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Synthetic Fuels

There are several pathways for producing hydrocarbon fuels from non-petroleum sources, such as electricity. However, we find that electrofuels, or synthetic fuels from electricity, are cost prohibitive at this time.

Environmental Impacts

The following compares greenhouse gas emissions from several methods of producing complex hydrocarbons.

The image: "synfuel_ghg.svg" cannot be found!

Sources: Lattanzio 1, Steele et al. 2, Tu et al. 3, EPA 4. Electrofuels, also known as power-to-fuel, are hydrocarbons that are produced from electrolyzed hydrogen. For these, the emissions intensity of electricity is taken from Schlömer et al. 5 and a conversion efficiency of 40-50% is applied, as estimated by Malins 6. No emissions other than those from electricity are assumed, though additional emissions should be attributed if the CO₂ source is from a flue gas and would otherwise be sequestered 6. Carbon capture and sequestration might also reduce emissions from coal- and gas-to-liquids 7.

Despite the low efficiency of electrofuel production, corn ethanol requires far more land per unit energy.

The image: "synfuel_landuse.svg" cannot be found!

The land use estimate of algal biodiesel is estimated from Atabani et al. 8. Yeh et al. 9 report land use from oil production. Data from Building Energy Codes Program 10 is used to estimate the primary energy behind electricity, Malins 6 gives the conversion efficiency, and Ong et al. 11 give the land use of solar power. Efficiency on gas-to-liquids is from Steynberg and Dry 12, and for coal-to-liquids from Höök and Aleklett 13. Additional land use estimates are taken from General Electric 14, Stevens et al. 15, World Energy Council 16.

Energy Requirements

As an energy carrier, liquid fuels require more primary energy input to produce than energy they contain. The conversion efficiency of primary energy into usable fuel varies by production method.

The image: "synfuel_primary.svg" cannot be found!

Sources: Höök and Aleklett 13 for coal-to-liquids and Steynberg and Dry 12 for gas-to-liquids. The low efficiency of electrofuels stem from two conversion processes: from a primary energy source into electricity, with efficiency about 32% (Building Energy Codes Program 10); and then from electricity into hydrocarbons, with efficiency 40-50% (Malins 6).

In cars, electrofuels are a much less efficient use of electricity than direct use in an electric vehicle, and also less efficient than hydrogen.

The image: "electricity_fuel_eff.svg" cannot be found!

Source: Malins 6. The low efficiency of electrofuels stems from additional losses from the internal combustion engine, which has an efficiency of about 30% in modern cars (fueleconomy.gov 17).

Economics of Synthetic Fuels

With the exception of sugarcane ethanol, most alternatives to petroleum-based gasoline are more expensive and not widely used without policy support.

The image: "synfuel_price.svg" cannot be found!

Sources: Biofuels and Emerging Technologies Team 18 for gas-to-liquids, Brynolf et al. 19 for electrofuels, Mantripragada and Rubin 20 for coal-to-liquids, Moyo et al. 21 for biofuels, and the EIA 22 for wholesale gasoline as of June 2019. Electrofuels are especially expensive due to energy losses in the production processes. Prices are highly dependent on the price of feedstock.

The conversion of coal and natural gas into liquid fuels carry heavy greenhouse gas and other environmental costs, and they are not likely to ever be economically attractive options 23, 24. Aside from sugarcane, biofuels are also unlikely to be economically sound, and they carry major land use impacts. Electrofuels can be an acceptable option only with a low-cost and low-impact electricity source, and even then their use is likely to be confined to sectors that are difficult to electrify directly, such as aviation and long-distance trucking 6.

Carbon abatement costs of electrofuels are as follows.

The image: "synfuel_cost.svg" cannot be found!

Cost of synthetic fuels, with a carbon cost of $50/ton, and estimated carbon abatement cost. A plant size of 50,000 barrels per day is assumed, as per 25.

With such high carbon abatement costs, it does not make sense for a private developer to build a synfuel plant.

