“Power-to-gas”的意思、由来-开放百科全书

Power-to-gas (often abbreviated P2G) is a technology that converts electrical power to a gas fuel.^[1] When using surplus power from wind generation, the concept is sometimes called windgas. There are currently three methods in use; all use electricity to split water into hydrogen and oxygen by means of electrolysis.{{fact|date=May 2018}}

In the first method, the resulting hydrogen is injected into the natural gas grid or is used in transport or industry.^[2] The second method is to combine the hydrogen with carbon dioxide and convert the two gases to methane (see natural gas) using a methanation reaction such as the Sabatier reaction, or biological methanation resulting in an extra energy conversion loss of 8%. The methane /SNG may then be fed into the natural gas grid or further converted in to LPG by synthesising SNG with partial reverse hydrogenation at high pressure and low temperature. LPG in turn can be converted into alkylate which is a premium gasoline blending stock because it has exceptional antiknock properties and gives clean burning.^[3] The third method uses the output gas of a wood gas generator or a biogas plant, after the biogas upgrader is mixed with the produced hydrogen from the electrolyzer, to upgrade the quality of the biogas.

Impurities, such as carbon dioxide, water, hydrogen sulfide, and particulates, must be removed from the biogas if the gas is used for pipeline storage to prevent damage.^[4]

Storage function

Power-to-gas systems may be deployed as adjuncts to wind parks or solar-electric generation. The excess power or off-peak power generated by wind generators or solar arrays may then be used at a later time for load balancing in the energy grid. Before switching to natural gas, the German gas networks were operated using towngas, which for 50–60 % consisted of hydrogen. The storage capacity of the German natural gas network is more than 200,000 GWh which is enough for several months of energy requirement. By comparison, the capacity of all German pumped storage power plants amounts to only about 40 GWh. The storage requirement in Germany is estimated at 16GW in 2023, 80GW in 2033 and 130GW in 2050.^[5] The transport of energy through a gas network is done with much less loss (<0.1%) than in a power network (8%). The storage costs per kilowatt hour are estimated at €0.10 for hydrogen and €0.15 for methane.^[6] The use of the existing natural gas pipelines for hydrogen was studied by the EU NaturalHy project^[7] and US DOE.^[8] The blending technology is also used in HCNG.

Efficiency

In 2013 the round-trip efficiency of power-to-gas-storage was well below 50%, with the hydrogen path being able to reach a maximum efficiency of ~ 43% and methane of ~ 39% by using combined-cycle powerplants. If cogeneration plants are used that produce both electricity and heat, efficiency can be above 60%, but is still less than pumped hydro or battery storage.^[9] However, there is potential to increase efficiency of power-to-gas storage. In 2015 a study published in Energy and Environmental Science found that by using reversible solid oxide electrochemical cells and recycling waste heat in the storage process a round-trip efficiency electricity to electricity of more than 70% can be reached at low cost.^[10] A 2019 study (first published in 2018) also using pressurized reversible solid oxide fuel cells and a similar methodology found that even roundtrip efficiencies (power-to-power) up to 80 % might be feasible.^[11]

Electrolysis technology

Power to hydrogen

In this method, electricity is used to split water into hydrogen and oxygen by means of electrolysis. The resulting hydrogen is injected into the natural gas grid or is used in transport or industry.^[2]

In December 2013, ITM Power, Mainova, and NRM Netzdienste Rhein-Main GmbH began injecting hydrogen into the German gas distribution network using ITM Power HGas, which is a rapid response proton exchange membrane electrolyser plant. The power consumption of the electrolyser is 315 kilowatts. It produces about 60 cubic meters per hour of hydrogen and thus in one hour can feed 3,000 cubic meters of hydrogen-enriched natural gas into the network.^[16]

