Biomass Pyrolysis Process

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 bio-diesel. 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 and gasification 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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14 Responses to Biomass Pyrolysis Process

  1. Pingback: Is There a Role for Small Biomass Power? | Power and Energy News ,Discussions and More

  2. Dhamodharan.M.BSc.Agri says:

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

  3. Is the market for biochar production viable?

  4. Jenn says:

    what are the advantages and disadvantages of slow pyrolisis?

  5. jiya ramtohul says:

    the ans is not written:-(

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  10. 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

  11. 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

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