View source for Earth:Carbon capture and utilization

[[File:CCU_vs_CCS.png|alt=|thumb|429x429px|Comparison between sequestration and utilization of captured carbon dioxide]]
'''Carbon capture and utilization''' ('''CCU''') is the process of capturing [[Chemistry:Carbon dioxide|carbon dioxide]] ([[Chemistry:Carbon|C]][[Chemistry:Oxygen|O]]<sub>2</sub>) from industrial processes and transporting it via pipelines to where one intends to use it in industrial processes.<ref name=":0">{{cite journal |last1=Cuéllar-Franca |first1=Rosa M. |last2=Azapagic |first2=Adisa |title=Carbon capture, storage and utilisation technologies: A critical analysis and comparison of their life cycle environmental impacts |journal=Journal of CO<sub>2</sub> Utilization |date=March 2015 |volume=9 |pages=82–102 |doi=10.1016/j.jcou.2014.12.001 |doi-access=free }}</ref>

Captured CO<sub>2</sub> can be converted to several products: one group being [[Chemistry:Alcohol|alcohol]]s, such as methanol, to  use as efuels and other [[Earth:Carbon-neutral fuel|alternative and renewable sources of energy]]. Other commercial products include plastics, concrete and reactants for various chemical synthesis.<ref>{{cite journal |last1=Dibenedetto |first1=Angela |last2=Angelini |first2=Antonella |last3=Stufano |first3=Paolo |title=Use of carbon dioxide as feedstock for chemicals and fuels: homogeneous and heterogeneous catalysis: Use of carbon dioxide as feedstock for chemicals and fuels |journal=Journal of Chemical Technology & Biotechnology |date=March 2014 |volume=89 |issue=3 |pages=334–353 |doi=10.1002/jctb.4229 }}</ref>

Regarding a single product, CCU does not result in a net carbon positive to the atmosphere. If, in addition, this product substitutes one of fossil origin an overall CO<sub>2</sub> emission reduction occurs.

There are several additional considerations to be taken into account. As CO<sub>2</sub> is a thermodynamically stable form of [[Chemistry:Carbon|carbon]], manufacturing products from it is energy intensive.<ref name=":4">{{Cite book|title=Introduction to Carbon Capture and Sequestration|last1=Smit|first1=Berend|last2=Reimer|first2=Jeffrey A|last3=Oldenburg|first3=Curtis M|last4=Bourg|first4=Ian C|date=2013-06-18|publisher=Imperial College Press|isbn=9781783263271|series=The Berkeley Lectures on Energy|doi=10.1142/p911}}</ref> The availability of other raw materials to create a product should also be considered before investing in CCU.

Considering the different potential options for capture and utilization, research suggests that those involving chemicals, fuels and microalgae have limited potential for {{CO2}} removal, while those that involve construction materials and agricultural use can be more effective.<ref>{{cite journal |last1=Hepburn |first1=Cameron |last2=Adlen |first2=Ella |last3=Beddington |first3=John |last4=Carter |first4=Emily A. |last5=Fuss |first5=Sabine |last6=Mac Dowell |first6=Niall |last7=Minx |first7=Jan C. |last8=Smith |first8=Pete |last9=Williams |first9=Charlotte K. |title=The technological and economic prospects for CO<sub>2</sub> utilization and removal |journal=Nature |date=6 November 2019 |volume=575 |issue=7781 |pages=87–97 |doi=10.1038/s41586-019-1681-6 |pmid=31695213 |bibcode=2019Natur.575...87H |doi-access=free |hdl=10044/1/75208 |hdl-access=free }}</ref>

The profitability of CCU depends partly on the [[Finance:Carbon price|carbon price]] of CO<sub>2</sub> being released into the atmosphere.
Carbon capture and utilization may offer a response to the global challenge of significantly reducing [[Earth:Greenhouse gas emissions|greenhouse gas emissions]] from major stationary (industrial) emitters.<ref>{{Cite web|url=https://www.c2es.org/content/carbon-capture/|title=Carbon Capture|website=Center for Climate and Energy Solutions|access-date=2020-04-22}}</ref> 
 
==Definition and distinction==
Carbon capture and utilization (CCU) is defined as capturing {{CO2}} from industrial processes and transporting it via pipelines to where one intends to use it in industrial processes. The pipelines are pressurized as the only option for transporting the {{CO2}} over long distances.<ref name="ichem">{{Cite journal |last=Mike Bilio, Solomon Brown, Michael Fairweather and Haroun Mahgerefteh |date=2009 |title={{CO2}} PIPELINES MATERIAL AND SAFETY CONSIDERATIONS |url=https://www.icheme.org/media/9558/xxi-paper-061.pdf |journal=IChemE}}</ref><ref name="crs">{{Cite journal |last=Paul W. Parfomak, Peter Folger |date=2008-01-17 |title=Carbon Dioxide ({{CO2}}) Pipelines for Carbon Sequestration: Emerging Policy Issues |url=https://www.everycrsreport.com/files/20080117_RL33971_e9b75f9639ed7835dcbc3c565c1b1e03b632b204.pdf |journal=CRS Report for Congress}}</ref>

