Grinding Pyrolysis

Pyrolysis is the thermal decomposition of biomass in the absence of air. The pyrolysis of biomass produces three products: non-condensable gases, liquid bio-oil and solid biochar.

Renergi's Pyrolysis Technology has been developed by the team led by John Curtin Distinguished Professor Chun-Zhu Li in the Fuels and Energy Technology Institute in Curtin University.

Following successful testing in a pilot plant, a 100 kg/hr demonstration plant has been designed, built and commissioned with funding from both the Western Australian State Government via its Low Emissions Energy Development Fund (LEED), and from ARENA.

A key feature of Renergi's pyrolysis technology is simultaneous pyrolysis and particle size reduction (grinding), hence its name “grinding pyrolysis”. As a result, the technology can accept biomass feedstock with a wide range of particle sizes ranging from microns to a few centimetres in one mixture or separately. This greatly reduces the grinding cost which is required by competing technologies.

Renergi's grinding pyrolysis technology needs little or no carrier gas for commercial operation. This has two additional benefits:

  • the overall process is greatly simplified for much increased efficiency; and
  • without the dilution of bio-oil vapour by inert carrier gas, the bio-oil vapour can be easily condensed and collected in a commercial scale operation.

The technology is modular, ideally suited to process the widely distributed biomass by minimising the cost to transport wet bulky biomass over a long distance. It can also easily reach large scales if a centralised biomass resource is available.

Renergi's Grinding Pyrolysis Technology can be used in a wide range of applications:

The production of advanced drop-in biofuels: This pyrolysis technology is part of Renergi's advanced biofuel technology.

Bio-oil as a heating oil: The bio-oil can be used as a heating oil following the ASTM standard ASTM D7544 - 12.

Co-firing with coal: Another commercial use of Renergi's grinding pyrolysis technology is for the co-firing of biomass with coal in the existing coal-fired power plant. An important problem in the co-firing of biomass and coal is the incomplete combustion of biomass because biomass cannot be ground fine enough using the existing grinding facilities in a coal-fired power plant that have been designed and optimised for grinding coal and not biomass. Renergi's grinding pyrolysis technology can grind and pyrolyse the biomass feedstock even having particle sizes of a few centimetres to produce biochar with a particle size smaller than 100 micron, similar to pulverised coal particles entering a pulverised-fuel combustion system.

Production of high-value carbon materials: The pyrolysis products can also be used to make high-value carbon materials.

Soil conditioning and carbon sequestration: Biochar from Renergi's pyrolysis technology is in the particle size range very close to that of natural biochar. Therefore, the biochar can be returned to agricultural soil to improve soil condition while sequestering carbon safely and permanently. Limited pot trials have given positive results.


Related recent literature:


C.-Z. Li, X. Wang and H. Wu. Method of and system for grinding pyrolysis of particulate carbonaceous feedstock, PCT/AU2011/000741.


  • D. Mourant, C. Lievens, R. Gunawan, Y. Wang, X. Hu, L. Wu, S.S.A. Syed-Hassan and C.-Z. Li, Effects of temperature on the yields and properties of bio-oil from the fast pyrolysis of mallee bark, Fuel, 2013, 108, 400-408.
  • H. Wu, K. Yip, Z.-Y. Kong, C.-Z. Li, D. Liu, Y. Yu and X. Gao, Removal and recycling of inherent inorganic nutrient species in mallee biomass and derived biochars by water leaching, Industrial & Engineering Chemistry Research, 2011, 50, 12143–12151.
  • D. Mourant, Z. Wang, M. He, X.S. Wang, M. Garcia-Perez, K.-C. Ling and C.-Z. Li, Mallee wood fast pyrolysis: effects of alkali and alkaline earth metallic species on the yield and composition of bio-oil, Fuel, 2011, 90, 2915-2922.
  • H. Abdullah, D. Mourant, C.-Z. Li and H. Wu, Bioslurry as a fuel. 3. Fuel and rheological properties of bioslurry prepared from the bio-oil and biochar of mallee biomass fast pyrolysis, Energy & Fuels, 2010, 24, 5669-5676.
  • M. Garcia-Perez, J. Shen, X.S. Wang and C.-Z. Li, Production and fuel properties of fast pyrolysis oil/bio-diesel blends, Fuel Processing Technology, 2010, 91, 296-305.
  • J. Shen, X.-S. Wang, M. Garcia-Perez, D. Mourant, M.J. Rhodes and C.-Z. Li, Effects of particle size on the fast pyrolysis of oil mallee woody biomass, Fuel, 2009, 88, 1810–1817.
  • M. Garcia-Perez, S. Wang, J. Shen, M. Rhodes, W.J. Lee and C.-Z. Li, Effects of temperature on the formation of lignin-derived oligomers during the fast pyrolysis of mallee woody biomass, Energy & Fuels, 2008, 22, 2022-2032.
  • M. Garcia-Perez, X.S. Wang, J. Shen, M.J. Rhodes, F. Tian, W.-J. Lee, H. Wu and C.-Z. Li, Fast pyrolysis of oil mallee woody biomass: Effect of temperature on the yield and quality of pyrolysis products, Industrial and Engineering Chemistry Research, 2008, 47, 1846-1854.

Renergi is a start-up private company established in 2012 to commercialise a suite of renewable energy technologies developed in the Fuels and Energy Technology Institute at Curtin University of Technology in Western Australia. The current technology focus at Renergi include biomass gasification for distributed power and heat generation, biomass pyrolysis and refinery for the production of biochar, bio-oil and advanced biofuels, and co-firing of biomass with coal in the existing coal-fired power stations.

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