Carbon-neutral fuel

Source: Wikipedia, the free encyclopedia.

Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint. In practice, this usually means fuels that are made using carbon dioxide (CO2) as a feedstock. Proposed carbon-neutral fuels can broadly be grouped into synthetic fuels, which are made by chemically hydrogenating carbon dioxide, and biofuels, which are produced using natural CO2-consuming processes like photosynthesis.[1]

The carbon dioxide used to make synthetic fuels may be

fossil fuels without requiring either electrification of the vehicle fleet or conversion to hydrogen or other fuels, enabling continued compatible and affordable vehicles.[4] In order to be truly carbon-neutral, any energy required for the process must be itself be carbon-neutral or emissions-free, like renewable energy or nuclear energy.[5][6][7][8]

If the

Carbon credits are likely to play an important role for carbon-negative fuels.[10]

Production of synthetic hydrocarbons

Synthetic hydrocarbons can be produced in chemical reactions between carbon dioxide, which can be captured from power plants or the air, and

hydrogen. The fuel, often referred to as electrofuel, stores the energy that was used in the production of the hydrogen.[11]

Hydrogen fuel is typically prepared by the

power to gas process. To minimize emissions, the electricity is produced using a low-emission energy source such as wind, solar, or nuclear power.[12]

Through the

power plants (as a synthetic natural gas), transported by pipeline, truck, or tanker ship, or be used in gas to liquids processes such as the Fischer–Tropsch process to make traditional fuels for transportation or heating.[4][13][14]

There are a few more fuels that can be created using hydrogen. Formic acid for example can be made by reacting the hydrogen with CO2. Formic acid combined with CO2 can form isobutanol.[15]

Methanol can be made from a chemical reaction of a carbon-dioxide molecule with three hydrogen molecules to produce methanol and water. The stored energy can be recovered by burning the methanol in a combustion engine, releasing carbon dioxide, water, and heat.

methane leaks are important since methane is nearly 100 times as potent as CO2, regarding the 20-year global warming potential. More energy can be used to combine methanol or methane into larger hydrocarbon fuel molecules.[4]

Researchers have also suggested using methanol to produce dimethyl ether. This fuel could be used as a substitute for diesel fuel due to its ability to self ignite under high pressure and temperature. It is already being used in some areas for heating and energy generation. It is nontoxic, but must be stored under pressure.[16] Larger hydrocarbons[17] and ethanol[18] can also be produced from carbon dioxide and hydrogen.

All synthetic hydrocarbons are generally produced at temperatures of 200–300 °C, and at pressures of 20 to 50 bar.

Catalysts are usually used to improve the efficiency of the reaction and create the desired type of hydrocarbon fuel. Such reactions are exothermic and use about 3 mol of hydrogen per mole of carbon dioxide involved. They also produce large amounts of water as a byproduct.[5]

Sources of carbon for recycling

The most economical source of carbon for recycling into fuel is

Carbon capture from ambient air is more costly, at between $94 and $232 per ton and is considered impractical for fuel synthesis or carbon sequestration.[22] Direct air capture is less developed than other methods. Proposals for this method involve using a caustic chemical to react with carbon dioxide in the air to produce carbonates. These can then be broken down and hydrated to release pure CO2 gas and regenerate the caustic chemical. This process requires more energy than other methods because carbon dioxide is at much lower concentrations in the atmosphere than in other sources.[4]

Researchers have also suggested using biomass as a carbon source for fuel production. Adding hydrogen to the biomass would reduce its carbon to produce fuel. This method has the advantage of using plant matter to cheaply capture carbon dioxide. The plants also add some chemical energy to the fuel from biological molecules. This may be a more efficient use of biomass than conventional biofuel because it uses most of the carbon and chemical energy from the biomass instead of releasing as much energy and carbon. Its main disadvantage is, as with conventional ethanol production, it competes with food production.[5]

Renewable and nuclear energy costs

Nighttime

wholesale electricity costs 2 to 5 cents/kWh during the day.[23] Commercial fuel synthesis companies suggest they can produce gasoline for less than petroleum fuels when oil costs more than $55 per barrel.[24]

