Emission intensity

{{Short description|Emission rate of a pollutant}} {{Use dmy dates|date=July 2022}} {{owidslider |start = 2024 |list = Template:OWID/carbon intensity electricity#gallery |location = commons |caption = |title = |language = |file = [[File:carbon intensity electricity, World, 2024 (cropped).svg|link=|thumb|upright=1.6|The carbon intensity of electricity measures the amount of greenhouse gases emitted per unit of electricity produced. The units are in grams of CO₂equivalents per kilowatt-hour of electricity.]] |startingView = World }} [[File:Co2-intensity.png|thumb|Carbon emission intensity of economies in kg of CO₂ per unit of GDP (2016)]]

An '''emission intensity''' (also '''carbon intensity''' or '''C.I.''') is the emission rate of a given [[pollutant]] relative to the intensity of a specific activity, or an industrial production process; for example [[gram]]s of [[carbon dioxide]] released per [[megajoule]] of energy produced, or the ratio of [[greenhouse gas emissions]] produced to [[gross domestic product]] (GDP). Emission intensities are used to derive estimates of [[air pollutant]] or greenhouse gas emissions based on the amount of fuel [[combustion|combusted]], the number of animals in [[animal husbandry]], on industrial production levels, distances traveled or similar activity data. Emission intensities may also be used to compare the environmental impact of different fuels or activities. In some case the related terms '''emission factor''' and '''carbon intensity''' are used interchangeably. The jargon used can be different, for different fields/industrial sectors; normally the term "carbon" excludes other pollutants, such as [[particulate]] emissions. One commonly used figure is '''carbon intensity per kilowatt-hour''' ('''CIPK'''), which is used to compare emissions from different sources of electrical power.

==Methodologies== Different methodologies can be used to assess the carbon intensity of a process. Among the most used methodologies there are: * The whole [[life-cycle assessment]] (LCA): this includes not only the carbon emissions due to a specific process, but also those due to the production and end-of-life of materials, plants and machineries used for the considered process. This is a quite complex method, requiring a big set of variables. * The well-to-wheels (WTW), commonly used in the Energy and Transport sectors: this is a simplified LCA considering the emissions of the process itself, the emissions due to the extraction and refining of the material (or fuel) used in the process (also "Upstream emissions"), but excluding the emissions due to the production and end-of-life of plants and machineries. This methodology is used, in the US, by the [[GREET model]] and in Europe in the [http://iet.jrc.ec.europa.eu/about-jec/jec-well-wheels-analyses-wtw JEC WTW] {{Webarchive|url=https://web.archive.org/web/20180629235946/http://iet.jrc.ec.europa.eu/about-jec/jec-well-wheels-analyses-wtw |date=29 June 2018 }}. * WTW-LCA hybrid methods, trying to fill in the gap between the WTW and LCA methods. In example, for an Electric Vehicle, an hybrid method considering also the GHG due to the manufacturing and the end of life of the battery gives GHG emissions 10–13% higher, compared to the WTW <ref>{{cite journal|last1=Moro A|last2=Helmers E|title=A new hybrid method for reducing the gap between WTW and LCA in the carbon footprint assessment of electric vehicles|journal=Int J Life Cycle Assess |volume=22|pages=4–14|doi=10.1007/s11367-015-0954-z|year=2017|issue=1 |doi-access=free|bibcode=2017IJLCA..22....4M }}</ref> * Methods not considering LCA aspects but only the emissions occurring during a specific process; i.e. just the combustion of a fuel in a power plant, without considering the Upstream emissions.<ref>This method is used by the [[International Energy Agency]] in the annual report: [https://www.iea.org/statistics/relateddatabases/co2emissionsfromfuelcombustion/ CO2 emissions from fuel combustion] {{Webarchive|url=https://web.archive.org/web/20180331011631/https://www.iea.org/statistics/relateddatabases/co2emissionsfromfuelcombustion/ |date=2018-03-31 }}.</ref>

