly toxic compound.
[37]
Although Europeans still use Bio-ether additives, the US no longer has
an oxygenate requirement therefore bio-ethers are no longer used as the
main fuel additive.
[38]
Biogas
Pipes carrying biogas
Biogas is
methane produced by the process of
anaerobic digestion of
organic material by
anaerobes.
[39] 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 be used as a biofuel or a fertilizer.
- Note: Landfill gas, a less clean form of biogas, is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere, it is a potential greenhouse gas.
- Farmers can produce biogas from manure from their cattle by using anaerobic digesters.[40]
Syngas
Main article:
Gasification, a mixture of
carbon monoxide,
hydrogen and other hydrocarbons, is produced by partial combustion of biomass, that is, combustion with an amount of
oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.
[30] Before partial combustion, the biomass is dried, and sometimes
pyrolysed.
The resulting gas mixture, syngas, is more efficient than direct
combustion of the original biofuel; more of the energy contained in the
fuel is extracted.
- Syngas may be burned directly in internal combustion engines, turbines or high-temperature fuel cells.[41] The wood gas generator, a wood-fueled gasification reactor, can be connected to an internal combustion engine.
- Syngas can be used to produce methanol, DME and hydrogen, or converted via the Fischer-Tropsch process
to produce a diesel substitute, or a mixture of alcohols that can be
blended into gasoline. Gasification normally relies on temperatures
greater than 700 °C.
- Lower-temperature gasification is desirable when co-producing biochar, but results in syngas polluted with tar.
Solid biofuels
Examples include
wood,
sawdust,
grass trimmings,
domestic refuse,
charcoal,
agricultural waste, nonfood
energy crops, and
dried manure.
When raw biomass is already in a suitable form (such as
firewood),
it can burn directly in a stove or furnace to provide heat or raise
steam. When raw biomass is in an inconvenient form (such as sawdust,
wood chips, grass, urban waste wood, agricultural residues), the typical
process is to densify the biomass. This process includes grinding the
raw biomass to an appropriate particulate size (known as hogfuel),
which, depending on the densification type, can be from 1 to 3 cm (0 to
1 in), which is then concentrated into a fuel product. The current
processes produce
wood pellets,
cubes, or pucks. The pellet process is most common in Europe, and is
typically a pure wood product. The other types of densification are
larger in size compared to a pellet, and are compatible with a broad
range of input feedstocks. The resulting densified fuel is easier to
transport and feed into thermal generation systems, such as boilers.
Industry has used sawdust, bark and chips for fuel for decades,
primary in the pulp and paper industry, and also bagasse (spent sugar
cane) fueled boilers in the sugar cane industry. Boilers in the range of
500,000 lb/hr of steam, and larger, are in routine operation, using
grate, spreader stoker, suspension burning and fluid bed combustion.
Utilities generate power, typically in the range of 5 to 50 MW, using
locally available fuel. Other industries have also installed wood waste
fueled boilers and dryers in areas with low cost fuel.
[42]
One of the advantages of biomass fuel is that it is often a
byproduct, residue or waste-product of other processes, such as farming,
animal husbandry and forestry.
[43] In theory, this means fuel and food production do not compete for resources, although this is not always the case.
[43]
A problem with the combustion of raw biomass is that it emits considerable amounts of
pollutants, such as
particulates and
polycyclic aromatic hydrocarbons.
Even modern pellet boilers generate much more pollutants than oil or
natural gas boilers. Pellets made from agricultural residues are usually
worse than wood pellets, producing much larger emissions of
dioxins and
chlorophenols.
[44]
In spite of the above noted study, numerous studies have shown
biomass fuels have significantly less impact on the environment than
fossil based fuels. Of note is the US Department of Energy Laboratory,
operated by Midwest Research Institute Biomass Power and Conventional
Fossil Systems with and without CO2 Sequestration – Comparing the
Energy Balance,
Greenhouse Gas Emissions and Economics Study. Power generation emits significant amounts of greenhouse gases (GHGs), mainly
carbon dioxide (
CO
2).
Sequestering CO
2 from the power plant
flue gas can significantly reduce the GHGs from the power plant itself, but this is not the total picture.
CO
2 capture and sequestration consumes additional energy, thus lowering the plant's
fuel-to-electricity efficiency. To compensate for this, more fossil fuel must be procured and consumed to make up for lost capacity.