CCU differs from ''[[Physics:Carbon capture and storage|carbon capture and storage]]'' (CCS) in that CCU does not aim nor result in permanent [[Earth:Carbon sequestration|geological storage]] of carbon dioxide. Instead, CCU aims to convert the captured carbon dioxide into more valuable substances or products; such as plastics, concrete or [[Chemistry:Electrofuel|efuel]]; while retaining the [[Chemistry:Carbon neutrality|carbon neutrality]] of the production processes.

CCU and CCS are sometimes discussed collectively as ''carbon capture, utilization, and sequestration'' (CCUS).

== Sources of carbon ==
CO<sub>2</sub> is typically captured from fixed point sources in heavy industry such as petrochemical plants.<ref>{{Cite web |title=Carbon capture, utilisation and storage - Fuels & Technologies |url=https://www.iea.org/fuels-and-technologies/carbon-capture-utilisation-and-storage |access-date=2022-06-08 |website=IEA |language=en-GB}}</ref> CO<sub>2</sub> captured from these exhaust stream itself varies in concentration. A typical coal power plant will have 10-12% CO<sub>2</sub> concentration in its [[Physics:Flue gas|flue gas]] exhaust stream.<ref name=":1">{{cite journal |last1=Xu |first1=Yixiang |last2=Isom |first2=Loren |last3=Hanna |first3=Milford A. |title=Adding value to carbon dioxide from ethanol fermentations |journal=Bioresource Technology |date=May 2010 |volume=101 |issue=10 |pages=3311–3319 |doi=10.1016/j.biortech.2010.01.006 |pmid=20110166 }}</ref> A biofuel refinery produces a high purity (99%) of CO<sub>2</sub> with small amount of impurities such as water and ethanol.<ref name=":1" /> The captured {{CO2}} contains impurities and the {{CO2}} transported through pipelines will contain impurities, such as ammonia, {{chem2|N2}} , {{H2S}} , C<sub>2</sub>+. CO +, {{chem2|O2}} +, [[Earth:NOx|{{NOx}}]], {{chem|SO|x}}+ and Arsenic. Hydrogen can cause [[Chemistry:Hydrogen embrittlement|hydrogen embrittlement]], and water can cause corrosion in steel pipes.<ref name="ichem"/>{{rp|424 }}

The separation process itself can be performed through separation processes such as [[Chemistry:Absorption|absorption]], [[Chemistry:Adsorption|adsorption]], or [[Chemistry:Membrane|membrane]]s.<ref>{{cite journal |last1=De Ras |first1=Kevin |last2=Van de Vijver |first2=Ruben |last3=Galvita |first3=Vladimir V |last4=Marin |first4=Guy B |last5=Van Geem |first5=Kevin M |title=Carbon capture and utilization in the steel industry: challenges and opportunities for chemical engineering |journal=Current Opinion in Chemical Engineering |date=December 2019 |volume=26 |pages=81–87 |doi=10.1016/j.coche.2019.09.001 |s2cid=210619173 |url=https://biblio.ugent.be/publication/8635595 }}</ref>

Another possible source of capture in CCU process involves the use of plantation. The idea originates from the observation in the [[Earth:Keeling Curve|Keeling curve]] that the CO<sub>2</sub> level in the atmosphere undergoes annual variation of approximately 5 ppm ([[Parts per million|parts per million]]), which is attributed to the seasonal change of vegetation and difference in land mass between the northern and southern hemisphere.<ref>{{cite journal |last1=Keeling |first1=Charles D. |title=The Concentration and Isotopic Abundances of Carbon Dioxide in the Atmosphere |journal=Tellus |date=January 1960 |volume=12 |issue=2 |pages=200–203 |doi=10.3402/tellusa.v12i2.9366 |bibcode=1960Tell...12..200K |doi-access=free }}</ref><ref>{{cite journal |last1=Keeling |first1=Charles D. |last2=Bacastow |first2=Robert B. |last3=Bainbridge |first3=Arnold E. |last4=Ekdahl Jr. |first4=Carl A. |last5=Guenther |first5=Peter R. |last6=Waterman |first6=Lee S. |last7=Chin |first7=John F. S. |title=Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii |journal=Tellus |date=January 1976 |volume=28 |issue=6 |pages=538–551 |doi=10.3402/tellusa.v28i6.11322 |bibcode=1976Tell...28..538K |doi-access=free }}</ref> However, the CO<sub>2</sub> sequestered by the plants will be returned to the atmosphere when the plants die. Thus, it is proposed to plant crops with [[Biology:C4 carbon fixation|{{C4}} photosynthesis]], given its rapid growth and high carbon capture rate, and then to process the biomass for applications such as [[Earth:Biochar|biochar]] that will be stored in the soil permanently.<ref>{{Citation|last=X, the moonshot factory|title=We Solve for X: Mike Cheiky on negative carbon liquid fuels|url=https://www.youtube.com/watch?v=zkYVlZ9v_0o|access-date=2018-12-08}}</ref>

