Biokerosene pp 607-635 | Cite as

Hydrothermal Liquefaction: A Promising Pathway Towards Renewable Jet Fuel

  • Patrick BillerEmail author
  • Arne Roth


Conversion of wet biomass and waste products via hydrothermal liquefaction (HTL) has been evolving as an alternative thermochemical technology for the production of liquid biofuels. Processing of biomass slurries with approximately 20 % solids content under high temperature and pressure mimics the natural formation of fossil crude on earth. With reaction times of around 10 to 30 minutes, temperatures of 350 °C and pressures of around 200 bar, HTL converts any biomass feedstock to a liquid bio-crude. This raw product roughly resembles petroleum, but exhibits higher oxygen contents (~10 %) and has a higher viscosity. Therefore, development of the hydrothermal liquefaction technology has concentrated on the upgrading of bio-crude via hydrotreatment to reduce its heteroatom content, viscosity, boiling point and density. Upgraded bio-crude can then be further refined via distillation or other established processes into renewable gasoline, diesel and jet fuel. The upgraded fuel’s chemical composition, with a high concentration of aliphatic hydrocarbons showing carbon numbers in the range of C8 to C18, appears promising for application as renewable jet fuel. The specific composition of the refined fuel products (as well as of the bio-crude) is, however, affected to a significant extent by the type of feedstock applied. For example, using lignocellulosic feedstock results in increased concentrations of aromatic hydrocarbons in the final product. The versatility of the HTL technology in terms of feedstocks and products represents a major advantage over other thermochemical conversion processes. Future developments should address tailoring the process to meet specific fuel requirements, e.g. those of renewable aviation fuels. Recent HTL reactor developments have led to proven continuous operation on a variety of feedstocks, but current reactor capacities of about ~1 bbl/d of bio-crude are still limited. Initial environmental and economic assessments of the hydrothermal liquefaction technology are promising, but in-depth studies covering a representative range of feedstock have not yet been published, rendering estimations of minimum fuel selling prices and greenhouse gas (GHG) balances of HTL derived liquid fuels difficult. To advance the technological maturity of hydrothermal liquefaction towards industrial implementation, development efforts should focus on process integration along the entire production chain encompassing pre-treatment, HTL processing, hydrotreatment, distillation and utilization of process water.