On August 28, 2013, E.ON Hanse, Solvicore, and Swissgas inaugurated a commercial power-to-gas unit in Falkenhagen, Germany. The unit, which has a capacity of two megawatts, can produce 360 cubic meters of hydrogen per hour.^[17] The plant uses wind power and Hydrogenics^[18] electrolysis equipment to transform water into hydrogen, which is then injected into the existing regional natural gas transmission system. Swissgas, which represents over 100 local natural gas utilities, is a partner in the project with a 20 percent capital stake and an agreement to purchase a portion of the gas produced. A second 800 kW power-to-gas project has been started in Hamburg/Reitbrook district^[19] and is expected to open in 2015.^[20]

In August 2013, a 140 MW wind park in Grapzow, Mecklenburg-Vorpommern owned by E.ON received an electrolyser. The hydrogen produced can be used in an internal combustion engine or can be injected into the local gas grid. The hydrogen compression and storage system stores up to 27 MWh of energy and increases the overall efficiency of the wind park by tapping into wind energy that otherwise would be wasted.^[21] The electrolyser produces 210 Nm³/h of hydrogen and is operated by RH2-WKA.^[22]

In January 2011, Secure Supplies Hydrogen, an internationally certified engineering and warrantied power to gas vendor of quality Australian and USA made Hydrogen Fueling equipment, Hydrogen Fueled Engines and Hydrogen Home /Business Solar fuel cell Kits entered the market. Project's deploying (2015-2020) are focused on renewable power investments. Value adding Sites to produce a Hydrogen fuel and transfer storage gas. Secure Supplies value adds all solar wind, geo thermal and hydropower projects. Enabling owners to achieve a higher ROI, to produce hydrogen gas grids to fuel industry and a variety of applications emission free.

End users include Port Operators, Farms, Green Community residential development or and Renewable power operators. Gas is sold to gas grid or transported and used to fuel fixed engines or fuel cell that run 24r to pump water or make power for business and communities projects.

Hydrogen Equipment along with Engineering and Service provision makes Secure Supplies is well positioned to supply key markets globally.^[23]

The INGRID project started in 2013 in Apulia, Italy. It is a four-year project with 39 MWh storage and a 1.2 MW electrolyser for smart grid monitoring and control.^[24] The hydrogen is used for grid balancing, transport, industry, and injection into the gas network.^[25]

The surplus energy from the 12 MW Prenzlau Windpark in Brandenburg, Germany^[26] will be injected into the gas grid from 2014 on.

The 6 MW Energiepark Mainz^[27] from Stadtwerke Mainz, RheinMain University of Applied Sciences, Linde and Siemens in Mainz (Germany) will open in 2015.

Power to gas and other energy storage schemes to store and utilize renewable energy are part of Germany's Energiewende (energy transition program).^[28]

In France, the MINERVE demonstrator of AFUL Chantrerie (Federation of Local Utilities Association) aims to promote the development of energy solutions for the future with elected representatives, companies and more generally civil society. It also aims to experiment other reactors, catalysts ...

The synthetic methane produced by the MINERVE demonstrator (0.6 Nm3 / h of CH4) is recovered as CNG fuel and as fuel in the boilers of the AFUL Chantrerie boiler plant. The installation was designed and built by the French SME Top Industrie, with the support of Leaf. It was received in November 2017 in the expected performances: 93.3% of CH4. This project was supported by the ADEME and the ERDF-Pays de la Loire Region, as well as by several other partners: Conseil départemental de Loire -Atlantic, Engie-Cofely, GRDF, GRTGaz, Nantes-Metropolis, Sydela and Sydev.^[29]

Grid injection without compression

The core of the system is a proton exchange membrane (PEM) electrolyser. The electrolyser converts electrical energy into chemical energy, which in turn facilitates the storage of electricity. A gas mixing plant ensures that the proportion of hydrogen in the natural gas stream does not exceed two per cent by volume, the technically permissible maximum value when a natural gas filling station is situated in the local distribution network. The electrolyser supplies the hydrogen-methane mixture at the same pressure as the gas distribution network, namely 3.5 bar.