== Examples of technology and application ==
{{Sustainable energy}}

=== CO<sub>2</sub> electrolysis ===
{{main|Chemistry:Electrochemical reduction of carbon dioxide}}

CO<sub>2</sub> electroreduction to a variety of value-added products has been under development for many years. Some major targets are [[Chemistry:Formate|formate]], [[Chemistry:Oxalate|oxalate]], and [[Chemistry:Methanol|methanol]], as electrochemical formation of these products from CO<sub>2</sub> would constitute a very environmentally sustainable practice.<ref>{{cite journal |author1=Robert Francke |author2=Benjamin Schille |author3=Michael Roemelt |title=Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts |year=2018 |journal=Chem. Rev. |volume=118 |issue=9 |pages=4631–4701 |doi=10.1021/acs.chemrev.7b00459|pmid=29319300 }}</ref>
For example, CO<sub>2</sub> can be captured and converted to [[Earth:Carbon-neutral fuel|carbon-neutral fuel]]s in an aqueous [[Chemistry:Catalysis|catalysis]] process.<ref>{{cite journal|last1=Song|first1=Yang|last2=Peng|first2=Rui|last3=Hensley|first3=Dale K.|last4=Bonnesen|first4=Peter V.|last5=Liang|first5=Liangbo|last6=Wu|first6=Zili|last7=Meyer|first7=Harry M.|last8=Chi|first8=Miaofang|last9=Ma|first9=Cheng|last10=Sumpter|first10=Bobby G.|last11=Rondinone|first11=Adam J.|date=2016-11-16|title=High-Selectivity Electrochemical Conversion of CO 2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode|journal=ChemistrySelect|volume=1|issue=19|pages=6055–6061|doi=10.1002/slct.201601169|s2cid=99987768 |doi-access=free}}
*{{cite web |date=October 12, 2016 |title=Nano-spike catalysts convert carbon dioxide directly into ethanol |website=Oak Ridge National Laboratory |url=https://www.ornl.gov/news/nano-spike-catalysts-convert-carbon-dioxide-directly-ethanol}}</ref><ref>{{cite journal |last1=Kim |first1=Dohyung |last2=Kley |first2=Christopher S. |last3=Li |first3=Yifan |last4=Yang |first4=Peidong |title=Copper nanoparticle ensembles for selective electroreduction of {{CO2}} to C<sub>2</sub>–{{C3}} products |journal=Proceedings of the National Academy of Sciences |date=2017-10-03 |volume=114 |issue=40 |pages=10560–10565 |doi=10.1073/pnas.1711493114 |pmid=28923930 |pmc=5635920 |bibcode=2017PNAS..11410560K |doi-access=free }}
*{{cite web |author=Sarah Yang |date=September 18, 2017 |title=Copper Catalyst Yields High Efficiency {{CO2}}-to-Fuels Conversion |website=University of California Berkeley |url=https://vcresearch.berkeley.edu/news/copper-catalyst-yields-high-efficiency-co2-fuels-conversion}}</ref> It is possible to convert CO<sub>2</sub> in this way directly to [[Chemistry:Ethanol|ethanol]], which can then be upgraded to [[Chemistry:Gasoline|gasoline]] and [[Chemistry:Jet fuel|jet fuel]].<ref>{{cite news |author1=Pacific Northwest National Laboratory |title=PNNL, Lanzatech team to make new jet fuel |url=http://www.ethanolproducer.com/articles/15663/pnnl-lanzatech-team-to-make-new-jet-fuel |work=Ethanol Producer Magazine |date=4 October 2018 }}</ref><ref>{{Cite journal |last1=Prajapati |first1=Aditya |last2=Sartape |first2=Rohan |last3=Galante |first3=Miguel T. |last4=Xie |first4=Jiahan |last5=Leung |first5=Samuel L. |last6=Bessa |first6=Ivan |last7=Andrade |first7=Marcio H. S. |last8=Somich |first8=Robert T. |last9=Rebouças |first9=Márcio V. |last10=Hutras |first10=Gus T. |last11=Diniz |first11=Nathália |last12=Singh |first12=Meenesh R. |date=2022-12-07 |title=Fully-integrated electrochemical system that captures CO<sub>2</sub> from flue gas to produce value-added chemicals at ambient conditions |url=https://pubs.rsc.org/en/content/articlelanding/2022/ee/d2ee03396h |journal=Energy & Environmental Science |language=en |volume=15 |issue=12 |pages=5105–5117 |doi=10.1039/D2EE03396H |s2cid=253862974 |issn=1754-5706}}</ref>