Taking this into consideration, the
global warming potential (GWP), which is a combination of
CO
2, methane (CH
4), and
nitrous oxide (N
2O) emissions, and energy balance of the system need to be examined using a
life cycle assessment. This takes into account the upstream processes which remain constant after
CO
2 sequestration, as well as the steps required for
additional power generation. Firing biomass instead of coal led to a
148% reduction in GWP.
A derivative of solid biofuel is
biochar, which is produced by biomass
pyrolysis.
Biochar made from agricultural waste can substitute for wood charcoal.
As wood stock becomes scarce, this alternative is gaining ground. In
eastern
Democratic Republic of Congo, for example, biomass
briquettes are being marketed as an alternative to charcoal to protect
Virunga National Park from
deforestation associated with
charcoal production.
[45]
Second-generation (advanced) biofuels
Second generation biofuels, also known as advanced biofuels, are fuels that 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 biomass or woody crops, agricultural residues or waste, which makes it harder to extract the required fuel.
Sustainable biofuels
Biofuels in the form of
liquid fuels
derived from plant materials, are entering the market, driven mainly by
the need to reduce climate gas emissions, but also by factors such as
oil price spikes and the need for increased
energy security. However, many of the biofuels that are currently being supplied have been criticised for their adverse impacts on the
natural environment,
food security, and
land use.
[46][47]
The challenge is to support biofuel development, including the development of new
cellulosic technologies, with responsible policies and economic instruments to help ensure that biofuel commercialization is
sustainable.
Responsible commercialization of biofuels represents an opportunity to
enhance sustainable economic prospects in Africa, Latin America and
Asia.
[46][47][48]
Biofuels by region
There are international organizations such as IEA Bioenergy,
[49] established in 1978 by the
OECD International Energy Agency
(IEA), with the aim of improving cooperation and information exchange
between countries that have national programs in bioenergy research,
development and deployment. The
UN International Biofuels Forum is formed by
Brazil,
China,
India,
Pakistan,
South Africa, the
United States and the
European Commission.
[50]
The world leaders in biofuel development and use are Brazil, the United
States, France, Sweden and Germany. Russia also has 22% of world's
forest,
[51]
and is a big biomass (solid biofuels) supplier. In 2010, Russian pulp
and paper maker, Vyborgskaya Cellulose, said they would be producing
pellets that can be used in heat and electricity generation from its
plant in Vyborg by the end of the year.
[52] The plant will eventually produce about 900,000 tons of pellets per year, making it the largest in the world once operational.
Biofuels currently make up 3.1%
[53]
of the total road transport fuel in the UK or 1,440 million litres. By
2020, 10% of the energy used in UK road and rail transport must come
from renewable sources – this is the equivalent of replacing 4.3 million
tonnes of fossil oil each year. Conventional biofuels are likely to
produce between 3.7 and 6.6% of the energy needed in road and rail
transport, while
advanced biofuels could meet up to 4.3% of the UK’s renewable transport fuel target by 2020.
[54]
Debates regarding the production and use of biofuel
There are various social, economic, environmental and technical
issues with biofuel production and use, which have been discussed in the
popular media and scientific journals. These include: the effect of
moderating
oil prices, the "
food vs fuel" debate,
poverty reduction potential,
carbon emissions levels,
sustainable biofuel production,
deforestation and
soil erosion, loss of
biodiversity,
[55] impact on
water resources, the possible modifications necessary to run the engine on biofuel, as well as
energy balance and efficiency. The
International Resource Panel,
which provides independent scientific assessments and expert advice on a
variety of resource-related themes, assessed the issues relating to
biofuel use in its first report
Towards sustainable production and use of resources: Assessing Biofuels.
[56]
"Assessing Biofuels" outlined the wider and interrelated factors that
need to be considered when deciding on the relative merits of pursuing
one biofuel over another. It concluded that not all biofuels perform
equally in terms of their impact on climate, energy security and
ecosystems, and suggested that environmental and social impacts need to
be assessed throughout the entire life-cycle.
Another issue with biofuel use and production is the US has changed
mandates many times because the production has been taking longer than
expected. The Renewable Fuel Standard (RFS) set by congress for 2010 was
pushed back to at best 2012 to produce 100 million gallons of pure
ethanol (not blended with a fossil fuel).