Different calculation methods can lead to different results. The results can largely vary also for different geographic regions and timeframes (see, in example, [http://www.sciencedirect.com/science/article/pii/S1361920916307933 how C.I. of electricity varies, for different European countries, and how varied in a few years]: from 2009 to 2013 the C.I. of electricity in the European Union fell on average by 20%,<ref>{{cite journal|last1=Moro A|last2=Lonza L|title=Electricity carbon intensity in European Member States: Impacts on GHG emissions of electric vehicles|journal=Transportation Research Part D: Transport and Environment|volume=64|pages=5–14|doi=10.1016/j.trd.2017.07.012|pmid=30740029|year=2018|pmc=6358150|bibcode=2018TRPD...64....5M }}</ref> So while comparing different values of Carbon Intensity it is important to correctly consider all the boundary conditions (or initial hypotheses) considered for the calculations. For example, Chinese oil fields emit between 1.5 and more than 40 g of CO_2e per [[Joule|MJ]] with about 90% of all fields emitting 1.5–13.5 g CO_2e.<ref name="Masnadi">{{cite journal|last1=Masnadi|first1=M.|title=Well-to-refinery emissions and net-energy analysis of China's crude-oil supply|journal=Nature Energy|date=2018|volume=3|issue=3|pages=220–226|doi=10.1038/s41560-018-0090-7|bibcode=2018NatEn...3..220M|s2cid=134193903}}</ref> Such highly skewed carbon intensity patterns necessitate disaggregation of seemingly homogeneous emission activities and proper consideration of many factors for understanding.<ref name="Höök2018">{{cite journal|last1=Höök|first1=M|title=Mapping Chinese supply|journal=Nature Energy|date=2018|volume=3|issue=3|pages=166–167|doi=10.1038/s41560-018-0103-6|bibcode=2018NatEn...3..166H|s2cid=169334867|url=http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-347592}}</ref>

[[File:AirPollutionSource.jpg|thumb|upright|An air pollution emission source]]

== Estimating emissions ==

Emission factors assume a linear relation between the intensity of the activity and the emission resulting from this activity:

''Emission_pollutant = Activity * Emission Factor_pollutant''

Intensities are also used in projecting possible future scenarios such as those used in the [[Intergovernmental Panel on Climate Change|IPCC]] assessments, along with projected future changes in population, economic activity and energy technologies. The interrelations of these variables is treated under the so-called [[Kaya identity]].

The level of uncertainty of the resulting estimates depends significantly on the source category and the pollutant. Some examples: *[[Carbon dioxide]] (CO₂) emissions from the combustion of fuel can be estimated with a high degree of certainty regardless of how the fuel is used as these emissions depend almost exclusively on the [[carbon]] content of the fuel, which is generally known with a high degree of precision. The same is true for [[sulphur dioxide]] (SO₂), since sulphur contents of fuels are also generally well known. Both carbon and sulphur are almost completely oxidized during combustion and all carbon and sulphur atoms in the fuel will be present in the [[flue gas]]es as CO₂ and SO₂ respectively. *In contrast, the levels of other air pollutants and non-CO₂ greenhouse gas emissions from combustion depend on the precise technology applied when fuel is combusted. These emissions are basically caused by either incomplete combustion of a small fraction of the fuel ([[carbon monoxide]], [[methane]], [[non-methane volatile organic compound]]s) or by complicated chemical and physical processes during the combustion and in the smoke stack or tailpipe. Examples of these are [[Atmospheric particulate matter|particulates]], NO_x, a mixture of [[nitric oxide]], NO, and [[nitrogen dioxide]], NO₂). *[[Nitrous oxide]] (N₂O) emissions from agricultural soils are highly uncertain because they depend very much on both the exact conditions of the soil, the application of [[fertilizers]] and [[Meteorology|meteorological]] conditions.

==Electric generation== {{Main|Life-cycle greenhouse gas emissions of energy sources}} A literature review of numerous total life cycle energy sources {{CO2}} emissions per unit of electricity generated, conducted by the [[Intergovernmental Panel on Climate Change]] in 2011, found that the {{CO2}} emission value, that fell within the 50th [[percentile]] of all total life cycle emissions studies were as follows.<ref name="IPCC Annex II">Moomaw, W., P. Burgherr, G. Heath, M. Lenzen, J. Nyboer, A. Verbruggen, [http://srren.ipcc-wg3.de/report/IPCC_SRREN_Annex_II.pdf 2011: Annex II: Methodology. In IPCC: Special Report on Renewable Energy Sources and Climate Change Mitigation (ref. page 10)]</ref>

{|class="wikitable sortable" |+ Lifecycle greenhouse gas emissions by electricity source<ref name="IPCC Annex II" /> |- ! Technology !! Description !! 50th percentile <br> (g {{CO2}}-eq/[[kWh]]_e) |- | [[Hydroelectricity|Hydroelectric]] || reservoir || 4 |- | [[Wind]] || [[List of onshore wind farms|onshore]] || 12 |- | [[Nuclear power|Nuclear]] || various [[generation II reactor]] types || 16 |- | [[Biomass]] || various || 230 |- | [[Concentrating solar power|Solar thermal]] || [[parabolic trough]] || 22 |- | [[Geothermal energy|Geothermal]] || [[hot dry rock]] || 45 |- | [[Solar PV]] || [[Polycrystalline silicon photovoltaics|Polycrystalline silicon]] || 46 |- | [[Natural gas]] || various combined cycle turbines without scrubbing || 469 |- | [[Coal]] || various generator types without scrubbing || 1001 |}

