BIOCOAL or WHITE COAL IN INDIA :- a solution to Delhi air pollution caused by rice stubble burning
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Biocoal is produced by processing dry biomass in an inert environment (no oxygen) at high temperatures, a process referred to as pyrolysis. Depending on the temperatures and the characteristics of the end product, the process may also be referred to as torrefaction.
What is Torrefaction?
Torrefaction is a thermal process to convert biomass into a coal-like material, which has better fuel characteristics than the original biomass.
It involves heating up straw, grass, saw mill residue and wood biomass to 250 degrees Celsius – 350 degrees Celsius.
This changes the elements of the biomass into ‘coal-like’ pellets.
These pellets can be used for combustion along with coal for industrial applications like steel and cement production
If scaled up, about 65% of the biomass could be converted to energy.
Biocoal is a coal similar to the coal. Difference stems from the fact that biocoal is produced artificially from biomass by means of hydrothermal carbonisation (HTC) technology and compared to fossil coal it offers several below-stated advantages.
White coal is a form of fuel produced by drying chopped wood over a fire. It differs from charcoal which is carbonised wood. White coal was used in England to melt lead ore from the mid-sixteenth to the late seventeenth centuries. It produces more heat than green wood but less than charcoal and thus prevents the lead evaporating. White coal could be used mixed with charcoal for other industrial uses than lead smelting. White coal was produced in distinctive circular pits with a channel, known as Q-pits. They are frequently found in the woods of South Yorkshire.
Nowadays white coal is made from
Groundnut shells
Cotton hulls and salks
Castor seed shells
Forest leaves; wood chips and shavings
Sugarcane bagasse
Rice husk and paddy straw
Mustard waste
Coir dust
Coffee husk
Sunflower waste
Maize stalks
Bajra (pearl millet) cobs
Sesame seeds oil cake
Wheat straw
Benefits of white coal:
White coal is cheaper than coal and fire wood.
There is no sulphur in the white coal, therefore no toxic gases.
Moisture content is nil.
Biomass briquettes have a higher practical thermal value.
Briquettes have consistent quality, have high burning efficiency, and are ideally sized for complete combustion.
Combustion is more uniform compared to coal and boiler response to changes in steam requirements is faster, due to higher quantity of volatile matter in briquettes.
Low ash contents.
The calorific value of the finished briquettes is approximately 3500 to 4000 kcal/kg.
India is fast becoming a major manufacturer and consumer of white coal. A large number of companies have switched their boiler fuels to use white coal instead of fossil fuels. White Coal manufacturing capacity is coming up in droves in the state of Gujarat, Maharashtra, Tamil Nadu and Rajasthan.
The production of White coal (Briquettes made of Biomass) using agricultural and forest waste is more common in North India.
Biocoal is ideal for de-centralised, local utilisation of biomass and biowaste with high humidity content, such as sludge from water-treatment plants, waste from food industry, including breweries or distilleries and also agriculture waste.
Thanks to the volume reduction by up to 75% and increased energy density there are options for longer-distance transporting of biocoal.
Biocoal meets the requirements on biomass stipulated by German laws on renewable energy sources (EEG) and on heating with renewable energy sources (EEWärmeG). Through incineration of one tonne of biocoal the user will spare approximately 2.5 tonnes of CO2 emissions
Advantages and Characteristics of HTC Coal
Biocoal is a highly homogenous fuel produced from highly heterogeneous biomass
CO2-neutral source of energy
~ 75% of biomass energy is transferred to the coal
High calorific value – up to 25 MJ/kg can be achieved when grasses or straw is used
Production of coal with defined calorific value
High incineration efficiency with low NOx emissions
Very low content of toxic materials, sulphur and heavy metals
Lower volume for storing when compared to biomass
Unlike biomass it is not subject to degradation
Lower transportation costs when compared to biomass
Removes problems with biomass clinkering in boilers
High temperature of ash fluxing ~ 1.400
Why Biocoal is needed in India ?
India is agriculture based country and generates more than 600 million tons of biomass waste from different crops and produces 140 million tons of rice straw alone annually. To dispose the rice straw for making field ready for next crop, farmers are burning it in the fields. The burning of rice straw in the agriculture field poses lot of environmental, health and economic issues in the various part of India. On one hand, rice straw is a good source of renewable energy but on the other it has got some inherent problems. Therefore, to mitigate the problems due to the burning of rice straw, in this study, an effort is made to convert rice straw into useful product by torrefaction process i.e. biocoal. In India, generally bituminous coal of gross calorific value (GCV) in range of 3500-4000 Kcal/kg and density 800-900 kg/m3 are used in the thermal power plant for generation of electricity. In this study, chopped rice straw is torrefied at different temperature ranging from 250 to 450°C in the protective environment. It is observed that rice straw density and GCV after torrefaction at 300°C increases from 0.22 g/cc to 0.50 g/cc and 3640 to 4342 Kcal/kg whereas, fixed carbon content increases from 21 to 34%. When torrefied at 400°C, the GCV is 5339 Kcal/kg and density 0.58 g/cc but at this temperature carbonization is started and fixed carbon content increases to 65%. The volume of torrefied product decreases significantly as compared to the rice straw and after pelletization of torrefied product, density is analogous to that of bituminous coal. Therefore, pellets can be stored together with coal and processed using the existing infrastructure for co-firing in thermal power plants. The 10% use of torrefied product with coal can consume 140 million tons of rice straw and as a consequence it reduces the consumption of fossil fuels. This can greatly solve the problems due to the burning of rice straw and reduce the greenhouse gas emission significantly.
