Biofuel
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Biofuel is a
In general, biofuels emit fewer
Global demand for biofuels is predicted to increase by 56% over 2022-2027.[9] By 2027 worldwide biofuel production is expected to supply 5.4% of the world's fuels for transport including 1% of aviation fuel.[10] Demand for aviation biofuel is forecast to increase.[11][12]
The two most common types of biofuel are bioethanol and biodiesel. Brazil is the largest producer of bioethanol, while the EU is the largest producer of biodiesel. The energy content in the global production of bioethanol and biodiesel is 2.2 and 1.8 EJ per year, respectively.[13]
Bioethanol is an
Biodiesel is produced from oils or fats using transesterification. It can be used as a fuel for vehicles in its pure form (B100), but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles.[14]
Terminology
The term biofuel is used in different ways. One definition is "Biofuels are biobased products, in solid, liquid, or gaseous forms. They are produced from crops or natural products, such as wood, or agricultural residues, such as molasses and bagasse."[2]: 173
Other publications reserve the term biofuel for liquid or gaseous fuels, used for transportation.[3]
The
Conventional biofuels (first generation)
First-generation biofuels (also denoted as "conventional biofuels") are made from food crops grown on arable land.[16][17]: 447 The crop's sugar, starch, or oil content is converted into biodiesel or ethanol, using transesterification, or yeast fermentation.[18]
Advanced biofuels
To avoid a "
The feedstock used to make the fuels either grow on arable land but are byproducts of the main crop, or they are grown on marginal land. Second-generation feedstocks also include straw, bagasse, perennial grasses, jatropha, waste vegetable oil, municipal solid waste and so forth.[20]
Types
Liquid
Ethanol
Biologically produced
Ethanol fuel is the most common biofuel worldwide, particularly
Other bioalcohols
Methanol is currently produced from
Biodiesel
Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using
Biodiesel can be used in any diesel engine and modified equipment when mixed with mineral diesel. It can also be used in its pure form (B100) in diesel engines, but some maintenance and performance problems may occur during wintertime utilization, since the fuel becomes somewhat more viscous at lower temperatures, depending on the feedstock used.[30]
Electronically controlled '
Biodiesel is an
In many European countries, a 5% biodiesel blend is widely used and is available at thousands of gas stations.
Green diesel
Straight vegetable oil
Straight unmodified edible vegetable oil is generally not used as fuel, but lower-quality oil has been used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and then used as a fuel. The IEA estimates that biodiesel production used 17% of global vegetable oil supplies in 2021.[21]
Oils and fats reacted with 10 pounds of a short-chain alcohol (usually methanol) in the presence of a catalyst (usually sodium hydroxide [NaOH] can be
Biogasoline
Biogasoline can be produced biologically and themochemically. Using biologicalical methods, a study led by Professor Lee Sang-yup at the Korea Advanced Institute of Science and Technology (KAIST) and published in the international science journal Nature used modified E. coli fed with glucose found in plants or other non-food crops to produce biogasoline with the produced enzymes. The enzymes converted the sugar into fatty acids and then turned these into hydrocarbons that were chemically and structurally identical to those found in commercial gasoline fuel.[50] The thermochemical approach of producing biogasoline are similar to those used to produced biodiesel.[39][40][41] Biogasoline may also be called drop-in gasoline or renewable gasoline.
Bioethers
Bioethers (also referred to as fuel
In transportation fuel there are six ether additives: dimethyl ether (DME), diethyl ether (DEE), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-amyl ethyl ether (TAEE).[55]
The European Fuel Oxygenates Association identifies MTBE and ETBE as the most commonly used ethers in fuel to replace lead. Ethers were introduced in Europe in the 1970s to replace the highly toxic compound.
Aviation biofuel
An
Biofuels are
Aviation biofuel can be produced from plant or animal sources such as
Gaseous
Biogas and biomethane
Biogas is a mixture composed primarily of
Biogas can be recovered from mechanical biological treatment waste processing systems. Landfill gas, a less clean form of biogas, is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere, it acts as a greenhouse gas.
In Sweden "waste-to-energy" power plants capture methane biogas from garbage and use it power transport systems.[67] Farmers can produce biogas from cattle manure via anaerobic digesters.[68]
Syngas
Syngas, a mixture of carbon monoxide, hydrogen and various hydrocarbons, is produced by partial combustion of biomass (combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water).[49] Before partial combustion the biomass is dried and sometimes pyrolysed. 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,
Syngas can be used to produce methanol, dimethyl ether 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
The term "biofuels" is also used for solid fuels that are made from biomass, even though this is less common.[3]
Research into other types
Algae-based biofuels
Algae can be produced in ponds or tanks on land, and out at sea.