In 2010, a team of process chemists led by Heather Willauer of the U.S. Navy, estimates that 100 megawatts of electricity can produce 160 cubic metres (41,000 US gal) of jet fuel per day and shipboard production from nuclear power would cost about $1,600 per cubic metre ($6/US gal). While that was about twice the petroleum fuel cost in 2010, it is expected to be much less than the market price in less than five years if recent trends continue.[needs update] Moreover, since the delivery of fuel to a carrier battle group costs about $2,100 per cubic metre ($8/US gal), shipboard production is already much less expensive.[25]

Willauer said seawater is the "best option" for a source of synthetic jet fuel.[26][27] By April 2014, Willauer's team had not yet made fuel to the standard required by military jets,[28][29] but they were able in September 2013 to use the fuel to fly a radio-controlled model airplane powered by a common two-stroke internal combustion engine.[30] Because the process requires a large input of electrical energy, a plausible first step of implementation would be for American nuclear-powered aircraft carriers (the Nimitz-class and the Gerald R. Ford-class) to manufacture their own jet fuel.[31] The U.S. Navy is expected to deploy the technology some time in the 2020s.[26]

In 2023, a study published by the NATO Energy Security Centre of Excellence, concluded that e-fuels offer one of the most promising decarbonization pathways for military mobility across the land, sea and air domains.[32]

Demonstration projects and commercial development

A 250 kilowatt methane synthesis plant was constructed by the Center for Solar Energy and Hydrogen Research (ZSW) at Baden-Württemberg and the Fraunhofer Society in Germany and began operating in 2010. It is being upgraded to 10 megawatts, scheduled for completion in autumn 2012.[33][34]

The

Svartsengi Power Station since 2011.[35] It has the capacity to produce 5 million liters per year.[36]

Werlte, Germany.[37] The plant is intended to produce transportation fuel to offset LNG used in their A3 Sportback g-tron automobiles, and can keep 2,800 metric tons of CO2 out of the environment per year at its initial capacity.[38]

Zero, a British-based company set up by former F1 engineer Paddy Lowe, has developed a process it terms 'petrosynthesis' to develop synthetic fuels from atmospheric carbon dioxide and water using renewable energy. In 2022 it began work on a demonstration production plant[39]
at Bicester Heritage near Oxford.

Commercial developments are taking place in

food oils from recovered flue gases.[43]

Greenhouse gas remediation

Carbon-neutral fuels can lead to greenhouse gas remediation because carbon dioxide gas would be reused to produce fuel instead of being released into the atmosphere. Capturing the carbon dioxide in flue gas emissions from power plants would eliminate their greenhouse gas emissions, although burning the fuel in vehicles would release that carbon because there is no economical way to capture those emissions.

demand growth and peak oil shortages increase the price of petroleum and fungible natural gas.[46][47]

Capturing CO2 directly from the air, known as direct air capture, or extracting carbonic acid from seawater would also reduce the amount of carbon dioxide in the environment, and create a closed cycle of carbon to eliminate new carbon dioxide emissions.[5] Use of these methods would eliminate the need for fossil fuels entirely, assuming that enough renewable energy could be generated to produce the fuel. Using synthetic hydrocarbons to produce synthetic materials such as plastics could result in permanent sequestration of carbon from the atmosphere.[4]

Technologies

Traditional fuels, methanol or ethanol

Some authorities have recommended producing methanol instead of traditional transportation fuels. It is a liquid at normal temperatures and can be toxic if ingested. Methanol has a higher octane rating than gasoline but a lower energy density, and can be mixed with other fuels or used on its own. It may also be used in the production of more complex hydrocarbons and polymers. Direct methanol fuel cells have been developed by Caltech's Jet Propulsion Laboratory to convert methanol and oxygen into electricity.[16] It is possible to convert methanol into gasoline, jet fuel or other hydrocarbons, but that requires additional energy and more complex production facilities.[4] Methanol is slightly more corrosive than traditional fuels, requiring automobile modifications on the order of US$100 each to use it.[5][48]

In 2016, a method using carbon spikes, copper nanoparticles and nitrogen that converts carbon dioxide to ethanol was developed.[49]

Microalgae

Fuel made from microalgae could potentially have a low carbon footprint and is an active area of research, although no large-scale production system has been commercialized to date. Microalgae are aquatic unicellular organisms. Although they, unlike most plants, have extremely simple cell structures, they are still photoautotrophic, able to use solar energy to convert carbon dioxide into carbohydrates and fats via photosynthesis. These compounds can serve as raw materials for biofuels like bioethanol or biodiesel.[50] Therefore, even though combusting microalgae-based fuel for energy would still produce emissions like any other fuel, it could be close to carbon-neutral if they, as a whole, consumed as much carbon dioxide as is emitted during combustion.