=== Carbon-neutral fuel ===
{{Main|Carbon-neutral fuel}}A carbon-neutral fuel can be synthesized by using the captured CO<sub>2</sub> from the atmosphere as the main hydrocarbon source. The fuel is then combusted and CO<sub>2</sub>, as the byproduct of the combustion process, is released back into the air. In this process, there is no net carbon dioxide released or removed from the atmosphere, hence the name carbon-neutral fuel.

==== Methanol fuel ====
A proven process to produce a hydrocarbon is to make [[Chemistry:Methanol|methanol]].  Traditionally, methanol is produced from natural gas.<ref>{{cite journal |last1=Garcia‐Garcia |first1=Guillermo |last2=Fernandez |first2=Marta Cruz |last3=Armstrong |first3=Katy |last4=Woolass |first4=Steven |last5=Styring |first5=Peter |title=Analytical Review of Life‐Cycle Environmental Impacts of Carbon Capture and Utilization Technologies |journal=ChemSusChem |date=18 February 2021 |volume=14 |issue=4 |pages=995–1015 |doi=10.1002/cssc.202002126|issn=1864-5631  |pmid=33314601 |pmc=7986834 }}</ref> Methanol is easily synthesized from {{CO2}} and H<sub>2</sub>.  Based on this fact the idea of a [[Chemistry:Methanol economy|methanol economy]] was born.

[[Chemistry:Methanol|Methanol]], or methyl alcohol, is the simplest member of the family of alcohol organic compound with a chemical formula of [[Chemistry:Carbon|C]][[Chemistry:Hydrogen|H]]<sub>3</sub>[[Chemistry:Oxygen|O]][[Chemistry:Hydrogen|H]]. [[Chemistry:Methanol fuel|Methanol fuel]] can be manufactured using the captured carbon dioxide while performing the production with renewable energy. Consequently, methanol fuel has been considered as an alternative to fossil fuels in power generation for achieving a carbon-neutral sustainability.<ref>{{cite journal |last1=Olah |first1=George A. |title=Beyond Oil and Gas: The Methanol Economy |journal=Angewandte Chemie International Edition |date=29 April 2005 |volume=44 |issue=18 |pages=2636–2639 |doi=10.1002/anie.200462121 |pmid=15800867 |url=http://d-nb.info/1149717262/04 }}</ref><ref>{{cite thesis |last1=Hagen |first1=David LeRoy |title=Methanol: its synthesis, use as fuel, economics, and hazards |date=1976 |publisher=University of Minnesota |id={{OSTI|7113633}} |oclc=43007998 }}</ref> Synthesis of methanol from carbon dioxide is done through a hydrogenation reaction in the presence of a [[Chemistry:Catalysis|catalyst]]. Commonly used catalysts are copper, zinc, and palladium. These reactions are typically performed under high pressure conditions to shift the reaction [[Chemistry:Equilibrium chemistry|equilibrium]] towards the methanol product via [[Biology:Le Chatelier's principle|Le Chatelier's Principle]].<ref>{{Cite journal |last1=Zhang |first1=Xinbao |last2=Zhang |first2=Guanghui |last3=Song |first3=Chunshan |last4=Guo |first4=Xinwen |date=2021 |title=Catalytic Conversion of Carbon Dioxide to Methanol: Current Status and Future Perspective |journal=Frontiers in Energy Research |volume=8 |doi=10.3389/fenrg.2020.621119 |issn=2296-598X |doi-access=free }}</ref> [[Company:Carbon Recycling International|Carbon Recycling International]], a company with production facility in Grindavik, Iceland, markets such Emission-to-Liquid renewable high octane methanol fuel with current 4,000 [[Tonne|tonne]]/year production capacity.<ref>{{Cite web|url=http://www.carbonrecycling.is/vulcanol/|title=Vulcanol|website=CRI - Carbon Recycling International|language=en-US|access-date=2018-12-08|archive-date=2019-10-31|archive-url=https://web.archive.org/web/20191031103631/https://www.carbonrecycling.is/vulcanol|url-status=dead}}</ref>