[57]
Current research
Research is ongoing into finding more suitable biofuel crops and
improving the oil yields of these crops. Using the current yields, vast
amounts of land and fresh water would be needed to produce enough oil to
completely replace fossil fuel usage. It would require twice the land
area of the US to be devoted to soybean production, or two-thirds to be
devoted to rapeseed production, to meet current US heating and
transportation needs.
[citation needed]
Specially bred mustard varieties can produce reasonably high oil yields and are very useful in
crop rotation
with cereals, and have the added benefit that the meal left over after
the oil has been pressed out can act as an effective and biodegradable
pesticide.
[58]
The
NFESC, with
Santa Barbara-based
Biodiesel Industries, is working to develop biofuels technologies for
the US navy and military, one of the largest diesel fuel users in the
world.
[59] A group of Spanish developers working for a company called
Ecofasa
announced a new biofuel made from trash. The fuel is created from
general urban waste which is treated by bacteria to produce fatty acids,
which can be used to make biofuels.
[60]
Ethanol biofuels
As the primary source of biofuels in North America, many organizations are conducting research in the area of
ethanol production. The National Corn-to-Ethanol Research Center (NCERC) is a research division of
Southern Illinois University Edwardsville dedicated solely to ethanol-based biofuel research projects.
[61] On the federal level, the
USDA
conducts a large amount of research regarding ethanol production in the
United States. Much of this research is targeted toward the effect of
ethanol production on domestic food markets.
[62] A division of the U.S.
Department of Energy, the
National Renewable Energy Laboratory (NREL), has also conducted various ethanol research projects, mainly in the area of cellulosic ethanol.
[63]
Cellulosic ethanol commercialization
is the process of building an industry out of methods of turning
cellulose-containing organic matter into fuel. Companies, such as
Iogen,
POET, and
Abengoa, are building refineries that can process
biomass and turn it into
bioethanol. Companies, such as
Diversa,
Novozymes, and
Dyadic, are producing enzymes that could enable a
cellulosic ethanol
future. The shift from food crop feedstocks to waste residues and
native grasses offers significant opportunities for a range of players,
from farmers to biotechnology firms, and from project developers to
investors.
[64]
As of 2013, the first commercial-scale plants to produce cellulosic
biofuels have begun operating. Multiple pathways for the conversion of
different biofuel feedstocks are being used. In the next few years, the
cost data of these technologies operating at commercial scale, and their
relative performance, will become available. Lessons learnt will lower
the costs of the industrial processes involved.
[65]
In parts of Asia and Africa where drylands prevail,
sweet sorghum
is being investigated as a potential source of food, feed and fuel
combined. The crop is particularly suitable for growing in arid
conditions, as it only extracts one seventh of the water used by
sugarcane. In
India, and other places, sweet sorghum stalks are used to produce biofuel by squeezing the juice and then fermenting into
ethanol.
[66]
A study by researchers at the
International Crops Research Institute for the Semi-Arid Tropics (
ICRISAT)
found that growing sweet sorghum instead of grain sorghum could
increase farmers incomes by US$40 per hectare per crop because it can
provide fuel in addition to food and animal feed. With grain sorghum
currently grown on over 11 million hectares (ha) in Asia and on 23.4
million ha in Africa, a switch to sweet sorghum could have a
considerable economic impact.
[67]
Algae biofuels
From 1978 to 1996, the
US NREL experimented with using algae as a biofuels source in the "
Aquatic Species Program".
[68] A self-published article by Michael Briggs, at the
UNH Biofuels Group, offers estimates for the realistic replacement of all
vehicular
fuel with biofuels by using algae that have a natural oil content
greater than 50%, which Briggs suggests can be grown on algae ponds at
wastewater treatment plants.
[69]
This oil-rich algae can then be extracted from the system and processed
into biofuels, with the dried remainder further reprocessed to create
ethanol. The production of algae to harvest oil for biofuels has not yet
been undertaken on a commercial scale, but
feasibility studies have been conducted to arrive at the above yield estimate. In addition to its projected high yield, algaculture — unlike
crop-based biofuels — does not entail a decrease in
food production, since it requires neither
farmland nor
fresh water.