Problem:
Emissions From Aviation
Solution:
Electrofuels for Aviation

References

  1. Lattanzio, R. "Canadian Oil Sands: Life-Cycle Assessments of Greenhouse Gas Emissions". Congressional Research Service. May 2012. ↩

  2. Steele, P., Puettmann, M., Penmetsa, V., Cooper, J. "Life-Cycle Assessment of Pyrolysis Bio-Oil Production". Forest Products Journal 62(4), pp. 326-334. 2012. ↩

  3. Tu, Q., Eckelman, M., Zimmerman, J. "Harmonized algal biofuel life cycle assessment studies enable direct process train comparison". Applied Energy 224, pp. 494-509. August 2018. ↩

  4. U.S. Environmental Protection Agency. "Lifecycle Greenhouse Gas Results". Accessed June 11, 2019. ↩

  5. Schlömer S., T. Bruckner, L. Fulton, E. Hertwich, A. McKinnon, D. Perczyk, J. Roy, R. Schaeffer, R. Sims, P. Smith, and R. Wiser. Annex III: Technology-specific cost and performance parameters. In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 2014. ↩

  6. Malins, C. "What role is there for electrofuel technologies in European transport’s low carbon future?". Cerulogy. November 2017. ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  7. Jaramillo, P., Griffin, M., Matthews, S. "Comparative Analysis of the Production Costs and Life-Cycle GHG Emissions of FT Liquid Fuels from Coal and Natural Gas". Environmental Science & Technology 42(20), pp. 7559-7565. 2008. ↩

  8. Atabani, A., Silitonga, A., Badruddin, I., Mahlia, T., Masjuki, H., Mekhilef, H. "A comprehensive review on biodiesel as an alternative energy resource and its characteristic". Renewable and Sustainable Energy Reviews, 16(4), pp. 2070-2093. May 2012. ↩

  9. Yeh, S., Jordaan, S., Brandt, A., Turetsky, M., Spatari, S., Keith, D. "Land Use Greenhouse Gas Emissions from Conventional Oil Production and Oil Sands". Environ. Sci. Technol., 44(22), pp. 8766-8772. October 2010. ↩

  10. Building Energy Codes Program. "Prototype Building Models High-rise Apartment". Building Technologies Office, Office of Energy Efficiency and Renewable Energy, U. S. Department of Energy. April 2011. ↩ ↩2

  11. Ong, S., Campbell, C., Denholm, P., Margolis R., Heath, G. "Land-Use Requirements for Solar Power Plants in the United States". June 2013. ↩

  12. Steynberg, A., Dry, M. Fischer-Tropsch Technology. Elsevier Science, Volume 152, 1st Edition, Hardcover ISBN: 9780444513540, eBook ISBN: 9780080472799. October 2004. ↩ ↩2

  13. Höök, M., Aleklett, K. "A review on coal to liquid fuels and its coal consumption". International Journal of Energy Research 34(10), pp. 848-864. October 2010. ↩ ↩2

  14. General Electric. "GE Global Power Plant Efficiency Analysis". Accessed June 22, 2019. ↩

  15. Stevens, L., Anderson, B., Cowan, C., Colton, K., Johnson, D. "The Footprint of Energy: Land Use of U.S. Electricity Production". Strata. June 2017. ↩

  16. World Energy Council. "Energy Efficiency Indicators". Accessed June 22, 2019. ↩

  17. fueleconomy.gov. "Where the Energy Goes: Gasoline Vehicles". Office of Energy Efficiency and Renewable Energy, U.S. Environmental Protection Agency. Accessed September 3, 2019. ↩

  18. Biofuels and Emerging Technologies Team. "Gas-To-Liquid (GTL) Technology Assessment in support of AEO2013". Energy Information Administration, U.S. Department of Energy. January 2013. ↩

  19. Brynolf, S., Taljegard, M., Grahn, M,. Hansson, J. "Electrofuels for the transport sector: A review of production costs". Renewable and Sustainable Energy Systems 81(2), pp. 1887-1905. January 2018. ↩

  20. Mantripragada, H., Rubin, E. "Performance, cost and emissions of coal-to-liquids (CTLs) plants using low-quality coals under carbon constraints". Fuel 103, pp. 805-813. October 2012. ↩

  21. Moyo, P., Moyo, M., Dube, D., Rusinga, O. "Biofuel Policy as a Key Driver for Sustainable Development in the Biofuel Sector: The Missing Ingredient in Zimbabwe’s Biofuel Pursuit". Modern Applied Science 8(1), pp. 36-58. December 2013. ↩

  22. U.S. Energy Information Administration. "Daily Prices". Accessed June 29, 2019. ↩

  23. Höök, M., Fantazzini, D., Angelantoni, A., Snowden, S. "Hydrocarbon liquefaction: viability as a peak oil mitigation strategy". Philosophical Transactions. Series A: Mathematical, physical, and engineering science, 372(2006). January 2014. ↩

  24. Ramberg, D., Chen, Y., Paltsev, S., Parsons, J. "The economic viability of gas-to-liquids technology and the crude oil–natural gas price relationship". Energy Economics 63, pp. 13-21. March 2017. ↩

  25. Industrial Environmental Research Laboratory. "Environmental Aspects of Synfuel Utilization". March 1981. ↩