Power to methane

The power to methane method is to combine hydrogen from an electrolyzer with carbon dioxide and convert the two gases to methane^[31] (see natural gas) using a methanation reaction such as the Sabatier reaction or biological methanation resulting in an extra energy conversion loss of 8%,{{cn|date=May 2018}} the methane may then be fed into the natural gas grid if the purity requirement is reached.^[32]

ZSW (Center for Solar Energy and Hydrogen Research) and SolarFuel GmbH (now ETOGAS GmbH) realized a demonstration project with 250 kW electrical input power in Stuttgart, Germany.^[33] The plant was put into operation on October 30, 2012.^[34]

The first industry-scale Power-to-Methane plant was realized by ETOGAS for Audi AG in Werlte, Germany. The plant with 6 MW electrical input power is using CO₂ from a waste-biogas plant and intermittent renewable power to produce synthetic natural gas (SNG) which is directly fed into the local gas grid (which is operated by EWE).^[35] The plant is part of the Audi e-fuels program. The produced synthetic natural gas, named Audi e-gas, enables CO₂-neutral mobility with standard CNG vehicles. Currently it is available to customers of Audi's first CNG car, the Audi A3 g-tron.^[36]

In April 2014 the European Union’s co-financed and from the KIT coordinated^[37] HELMETH^[38] (Integrated High-Temperature ELectrolysis and METHanation for Effective Power to Gas Conversion) research project started.^[39] The objective of the project is the proof of concept of a highly efficient Power-to-Gas technology by thermally integrating high temperature electrolysis (SOEC technology) with CO₂-methanation.

Through the thermal integration of exothermal methanation and steam generation for the high temperature steam electrolysis conversion efficiency > 85% (higher heating value of produced methane per used electrical energy) are theoretically possible. The process consists of a pressurized high-temperature steam electrolysis and a pressurized CO₂-methanation module.

The project was completed in 2017 and achieved an efficiency of 76 % for the prototype with an indicated growth potential of 80 % for industrial scale plants^[40]. The operating conditions of the CO₂-methanation are a gas pressure of 10 - 30 bar, a SNG production of 1 - 5.4 m³/h (NTP) and a reactant conversion that produces SNG with H₂ < 2 vol.-% resp. CH₄ > 97 vol.-%^[41]. Thus, the generated substitute natural gas can be injected in the entire German natural gas network without limitations^[42]. As a cooling medium for the exothermic reaction boiling water is used at up to 300 °C, which corresponds to a water vapour pressure of about 87 bar. The SOEC works with a pressure of up to 15 bar, steam conversions of up to 90% and generates one standard cubic meter of hydrogen from 3.37 kWh of electricity as feed for the methanation.

The technological maturity of Power to Gas is evaluated in the European 27 partner project STORE&GO, which has started in March 2016 with a runtime of four years.^[43] Three different technological concepts are demonstrated in three different European countries (Falkenhagen/Germany, Solothurn/Switzerland, Troia/Italy). The technologies involved include biological and chemical methanation, direct capture of CO₂ from atmosphere, liquefaction of the synthesized methane to bio-LNG, and direct injection into the gas grid. The overall goal of the project is to assess those technologies and various usage paths under technical,^[44] economic,^[45]

and legal ^[46] aspects to identify business cases on the short and on the long term. The project is co-funded by the European Union’s Horizon 2020 research and innovation programme (18 million euro) and the Swiss government (6 million euro), with another 4 million euro coming from participating industrial partners.^[47] The coordinator of the overall project is the research center of the

Microbial methanation

The biological methanation combines both processes, the electrolysis of water to form hydrogen and the subsequent CO₂ reduction to methane using this hydrogen. During this process, methane forming microorganisms (methanogenic archaea or methanogens) release enzymes that reduce the overpotential of a non-catalytic electrode (the cathode) so that it can produce hydrogen.^[49]^[50] This microbial power-to-gas reaction occurs at ambient conditions, i.e. room temperature and pH 7, at efficiencies that routinely reach 80-100%.^[51]^[52] However, methane is formed more slowly than in the Sabatier reaction due to the lower temperatures. A direct conversion of CO₂ to methane has also been postulated, circumventing the need for hydrogen production.^[53]