{| class="wikitable sortable" style="font-size:95%; text-align:right;" |+ Emission factors of common fuels ! Fuel/<br>Resource ! Thermal<br>g(CO_2e)/MJ_th ! Energy Intensity (min & max estimate)<br>W·h_th/W·h_e ! Electric (min & max estimate) <br>g(CO₂)/kW·h_e |- | align=left|[[wood]] | {{Nts|115}}<ref name=Hillebrand>[http://www.seai.ie/Archive1/Files_Misc/IEABioenergyAgreementTask38CaseStudy.pdf Hillebrand, K. 1993. The Greenhouse Effects of Peat Production and Use Compared with Coal, Natural Gas and Wood. Technical Research Centre of Finland] {{webarchive|url=https://web.archive.org/web/20131104202934/http://www.seai.ie/Archive1/Files_Misc/IEABioenergyAgreementTask38CaseStudy.pdf |date=2013-11-04 }}. Seai.ie</ref> | | |- | align=left|[[Peat]] | {{Nts|106}}<ref>[http://www.imcg.net/imcgnl/nl0702/kap05.htm The CO2 emission factor of peat fuel 106&nbsp;g&nbsp;CO₂/MJ], {{webarchive|url=https://web.archive.org/web/20100707134451/http://www.imcg.net/imcgnl/nl0702/kap05.htm |date=2010-07-07 }}. Imcg.net. Retrieved on 2011-05-09.</ref><br>{{Nts|110}}<ref name=Hillebrand/> | | |- | align=left|[[Coal]] | {{Ntsh|92.51}}B:91.50–91.72<br>Br:94.33<br>88 | {{Ntsh|2.99}}B:2.62–2.85<ref name="ISA2008">{{cite journal|last1=Bilek |first1=Marcela |last2=Hardy |first2=Clarence |last3=Lenzen |first3=Manfred |last4=Dey |first4=Christopher |title=Life-cycle energy balance and greenhouse gas emissions of nuclear energy: A review |journal=Energy Conversion & Management |date=August 2008 |volume=49 |issue=8 |pages=2178–2199 |url=http://www.isa.org.usyd.edu.au/publications/documents/ISA_Nuclear_Report.pdf |url-status=dead |archive-url=https://web.archive.org/web/20091025164626/http://www.isa.org.usyd.edu.au/publications/documents/ISA_Nuclear_Report.pdf |archive-date=2009-10-25 |doi=10.1016/j.enconman.2008.01.033 }}</ref><br>Br:3.46<ref name="ISA2008"/><br>3.01 | {{Ntsh|994}}B:863–941<ref name="ISA2008"/><br>Br:1,175<ref name="ISA2008"/><br>955<ref name="IPCC">{{cite journal |first1=Ingvar B. |last1=Fridleifsson |first2=Ruggero |last2=Bertani |first3=Ernst |last3=Huenges |first4=John W. |last4=Lund |first5=Arni |last5=Ragnarsson |first6=Ladislaus |last6=Rybach |date=2008-02-11 |title=The possible role and contribution of geothermal energy to the mitigation of climate change |journal=IPCC Scoping Meeting on Renewable Energy Sources |editor=O. Hohmeyer and T. Trittin |location=Luebeck, Germany |pages=59–80 |url=http://iga.igg.cnr.it/documenti/IGA/Fridleifsson_et_al_IPCC_Geothermal_paper_2008.pdf |archive-url=https://web.archive.org/web/20110722030340/http://iga.igg.cnr.it/documenti/IGA/Fridleifsson_et_al_IPCC_Geothermal_paper_2008.pdf |archive-date=2011-07-22 |access-date=2009-04-06 |url-status=dead }}</ref> |- | align=left|[[Oil]] | {{Nts|73}}<ref name="strategic">{{Citation |last1=Hanova |first1=J |last2=Dowlatabadi |first2=H |date=9 November 2007 |title=Strategic GHG reduction through the use of ground source heat pump technology |periodical=Environmental Research Letters |place=UK |publisher=IOP Publishing |volume=2 |issue=4 |pages=044001 8pp |issn=1748-9326 |doi=10.1088/1748-9326/2/4/044001 |bibcode=2007ERL.....2d4001H|doi-access=free }}</ref> | {{Nts|3.40}} | {{Nts|893}}<ref name="IPCC"/> |- | align=left|[[Natural gas]] | {{Ntsh|68.30}}cc:68.20<br>oc:68.40<br>51<ref name="strategic"/> | {{Ntsh|2.7}}cc:2.35 (2.20 – 2.57)<ref name="ISA2008"/><br>oc:3.05 (2.81 – 3.46)<ref name="ISA2008"/> | {{Ntsh|664}}cc:577 (491–655)<ref name="ISA2008"/><br>oc:751 (627–891)<ref name="ISA2008"/><br>599<ref name="IPCC"/> |- | align=left|[[Geothermal power|Geothermal<br>Power]] | {{Nts|3}}~ | | {{Ntsh|40}}T_L0–1<ref name="IPCC"/><br>T_H91–122<ref name="IPCC"/> |- | align=left|[[Uranium]]<br>[[Nuclear power]] | | {{Ntsh|0.19}}W_L0.18 (0.16~0.40)<ref name="ISA2008"/><br>W_H0.20 (0.18~0.35)<ref name="ISA2008"/> | {{Ntsh|62.5}}W_L60 (10~130)<ref name="ISA2008"/><br>W_H65 (10~120)<ref name="ISA2008"/> |- | align=left|[[Hydroelectricity]] | | {{Nts|0.046}} (0.020 – 0.137)<ref name="ISA2008"/> | {{Nts|15}} (6.5 – 44)<ref name="ISA2008"/> |- | align=left|[[Concentrating solar power|Conc. Solar Pwr]] | | | {{Nts|40}}±15# |- | align=left|[[Photovoltaics]] | | {{Nts|0.33}} (0.16 – 0.67)<ref name="ISA2008"/> | {{Nts|106}} (53–217)<ref name="ISA2008"/> |- | align=left|[[Wind power]] | | {{Nts|0.066}} (0.041 – 0.12)<ref name="ISA2008"/> | {{Nts|21}} (13–40)<ref name="ISA2008"/> |} Note: 3.6 MJ = [[megajoule]](s) == 1&nbsp;kW·h = [[kilowatt-hour]](s), thus 1 g/MJ = 3.6 g/kW·h.