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Biocoal is produced by processing dry biomass in an inert environment (no oxygen) at high temperatures, a process referred to as pyrolysis. Depending on the temperatures and the characteristics of the end product, the process may also be referred to as torrefaction.
What is Torrefaction?
Torrefaction is a thermal process to convert biomass into a coal-like material, which has better fuel characteristics than the original biomass.
It involves heating up straw, grass, saw mill residue and wood biomass to 250 degrees Celsius – 350 degrees Celsius.
This changes the elements of the biomass into ‘coal-like’ pellets.
These pellets can be used for combustion along with coal for industrial applications like steel and cement production
If scaled up, about 65% of the biomass could be converted to energy.
Biocoal is a coal similar to the coal. Difference stems from the fact that biocoal is produced artificially from biomass by means of hydrothermal carbonisation (HTC) technology and compared to fossil coal it offers several below-stated advantages.
White coal is a form of fuel produced by drying chopped wood over a fire. It differs from charcoal which is carbonised wood. White coal was used in England to melt lead ore from the mid-sixteenth to the late seventeenth centuries. It produces more heat than green wood but less than charcoal and thus prevents the lead evaporating. White coal could be used mixed with charcoal for other industrial uses than lead smelting. White coal was produced in distinctive circular pits with a channel, known as Q-pits. They are frequently found in the woods of South Yorkshire.
Nowadays white coal is made from
Groundnut shells
Cotton hulls and salks
Castor seed shells
Forest leaves; wood chips and shavings
Sugarcane bagasse
Rice husk and paddy straw
Mustard waste
Coir dust
Coffee husk
Sunflower waste
Maize stalks
Bajra (pearl millet) cobs
Sesame seeds oil cake
Wheat straw
Benefits of white coal:
White coal is cheaper than coal and fire wood.
There is no sulphur in the white coal, therefore no toxic gases.
Moisture content is nil.
Biomass briquettes have a higher practical thermal value.
Briquettes have consistent quality, have high burning efficiency, and are ideally sized for complete combustion.
Combustion is more uniform compared to coal and boiler response to changes in steam requirements is faster, due to higher quantity of volatile matter in briquettes.
Low ash contents.
The calorific value of the finished briquettes is approximately 3500 to 4000 kcal/kg.
India is fast becoming a major manufacturer and consumer of white coal. A large number of companies have switched their boiler fuels to use white coal instead of fossil fuels. White Coal manufacturing capacity is coming up in droves in the state of Gujarat, Maharashtra, Tamil Nadu and Rajasthan.
The production of White coal (Briquettes made of Biomass) using agricultural and forest waste is more common in North India.
Biocoal is ideal for de-centralised, local utilisation of biomass and biowaste with high humidity content, such as sludge from water-treatment plants, waste from food industry, including breweries or distilleries and also agriculture waste.
Thanks to the volume reduction by up to 75% and increased energy density there are options for longer-distance transporting of biocoal.
Biocoal meets the requirements on biomass stipulated by German laws on renewable energy sources (EEG) and on heating with renewable energy sources (EEWärmeG). Through incineration of one tonne of biocoal the user will spare approximately 2.5 tonnes of CO2 emissions
Advantages and Characteristics of HTC Coal
Biocoal is a highly homogenous fuel produced from highly heterogeneous biomass
CO2-neutral source of energy
~ 75% of biomass energy is transferred to the coal
High calorific value – up to 25 MJ/kg can be achieved when grasses or straw is used
Production of coal with defined calorific value
High incineration efficiency with low NOx emissions
Very low content of toxic materials, sulphur and heavy metals
Lower volume for storing when compared to biomass
Unlike biomass it is not subject to degradation
Lower transportation costs when compared to biomass
Removes problems with biomass clinkering in boilers
High temperature of ash fluxing ~ 1.400
Why Biocoal is needed in India ?
India is agriculture based country and generates more than 600 million tons of biomass waste from different crops and produces 140 million tons of rice straw alone annually. To dispose the rice straw for making field ready for next crop, farmers are burning it in the fields. The burning of rice straw in the agriculture field poses lot of environmental, health and economic issues in the various part of India. On one hand, rice straw is a good source of renewable energy but on the other it has got some inherent problems. Therefore, to mitigate the problems due to the burning of rice straw, in this study, an effort is made to convert rice straw into useful product by torrefaction process i.e. biocoal. In India, generally bituminous coal of gross calorific value (GCV) in range of 3500-4000 Kcal/kg and density 800-900 kg/m3 are used in the thermal power plant for generation of electricity. In this study, chopped rice straw is torrefied at different temperature ranging from 250 to 450°C in the protective environment. It is observed that rice straw density and GCV after torrefaction at 300°C increases from 0.22 g/cc to 0.50 g/cc and 3640 to 4342 Kcal/kg whereas, fixed carbon content increases from 21 to 34%. When torrefied at 400°C, the GCV is 5339 Kcal/kg and density 0.58 g/cc but at this temperature carbonization is started and fixed carbon content increases to 65%. The volume of torrefied product decreases significantly as compared to the rice straw and after pelletization of torrefied product, density is analogous to that of bituminous coal. Therefore, pellets can be stored together with coal and processed using the existing infrastructure for co-firing in thermal power plants. The 10% use of torrefied product with coal can consume 140 million tons of rice straw and as a consequence it reduces the consumption of fossil fuels. This can greatly solve the problems due to the burning of rice straw and reduce the greenhouse gas emission significantly.
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