Editing Biofuel (section)

== Terminology ==
{{See also|Biomass (energy)#Terminology}}
[[File:Types and generation of biofuels.png|thumb|upright=1.2|Types and generation of biofuels]]
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."<ref name="mw-2020">{{Cite book |title=Future energy : improved, sustainable and clean options for our planet |date=2020 |editor=T. M. Letcher |isbn=978-0-08-102887-2 |edition=3rd |location=Amsterdam, Netherlands |chapter=Chapter 9: Biofuels for transport |oclc=1137604985}}</ref>{{rp|173}}

Other publications reserve the term biofuel for ''liquid'' or ''gaseous'' fuels, used for transportation.<ref name="www.eia.gov-2023">{{Cite web |title=Biofuels explained - U.S. Energy Information Administration (EIA) |url=https://www.eia.gov/energyexplained/biofuels/ |access-date=2023-01-24 |website=www.eia.gov}}</ref>

The [[IPCC Sixth Assessment Report]] defines ''biofuel'' as "A fuel, generally in liquid form, produced from [[Biomass (energy)|biomass]]. Biofuels include [[bioethanol]] from sugarcane, sugar beet or maize, and [[biodiesel]] from canola or soybeans.".<ref name="ipcc_glossary">IPCC, 2022: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_AnnexVII.pdf Annex I: Glossary] [van Diemen, R., J.B.R. Matthews, V. Möller, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, A. Reisinger, S. Semenov (eds)]. In IPCC, 2022: [https://www.ipcc.ch/report/ar6/wg3/ Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.020</ref>{{rp|1795}} It goes on to define ''biomass'' in this context as "organic material excluding the material that is fossilised or embedded in geological formations".<ref name="ipcc_glossary" />{{rp|1795}} This means that [[coal]] or other [[fossil fuel]]s is not a form of biomass in this context.

=== Conventional biofuels (first generation)  ===
''First-generation biofuels'' (also denoted as "conventional biofuels") are made from food crops grown on arable land.<ref>{{Cite journal |last1=Cavelius |first1=Philipp |last2=Engelhart-Straub |first2=Selina |last3=Mehlmer |first3=Norbert |last4=Lercher |first4=Johannes |last5=Awad |first5=Dania |last6=Brück |first6=Thomas |date=2023-03-30 |title=The potential of biofuels from first to fourth generation |journal=PLOS Biology |language=en |volume=21 |issue=3 |pages=e3002063 |doi=10.1371/journal.pbio.3002063 |doi-access=free |issn=1545-7885 |pmc=10063169 |pmid=36996247}}</ref><ref name="Letcher_ch21">{{Cite book |title=Future energy : improved, sustainable and clean options for our planet |date=2020 |editor=T. M. Letcher |isbn=978-0-08-102887-2 |edition=3rd |location=Amsterdam, Netherlands |chapter=Chapter 21: Energy from biomass |oclc=1137604985}}</ref>{{rp|447}} The crop's sugar, starch, or oil content is converted into [[biodiesel]] or [[ethanol]], using [[transesterification]], or yeast fermentation.<ref name="bio">{{Cite web|url=http://www.biofuelsdigest.com/bdigest/2010/05/18/3g-4g-a-taxonomy-for-far-out-%E2%80%94-but-not-far-away-%E2%80%94-biofuels/|title=What are – and who's making – 2G, 3G and 4G biofuels? : Biofuels Digest - biofuels, biodiesel, ethanol, algae, jatropha, green gasoline, green diesel, and biocrude daily news|date=21 May 2010|archive-url=https://web.archive.org/web/20100521143237/http://www.biofuelsdigest.com/bdigest/2010/05/18/3g-4g-a-taxonomy-for-far-out-%E2%80%94-but-not-far-away-%E2%80%94-biofuels/|archive-date=21 May 2010}}</ref>

=== Advanced biofuels ===
To avoid a "[[Food vs. fuel|food versus fuel]]" dilemma, [[second-generation biofuels]] and third-generation biofuels (also called [[Advanced Biofuels|advanced biofuels]] or [[sustainable biofuel]]s or drop-in biofuels) are made from feedstocks which do not directly compete with food or feed crop such as waste products and energy crops.<ref>{{Cite web |last=European Parliament |title=Advanced biofuels |url=https://www.europarl.europa.eu/RegData/etudes/BRIE/2017/603972/EPRS_BRI(2017)603972_EN.pdf |access-date=19 April 2024}}</ref> A wide range of renewable residue feedstocks such as those derived from agriculture and forestry activities like rice straw, rice husk, wood chips, and sawdust can be used to produce advanced biofuels through biochemical and thermochemical processes.<ref name="Letcher_ch21" />{{rp|448}} <ref>{{cite book | chapter-url=https://link.springer.com/chapter/10.1007/978-3-031-61637-2_3 | doi=10.1007/978-3-031-61637-2_3 | chapter=Renewable Residues as Feedstock for Drop-in Biofuel Production | title=The Microbiology of the Drop-in Biofuel Production | series=Biofuel and Biorefinery Technologies | date=2024 | volume=15 | pages=41–74 | isbn=978-3-031-61636-5 | vauthors = Flores LF, Osorio-Gonzalez CS, Saini R, Brar SK | publisher=Springer }}</ref>

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.<ref>{{Cite web|url=http://biofuel.org.uk/second-generation-biofuels.html|title=Biofuels – Second Generation Biofuels|website=biofuel.org.uk|access-date=18 January 2018|archive-date=15 July 2019|archive-url=https://web.archive.org/web/20190715112931/http://biofuel.org.uk/second-generation-biofuels.html|url-status=live}}</ref>