Legend: {{nowrap|1=B = Black coal (supercritical)–(new subcritical)}}, {{nowrap|1=Br = [[Brown coal]] (new subcritical)}}, {{nowrap|1=cc = combined cycle}}, {{nowrap|1=oc = open cycle}}, {{nowrap|1=T_L = low-temperature/closed-circuit (geothermal doublet)}}, {{nowrap|1=T_H = high-temperature/open-circuit}}, {{nowrap|1=W_L = Light Water Reactors}}, {{nowrap|1=W_H = Heavy Water Reactors}}, {{nowrap|1=#Educated estimate}}.

==Carbon intensity of regions== {{See also|List of countries by carbon intensity of GDP}} {| | [[File:GHG intensity 2000.svg|thumb|upright=1.2|alt=Refer to caption.|Greenhouse gas intensity in the year 2000, including land-use change.]] | [[File:Carbon intensity of GDP (using PPP) for different regions, 1982-2011.png|thumb|upright=1.2|alt=Refer to caption.|Carbon intensity of GDP (using PPP) for different regions, 1982–2011.]] | [[File:Carbon intensity of GDP (using MER) for different regions, 1982-2011 (corrected).png|thumb|upright=1.2|alt=Refer to caption.|Carbon intensity of GDP (using MER) for different regions, 1982–2011.]] |} The following tables show carbon intensity of GDP in [[market exchange rate]]s (MER) and [[purchasing power parity|purchasing power parities]] (PPP). Units are [[metric tons]] of carbon dioxide per thousand year 2005 [[US dollar]]s. Data are taken from the [[US Energy Information Administration]].<ref name="eia carbon intensity data"> {{citation |author=US EIA |title=International Energy Statistics |access-date=21 December 2013 |chapter=Carbon intensity |chapter-url=http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=90&pid=44&aid=8 |publisher=US Energy Information Administration (EIA)}}. [https://web.archive.org/web/20131014010711/http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=91&pid=46&aid=31 Archived page.] Public-domain source: 'U.S. Government publications are in the public domain and are not subject to copyright protection. You may use and/or distribute any of our data, files, databases, reports, graphs, charts, and other information products that are on our website or that you receive through our email distribution service. However, if you use or reproduce any of our information products, you should use an acknowledgment, which includes the publication date, such as: "Source: U.S. Energy Information Administration (Oct 2008)."' [http://www.eia.gov/about/copyrights_reuse.cfm] and [https://web.archive.org/web/20140125102824/http://www.eia.gov/about/copyrights_reuse.cfm archived page]. </ref> Annual data between 1980 and 2009 are averaged over three decades: 1980–89, 1990–99, and 2000–09.

{| class="wikitable sortable" |+ Carbon intensity of GDP, measured in MER<ref name="eia carbon intensity data"/> |- ! !! 1980–89 !! 1990–99 !! 2000–09 |- | [[Africa]]||1.13149||1.20702||1.03995 |- | [[Asia]] & [[Oceania]]||0.86256||0.83015||0.91721 |- | [[Central America|Central]] & [[South America]]||0.55840||0.57278||0.56015 |- | [[Eurasia]]||NA||3.31786||2.36849 |- | [[Europe]]||0.36840||0.37245||0.30975 |- | [[Middle East]]||0.98779||1.21475||1.22310 |- | [[North America]]||0.69381||0.58681||0.48160 |- | [[Earth|World]]||0.62170||0.66120||0.60725 |}