  1. [1]
    Zhang L, Xu C, Champagne P (2010) Overview of recent advances in thermo-chemical conversion of biomass. Energ Convers Manage 51(5):969–982CrossRefGoogle Scholar
  2. [2]
    Garcia Alba L et al. (2012) Hydrothermal Treatment (HTT) of microalgae: evaluation of the process as conversion method in an algae biorefinery concept. Energy Fuels 26(1): 642–657CrossRefGoogle Scholar
  3. [3]
    Dãrãban IM et al (2015) Pretreatment methods to obtain pumpable high solid loading wood–water slurries for continuous hydrothermal liquefaction systems. Biomass Bioenerg 81:437–443CrossRefGoogle Scholar
  4. [4]
    Lappa E et al (2016) Hydrothermal liquefaction of Miscanthus × Giganteus: preparation of the ideal feedstock. Biomass Bioenerg 87:17–25CrossRefGoogle Scholar
  5. [5]
    Biller P et al (2016) Effect of hydrothermal liquefaction aqueous phase recycling on bio-crude yields and composition. Bioresource Technol 220:190–199CrossRefGoogle Scholar
  6. [6]
    Elliott DC et al (2013) Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor. Algal Res 2(4):445–454CrossRefGoogle Scholar
  7. [7]
    Cherad R et al. (2016) Hydrogen production from the catalytic supercritical water gasification of process water generated from hydrothermal liquefaction of microalgae. Fuel 166: 24 –28CrossRefGoogle Scholar
  8. [8]
    Biller P et al (2012) Nutrient recycling of aqueous phase for microalgae cultivation from the hydrothermal liquefaction process. Algal Res 1(1):70–76MathSciNetCrossRefGoogle Scholar
  9. [9]
    Zhu Z et al (2015) Subcritical hydrothermal liquefaction of barley straw in fresh water and recycled aqueous phase. In: World sustainable energy days next 2014. Springer, New York, pp 121–128Google Scholar
  10. [10]
    Ramos-Tercero EA, Bertucco A, Brilman DWF (2015) Process water recycle in hydrothermal liquefaction of microalgae to enhance bio-oil yield. Energ Fuel 29(4):2422–2430CrossRefGoogle Scholar
  11. [11]
    Uddin MH et al (2014) Effects of water recycling in hydrothermal carbonization of loblolly pine. Environ Prog Sustain Energy 33(4):1309–1315Google Scholar
  12. [12]
    Pedersen TH et al (2016) Continuous hydrothermal co-liquefaction of aspen wood and glycerol with water phase recirculation. Appl Energ 162:1034–1041CrossRefGoogle Scholar
  13. [13]
    Villadsen SR et al (2012) Development and application of chemical analysis methods for investigation of bio-oils and aqueous phase from hydrothermal liquefaction of biomass. Energ Fuel 26(11):6988–6998CrossRefGoogle Scholar
  14. [14]
    Snowden-Swan LJ et al (2016) Hydrothermal liquefaction and upgrading of municipal wastewater treatment plant sludge: a preliminary techno-economic analysis. Pacific Northwest National Laboratory (PNNL), RichlandGoogle Scholar
  15. [15]
    Elliott DC et al (2015) Hydrothermal liquefaction of biomass: developments from batch to continuous process. Bioresource Technol 178(0):147–156CrossRefGoogle Scholar
  16. [16]
    Albrecht KO et al (2016) Impact of heterotrophically stressed algae for biofuel production via hydrothermal liquefaction and catalytic hydrotreating in continuous-flow reactors. Algal Research 14:17–27CrossRefGoogle Scholar
  17. [17]
    Zhu Y et al (2014) Techno-economic analysis of liquid fuel production from woody biomass via hydrothermal liquefaction (HTL) and upgrading. Appl Energ 129(0):384–394CrossRefGoogle Scholar
  18. [18]
    Elliott DC et al (2013) Hydrothermal processing of macroalgal feedstocks in continuous-flow reactors. ACS Sustain Chem Eng 2(2):207–215CrossRefGoogle Scholar
  19. [19]
    Anastasakis K, Ross AB (2011) Hydrothermal liquefaction of the brown macro-alga Laminaria Saccharina: effect of reaction conditions on product distribution and composition. Bioresource Technol 102(7):4876–4883CrossRefGoogle Scholar
  20. [20]
    Jazrawi C et al (2013) Pilot plant testing of continuous hydrothermal liquefaction of microalgae. Algal Res 2(3):268–277CrossRefGoogle Scholar
  21. [21]
    Vardon DR et al (2011) Chemical properties of biocrude oil from the hydrothermal liquefaction of Spirulina algae, swine manure, and digested anaerobic sludge. Bioresource Technol 102(17):8295–8303CrossRefGoogle Scholar
  22. [22]
    Malins K et al (2015) Bio-oil from thermo-chemical hydro-liquefaction of wet sewage sludge. Bioresource Technol 187(0):23–29CrossRefGoogle Scholar
  23. [23]
    Mørup A et al (2015) Construction and commissioning of a continuous reactor for hydrothermal liquefaction. Ind Eng Chem Res 54(22): 5935–5947CrossRefGoogle Scholar
  24. [24]
    Biller P et al (2015) Hydroprocessing of bio-crude from continuous hydrothermal liquefaction of microalgae. Fuel 159:197–205CrossRefGoogle Scholar
  25. [25]
    Ocfemia et al (2006) Hydrothermal processing of swine manure into oil using a continuous reactor system: development and testing. American Society of Agricultural Engineers: St. Joseph, p 9Google Scholar
  26. [26]
    Aarhus University (2016) HTL pilot plant. Accessed 5 Oct 2016
  27. [27]
    Jensen CU, Hoffmann J, Rosendahl LA (2016) Co-processing potential of HTL bio-crude at petroleum refineries. Part 2: a parametric hydrotreating study. Fuel 165:536–543CrossRefGoogle Scholar
  28. [28]
    Hoffmann J,Jensen CU, Rosendahl LA (2016) Co-processing potential of HTL bio-crude at petroleum refineries – Part 1: fractional distillation and characterization. Fuel 165:526–535CrossRefGoogle Scholar
  29. [29]
    López Barreiro D et al (2016) Heterogeneous catalytic upgrading of biocrude oil produced by hydrothermal liquefaction of microalgae: state of the art and own experiments. Fuel Process Technol 148:117–127CrossRefGoogle Scholar