The advantages of microalgae are their higher CO2-fixation efficiency compared to most plants[51] and their ability to thrive in a wide variety of aquatic habitats.[52] Their main disadvantage is their high cost. It has been argued that their unique and highly variable chemical compositions may make it attractive for specific applications.[50]

Microalgae also can be used as livestock feed due to their proteins. Even more, some species of microalgae produce valuable compounds such as pigments and pharmaceuticals.[53]

Production

Raceway pond used for the cultivation of microalgae. The water is kept in constant motion with a powered paddle wheel.

Two main ways of cultivating microalgae are raceway pond systems and photo-bioreactors. Raceway pond systems are constructed by a closed loop oval channel that has a paddle wheel to circulate water and prevent sedimentation. The channel is open to the air and its depth is in the range of 0.25–0.4 m (0.82–1.31 ft).[50] The pond needs to be kept shallow since self-shading and optical absorption can cause the limitation of light penetration through the solution of algae broth. PBRs's culture medium is constructed by closed transparent array of tubes. It has a central reservoir which circulated the microalgae broth. PBRs is an easier system to be controlled compare to the raceway pond system, yet it costs a larger overall production expenses.[citation needed]

The carbon emissions from microalgae biomass produced in raceway ponds could be compared to the emissions from conventional biodiesel by having inputs of energy and nutrients as carbon-intensive. The corresponding emissions from microalgae biomass produced in PBRs could also be compared and might even exceed the emissions from conventional fossil diesel. The inefficiency is due to the amount of electricity used to pump the algae broth around the system. Using co-product to generate electricity is one strategy that might improve the overall carbon balance. Another thing that needs to be acknowledged is that environmental impacts can also come from water management, carbon dioxide handling, and nutrient supply, several aspects that could constrain system design and implementation options. But, in general, Raceway Pond systems demonstrate a more attractive energy balance than PBR systems.[citation needed]

Economy

Production cost of microalgae-biofuel through implementation of raceway pond systems is dominated by the operational cost which includes labour, raw materials, and utilities. In raceway pond system, during the cultivation process, electricity takes up the largest energy fraction of total operational energy requirements. It is used to circulate the microalgae cultures. It takes up an energy fraction ranging from 22% to 79%.[50] In contrast, capital cost dominates the cost of production of microalgae-biofuel in PBRs. This system has a high installation cost though the operational cost is relatively lower than raceway pond systems.[citation needed]

Microalgae-biofuel production costs a larger amount of money compared to fossil fuel production. The cost estimation of producing microalgae-biofuel is around $3.1 per litre ($11.57/US gal),[54] which is considerably more expensive than conventional gasoline. However, when compared with electrification of the vehicle fleet – a key advantage of such biofuel is the avoidance of the costly distribution of large amounts of electrical energy (as is required to convert existing vehicle fleets to battery electric technology), therein allowing for the re-use of the existing liquid-fuel transportation infrastructure. Biofuel such as ethanol is also greatly more energy dense than current battery technologies (approximately 6x as much[55]) further promoting its economic viability.

Environmental impact

The construction of large-scale microalgae cultivation facilities would inevitably result in negative environmental impacts related to land use change, such as the destruction of existing natural habitats. Microalgae can also under certain conditions emit greenhouse gases, like methane or nitrous oxide, or foul-smelling gases, like hydrogen sulfide, although this has not been widely studied to date. If poorly managed, toxins naturally produced by microalgae may leak into the surrounding soil or ground water.[56]

Production

Water undergoes electrolysis at high temperatures to form hydrogen gas and oxygen gas. The energy to perform this is extracted from renewable sources such as wind power. Then, the hydrogen is reacted with compressed carbon dioxide captured by direct air capture. The reaction produces blue crude which consists of hydrocarbon. The blue crude is then refined to produce high efficiency E-diesel.[57][58] This method is, however, still debatable because with the current production capability it can only produce 3,000 liters in a few months, 0.0002% of the daily production of fuel in the US.[59] Furthermore, the thermodynamic and economic feasibility of this technology have been questioned. An article suggests that this technology does not create an alternative to fossil fuel but rather converting renewable energy into liquid fuel. The article also states that the energy return on energy invested using fossil diesel is 18 times higher than that for e-diesel.[60]