{| class="wikitable sortable" |+ Carbon intensity of GDP, measured in PPP<ref name="eia carbon intensity data"/> |- ! !! 1980–89 !! 1990–99 !! 2000–09 |- | Africa||0.48844||0.50215||0.43067 |- | Asia & Oceania||0.66187||0.59249||0.57356 |- | Central & South America||0.30095||0.30740||0.30185 |- | Eurasia||NA||1.43161||1.02797 |- | Europe||0.40413||0.38897||0.32077 |- | Middle East||0.51641||0.65690||0.65723 |- | North America||0.66743||0.56634||0.46509 |- | World||0.54495||0.54868||0.48058 |}

In 2009 CO₂ intensity of GDP in the OECD countries reduced by 2.9% and amounted to 0.33 kCO₂/$05p in the OECD countries.<ref>{{cite web|url=http://yearbook.enerdata.net/CO2-intensity-data.html|title=CO2 intensity – Map World CO2 Intensity by region – Enerdata|website=yearbook.enerdata.net}}</ref> ("$05p" = 2005 US dollars, using purchasing power parities). The USA posted a higher ratio of 0.41 kCO₂/$05p while Europe showed the largest drop in CO₂ intensity compared to the previous year (−3.7%). CO₂ intensity continued to be roughly higher in non-OECD countries. Despite a slight improvement, China continued to post a high CO₂ intensity (0.81 kCO₂/$05p). CO₂ intensity in Asia rose by 2% during 2009 since energy consumption continued to develop at a strong pace. Important ratios were also observed in countries in CIS and the Middle East.

=== Carbon intensity in Europe ===

Total CO₂ emissions from energy use were 5% below their 1990 level in 2007.<ref>{{cite web|url=http://www.odyssee-indicators.org/|title=Energy Efficiency Trends & Policies – ODYSSEE-MURE|website=www.odyssee-indicators.org}}</ref> Over the period 1990–2007, CO₂ emissions from energy use have decreased on average by 0.3%/year although the economic activity (GDP) increased by 2.3%/year. After dropping until 1994 (−1.6%/year), the CO₂ emissions have increased steadily (0.4%/year on average) until 2003 and decreased slowly again since (on average by 0.6%/year). Total CO₂ emissions per capita decreased from 8.7 t in 1990 to 7.8 t in 2007, that is to say a decrease by 10%. Almost 40% of the reduction in CO₂ intensity is due to increased use of energy carriers with lower emission factors. Total CO₂ emissions per unit of GDP, the “CO₂ intensity”, decreased more rapidly than energy intensity: by 2.3%/year and 1.4%/year, respectively, on average between 1990 and 2007.<ref>This section deals with CO₂ emissions from energy combustion published in official inventories from the European Environment Agency. The indicators are not expressed under normal climate conditions (i. e. with climate corrections) to comply with the official definition of CO₂ inventories. CO₂ emissions of final consumers include the emissions of auto producers.</ref>

However, while the reports from 2007 suggest that the CO₂ emissions are going down recent studies find that the global emissions are rapidly escalating. According to the Climate Change 2022 Mitigation of Climate Change report, conducted by the IPCC, it states that it 2019 the world emissions output was 59 gigatonnes.<ref name="Dickie">{{Cite news |last=Dickie |first=Gloria |author-link=Gloria Dickie |date=2022-04-04 |title=Factbox: Key takeaways from the IPCC report on climate change mitigation |language=en |work=Reuters |url=https://www.reuters.com/business/environment/key-takeaways-ipcc-report-climate-change-mitigation-2022-04-04/ |access-date=2022-04-05}}</ref> This shows that global emissions has grown rapidly, increasing by about 2.1% each year compared from the previous decade.<ref name="Dickie"/>

The [[Commodity Exchange Bratislava]] (CEB) has calculated carbon intensity for [[Voluntary Emissions Reduction]] projects carbon intensity in 2012 to be 0.343 tn/MWh.<ref>[http://www.kbb.sk/files/calculation-of-cabon-intensity-2012.pdf Calculation of carbon intensity in 2012] {{Webarchive|url=https://web.archive.org/web/20161220041426/http://www.kbb.sk/files/calculation-of-cabon-intensity-2012.pdf |date=20 December 2016 }} kbb.sk, Slovakia</ref>

A 2024 report shows an increase of renewable energy production, reaching 50% of the energy mix <ref>[https://www.nowtricity.com/yearly-report/2024/ Nowtricity 2024 yearly report]</ref>