'''Dimethyl Ether'''

[[Chemistry:Dimethyl ether|Dimethyl Ether]] has shown promise as a carbon neutral fuel as a potential alternative to [[Chemistry:Diesel fuel|diesel fuel]]. Dimethyl Ether has typically been synthesized from a dehydration reaction of methanol in the presence of an acid catalyst, but researchers have recently developed a one step method to convert carbon dioxide into dimethyl ether using a bifunctional catalyst and similar conditions to the synthesis of methanol from syngas.<ref>{{Cite journal |last1=Mota |first1=Noelia |last2=Millán Ordoñez |first2=Elena |last3=Pawelec |first3=Bárbara |last4=Fierro |first4=José Luis G. |last5=Navarro |first5=Rufino M. |date=2021 |title=Direct Synthesis of Dimethyl Ether from CO<sub>2</sub>: Recent Advances in Bifunctional/Hybrid Catalytic Systems |journal=Catalysts |language=en |volume=11 |issue=4 |pages=411 |doi=10.3390/catal11040411 |issn=2073-4344 |doi-access=free |hdl=10261/236211 |hdl-access=free }}</ref>

=== Chemical synthesis ===
As a highly desirable C<sub>1</sub> (one-carbon) chemical feedstock, CO<sub>2</sub> captured previously can be converted to a diverse range of products. Some of these products include: [[Physics:Polycarbonate|polycarbonate]]s (via Zinc based [[Chemistry:Catalysis|catalyst]]) or other organic products such as [[Chemistry:Acetic acid|acetic acid]],<ref name=":2">{{Cite book|url=https://www.nap.edu/catalog/10153/carbon-management-implications-for-r-d-in-the-chemical-sciences|title=Carbon Management: Implications for R & D in the Chemical Sciences and Technology (A Workshop Report to the Chemical Sciences Roundtable)|last=Council|first=National Research|date=2001-06-27|isbn=9780309075732|language=en|doi=10.17226/10153|pmid=20669488}}</ref> [[Chemistry:Urea|urea]],<ref name=":2" /> and [[Chemistry:Polyvinyl chloride|PVC]].<ref name=":3">{{Cite web|date=March 2011|title=Accelerating the uptake of CCS: industrial use of captured carbon dioxide|url=https://www.globalccsinstitute.com/archive/hub/publications/14026/accelerating-uptake-ccs-industrial-use-captured-carbon-dioxide.pdf|access-date=3 October 2020|website=globalccsinstitute.com|publisher=Global CCS Institute}}</ref> Currently 75% (112 million tons) of urea production, 2% (2 million tons) of methanol production, 43% (30 thousand tons) of salicylic acid production, and 50% (40 thousand tons) of cyclic carbonates production utilize CO<sub>2</sub> as a feedstock.<ref>{{cite journal |author1=Erdogan Alper |author2=Ozge Yuksel Orhan |title=CO<sub>2</sub> utilization: Developments in conversion processes |year=2017 |journal=Petroleum |volume=3 |pages=109–126 |doi=10.1016/j.petlm.2016.11.003|doi-access=free }}</ref> Chemical synthesis is not a permanent storage/utilization of CO<sub>2</sub>, as [[Chemistry:Aliphatic compound|aliphatic]] (straight chain) compounds may degrade and release CO<sub>2</sub> back to the atmosphere as early as 6 months.<ref name=":3" /> As the use of fossil fuels decreases, removing carbon dioxide from the air is increasingly seen as a way to stop the long-term accumulation of greenhouse gases in the atmosphere. Carbon emissions and storage coupled with reductions in fossil fuel use are known as "negative emissions".