By 2017, due to economic considerations, most efforts to produce fuel from algae have been abandoned or changed to other applications.[80]
Electrofuels and solar fuels
This class of biofuels includes
Third and fourth-generation biofuels also include biofuels that are produced by bioengineered organisms i.e. algae and cyanobacteria.[82] Algae and cyanobacteria will use water, carbon dioxide, and solar energy to produce biofuels.[82] This method of biofuel production is still at the research level. The biofuels that are secreted by the bioengineered organisms are expected to have higher photon-to-fuel conversion efficiency, compared to older generations of biofuels.[82] One of the advantages of this class of biofuels is that the cultivation of the organisms that produce the biofuels does not require the use of arable land.[83] The disadvantages include the cost of cultivating the biofuel-producing organisms being very high.[83]
Bio-digesters
A bio-digester is a mechanized toilet that uses decomposition and sedimentation to turn human waste into a renewable fuel called biogas. Biogas can be made from substances like agricultural waste and sewage.[84][85] The bio-digester uses a process called anaerobic digestion to produce biogas. Anaerobic digestion uses a chemical process to break down organic matter with the use of microorganisms in the absence of oxygen to produce biogas.[86] The processes involved in anaerobic respiration are hydrolysis, acidogenesis, acetogenesis, and methanogenesis.[87]
Extent of production and use
Global biofuel production was 81
An assessment from 2017 found that: "Biofuels will never be a major transport fuel as there is just not enough land in the world to grow plants to make biofuel for all vehicles. It can however, be part of an energy mix to take us into a future of renewable energy."[4]: 11
In 2021 worldwide biofuel production provided 4.3% of the world's fuels for transport, including a very small amount of aviation biofuel.[10] By 2027 worldwide biofuel production is expected to supply 5.4% of the world's fuels for transport including 1% of aviation fuel.[10]
The US, Europe, Brazil and Indonesia are driving the majority of biofuel consumption growth. This demand for biodiesel, renewable diesel and biojet fuel is projected to increase by 44% (21 billion litres) over 2022-2027.[89]
Issues
This article needs to be updated.(March 2024) |
This article has an unclear citation style. (July 2023) |
Environmental impacts
Estimates about the climate impact from biofuels vary widely based on the methodology and exact situation examined.[6]
In general, biofuels emit fewer
The use of second generation biofuels is thought to increase environmental sustainability, since the non-food part of plants is being used to produce second-generation biofuels, instead of being disposed.[97] But the use of second-generation biofuels increases the competition for lignocellulosic biomass, increasing the cost of these biofuels.[98]
Third generation biofuels, produced from Algae, in theory shouldn't have as negative an impact on the environment than first or second generation biofuels, due to lower changes in land use and not requiring pesticide use for production.[99] When looking at the data however, it has been shown that the environmental cost to produce the infrastructure and energy required for third generation biofuel production, is higher than the benefits provided from the biofuels use.[100]
The European Commission has officially approved a measure to phase out palm oil-based biofuels by 2030.[101][102] Unsustainable palm oil agriculture has caused significant environmental and social problems, including deforestation and pollution.
The production of biofuels can be very energy intensive, which if generated from non-renewable sources can heavily mitigate the benefits gained through biofuel use. A solution proposed to solve this issue is to supply biofuel production facilities with excess nuclear energy, which can supplement the energy provided by fossil fuels.[103] This can provide a carbon inexpensive solution, to help reduce the environmental impacts of biofuel production.
Indirect land use change impacts of biofuels
This article needs to be updated.(August 2021) |
The
As farmers worldwide respond to higher crop prices in order to maintain the global food supply-and-demand balance, pristine lands are cleared to replace the food crops that were diverted elsewhere to biofuels' production. Because natural lands, such as rainforests and grasslands, store carbon in their soil and biomass as plants grow each year, clearance of wilderness for new farms translates to a net increase in greenhouse gas emissions. Due to this off-site change in the carbon stock of the soil and the biomass, indirect land use change has consequences in the greenhouse gas (GHG) balance of a biofuel.[104][105][106][107]
Other authors have also argued that indirect land use changes produce other significant social and environmental impacts, affecting biodiversity, water quality, food prices and supply, land tenure, worker migration, and community and cultural stability.[106][108][109][110]See also
- Bioenergy Europe
- BioEthanol for Sustainable Transport
- Biofuels Center of North Carolina
- Biogas powerplant
- International Renewable Energy Agency
- List of biofuel companies and researchers
- List of vegetable oils used for biofuel
- Renewable energy by country
- Renewable Energy Transition
- Residue-to-product ratio
- Sustainable aviation fuel
- Sustainable transport
- Table of biofuel crop yields
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External links
- Biofuels Journal
- Alternative Fueling Station Locator Archived 14 July 2008 at the EERE)
- Towards Sustainable Production and Use of Resources: Assessing Biofuels by the United Nations Environment Programme, October 2009.
- Biofuels guidance for businesses, including permits and licences required on NetRegs.gov.uk
- How Much Water Does It Take to Make Electricity?—Natural gas requires the least water to produce energy, some biofuels the most, according to a new study.
- International Conference on Biofuels Standards – European Union Biofuels Standardization
- Biofuels from Biomass: Technology and Policy Considerations Thorough overview from MIT
- The Guardian news on biofuels
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- Biofuels Factsheet by the University of Michigan's Center for Sustainable Systems
- Learn Biofuels – Educational Resource for Students