According to data from the European Commission, in order to achieve the EU goal of decreasing greenhouse gas emissions by at least 55% by 2030 compared to 1990, EU-based energy investment has to double from the previous decade to more than €400 billion annually this decade. This includes the roughly €300 billion in yearly investment required for energy efficiency and the roughly €120 billion required for power networks and renewable energy facilities.<ref>{{Cite journal |last=Bank |first=European Investment |date=2023-02-02 |title=Energy Overview 2023 |url=https://www.eib.org/en/publications/20220286-energy-overview-2023 |language=EN}}</ref><ref>{{Cite web |title=2030 Climate Target Plan |url=https://climate.ec.europa.eu/eu-action/european-green-deal/2030-climate-target-plan_en |access-date=2023-03-09 |website=climate.ec.europa.eu |date=14 July 2021 |language=en}}</ref>

== Emission factors for greenhouse gas inventory reporting ==

One of the most important uses of emission factors is for the reporting of national [[Greenhouse gas inventory|greenhouse gas inventories]] under the [[United Nations Framework Convention on Climate Change]] (UNFCCC). The so-called [[United Nations Framework Convention on Climate Change#Annex I countries|Annex I Parties]] to the UNFCCC have to annually report their national total emissions of greenhouse gases in a formalized reporting format, defining the source categories and fuels that must be included.

The UNFCCC has accepted the '''Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories''',<ref>{{cite web |url=http://www.ipcc-nggip.iges.or.jp/public/gl/invs6.html |title=Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories |publisher=IPCC |author=Task Force on National Greenhouse Gas Inventories |year=1996 |access-date=19 August 2012}}</ref> developed and published by the [[Intergovernmental Panel on Climate Change]] (IPCC) as the emission estimation methods that must be used by the parties to the convention to ensure transparency, completeness, consistency, comparability and accuracy of the national greenhouse gas inventories.<ref>{{cite web|url=http://unfccc.int/resource/docs/2004/sbsta/08.pdf |title=FCCC/SBSTA/2004/8 |access-date=2018-08-20}}</ref> These IPCC Guidelines are the primary source for default emission factors. Recently IPCC has published the '''2006 IPCC Guidelines for National Greenhouse Gas Inventories'''. These and many more greenhouse gas emission factors can be found on IPCC's Emission Factor Database.<ref>{{cite web |url=http://www.ipcc-nggip.iges.or.jp/EFDB/main.php |title=Emission Factor Database – Main Page |publisher=IPCC |year=2012 |access-date=19 August 2012}}</ref> Commercially applicable organisational greenhouse gas emission factors can be found on the search engine, EmissionFactors.com.<ref>{{cite web |url=http://emissionfactors.com/ |title=Emission Factors |work=emissionfactors.com |year=2012 |access-date=19 August 2012 |archive-date=25 August 2012 |archive-url=https://web.archive.org/web/20120825152938/http://emissionfactors.com/ |url-status=dead }}</ref>

Particularly for non-CO_2e emissions, there is often a high degree of uncertainty associated with these emission factors when applied to individual countries. In general, the use of country-specific emission factors would provide more accurate estimates of emissions than the use of the default emission factors. According to the IPCC, if an activity is a major source of emissions for a country ('key source'), it is 'good practice' to develop a country-specific emission factor for that activity.

== Emission factors for air pollutant inventory reporting == The [[UNECE|United Nations Economic Commission for Europe]] and the EU [[National Emission Ceilings Directive]] (2016) require countries to produce annual National Air Pollution Emission Inventories under the provisions of the [[Convention on Long-Range Transboundary Air Pollution]] (CLRTAP).

The [[European Monitoring and Evaluation Programme]] (EMEP) Task Force of the [[European Environment Agency]] has developed methods to estimate emissions and the associated emission factors for air pollutants, which have been published in the EMEP/CORINAIR Emission Inventory Guidebook<ref>[https://www.eea.europa.eu/themes/air/emep-eea-air-pollutant-emission-inventory-guidebook EMEP/CORINAIR Emission Inventory Guidebook].eea.europa.eu, 2016, retrieved 13.7.2018</ref><ref>{{cite web|url=http://www.emep.int/|title=EMEP Home|website=www.emep.int}}</ref> on Emission Inventories and Projections TFEIP.<ref>[https://web.archive.org/web/20080315073635/http://tfeip-secretariat.org/unece.htm TFEIP], 2008-03-15 tfeip-secretariat</ref>

== Intensity targets == Coal, being mostly carbon, emits a lot of {{CO2}} when burnt: it has a high {{CO2}} emission intensity. Natural gas, being methane ({{CH4}}), has 4 hydrogen atoms to burn for each one of carbon and thus has medium {{CO2}} emission intensity.

== Sources of emission factors ==

=== Greenhouse gases === *[https://web.archive.org/web/20080405110339/http://www.ipcc-nggip.iges.or.jp/public/2006gl/index.htm 2006 IPCC Guidelines for National Greenhouse Gas Inventories ] *[https://web.archive.org/web/20080321094829/http://www.ipcc-nggip.iges.or.jp/public/gl/invs6.htm Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (reference manual)]. *[http://www.ipcc-nggip.iges.or.jp/EFDB/main.php IPCC Emission Factor Database] *[http://www.ec.gc.ca/pdb/ghg/inventory_report/2005_report/tdm-toc_eng.cfm National Inventory Report: Greenhouse Gas Sources and Sinks in Canada]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}. * [https://web.archive.org/web/20100707144526/http://www.naei.org.uk/emissions/index.php United Kingdom's emission factor database].