Carbon dioxide also could be used in chemoenzymatic processes to synthesize starch without cells. In nature starch is usually synthesized within cells from carbon dioxide via photosynthesis. In cell-free synthesis, carbon dioxide is reduced to methanol with an inorganic catalyst; then methanol is converted to three carbon sugar units. The three carbon sugar units will be converted to six carbon sugar units and finally polymerize into starch. Compared to photosynthesis, which involves sixty biochemical reactions, cell-free synthesis needs eleven steps. This means cell-free synthesis can be faster than photosynthesis. The synthesis rate is 8.5 times that of corn starch, and the absorbance rate of carbon dioxide is more efficient than that of plants.<ref>{{cite journal |last1=Cai |first1=Tao |last2=Sun |first2=Hongbing |last3=Qiao |first3=Jing |last4=Zhu |first4=Leilei |last5=Zhang |first5=Fan |last6=Zhang |first6=Jie |last7=Tang |first7=Zijing |last8=Wei |first8=Xinlei |last9=Yang |first9=Jiangang |last10=Yuan |first10=Qianqian |last11=Wang |first11=Wangyin |last12=Yang |first12=Xue |last13=Chu |first13=Huanyu |last14=Wang |first14=Qian |last15=You |first15=Chun |last16=Ma |first16=Hongwu |last17=Sun |first17=Yuanxia |last18=Li |first18=Yin |last19=Li |first19=Can |last20=Jiang |first20=Huifeng |last21=Wang |first21=Qinhong |last22=Ma |first22=Yanhe |title=Cell-free chemoenzymatic starch synthesis from carbon dioxide |url=https://www.science.org/doi/abs/10.1126/science.abh4049 |journal=Science |pages=1523–1527 |language=en |doi=10.1126/science.abh4049 |date=24 September 2021|volume=373 |issue=6562 |pmid=34554807 |bibcode=2021Sci...373.1523C |s2cid=237615280 |doi-access=free }}</ref> This method is still developing, and the first publication on the topic was only in 2021, so there are still some problems. First, this method needs significant energy inputs, just as plants need sunlight. If the electricity used is not produced cleanly, large carbon dioxide emissions will still result. Moreover, high costs present a barrier to commercialization.

In 2023, an international team of researchers at the University of Sydney and the University of Toronto developed a new [[Chemistry:Acid|acid]]-based electrochemical process for the conversion of {{CO2}} captured from emission sources or directly from air.<ref>{{cite web |url=https://www.sydney.edu.au/news-opinion/news/2023/03/15/more-efficient-transformation-of-captured-co2-developed-by-resea.html| title=New process gives {{CO2}} conversion more "bang for buck" |website=University of Sydney |access-date=12 April 2023}}</ref>

=== Enhanced oil or gas recovery  ===

In enhanced oil recovery, the captured CO<sub>2</sub> is injected into depleted oil fields with the goal to increase the amount of oil to be extracted by the wells. This method is proven to increase oil output by 5-40%.<ref name=":3" />

Carbon Sequestration with Enhanced Gas Recovery (CSEGR) is a process in which CO<sub>2</sub> is injected deep in the gas reservoir and as a result, at the gas wells which are some distance away, methane (CH<sub>4</sub>) is produced. This process by active injection of CO<sub>2</sub> causes repressurization and methane displacement, so that the gas recovery becomes enhanced compared to water-drive or depletion-drive operations.<ref>{{cite journal |last1=Oldenburg |first1=Curtis M. |title=Carbon sequestration in natural gas reservoirs: Enhanced gas recovery and natural gas storage |date=8 April 2003 |url=https://www.osti.gov/servlets/purl/813580 |website=Office of Scientific and Technical Information |publisher=U.S. Department of Energy |language=en |osti=813580}}</ref>

=== Carbon mineralization ===
{{main|Chemistry:Mineralization (soil science)}}
Carbon dioxide from sources such as [[Physics:Flue gas|flue gas]] are reacted with minerals such as [[Chemistry:Magnesium oxide|magnesium oxide]] and [[Chemistry:Calcium oxide|calcium oxide]] to form stable solid carbonates. These minerals can be mined, or existing [[Earth:Brine|brine]] and waste industrial minerals (including [[Chemistry:Slag|slag]]) can be reused.<ref name=":5">{{Cite book|title=Report: Greenhouse Gas Removal|year=2018|isbn=978-1-78252-349-9|url=https://royalsociety.org/-/media/policy/projects/greenhouse-gas-removal/royal-society-greenhouse-gas-removal-report-2018.pdf|pages=54|publisher=Royal Society }}</ref>  The carbonates produced can be used for construction, consumer products, and as an alternative for carbon capture and sequestration (CCS).

Approximately 1 tonne of CO<sub>2</sub> is removed from the air for every 3.7 tonnes of mineral carbonate produced.<ref name=":5"/>