Microorganisms involved in the microbial power-to-gas reaction are typically members of the order Methanobacteriales. Genera that were shown to catalyze this reaction are Methanobacterium,^[54]^[55] Methanobrevibacter,^[56] and Methanothermobacter (thermophile).^[57]

Power to food

The synthetic methane generated from electricity can also be used for generating protein rich feed for cattle, poultry and fish economically by cultivating Methylococcus capsulatus bacteria culture with tiny land and water foot print.^[58]^[59]^[60] The carbon dioxide gas produced as by product from these plants can be recycled in the generation of synthetic methane (SNG). Similarly, oxygen gas produced as by product from the electrolysis of water and the methanation process can be consumed in the cultivation of bacteria culture. With these integrated plants, the abundant renewable solar / wind power potential can be converted in to high value food products with out any water pollution or green house gas (GHG) emissions.^[61]

Biogas-upgrading to biomethane

In the third method the carbon dioxide in the output of a wood gas generator or a biogas plant after the biogas upgrader is mixed with the produced hydrogen from the electrolyzer to produce methane. The free heat coming from the electrolyzer is used to cut heating costs in the biogas plant. The impurities carbon dioxide, water, hydrogen sulfide, and particulates must be removed from the biogas if the gas is used for pipeline storage to prevent damage.

2014-Avedøre wastewater Services in Avedøre, Kopenhagen (Denmark) is adding a 1 MW electrolyzer plant to upgrade the anaerobic digestion biogas from sewage sludge.^[62] The produced hydrogen is used with the carbon dioxide from the biogas in a Sabatier reaction to produce methane. Electrochaea^[63] is testing another project outside P2G BioCat with biocatalytic methanation. The company uses an adapted strain of the thermophilic methanogen Methanothermobacter thermautotrophicus and has demonstrated its technology at laboratory-scale in an industrial environment.^[64] A pre-commercial demonstration project with a 10,000-liter reactor vessel was executed between January and November 2013 in Foulum, Denmark.^[65]

In 2016 Torrgas, Siemens, Stedin, Gasunie, A.Hak, Hanzehogeschool/EnTranCe and Energy Valley intend to open a 12 MW Power to Gas facility in Delfzijl (The Netherlands) where biogas from Torrgas (biocoal) will be upgraded with hydrogen from electrolysis and delivered to nearby industrial consumers.^[66]

Power to syngas

Initiatives

Other initiatives to create syngas from carbon dioxide and water may use different water splitting methods.

The US Naval Research Laboratory (NRL) is designing a power-to-liquids system using the Fischer-Tropsch Process to create fuel on board a ship at sea,^[104] with the base products carbon dioxide (CO₂) and water (H₂O) being derived from sea water via "An Electrochemical Module Configuration For The Continuous Acidification Of Alkaline Water Sources And Recovery Of CO₂ With Continuous Hydrogen Gas Production".^[105]^[106]