History

Investigation of carbon-neutral fuels has been ongoing for decades. A 1965 report suggested synthesizing methanol from carbon dioxide in air using nuclear power for a mobile fuel depot.

vehicle fleets for the use of carbon-neutral methanol with the further synthesis of gasoline.[48]

See also

References

Books and reports

  • Sustainable Synthetic Carbon Based Fuels for Transport. London: Royal Society. 2019. .

Notes

  1. ^ Trakimavičius, Lukas (October 6, 2021). "Synthetic fuels can bolster energy security in the Baltic region". EurActiv. Archived from the original on October 6, 2021. Retrieved October 12, 2021.
  2. ^ Leighty and Holbrook (2012) "Running the World on Renewables: Alternatives for Trannd Low-cost Firming Storage of Stranded Renewable as Hydrogen and Ammonia Fuels via Underground Pipelines" Proceedings of the ASME 2012 International Mechanical Engineering Congress & Exposition November 9–15, 2012, Houston, Texas
  3. ^ "Air Fuel Synthesis shows petrol from air has future". Archived from the original on 2019-06-05. Retrieved 2019-06-05.
  4. ^
    S2CID 3560886. Archived from the original
    (PDF) on May 8, 2013. Retrieved September 7, 2012. (Review.)
  5. ^
    S2CID 2055798. Archived from the original
    (PDF) on May 25, 2013. Retrieved September 7, 2012. (Review.)
  6. . (Review.)
  7. ^ (PDF) from the original on 2015-12-11. Retrieved 2019-07-16. (Review.)
  8. ^ from the original on November 23, 2021. Retrieved July 6, 2013.
  9. ^ McKie, Robin (2021-01-16). "Carbon capture is vital to meeting climate goals, scientists tell green critics". The Guardian. Archived from the original on 2021-04-30. Retrieved 2021-04-28.
  10. .
  11. S2CID 3560886. Archived from the original
    (PDF) on 8 May 2013. Retrieved 18 October 2012.
  12. ^ Royal Society 2019, p. 7.
  13. ^ .
  14. .
  15. ^ https://cleanleap.com/extracting-energy-air-future-fuel Archived 2020-10-03 at the Wayback Machine Extracting energy from air – is this the future of fuel?
  16. ^
    S2CID 25108611
    .
  17. ^ "Integration of Power to Gas/Power to Liquids into the ongoing transformation process" (PDF). June 2016. p. 12. Archived (PDF) from the original on August 11, 2017. Retrieved August 10, 2017.
  18. ^ "Technical Overview". Archived from the original on 2019-05-09. Retrieved 2017-08-10.
  19. ^ a b Socolow, Robert; et al. (June 1, 2011). Direct Air Capture of CO2 with Chemicals: A Technology Assessment for the APS Panel on Public Affairs (PDF) (peer reviewed literature review). American Physical Society. Archived (PDF) from the original on September 3, 2019. Retrieved September 7, 2012.
  20. ^ DiMascio, Felice; Willauer, Heather D.; Hardy, Dennis R.; Lewis, M. Kathleen; Williams, Frederick W. (July 23, 2010). Extraction of Carbon Dioxide from Seawater by an Electrochemical Acidification Cell. Part 1 – Initial Feasibility Studies (PDF) (memorandum report). Washington, DC: Chemistry Division, Navy Technology Center for Safety and Survivability, U.S. Naval Research Laboratory. Archived from the original on March 2, 2020. Retrieved September 7, 2012.
  21. ^ Willauer, Heather D.; DiMascio, Felice; Hardy, Dennis R.; Lewis, M. Kathleen; Williams, Frederick W. (April 11, 2011). Extraction of Carbon Dioxide from Seawater by an Electrochemical Acidification Cell. Part 2 – Laboratory Scaling Studies (memorandum report). Washington, DC: Chemistry Division, Navy Technology Center for Safety and Survivability, U.S. Naval Research Laboratory. Archived from the original on April 13, 2013. Retrieved September 7, 2012.
  22. S2CID 134813287
    .