=== Biofuel from microalgae ===
{{Main|Biology:Algae fuel}}
[[File:Algae fuel in a beaker.jpg|thumb|Fuels can be produced from algae]]
A study has suggested that microalgae can be used as an alternative source of energy.<ref>{{cite journal |last1=Oncel |first1=Suphi S. |title=Microalgae for a macroenergy world |journal=Renewable and Sustainable Energy Reviews |date=October 2013 |volume=26 |pages=241–264 |doi=10.1016/j.rser.2013.05.059 }}</ref> A pond of microalgae is fed with a source of carbon dioxide such as flue gas, and the microalgae is then allowed to proliferate. The algae is then harvested and the biomass obtained is then converted to biofuel. About 1.8 tonnes of CO<sub>2</sub> can be removed from the air per 1 tonne of dry algal biomass produced, though this number actually varies depending on the species.<ref>{{cite web|url=http://www.globalccsinstitute.com/publications/accelerating-uptake-ccs-industrial-use-captured-carbon-dioxide/online/28426#c25|title=Accelerating the uptake of CCS: Industrial use of captured carbon dioxide|publisher=Global CCS Institute|access-date=7 October 2021|archive-url=https://web.archive.org/web/20120916011508/http://www.globalccsinstitute.com/publications/accelerating-uptake-ccs-industrial-use-captured-carbon-dioxide/online/28426#c25|archive-date=16 September 2012|url-status=dead}}</ref> The CO<sub>2</sub> captured will be stored non-permanently as the biofuel produced will then be combusted and the CO<sub>2</sub> will be released back into the air. However, the CO<sub>2</sub> released was first captured from the atmosphere and releasing it back into the air makes the fuel a [[Earth:Carbon-neutral fuel|carbon-neutral fuel]]. Microalgae biofuels are considered to be a part of the third generation of biofuels, being an alternative energy source for fossil fuels without the disadvantages accompanying first and second generation biofuels.<ref>{{cite journal |last1=Medipally |first1=Srikanth |last2=Yussof |first2=Fatimah |last3=Banerjee |first3=Sanjoy |last4=Shariff |first4=M. |title=Microalgae as Sustainable Renewable Energy Feedstock for Biofuel Production |journal=BioMed Res. Int. |date=March 22, 2015 |volume=2015 |page=519513 |doi=10.1155/2015/519513 |pmid=25874216 |pmc=4385614 |doi-access=free }}</ref> This technology is not mature yet.<ref>{{Cite web|url=https://www.chemengonline.com/mechanical-co2-sequestration-improves-algae-production/|title = Mechanical {{CO2}} sequestration improves algae production|date = March 2019}}</ref> Current microalgal culture systems have not been designed for high throughput biomass growth and carbon capture. Raceways, high-rate algal ponds, and photobioreactors are the most widely used for microalgal cultivation at a large-scale. The limitations of these systems are related to microalgal growth requirements. Ponds are operated at narrow depth to ensure sufficient light distribution and thus need a large land surface.<ref>{{Cite journal |last1=Nguyen |first1=Luong N. |last2=Vu |first2=Minh T. |last3=Vu |first3=Hang P. |last4=Johir |first4=Md. Abu Hasan |last5=Labeeuw |first5=Leen |last6=Ralph |first6=Peter J. |last7=Mahlia |first7=T. M. I. |last8=Pandey |first8=Ashok |last9=Sirohi |first9=Ranjna |last10=Nghiem |first10=Long D. |date=2023-01-17 |title=Microalgae-based carbon capture and utilization: A critical review on current system developments and biomass utilization |url=https://doi.org/10.1080/10643389.2022.2047141 |journal=Critical Reviews in Environmental Science and Technology |volume=53 |issue=2 |pages=216–238 |doi=10.1080/10643389.2022.2047141 |bibcode=2023CREST..53..216N |s2cid=247350232 |issn=1064-3389}}</ref>

=== Agriculture ===
{{Main|Earth:Biochar}}
An approach that is also proposed as a climate change mitigation effort is to perform plant-based carbon capture.<ref>{{cite journal |last1=Matovic |first1=Darko |title=Biochar as a viable carbon sequestration option: Global and Canadian perspective |journal=Energy |date=April 2011 |volume=36 |issue=4 |pages=2011–2016 |doi=10.1016/j.energy.2010.09.031 }}</ref> The resulting biomass can then be used for [[Earth:Biofuel|fuel]], while the biochar byproduct is then utilized for applications in agriculture as soil-enhancer. [https://www.coolplanet.com Cool Planet] is a private company with an R&D plant in Camarillo, California, performed development of biochar for agricultural applications and claimed that their product can increase crops yield by 12.3% and three-fold return of investment via improvement of soil health and nutrient retention.<ref>{{Cite web|url=https://www.coolplanet.com/wp-content/uploads/2018/03/Cool-Planet-Completes-100th-Independent-Trial-of-Cool-Terra%C2%AE-1.pdf|title=Cool Planet Completes 100th Independent Trial of Cool Terra®|date=19 March 2018|website=Cool Planet}}</ref>{{unreliable source?|date=June 2021}} However, the claims on the efficacy of plant-based carbon capture for climate change mitigation has received a fair amount of skepticism.<ref>{{Cite web|url=https://www.theverge.com/2014/4/14/5561250/cool-planet|title=The inventor of everything|last=Popper|first=Ben|date=2014-04-14|website=The Verge|language=en-US|access-date=2018-12-08}}</ref>