=== Air pollutants === *[https://archive.today/20100924132127/http://www.epa.gov/ttn/chief/ap42/index.html AP 42, Compilation of Air Pollutant Emission Factors] [[US Environmental Protection Agency]] *[https://web.archive.org/web/20080328084843/http://reports.eea.europa.eu/EMEPCORINAIR5/en/page002.html EMEP/CORIMAIR 2007 Emission Inventory Guidebook]. *[https://web.archive.org/web/20060904125610/http://files.harc.edu/Projects/AirQuality/Projects/H005.2002/H5FinalReport.pdf Fugitive emissions leaks from ethylene and other chemical plants].

==Well-to-refinery carbon intensity (CI) of all major active oil fields globally==

In an August 31, 2018 article by Masnadi et al. which was published by ''[[Science (journal)|Science]]'', the authors used "open-source oil-sector CI modeling tools" to "model well-to-refinery carbon intensity (CI) of all major active oil fields globally—and to identify major drivers of these emissions."<ref name="Science_Mashnadi_20180831">{{Cite journal| doi = 10.1126/science.aar6859| issn = 0036-8075| volume = 361| issue = 6405| pages = 851–853| last1 = Masnadi| first1 = Mohammad S.| last2 = El-Houjeiri| first2 = Hassan M.| last3 = Schunack| first3 = Dominik| last4 = Li| first4 = Yunpo| last5 = Englander| first5 = Jacob G.| last6 = Badahdah| first6 = Alhassan| last7 = Monfort| first7 = Jean-Christophe| last8 = Anderson| first8 = James E.| last9 = Wallington| first9 = Timothy J.| last10 = Bergerson| first10 = Joule A.| last11 = Gordon| first11 = Deborah| last12 = Koomey| first12 = Jonathan| last13 = Przesmitzki| first13 = Steven| last14 = Azevedo| first14 = Inês L.| last15 = Bi| first15 = Xiaotao T.| last16 = Duffy| first16 = James E.| last17 = Heath| first17 = Garvin A.| last18 = Keoleian| first18 = Gregory A.| last19 = McGlade| first19 = Christophe| last20 = Meehan| first20 = D. Nathan| last21 = Yeh| first21 = Sonia| last22 = You| first22 = Fengqi| last23 = Wang| first23 = Michael| last24 = Brandt| first24 = Adam R.| title = Global carbon intensity of crude oil production| journal = Science| date = August 31, 2018| pmid = 30166477| bibcode = 2018Sci...361..851M| osti = 1485127| s2cid = 52131292| url = https://www.osti.gov/biblio/1485127}}</ref> They compared 90 countries with the highest crude oil footprint.<ref name="Science_Mashnadi_20180831"/><ref name="Twitter_Leach_20190930">{{Cite web| title =AB barrels are not below the global average| work = Twitter| access-date = October 23, 2019 | date =September 30, 2019 | url = https://twitter.com/andrew_leach/status/1178837074096480256/photo/1}}</ref> The ''Science'' study, which was conducted by [[Stanford University]] found that [[Canadian]] [[crude oil]] is the "fourth-most greenhouse gas (GHG) intensive in the world" behind [[Algeria]], [[Venezuela]] and [[Cameroon]].<ref name="foreignaffairs_NZ_20191011">{{Cite news| title = MIL-OSI New Zealand: How (and where) Greenpeace is campaigning for a world beyond oil |work= Foreign Affairs via Multimedia Investments Ltd (MIL) Open Source Intelligence (OSI) | access-date = October 23, 2019| date = October 10, 2019 |url = https://foreignaffairs.co.nz/2019/10/11/mil-osi-new-zealand-how-and-where-greenpeace-is-campaigning-for-a-world-beyond-oil/}}</ref><ref name="macleans_Markusoff_20191016">{{cite magazine |magazine=Maclean's |title=Scrubbing the oil sands' record |first=Jason |last=Markusoff |date=October 16, 2019 | access-date = October 23, 2019 |url=https://www.macleans.ca/economy/scrubbing-the-oil-sands-record/}}</ref>