  23. ^ Electricity Price Archived 2019-01-16 at the Wayback Machine NewFuelist.com (compare to off-peak wind power price graph. Archived 2014-10-06 at the Wayback Machine) Retrieved September 7, 2012.
  24. ^ Holte, Laura L.; Doty, Glenn N.; McCree, David L.; Doty, Judy M.; Doty, F. David (2010). Sustainable Transportation Fuels From Off-peak Wind Energy, CO2 and Water (PDF). 4th International Conference on Energy Sustainability, May 17–22, 2010. Phoenix, Arizona: American Society of Mechanical Engineers. Archived (PDF) from the original on November 15, 2011. Retrieved September 7, 2012.
  25. ^ Willauer, Heather D.; Hardy, Dennis R.; Williams, Frederick W. (September 29, 2010). Feasibility and Current Estimated Capital Costs of Producing Jet Fuel at Sea (memorandum report). Washington, DC: Chemistry Division, Navy Technology Center for Safety and Survivability, U.S. Naval Research Laboratory. Archived from the original on April 8, 2013. Retrieved September 7, 2012.
  26. ^ a b Tozer, Jessica L. (April 11, 2014). "Energy Independence: Creating Fuel from Seawater". Armed with Science. U.S. Department of Defense. Archived from the original on April 12, 2014.
  27. ^ Koren, Marina (December 13, 2013). "Guess What Could Fuel the Battleships of the Future?". National Journal. Archived from the original on June 3, 2015. Retrieved October 7, 2018.
  28. ^ Tucker, Patrick (April 10, 2014). "The Navy Just Turned Seawater Into Jet Fuel". Defense One. Archived from the original on March 27, 2019. Retrieved October 7, 2018.
  29. ^ Ernst, Douglas (April 10, 2014). "U.S. Navy to turn seawater into jet fuel". The Washington Times. Archived from the original on September 7, 2018. Retrieved October 7, 2018.
  30. ^ Parry, Daniel (April 7, 2014). "Scale Model WWII Craft Takes Flight With Fuel From the Sea Concept". Naval Research Laboratory News. Archived from the original on August 22, 2017. Retrieved October 8, 2018.
  31. ^ Putic, George (May 21, 2014). "US Navy Lab Turns Seawater Into Fuel". VOA News. Archived from the original on June 1, 2016. Retrieved October 7, 2018.
  32. ^ Trakimavicius, Lukas (December 2023). "Mission Net-Zero: Charting the Path for E-fuels in the Military". NATO Energy Security Centre of Excellence.
  33. ^ Center for Solar Energy and Hydrogen Research Baden-Württemberg (2011). "Verbundprojekt 'Power-to-Gas'". zsw-bw.de (in German). Archived from the original on February 16, 2013. Retrieved September 9, 2012.
  34. ^ Center for Solar Energy and Hydrogen Research (July 24, 2012). "Bundesumweltminister Altmaier und Ministerpräsident Kretschmann zeigen sich beeindruckt von Power-to-Gas-Anlage des ZSW". zsw-bw.de (in German). Archived from the original on September 27, 2013. Retrieved September 9, 2012.
  35. ^ "George Olah CO2 to Renewable Methanol Plant, Reykjanes, Iceland" Archived 2021-01-25 at the Wayback Machine (Chemicals-Technology.com)
  36. ^ "First Commercial Plant" Archived February 4, 2016, at the Wayback Machine (Carbon Recycling International)
  37. ^ Okulski, Travis (June 26, 2012). "Audi's Carbon Neutral E-Gas Is Real And They're Actually Making It". Jalopnik (Gawker Media). Archived from the original on 11 February 2021. Retrieved 29 July 2013.
  38. ^ Rousseau, Steve (June 25, 2013). "Audi's New E-Gas Plant Will Make Carbon-Neutral Fuel". Popular Mechanics. Archived from the original on 6 October 2014. Retrieved 29 July 2013.
  39. ^ Calderwood, Dave (2022-10-05). "Zero Petroleum to produce synthetic fuels at Bicester". FLYER. Retrieved 2023-01-13.
  40. ^ "Doty Windfuels". Archived from the original on 2015-05-24. Retrieved 2012-09-04.
