BIOMASS BRIQUETTES: TURNING WASTE INTO GREEN ENERGY

Introduction to Biomass 

The importance of energy demands that have increased exponentially over the past century has led to the sourcing of other ideal energy solutions as the potential replacement alternative to conventional fossil fuels. However, the utilization of fossil fuels has created severe environmental issues. The identification of other renewable sources is beneficial to replace energy utilization globally. 

Biomass is a highly favourable sustainable alternative to renewable resources that can produce cleaner, cheaper, and readily available energy sources in the future. Today, the renewable energy source of power generation has become very promising. As we know that conventional or non-renewable sources of energy are very limited and are depleting very rapidly. 

Increasing energy needs of the world and continually growing population there is a power demand gap and it needs alternate sources of energy. So, there is a view to generating more and more power from renewable sources of energy. There are various forms of renewable energy sources. Biomass is one of the important sources of renewable energy. India has a huge volume of potential for renewable energy sources. 

In India, about 500 million metric tons of biomass energy is produced every year. According to International Energy Agency (IEA), Renewable energy could meet almost half of the global energy demand by 2050. With the ever-increasing demand for energy, there has also been a rapid increase in the number of agro-waste residues. 

Given the need of the hour to battle the deteriorating environment, waste-to-energy conversions have gained a lot of momentum today, with ‘Bioenergy’ being adopted and implemented worldwide for industrial to domestic power generation as well as in Process industries. 

India produces about 500 million tons (Mt) of crop residues annually. Processing of agricultural produce through milling and packaging also produces a substantial number of residues. Crop residues are natural resources with tremendous value to farmers. These residues are used as animal feed, composting, thatching for rural homes and fuel for domestic and industrial use. About 25% of nitrogen, 25% of phosphorus, 50% of Sulphur and 75% of potassium uptake by cereal crops are retained in residues, making them valuable sources of nutrients. 

However, a large portion of the residues, about 140 Mt, is burned in the field primarily to clear the field from straw and stubble after the harvest of the preceding crop. The problem is severe in irrigated agriculture, particularly in the mechanized rice-wheat system. 

The main reasons for burning crop residues in the field include the unavailability of labour, the high cost of removing the residues and the use of combines in rice-wheat cropping systems especially in the Indo-Gangetic plains (IGP). Primary crop types whose residues are typically burned include rice, wheat, cotton, maize, millet, sugarcane, jute, rapeseed-mustard, and groundnut. Farmers in northwest India dispose of a large part of rice straw by burning it in situ. 

Energy from biomass is reliable as it is free of fluctuation unlike wind power and does not need storage to be used in times of non-availability as is the case with solar. Still, it is not the preferred renewable energy source till now, the primary reason that may be cited is the biomass supply chain. Biomass availability is not certain for the whole year.

Biomass from agriculture is available only after the harvesting period which can stretch only for 2-3 months in a year. So, there is a need to procure and then store a required quantity of biomass within this stipulated time. Some of the Indian states leading the pack in establishing biomass-based power supply are Karnataka, Andhra Pradesh, Rajasthan, Gujrat, and Maharashtra.

These states having agricultural-based economies have not properly been able to utilize the opportunity and figure low on biomass energy utilization. Only Uttar Pradesh has utilized a large part of the biomass potential in the north Indian States and that is mainly due to the sugarcane industry and the co-generation power plants. 

Biomass is any organic matter—wood, crops, seaweed, animal wastes—that can be used as an energy source. Biomass is probably our oldest source of energy after the sun. For thousands of years, people have burned wood to heat their homes and cook their food. Biomass gets its energy from the sun. All organic matter contains stored energy from the sun. 

During a process called photosynthesis, sunlight gives plants the energy they need to convert water and carbon dioxide into oxygen and sugars. These sugars, called carbohydrates, supply plants and the animals that eat plants with energy. Foods rich in carbohydrates are a good source of energy for the human body. Biomass is a renewable energy source because its supplies are not limited. We can always grow trees and crops, and waste will always exist. 

‘Biomass Briquettes’ are the products of the low-pressure compaction of biomass like sawdust, agricultural waste, paper, etc. Compression allows the biomass to burn longer than if it were left loose and can burn at the same temperatures and for an equal duration as coal. 

It is a pressing priority that we should put all the agro waste to good use and not just contribute to green energy generation, but also prevent the serious damage that happens after the improper disposal of agricultural wastes (E.g., burning of stubble). 