See also

Notes

1. ^DLR-Power to gas in transport-Status quo and perspectives for development
2. ^¹{{cite journal|title=Fuel cell electric vehicles and hydrogen infrastructure: status 2012|journal=Energy & Environmental Science|volume=5|issue=10|pages=8780|url=https://www.researchgate.net/publication/233987484|last1=Eberle|first1=Ulrich|first2=Bernd|last2=Mueller|first3=Rittmar|last3=von Helmolt|accessdate=2014-12-16|doi=10.1039/C2EE22596D|year=2012}}
3. ^{{cite web | url=https://www.bpnews.com/index.php/publications/magazine/current-issue/830-u-s-is-world-s-largest-lpg-exporter-but-when-will-market-balance | title= BPN Butane – Propane news| accessdate=10 April 2017}}
4. ^NREL 2013: Blending hydrogen into natural gas pipeline networks: A review of key issues
5. ^Electricity storage in the German energy transition
6. ^{{cite web |url=http://www.hi-tech-online.com/en/hitech-213/hifuture/windpower-to-hydrogen.html |title=Wind power to hydrogen |work=hi!tech |publisher=Siemens |accessdate=2014-06-21 }}
7. ^{{cite web |url=http://issuu.com/exergia/docs/naturalhy_brochure?e=1774604/5468248 |title=Using the Existing Natural Gas System for Hydrogen |author=NaturalHY Project |publisher=EXERGIA |accessdate=2014-06-21 }}
8. ^NREL - Blending hydrogen into natural gas pipeline networks A review of key issues
9. ^Volker Quaschning, Regenerative Energiesysteme. Technologie - Berechnung - Simulation, Hanser 2013, p 373.
10. ^{{cite journal | last1 = Jensen |display-authors=etal | year = 2015 | title = Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4 | url = http://orbit.dtu.dk/en/publications/largescale-electricity-storage-utilizing-reversible-solid-oxide-cells-combined-with-underground-storage-of-co2-and-ch4(756c6f2e-6c04-4b07-b894-9c386172ae19).html| journal = Energy and Environmental Science | volume = 8 | issue = 8| pages = 2471–2479 | doi = 10.1039/c5ee01485a }}
11. ^{{cite journal | last1 = Butera | first1 =Giacomo|display-authors=etal | year = 2019 | title = A novel system for large-scale storage of electricity as synthetic natural gas using reversible pressurized solid oxide cells | url = | journal = Energy | volume = 166 | issue = | pages = 738–754 | doi = 10.1016/j.energy.2018.10.079 }}
12. ^(German) Fraunhofer -Energiewirtschaftliche und ökologische Bewertung eines Windgas-Angebotes, p. 18
13. ^[https://www.di-verlag.de/media/content/GFE/issue_2_14/gfe2_14_fb_Grond.pdf?xaf26a=dbd42d30845f7a82752d5e8bc6b751a6 Power-to-gas: Climbing the technology readiness ladder]
14. ^{{Cite web | url=http://www.itm-power.com/news-item/first-sale-of-power-to-gas-plant-in-germany/ | title=First Sale of 'Power-to-Gas' Plant in Germany –}}
15. ^Ground broken at ITM Power power-to-gas pilot plant in Frankfurt {{webarchive|url=https://web.archive.org/web/20131111103354/http://www.fuelcelltoday.com/news-events/news-archive/2013/july/ground-broken-at-itm-power-power-to-gas-pilot-plant-in-frankfurt |date=2013-11-11 }}
16. ^{{Cite web | url=http://www.itm-power.com/news-item/injection-of-hydrogen-into-the-german-gas-distribution-grid/ | title=Injection of Hydrogen into the German Gas Distribution Grid –}}
17. ^{{Cite web | url=http://www.eon.com/en/media/news/press-releases/2013/8/28/eon-inaugurates-power-to-gas-unit-in-falkenhagen-in-eastern-germany.html | title=Press releases}}
18. ^Hydrogenics and Enbridge to develop utility-scale energy storage
19. ^E.on Hanse starts construction of power-to-gas facility in Hamburg
20. ^E.ON power-to-gas pilot unit in Falkenhagen first year of operation