Because oil deposits differ in carbon intensity, and because a substantial share of known oil reserves must remain unextracted to keep global warming below 2 °C or to limit overshooting of the 1.5 °C target,<ref>{{Cite journal|last1=Welsby|first1=Dan|last2=Price|first2=James|last3=Pye|first3=Steve|last4=Ekins|first4=Paul|date=8 September 2021|title=Unextractable fossil fuels in a 1.5 °C world|journal=Nature|language=en|volume=597|issue=7875|pages=230–234|doi=10.1038/s41586-021-03821-8|pmid=34497394|bibcode=2021Natur.597..230W|s2cid=237455006|issn=1476-4687|doi-access=free}}</ref><ref name="McGlade2015">{{cite journal |last1=McGlade |first1=Christophe |last2=Ekins |first2=Paul |title=The geographical distribution of fossil fuels unused when limiting global warming to 2 °C |journal=Nature |year=2015 |volume=517 |issue=7533 |pages=187–190 |doi=10.1038/nature14016 |url=https://doi.org/10.1038/nature14016 |issn=1476-4687 |url-access=subscription }}</ref> the question of which oil deposits should be phased out is of significant importance. A 2026 study by Renaud Coulomb, Fanny Henriet et Léo Reitzmann<ref>{{cite journal |last1=Coulomb |first1=Renaud |last2=Henriet |first2=Fanny |last3=Reitzmann |first3=Léo |title=“Bad” Oil, “Worse” Oil, and Carbon Misallocation |journal=The Review of Economic Studies |volume=93 |issue=1 |date=January 2026 |pages=404–437 |doi=10.1093/restud/rdaf018 |url=https://doi.org/10.1093/restud/rdaf018}}</ref> published in the [[Review of Economic Studies]] quantifies the additional emissions and economic costs associated with the historical extraction of high–carbon-intensity oil deposits. The study shows that accounting for heterogeneity in the carbon intensity of oil deposits could have reduced cumulative emissions by about 11 GtCO₂-equivalent between 1992 and 2018, without changing global oil demand, by avoiding the extraction of higher-carbon intensity deposits. These results imply the existence of a substantial supply-side ecological debt for major producers of high-carbon-intensity oil (e.g., Algeria, Canada, Venezuela). Looking forward, the study estimates that avoiding these high-carbon intensity deposits could avoid approximately 9.3 gigatonnes of CO₂-equivalent emissions, valued at US$1.9 trillion, along a future demand pathway consistent with achieving net-zero emissions by 2050.

== See also == {{portal|Global warming|Environment}} {{colbegin}} * [[Air pollution]] * [[AP 42 Compilation of Air Pollutant Emission Factors]] * [[Carbon footprint]] * [[Emission inventory]] * [[Energy intensity]] * [[Greenhouse gas]] and [[Greenhouse effect]] * [[IPCC list of greenhouse gases]] * [[Kaya identity]] * [[Life-cycle greenhouse gas emissions of energy sources]] * [[List of countries by carbon intensity of GDP]] * [[Low-carbon economy]] * [[Low-carbon fuel standard]] * [[Mobile emission reduction credit]] * [[Radiative forcing]] * [[Resource intensity]] * [[Spheroidal carbonaceous particles]] * [[Vehicle emission standard]] {{colend}}

== References == {{Reflist}}

==External links== * [https://www.washingtonpost.com/wp-dyn/content/article/2005/07/01/AR2005070101915.html Washington Post article with an example of change in carbon intensity] * [http://www.earth.org.uk/note-on-UK-grid-CO2-intensity-variations.html A Note On Variations in UK Grid Electricity CO_2e Intensity with Time] * [http://www.grida.no/climate/ipcc/emission/046.htm IPCC Special Report on Emissions Scenarios] * [http://yearbook.enerdata.net/ Statistical Energy Review 2012] * [http://www.odyssee-indicators.org/overview/overview.php World Energy Council:Odyssee Database] * [https://www.iea.org/statistics/relateddatabases/co2emissionsfromfuelcombustion/ International Energy Agency: CO2 emissions from fuel combustion] {{Webarchive|url=https://web.archive.org/web/20180331011631/https://www.iea.org/statistics/relateddatabases/co2emissionsfromfuelcombustion/ |date=2018-03-31 }} * [http://www.sciencedirect.com/science/article/pii/S1361920916307933 Electricity carbon intensity in European Member States: Impacts on GHG emissions of electric vehicles] * [https://link.springer.com/article/10.1007/s11367-015-0954-z A hybrid LCA-WTW method to assess the carbon footprint of electric vehicles ] * [http://www.carboun.com/infographics/climate-change-in-the-middle-east-and-north-africa-carbon-emissions/ Carbon emissions intensity from different regions] {{Webarchive|url=https://web.archive.org/web/20180106063831/http://www.carboun.com/infographics/climate-change-in-the-middle-east-and-north-africa-carbon-emissions/ |date=6 January 2018 }} {{Global warming}}

{{DEFAULTSORT:Emission Intensity}} [[Category:Air pollution emissions]] [[Category:Atmospheric dispersion modeling]] [[Category:Industrial emissions control]] [[Category:Environmental engineering]] [[Category:Energy economics]] [[Category:Greenhouse gas emissions]]