== Environmental impacts ==
[[File:CCU projects - 2011.png|thumb|273x273px|Sites of Carbon Capture and Utilization projects and development, per 2011 report from Global CCS Institute.<ref>{{Cite web|url=http://hub.globalccsinstitute.com/publications/accelerating-uptake-ccs-industrial-use-captured-carbon-dioxide/demonstration-projects|title=Demonstration projects {{!}} Global CCS Institute|website=hub.globalccsinstitute.com|access-date=2018-12-07|archive-date=2019-04-12|archive-url=https://web.archive.org/web/20190412141429/http://hub.globalccsinstitute.com/publications/accelerating-uptake-ccs-industrial-use-captured-carbon-dioxide/demonstration-projects|url-status=dead}}</ref>|alt=]] 
Pipelines can fail through either ductile fracture and/or a brittle fracture.<ref name="ichem"/>{{rp|425 }}

As of 2015, 16 life cycle environmental impact analyses had been done to assess the impacts of four main CCU technologies against conventional CCS: Chemical synthesis, carbon mineralization, biodiesel production, as well as Enhanced Oil Recovery (EOR). These technologies were assessed based on 10 Life-cycle assessment (LCA) impacts such as: acidification potential, eutrophication potential, global warming potential, and ozone depletion potential. The conclusion from the 16 different models was that chemical synthesis has the highest global warming potential (216 times that of CCS) while enhanced oil recovery has the least global warming potential (1.8 times that of CCS).<ref name=":0"/>{{Clarify|reason=gwp explained wrong?|date=October 2021}}

Life-cycle assessments (LCA) are not standardized as studies that perform them use different assessment methodologies and parameter that change the results of the LCA. Enhanced methodology guidelines and standardization of practice are necessary to better gauge and compare the impact of the various CCU technologies.<ref>{{Cite journal |last1=Thonemann |first1=Nils |last2=Zacharopoulos |first2=Leon |last3=Fromme |first3=Felix |last4=Nühlen |first4=Jochen |date=2022-01-15 |title=Environmental impacts of carbon capture and utilization by mineral carbonation: A systematic literature review and meta life cycle assessment |url=https://www.sciencedirect.com/science/article/pii/S0959652621042335 |journal=Journal of Cleaner Production |language=en |volume=332 |pages=130067 |doi=10.1016/j.jclepro.2021.130067 |s2cid=245201124 |issn=0959-6526|doi-access=free }}</ref>

==Regulation==
In the US, Federal Energy Regulatory Commission (FERC) and the Surface Transportation Board (STB) exercise jurisdiction.<ref name=crs/> The Corps of Engineeers may issue nationwide permits.<ref name="sehn">{{Cite journal |date=2023-08-28 |title=Who must protect the rivers, streams and wetlands from {{CO2}} Pipelines? |url=https://www.sehn.org/sehn/2023/8/24/who-must-protect-the-rivers-streams-and-wetlands-from-co2-pipelines |language=en-US}}</ref>

== See also ==
*[[Physics:Carbon capture and storage|Carbon capture and storage]]
*Carbon neutral fuel
*[[Earth:Carbon sequestration|Carbon sequestration]]
*[[Earth:Climate change mitigation|Climate change mitigation]]
*[[Earth:Greenhouse gas removal|Greenhouse gas removal]]
*List of energy topics
*Low-carbon economy
*Solar Foods Ltd.
{{div col end}}

== References ==
<references />

== Further reading ==

* {{cite book |doi=10.1142/p911 |title=Introduction to Carbon Capture and Sequestration |series=The Berkeley Lectures on Energy |year=2014 |volume=1 |isbn=978-1-78326-327-1 }}
* {{cite report |doi=10.26356/CARBONCAPTURE |date=2018 |title=Novel carbon capture and utilisation technologies: Research and climate aspects Berlin: SAPEA |website=Science Advice for Policy by European Academies}}
*[https://www.dtu.dk/english/news/2019/09/new-route-to-carbon-neutral-fuels-from-carbon-dioxide-discovered-by-stanford-dtu-team?id=4feafcd3-bf1d-4e02-80ea-ea018bfc6caf New route to carbon-neutral fuels from carbon dioxide discovered by Stanford-DTU team]

{{global warming}}

{{DEFAULTSORT:Carbon capture and utilization}}
[[Category:Carbon dioxide]]
[[Category:Carbon capture and storage| ]]
[[Category:Climate engineering]]

{{Sourceattribution|Carbon capture and utilization}}