21. ^{{cite news|title=German wind park with 1 MW Hydrogenics electrolyser for Power-to-Gas energy storage|url=http://www.renewableenergyfocus.com/view/35124/german-wind-park-with-1-mw-hydrogenics-electrolyser-for-power-to-gas-energy-storage/|accessdate=21 July 2017|work=Renewable Energy Focus|date=17 October 2013}}
22. ^RH2-WKA
23. ^{{cite web |url=http://danieldonatelli.wix.com/hydrogen-generator |title=Gas Electricity Power Plants Generator |accessdate=2015-12-08 |deadurl=yes |archiveurl=https://web.archive.org/web/20151208164722/http://danieldonatelli.wix.com/hydrogen-generator |archivedate=2015-12-08 |df= }}
24. ^INGRID Project to Launch 1.2 MW Electrolyser with 1 Ton of Storage for Smart Grid Balancing in Italy
25. ^Grid balancing, Power to Gas (PtG)
26. ^Prenzlau Windpark (Germany)
27. ^Energiepark Mainz
28. ^{{cite news|title=Renewable power: Germany’s energy gamble: An ambitious plan to slash greenhouse-gas emissions must clear some high technical and economic hurdles.|url=http://www.nature.com/news/renewable-power-germany-s-energy-gamble-1.12755|accessdate=April 10, 2013|newspaper=Nature|date=April 10, 2013|first=Quirin|last=Schiermeier}}
29. ^{{cite journal|title=Un démonstrateur Power to gas en service à Nantes|url=https://www.lemoniteur.fr/article/un-demonstrateur-power-to-gas-en-service-a-nantes-35321848|journal=Lemoniteur.fr|language=fr|date=2018|access-date=9 February 2018}}.
30. ^{{Cite web | url=http://www.energie-und-wende.de/no_cache/service/presse/presseinformationen/presseinformationen-detail/article/pressemitteilung-41.html | title=Energiewende & Dekarbonisierung Archive}}
31. ^DNV-Kema Systems analyses power to gas
32. ^{{cite journal|last1=Ghaib|first1=Karim|last2=Ben-Fares|first2=Fatima-Zahrae|title=Power-to-Methane: A state-of-the-art review|journal=Renewable and Sustainable Energy Reviews|date=2018|volume=81|pages=433–446|doi=10.1016/j.rser.2017.08.004|url=http://docdroid.net/IfMKlA3/power-to-methane.pdf|accessdate=1 May 2018}}
33. ^{{cite news |url=https://www.reuters.com/article/us-tennet-thyssengas-powertogas/german-network-companies-join-up-to-build-power-to-gas-plant-idUSKCN1MQ25R |title=German network companies join up to build power-to-gas plant |accessdate=17 October 2018|newspaper=Reuters |date=2018-10-16 }}
34. ^{{cite web |url=http://www.zsw-bw.de/infoportal/presseinformationen/presse-detail/weltweit-groesste-power-to-gas-anlage-zur-methan-erzeugung-geht-in-betrieb.html |title=Archived copy |accessdate=2017-12-01 |deadurl=yes |archiveurl=https://web.archive.org/web/20121107140857/http://www.zsw-bw.de/infoportal/presseinformationen/presse-detail/weltweit-groesste-power-to-gas-anlage-zur-methan-erzeugung-geht-in-betrieb.html |archivedate=2012-11-07 |df= }}
35. ^http://www.audi.com/content/com/brand/en/vorsprung_durch_technik/content/2013/10/energy-turnaround-in-the-tank.html
36. ^{{Cite web | url=http://www.audi.com/corporate/en/corporate-responsibility/we-live-responsibility/product/audi-e-gas-new-fuel.html | title=Company}}
37. ^{{cite web | url=http://vbt.ebi.kit.edu/index.pl/en/proj_steckb/HELMETH | title=Engler-Bunte-Institute Division of Combustion Technology - Project HELMETH | accessdate=2014-10-31}}
38. ^{{cite web | url=http://www.helmeth.eu/ | title=Project homepage - HELMETH | accessdate=2014-10-31}}
39. ^{{cite web | url=http://www.kit.edu/kit/english/pi_2014_14950.php | title=Karlsruhe Institute of Technology - Press Release 044/2014 | accessdate=2014-10-31}}
40. ^{{cite web |url=https://www.kit.edu/kit/pi_2018_009_power-to-gas-mit-hohem-wirkungsgrad.php |title=Karlsruhe Institute of Technology - Press Release 009/2018 |accessdate=2018-02-21}}
