Biomass Pyrolysis Process

Biomass pyrolysis is the thermal decomposition of biomass occurring in the absence of oxygen. It is the fundamental chemical reaction that is the precursor of both the combustion and gasification processes and occurs naturally in the first two seconds. The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide.

Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450 0C, when the heating rate is quite slow, and mainly gases at high temperatures, greater than 800 0C, with rapid heating rates. At an intermediate temperature and under relatively high heating rates, the main product is bio-oil.

Pyrolysis can be performed at relatively small scale and at remote locations which enhance energy density of the biomass resource and reduce transport and handling costs.  Pyrolysis offers a flexible and attractive way of converting solid biomass into an easily stored and transported liquid, which can be successfully used for the production of heat, power and chemicals.

A wide range of biomass feedstocks can be used in pyrolysis processes. The pyrolysis process is very dependent on the moisture content of the feedstock, which should be around 10%. At higher moisture contents, high levels of water are produced and at lower levels there is a risk that the process only produces dust instead of oil. High-moisture waste streams, such as sludge and meat processing wastes, require drying before subjecting to pyrolysis.


The efficiency and nature of the pyrolysis process is dependent on the particle size of feedstocks. Most of the pyrolysis technologies can only process small particles to a maximum of 2 mm keeping in view the need for rapid heat transfer through the particle. The demand for small particle size means that the feedstock has to be size-reduced before being used for pyrolysis.

Pyrolysis processes can be categorized as slow pyrolysis or fast pyrolysis. Fast pyrolysis is currently the most widely used pyrolysis system. Slow pyrolysis takes several hours to complete and results in biochar as the main product. On the other hand, fast pyrolysis yields 60% bio-oil and takes seconds for complete pyrolysis. In addition, it gives 20% biochar and 20% syngas.


Bio-oil is a dark brown liquid and has a similar composition to biomass. It has a much higher density than woody materials which reduces storage and transport costs. Bio-oil is not suitable for direct use in standard internal combustion engines. Alternatively, the oil can be upgraded to either a special engine fuel or through gasification processes to a syngas and then biodiesel. Bio-oil is particularly attractive for co-firing because it can be more readily handled and burned than solid fuel and is cheaper to transport and store.

Bio-oil can offer major advantages over solid biomass ands gaification due to the ease of handling, storage and combustion in an existing power station when special start-up procedures are not necessary. In addition, bio-oil is also a vital source for a wide range of organic compounds and speciality chemicals.

About Salman Zafar

Salman Zafar is the CEO of BioEnergy Consult, and an international consultant, advisor and trainer with expertise in waste management, biomass energy, waste-to-energy, environment protection and resource conservation. His geographical areas of focus include Asia, Africa and the Middle East. Salman has successfully accomplished a wide range of projects in the areas of biogas technology, biomass energy, waste-to-energy, recycling and waste management. Salman has participated in numerous national and international conferences all over the world. He is a prolific environmental journalist, and has authored more than 300 articles in reputed journals, magazines and websites. In addition, he is proactively engaged in creating mass awareness on renewable energy, waste management and environmental sustainability through his blogs and portals. Salman can be reached at or
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27 Responses to Biomass Pyrolysis Process

  1. Dhamodharan.M.BSc.Agri says:

    I need to implant 1 tpd pyrolysis plant n India to extract oil from plastics and tyre

  2. Is the market for biochar production viable?

  3. Jenn says:

    what are the advantages and disadvantages of slow pyrolisis?

  4. jiya ramtohul says:

    the ans is not written:-(

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  9. Hnin Pwint Phyu says:

    Could you share me how can I stop Carbon monoxide emission from the pyrolysis, please?

    • Salman Zafar says:

      Dear Hnin
      Thanks for your query
      Carbon monoxide from the pyrolysis process is contributed by syngas. Carbon monoxide can be removed by catalytic oxidation or membrane separation processes.
      Hope I have been of some help.
      Best wishes

      Salman Zafar

  10. Nikunj Poddar says:

    Hi Salman
    We want to do pyrolysis process for rice husk to obtain a kind of bio diesel from it
    Is it possible and if yes, how?

    • Salman Zafar says:

      Dear Nikunj
      The product of the pyrolysis is bio oil or pyrolysis oil. Bio oil can be upgraded to biodiesel but such technologies are still in the development phase and very expensive.
      Hope this information is of interest.

      Best wishes
      Salman Zafar

      • Debojyoti Roy says:

        Dear Salman,

        We are in a process to implement a Plan on Slow Pyrolysis of Biomass (mainly agriculture waste) to produce Biochar and then activate the Biochar to produce activated carbon. Which is more commercially viable, Slow Pyrolysis or Fast Pyrolysis to produce Biochar.

        • Salman Zafar says:

          Dear Debojyoti
          Thanks for the message.
          Slow pyrolysis is the preferred route for production of biochar/activated carbon. Fast pyrolysis is more inclined towards production of bio oil.
          Hope I have been of some help.

          Best wishes

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  15. Bernhardt Cadbury says:

    Dear Salman,
    Great to have you here as we want a Multi-Purpose Pyrolysis Plant machinery to Convert Waste Woody Biomass into Carbonized Charcoal Briquettes, Biocoal, Biochar and Biofuels as Renewable Fuel. We would be very grateful if you can please help us to make the right plant machinery choice. Thank you

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  21. Amit says:

    Hello Salman
    Which quality of Bio Oil recover from Rice husk fast Pyrolysis plz send me specification and how as process and cost of project if we are setup 3 Ton per Hr plant in Chhattisgarh India

  22. Subbha Rao says:

    Currently i am attached to a pyrolysis technology which is capable of consuming 3 MT per hr. We are consuming mainly oil palm biomass mainly EFB pallets and Palm shells. The whole idea of this project is support burner fuel. from my observation and understanding … The type of bio oils produce mainly water and none water solubles. The water soluble is actually know as Wood Vinegar ( WV ) in general and this is not suitable as burner fuel. The burner quality fuels are about 5 to 8% to feed. And the rest of the liquid ( about 30% to the feed ) or WV. Please don’t get confused with the term used as Bio-fuel.. The char is about 25% but we just can’t export due to some volatile presence and we need dedicated vessels or assume they are categorized as Coal. They burn faster than charcoal which make then not so suitable as briquettes. But Char is a good feed stock for bio char ( Biochar = Char inoculate with microbes ) Due to export restrictions we must look for local use mainly to rehabilitate soil. The gas produce which is about 25% has very low calorific value ( 5k to 6kcal per kg ) . We are planing to fuel a dual fuel ICE. Even at 25% gas to feed the estimations indicating that we can generate surplus electricity. Hopefully we can share some data about the gas potentials by end of May 2020.
    For those interested in Pyrolysis of biomass i strongly suggest to explore the potential use of WV as herbicides , fungicides and growth enhancer. Without this we have to dispose the WV and we are wasting our time. The burner grade fuel and the Char can be sold as fuel where the pricing can be correlated with fossil fuels by kCal to kCal.

  23. Joseph Holden says:

    With respect to municipal solid waste what toxic and hazardous byproducts are generated by pyrolisis. Incineration of MSW generates dioxin and the ash generally contains lead, etc. The USEPA requires testing of ash via the toxicity characteristic leaching procedure (TCLP) with stabilization of ash that fails and burial in a haz. waste landfill.

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