Biofuel

This article is about mainly liquid or gaseous fuels used for transport. For other applications, see Bioenergy.

A sample of biodiesel
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Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste.[1][2][3] Biofuels are mostly used for transportation, but can also be used for heating and electricity.[4]: 173 [5] Biofuels (and bioenergy in general) are regarded as a renewable energy source.[6]: 11  The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and ongoing deforestation and biodiversity loss as a result of biofuel production.

In general, biofuels emit fewer greenhouse gas emissions when burned in an engine and are generally considered carbon-neutral fuels as the carbon emitted has been captured from the atmosphere by the crops used in production.[7] However, life-cycle assessments of biofuels have shown large emissions associated with the potential land-use change required to produce additional biofuel feedstocks.[8][9] The outcomes of lifecycle assessments (LCAs) for biofuels are highly situational and dependent on many factors including the type of feedstock, production routes, data variations, and methodological choices. This could be added to emphasize the complexity and variability in assessing the environmental impacts of biofuels.[10] Estimates about the climate impact from biofuels vary widely based on the methodology and exact situation examined.[8] Therefore, the climate change mitigation potential of biofuel varies considerably: in some scenarios emission levels are comparable to fossil fuels, and in other scenarios the biofuel emissions result in negative emissions.

Global demand for biofuels is predicted to increase by 56% over 2022–2027.[11] By 2027 worldwide biofuel production is expected to supply 5.4% of the world's fuels for transport including 1% of aviation fuel.[12] Demand for aviation biofuel is forecast to increase.[13][14] However some policy has been criticised for favoring ground transportation over aviation.[15]

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.[16]

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as maize, 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 (E100), but it is usually used as a gasoline additive to increase octane ratings and improve vehicle emissions.

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.[17]

  1. ^ "Biofuel | Definition, Types, & Pros and Cons | Britannica". www.britannica.com. 18 March 2024. Retrieved 2 April 2024.
  2. ^ Mahapatra S, Kumar D, Singh B, Sachan PK (2021). "Biofuels and their sources of production: A review on cleaner sustainable alternative against conventional fuel, in the framework of the food and energy nexus". Energy Nexus. 4: 100036. doi:10.1016/j.nexus.2021.100036.
  3. ^ Malode SJ, Prabhu KK, Mascarenhas RJ, Shetti NP, Aminabhavi TM (2021). "Recent advances and viability in biofuel production". Energy Conversion and Management: X. 10: 100070. doi:10.1016/j.ecmx.2020.100070.
  4. ^ Cite error: The named reference mw-2020 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference www.eia.gov-2023 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Letcher chapter 1 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Lewandrowski Rosenfeld Pape Hendrickson pp. 361–375 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Jeswani-2020 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Lark Hendricks Smith Pates 2022 p. was invoked but never defined (see the help page).
  10. ^ Jeswani HK, Chilvers A, Azapagic A (November 2020). "Environmental sustainability of biofuels: a review". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 476 (2243). Bibcode:2020RSPSA.47600351J. doi:10.1098/rspa.2020.0351. ISSN 1364-5021. PMC 7735313. PMID 33363439.
  11. ^ "Biofuel is approaching a feedstock crunch. How bad? And what must be done?". Energy Post. 23 January 2023. Retrieved 14 March 2024.
  12. ^ Cite error: The named reference IEA-2022 was invoked but never defined (see the help page).
  13. ^ "Biofuel is approaching a feedstock crunch. How bad? And what must be done?". Energy Post. 23 January 2023. Retrieved 30 January 2023.
  14. ^ "How to scale Sustainable Aviation Fuel in the next decade". World Economic Forum. Retrieved 30 January 2023.
  15. ^ "More Electric Cars Are Key To Meeting SAF Targets, Boeing Says | Aviation Week Network". aviationweek.com. Retrieved 16 September 2024.
  16. ^ "Renewables Report 2022". IEA. 6 December 2022.
  17. ^ Bayetero CM, Yépez CM, Cevallos IB, Rueda EH (January 2022). "Effect of the use of additives in biodiesel blends on the performance and opacity of a diesel engine". Materials Today: Proceedings. Advances in Mechanical Engineering Trends. 49: 93–99. doi:10.1016/j.matpr.2021.07.478. ISSN 2214-7853. S2CID 238787289.