41. ^{{cite web |url=http://www.helmeth.eu/ |title=Project homepage - HELMETH | accessdate=2018-02-21}}
42. ^[https://www.beuth.de/de/norm/din-en-16723-2/265820994 DIN EN 16723-2:2017-10 - Erdgas und Biomethan zur Verwendung im Transportwesen und Biomethan zur Einspeisung ins Erdgasnetz]
43. ^{{cite web | url=http://www.dvgw.de/en/english-pages/dvgw/news-details/meldung/21697/liste/29071/link//9fdb2cfb8c7bd1d3c7811603a2bcd6d3/ | title=Deutscher Verein des Gas und Wasserfaches e.V.: Press release - Project Store&Go | accessdate=2016-12-12}}
44. ^{{cite web | url=http://www.wattdor4all.ch/projects/storego-erdgasnetz-als-riesen-batterie/ | title=Watt d'Or 4 all: "Store&Go" – Erdgasnetz als Riesen-Batterie | accessdate=2016-12-12 | deadurl=yes | archiveurl=https://web.archive.org/web/20170221014103/http://www.wattdor4all.ch/projects/storego-erdgasnetz-als-riesen-batterie/ | archivedate=2017-02-21 | df= }}
45. ^{{cite web | url=http://www.energieinstitut-linz.at/v2/portfolio-item/store-and-go/ | title=Store&Go, Innovative large-scale energy STORagE technologies AND Power-to-Gas concepts after Optimisation | accessdate=2016-12-12}}
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47. ^{{cite web | url=http://www.storeandgo.info/ | title=Project homepage - STORE&GO| accessdate=2016-12-12}}
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62. ^Excess wind power is turned into green gas in Avedøre
63. ^Electrochaea
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66. ^Power-to-Gas plant for Delfzijl
67. ^{{cite web|title=Sunshine to Petrol|url=http://energy.sandia.gov/energy/renewable-energy/solar-energy/sunshine-to-petrol/|website=Sandia National Laboratories|publisher=United States Department of Energy (DOE)|accessdate=15 May 2015}}
68. ^SNL: Sunshine to Petrol - Solar Recycling of Carbon Dioxide into Hydrocarbon Fuels
69. ^{{cite web|title=Sandia and Sunshine-to-Petrol™: Renewable Drop-in Transportation Fuels|url=https://www.fbo.gov/index?s=opportunity&mode=form&id=698e254d2c8fea2fc478add76d2aac1c&tab=core&_cview=0|website=Federal Business Opportunities|publisher=U.S. Federal Government|accessdate=15 May 2015|date=Oct 29, 2013}}
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72. ^Onur Taylan and Halil Berberoglu (2013). Fuel Production Using Concentrated Solar Energy, Application of Solar Energy, Prof. Radu Rugescu (Ed.), {{ISBN|978-953-51-0969-3}}, InTech, DOI: 10.5772/54057. Available from: Intechopen.com
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75. ^Newsletter NewCO2Fuels, Issue 1, September 2012
76. ^From challenge to opportunity New {{chem|C|O|2}} Fuels: An Introduction...
77. ^{{cite web|title=SOLAR-JET Project|url=http://www.solar-jet.aero/page/about-solar-jet/objectives.php|website=SOLAR-JET|publisher=SOLAR-JET Project Office: ARTTIC|accessdate=15 May 2015}}
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82. ^Brewing fuels in a solar furnace
83. ^Syntrolysis, Synthetic Fuels from Carbon Dioxide, Electricity and Steam
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86. ^Nuclear Hydrogen Initiative Overview
87. ^[https://www.iaea.org/About/Policy/GC/GC57/GC57InfDocuments/English/gc57inf-2-att1_en.pdf Nuclear Hydrogen Production Technology]
88. ^Electrolysis For Synthetic Fuel Production {{webarchive|url=https://web.archive.org/web/20150530075842/http://www.topsoe.com/sites/default/files/topsoe_scot_electrolysis_synthetic_fuel_production.pdf |date=2015-05-30 }}