  30. [30]
    Li Z, Savage PE (2013) Feedstocks for fuels and chemicals from algae: treatment of crude bio-oil over HZSM-5. Algal Res 2(2):154–163CrossRefGoogle Scholar
  31. [31]
    Garcia Alba L. (2013) Algae biorefinery: An experimental study on liquid fuels production and nutrients recycling. Phd. thesis. Available at
  32. [32]
    Yu J et al. Catalytic hydrotreatment of bio-crude produced from hydrothermal liquefaction of aspen wood: A catalyst screening and parameter optimization study. Sustain Energy Fuel (In press)Google Scholar
  33. [33]
    Zhang C et al (2016) Recent development in studies of alternative jet fuel combustion: progress, challenges, and opportunities. Renew Sust Energ Rev 54:120–138CrossRefGoogle Scholar
  34. [34]
    Nabi MN et al (2015) Fuel characterisation, engine performance, combustion and exhaust emissions with a new renewable Licella biofuel. Energ Convers Manage 96:588–598CrossRefGoogle Scholar
  35. [35]
    Jones SB et al (2014) Process design and economics for the conversion of algal biomass to hydrocarbons: whole algae hydrothermal liquefaction and upgrading. p. Medium: ED; Size: PDFNCrossRefGoogle Scholar
  36. [36]
    Pedersen TH, Rosendahl LA (2015) Production of fuel range oxygenates by supercritical hydrothermal liquefaction of lignocellulosic model systems. Biomass Bioenerg 83:206–215CrossRefGoogle Scholar
  37. [37]
    Jarvis JM et al (2016) Impact of iron porphyrin complexes when hydroprocessing algal HTL biocrude. Fuel 182:411–418CrossRefGoogle Scholar
  38. [38]
    Zhu Y et al (2013) Development of hydrothermal liquefaction and upgrading technologies for lipid-extracted algae conversion to liquid fuels. Algal Res 2(4):455–464CrossRefGoogle Scholar
  39. [39]
    Summers HM et al (2015) Techno-economic feasibility and life cycle assessment of dairy effluent to renewable diesel via hydrothermal liquefaction. Bioresour Technol 196: 431–440CrossRefGoogle Scholar
  40. [40]
    Ou L et al (2015) Techno-economic analysis of transportation fuels from defatted microalgae via hydrothermal liquefaction and hydroprocessing. Biomass Bioenerg 72:45–54CrossRefGoogle Scholar
  41. [41]
    de Jong S et al (2015) The feasibility of short-term production strategies for renewable jet fuels – a comprehensive techno-economic comparison. Biofuels Bioprod Biorefin 9(6):778–800CrossRefGoogle Scholar
  42. [42]
    Jena U et al (2015) Oleaginous yeast platform for producing biofuels via co-solvent hydrothermal liquefaction. Biotechnol Biofuels 8(1):1–19MathSciNetCrossRefGoogle Scholar
  43. [43]
    Liu X et al (2013) Pilot-scale data provide enhanced estimates of the life cycle energy and emissions profile of algae biofuels produced via hydrothermal liquefaction. Bioresource Technol 148:163–171CrossRefGoogle Scholar
  44. [44]
    Jones SB et al (2009) Production of gasoline and diesel from biomass via fast pyrolysis, hydrotreating and hydrocracking: a design case. Pacific Northwest National Laboratory, RichlandGoogle Scholar
  45. [45]
    Snowden-Swan LJ, Male JL (2012) Summary of fast pyrolysis and upgrading GHG analyses. Pacific Northwest National Laboratory (PNNL), RichlandCrossRefGoogle Scholar
  46. [46]
    Zaimes GG et al (2015) Biofuels via fast pyrolysis of perennial grasses: a life cycle evaluation of energy consumption and greenhouse gas emissions. Environ Sci Technol 49(16):10007–10018CrossRefGoogle Scholar
  47. [47]
    Connelly EB et al (2015) Life cycle assessment of biofuels from algae hydrothermal liquefaction: the upstream and downstream factors affecting regulatory compliance. Energ Fuel 29(3):1653–1661CrossRefGoogle Scholar
  48. [48]
    Fortier M-OP et al (2014) Life cycle assessment of bio-jet fuel from hydrothermal liquefaction of microalgae. Appl Energ 122:73–82CrossRefGoogle Scholar
  49. [49]
    Steeper Energy Aps (2016). Accessed 5 Oct 2016
  50. [50]
    Frans G, Jaap EN (2015) Biomass to liquid fuels via HTU, in biomass power for the world. Pan Stanford, Singapore, p 631–664Google Scholar
  51. [51]
    Energy UDo (2013) Sapphire Energy Integrated Algal Biorefinery (IABR). DOE/EE-0841Google Scholar
  52. [52]
    Fröling M, Peterson A, Tester JW (2005) Hydrothermal processing in biorefineries a case study of the environmental performence. In: 7th World Congress of Chemical Engineers, Glasgow, 10–14 July 2005Google Scholar
  53. [53]
    Mørup A et al (2015) Construction and commissioning of a continuous reactor for hydrothermal liquefaction. Ind Eng Chem Res 54(22):5935–5947CrossRefGoogle Scholar
  54. [54]
    Tommaso G et al (2015) Chemical characterization and anaerobic biodegradability of hydrothermal liquefaction aqueous products from mixed-culture wastewater algae. Bioresource Technol 178:139–146CrossRefGoogle Scholar
  55. [55]
    Lee A et al (2016) Technical issues in the large-scale hydrothermal liquefaction of microalgal biomass to biocrude. Curr Opin Biotech 38:85–89CrossRefGoogle Scholar
  56. [56]
    Titirici M-M, Thomas A, Antonietti M(2007) Back in the black: hydrothermal carbonization of plant material as an efficient chemical process to treat the CO2 problem? New J Chem 31(6):787–789CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany 2018

Authors and Affiliations

  1. 1.Aarhus Institute of Advanced StudiesAarhus UniversityAarhusDenmark
  2. 2.Department of ChemistryAarhus UniversityAarhusDenmark
  3. 3.Bauhaus LuftfahrtTaufkirchen (bei München)Germany

Personalised recommendations