  41. ^ "CoolPlanet Energy Systems". Archived from the original on 2013-03-05. Retrieved 2012-09-04.
  42. ^ "Air Fuel Synthesis, Ltd". Archived from the original on 2015-04-27. Retrieved 2012-09-04.
  43. ^ "Kiverdi Receives Energy Commission Funding for Its Pioneering Carbon Conversion Platform". Yahoo! Finance. September 5, 2012. Retrieved September 12, 2012.[dead link]
  44. ^ DiPietro, Phil; Nichols, Chris; Marquis, Michael (January 2011). Coal-Fired Power Plants in the United States: Examination of the Costs of Retrofitting with CO2 Capture Technology, Revision 3 (PDF) (report NETL-402/102309). National Energy Technology Laboratory, U.S. Department of Energy. DOE contract DE-AC26-04NT41817. Archived from the original (PDF) on September 4, 2012. Retrieved September 7, 2012.
  45. (PDF) from the original on March 17, 2017. Retrieved September 7, 2012. (Review.)
  46. . (Review.)
  47. .
  48. ^ a b Steinberg, Meyer (August 1995). The Carnol Process for CO2 Mitigation from Power Plants and the Transportation Sector (PDF) (informal report BNL–62110). Upton, New York: Department of Advanced Technology, Brookhaven National Laboratory. (Prepared for the U.S. Department of Energy under Contract No. DE-AC02-76CH00016). Archived from the original on November 22, 2021. Retrieved September 7, 2012.
  49. ^ Johnston, Ian (2016-10-19). "Scientists accidentally turn pollution into renewable energy". The Independent. Archived from the original on 2016-10-20. Retrieved 2016-10-19.
  50. ^
    ISSN 0961-9534
    .
  51. .
  52. .
  53. from the original on 2021-04-28. Retrieved 2021-04-28.
  54. .
  55. ^ "The role of hydrogen and ammonia in meeting the net zero challenge" (PDF). The Royal Society. Archived (PDF) from the original on 2 July 2021. Retrieved 25 February 2024.
  56. S2CID 55670420
    .
  57. ^ "How to Make Diesel Fuel from Water and Air – Off Grid World". Off Grid World. 2015-05-25. Archived from the original on 2018-12-07. Retrieved 2018-11-30.
  58. ^ MacDonald, Fiona. "Audi Has Successfully Made Diesel Fuel From Carbon Dioxide And Water". ScienceAlert. Archived from the original on 2018-12-07. Retrieved 2018-11-30.
  59. ^ "Reality check: Audi making e-diesel from air and water won't change the car industry". Alphr. Archived from the original on 2015-09-01. Retrieved 2018-12-07.
  60. ^ Mearns, Euan (2015-05-12). "The Thermodynamic and Economic Realities of Audi's E Diesel". Energy Matters. Archived from the original on 2017-02-05. Retrieved 2018-12-07.
  61. . (General, Miscellaneous, and Progress Reports — TID–4500, 46th Ed.).
  62. from the original on 2021-09-27. Retrieved 2021-09-27.
  63. ^ Bushore, U.S. Navy Lieutenant Robin Paul (May 1977). Synthetic Fuel Generation Capabilities of Nuclear Power Plants with Applications to Naval Ship Technology (M.Sc. thesis). Cambridge, Massachusetts: Department of Ocean Engineering, Massachusetts Institute of Technology. Retrieved September 7, 2012.
  64. ^ Terry, U.S. Navy Lieutenant Kevin B. (June 1995). Synthetic Fuels for Naval Applications Produced Using Shipboard Nuclear Power (M.Sc. thesis). Cambridge, Massachusetts: Department of Nuclear Engineering, Massachusetts Institute of Technology. Archived from the original on August 10, 2012. Retrieved September 7, 2012.
  65. ^ Steinberg, M.; et al. (1984). A Systems Study for the Removal, Recovery and Disposal of Carbon Dioxide from Fossil Power Plants in the U.S. (technical report DOE/CH/0016-2). Washington, D.C.: U.S. Department of Energy, Office of Energy Research, Carbon Dioxide Research Division. Archived from the original on November 21, 2021. Retrieved September 8, 2012.

Further reading

External links