Briquettes are high-density biomass renewable fuels that are obtained as the product of biomass 

briquetting machines. They have high calorific value and less moisture content, so they have complete combustion. The rising need is due to the rising demand for renewable energy as non-renewable fossil fuels are about too extinct. They are cheaper as compared to the other source of energy. Briquettes have the brightest future as the raw material is easily available and the product has a huge ready market available. 

Due to global awareness, the demand for bio-mass briquettes is increasing. More and more sectors are setting up their own briquetting plant to reuse the waste obtained from their industries into them industries again. The government has started providing subsidies and started giving benefits for the plant setup. They are giving us tax benefits, incentives, and many other helps. The viability is thus very high. We can reproduce the investment within the span of two years. 

  • Rising demand due to increasing cost of fossil fuels like coal, wood, etc. • Renewable sources of fuel and energy
  • Tax benefits and incentives
  • Earlier viability 
  • Relaxed rules
  • Pollution-free briquettes as there is no presence of sulfur content • Easy mobility and transportation
  • Contain high density

Sources of Biomass 

  1. Field and Plantation Biomass: 
  • Agricultural crop residues- Cobs, stalks, Straw, Cane thrash, etc.
  • Edible matters from crops- Environmentally spoiled grains, pulses, fruits, nuts, spices,    seeds, lint, etc.
  • Plantation debris- Leaves, stubbles, barks, trunks, etc.
  • Livestock wastes from fields, slaughterhouses, animal husbandry, etc.
  1. Industrial biomass 
  • Agro-industrial processed biomass and their wastes – Husk, Oil cake, Sugar bagasse, 
  • Sugar molasses, Whey, Fruit, pulp debris, Sawdust, Wood pulp, etc. 
  1. Forest biomass Timber, Forest floor derbies, etc. 
  1. Urban waste biomass Municipal solid wastes, Sewage sludge, Kitchen, and canteen wastes, etc. 
  1. Aquatic biomass Microalgae blooms, Seaweeds (E.g., Kelp), Freshwater weeds (E.g., Water Hyacinth), Dead fishes, etc. 

Types Of Biomass Briquette materials used 

  • Groundnut shell: Because of low ash (5-8%) and a moisture content of less than 10%, it is also an excellent material for briquetting.
  • Soyabean: This material uses Soya stalks, having high ash % than GNS & Groundnut shell
  • Cotton sticks: This material is required to be chopped and then stored in dry form. It tends to degrade during storage. Also, it has a higher content of alkaline minerals and
    needs to be used with caution.
  • Bagasse/bagasse pith: These residues have a high moisture content of 50% after milling, hence drying is energy intensive. They have low ash content and a correspondingly high heating value.
  • Pith is the small fibrous material which has to be removed from bagasse before bagasse
    is used as feedstock for making paper. Due to shortages of wood and increasing demand for paper and pulp, an ever-increasing number of paper units are switching over to bagasse as feed material. The amount of pith available is almost equal to the tonnage of paper produced by a paper mill. For example, a 60 TPD mill will generate 60 TPD of bagasse pith. This material does not require milling before it is briquetted. At present, this pith is available from sugar mills at much lower costs. This is a potential material for briquetting.
  • Coffee husk: An excellent material for briquetting having low ash and available with 10% moisture content. The material is available in the coffee-growing areas of Karnataka and Kerala.
  • Mustard stalks: Like cotton sticks, it is also an appropriate material for briquetting.
  • Prosopis Juliflora is an invasive weed (biomass) available in abundant quantities in Kenya. This provides an opportunity for making briquettes in areas where it is found.
  • Rice husk: The rice husk, also called rice hull, is the coating on a seed or grain of rice. It is formed from hard materials, including silica and lignin, to protect the seed during the growing season. Each kg of milled white rice results in roughly 0.28 kg of rice husk as a by-product of rice production during milling.
Sr. No.Fuel TypeGCVAsh
1Biomass Briquettes3650-3800Appx 10%
2Wood logs and Wood chips2900-3500Below 5%
3Cashew Nutshell3600-4000Below 5%
4Cut/Crushed briquettes3650-3800Below 10%
5Rice Husk2800-3100Below 10%
6Saw Dust3700-3800Below 10%

Moisture 

Below 10% Below 35% Below 10% Below 10% Below 10% Appx 10% 

Author 

Mr Vaibhav Bode

(CEAT Limited)

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