89. ^{{cite web|title=The WindFuels™ Primer - Basic Explanation for the Non-scientist|url=http://dotyenergy.com/Introduction/primer.htm|website=Doty Energy|publisher=Doty Energy|accessdate=16 May 2015}}
90. ^Securing Our Energy Future by Efficiently Recycling CO₂ into Transportation Fuels
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92. ^Case Study: AFS demonstrator unit
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97. ^{{cite web|title=BGU Researchers invent Green Alternative to Crude Oil|url=http://in.bgu.ac.il/en/Pages/news/oil_greenalternative.aspx|website=Ben-Gurion University of the Negev|publisher=Ben-Gurion University of the Negev|accessdate=17 May 2015|date=13 November 2013}}
98. ^{{cite web|title=Recent Success Story: Converting carbon dioxide, a damaging greenhouse gas, into fuel that may be used for transportation|url=http://www.i-saef.org/early-success.html|website=I-SAEF|publisher=Israel Strategic Alternative Energy Foundation|accessdate=15 May 2015}}
99. ^{{cite web|title=BGU Researchers Develop New Type of Crude Oil Using Carbon Dioxide and Hydrogen|url=http://www.bgustudyabroad.org/media-center/news-releases/bgu-crude-oil.html|website=American Associates (Ben-Gurion University of the Negev)|publisher=American Associates (AABGU)|accessdate=15 May 2015|deadurl=yes|archiveurl=https://web.archive.org/web/20150518102319/http://www.bgustudyabroad.org/media-center/news-releases/bgu-crude-oil.html|archivedate=18 May 2015|df=}}
100. ^{{cite web|title=BGU researchers developing more efficient process for hydrogenation of CO2 to synthetic crude|url=http://www.greencarcongress.com/2013/11/20131121-bgu.html|website=Green Car Congress|publisher=BioAge Group, LLC|accessdate=15 May 2015|date=21 November 2013}}
101. ^{{cite web|title=Fuel of the future: Research facility in Dresden produces first batch of Audi e-diesel|url=https://www.audi-mediaservices.com/publish/ms/content/en/public/pressemitteilungen/2015/04/21/fuel_of_the_future.html|website=Audi MediaServices - Press release|publisher=AUDI AG.|accessdate=23 May 2015|location=Ingolstadt/Berlin|date=2015-04-21}}
102. ^{{cite web|last1=Rapier|first1=Robert|title=Is Audi's Carbon-Neutral Diesel a Game-Changer?|url=http://www.energytrendsinsider.com/2015/04/30/is-audis-carbon-neutral-diesel-a-game-changer/|website=Energy Trends Insider|publisher=Energy Trends Insider|accessdate=15 May 2015}}
103. ^{{cite web|last1=Novella|first1=Steven|authorlink=Steven Novella|title=Apr 28 2015 Audi's E-Diesel|url=http://theness.com/neurologicablog/index.php/audis-e-diesel/|website=The NeuroLogicaBlog - Technology|publisher=Steven Novella, MD|accessdate=24 May 2015|date=28 April 2015}}
104. ^{{cite web|title=How the United States Navy Plans to Turn Seawater into Jet Fuel|url=http://www.altenergy.org/new_energy/seawater-into-jet-fuel.html|website=Alternative Energy|publisher=altenergy.org|accessdate=8 May 2015}}
105. ^{{cite web|title=Patent: US 20140238869 A1|url=http://www.google.com/patents/US20140238869?cl=en|website=Google Patents|publisher=Google Inc.|accessdate=8 May 2015}}
106. ^The total carbon content of the world's oceans is roughly 38,000 GtC. Over 95% of this carbon is in the form of dissolved bicarbonate ion (HCO₃ ⁻). (Cline 1992, The Economics of Global Warming; Institute for International Economics: Washington D.C.). The dissolved bicarbonate and carbonate of the ocean is essentially bound CO₂ and the sum of these species along with gaseous CO₂, shown in the following equation, represents the total carbon dioxide concentration [CO₂]_T, of the world's oceans. Σ[CO₂]_T=[CO₂(g)]_l+[HCO₃ ⁻]+[CO₃ ²⁻]