Pyrolysis: A Sustainable Way to Generate Energy from Waste

Lignocellulosic biomass is considered as a promising environmentally friendly substitute resource for carbon‐based fuels and chemicals. The existing global supply of energy depends on non‐renewable fuels such as oil, gas and coal formed naturally beneath the earth's crust. However, the amount of fossil fuel is limited now. Due to the growing population of the world, the consumption of energy per capita is increasing. Thus, the inevitability of continuing alternatives to generating the possible sources of energy is evident. Utilization of biomass to produce value‐added products is receiving great attention by researchers. Furthermore, the inorganic constituent of biomass is negligible and it contains minor quantities of nitrogen, sulphur and ash. Therefore, combustion of biomass is advantageous as it produces less toxic gases such as nitrogen oxides (NOx), sulphur dioxide (SO2) and smoke compared to other conventional fuels. Even the emission of carbon dioxide (CO2) can be controlled by recycling it through photosynthesis. Though many theoretical methods were undertaken for the conversion in the short run; what is required are practical phase application and demonstration with appropriate calculation of material and energy balance. Industrial‐scale thermochemical production of liquids, bio‐oils, by fast or flash pyrolysis has been established but it has so far not been implemented for commercialization of the overall practice.
Different types of thermochemical and even biological processes have been adopted to convert biomass into value‐added products. Among those processes, pyrolysis is more convenient since it has several advantages of storing, transportation and flexibility in solicitation such as turbines, combustion appliances, boilers, engines, etc. In some cases, solid biomass and waste are precisely challenging to process for pyrolysis research. It is now at a preliminary stage in terms of expansion and yet requires resolving numerous practical obstacles to contend with conventional fossil fuel–centered procedures. The preparation of liquid biofuels including other products like solid char and gas by pyrolysis of various lignocellulosic residues has been comprehensively explored earlier. Some of these biomass species are Beachwood, bagasse woody biomass, straws, seedcakes and municipal solid waste (MSW), illustrating different types of existing biomass conversion process with their respective output.