Many companies are pursuing algae bioreactors for various purposes,
including scaling up biofuels production to commercial levels.
[70][71] Prof.
Rodrigo E. Teixeira from the
University of Alabama in Huntsville demonstrated the extraction of biofuels lipids from wet algae using a simple and economical reaction in
ionic liquids.
[72]
Jatropha
Several groups in various sectors are conducting research on
Jatropha curcas, a poisonous shrub-like tree that produces seeds considered by many to be a viable source of biofuels feedstock oil.
[73]
Much of this research focuses on improving the overall per acre oil
yield of Jatropha through advancements in genetics, soil science, and
horticultural practices.
SG Biofuels,
a San Diego-based jatropha developer, has used molecular breeding and
biotechnology to produce elite hybrid seeds that show significant yield
improvements over first-generation varieties.
[74]
SG Biofuels also claims additional benefits have arisen from such
strains, including improved flowering synchronicity, higher resistance
to pests and diseases, and increased cold-weather tolerance.
[75]
Plant Research International, a department of the
Wageningen University and Research Centre
in the Netherlands, maintains an ongoing Jatropha Evaluation Project
that examines the feasibility of large-scale jatropha cultivation
through field and laboratory experiments.
[76]
The Center for Sustainable Energy Farming (CfSEF) is a Los
Angeles-based nonprofit research organization dedicated to jatropha
research in the areas of plant science, agronomy, and horticulture.
Successful exploration of these disciplines is projected to increase
jatropha farm production yields by 200-300% in the next 10 years.
[77]
Fungi
A group at the
Russian Academy of Sciences in
Moscow,
in a 2008 paper, stated they had isolated large amounts of lipids from
single-celled fungi and turned it into biofuels in an economically
efficient manner. More research on this fungal species,
Cunninghamella japonica, and others, is likely to appear in the near future.
[78] The recent discovery of a variant of the fungus
Gliocladium roseum points toward the production of so-called
myco-diesel from cellulose. This organism was recently discovered in the rainforests of northern
Patagonia, and has the unique capability of converting cellulose into medium-length hydrocarbons typically found in diesel fuel.
[79]
Animal Gut Bacteria
Microbial gastrointestinal flora in a variety of animals have shown
potential for the production of biofuels. Recent research has shown that
TU-103, a strain of
Clostridium bacteria found in Zebra feces, can convert nearly any form of cellulose into butanol fuel.
[80] Microbes in panda waste are being investigated for their use in creating
biofuels from bamboo and other plant materials.
[81]
Greenhouse gas emissions
Some scientists have expressed concerns about land-use change in
response to greater demand for crops to use for biofuel and the
subsequent carbon emissions.
[82]
The payback period, that is, the time it will take biofuels to pay back
the carbon debt they acquire due to land-use change, has been estimated
to be between 100 and 1000 years, depending on the specific instance
and location of land-use change. However, no-till practices combined
with cover-crop practices can reduce the payback period to three years
for grassland conversion and 14 years for forest conversion.
[83]
A study conducted in the Tocantis State, in northern Brazil, found
that many families were cutting down forests in order to produce two
conglomerates of oilseed plants, the J. curcas (JC group) and the R.
communis (RC group). This region is composed of 15% Amazonian rainforest
with high biodiversity, and 80% Cerrado forest with lower biodiversity.
During the study, the farmers that planted the JC group released over
2193 Mg CO2, while losing 53-105 Mg CO2 sequestration from
deforestation; and the RC group farmers released 562 Mg CO2, while
losing 48-90 Mg CO2 to be sequestered from forest depletion.
[84]
The production of these types of biofuels not only led into an
increased emission of carbon dioxide, but also to lower efficiency of
forests to absorb the gases that these farms were emitting. This has to
do with the amount of fossil fuel the production of fuel crops involves.
In addition, the intensive use of monocropping agriculture requires
large amounts of water irrigation, as well as of fertilizers, herbicides
and pesticides. This does not only lead to poisonous chemicals to
disperse on water runoff, but also to the emission of nitrous oxide
(NO2) as a fertilizer byproduct, which is three hundred times more
efficient in producing a greenhouse effect than carbon dioxide (CO2).
[85]
Biofuels made from waste biomass or from biomass grown on abandoned agricultural lands incur little to no carbon debt.
[86]
