Can Coal be Replaced with Biomass Briquettes?



India’s natural coal reserves are estimated to last another century and yet, coal shortage and fluctuating prices pose a threat to our country’s energy security. According to an article published by Business Standard, India is likely to face a supply shortage of about 42 million tons of coal in the third quarter of 2022. This is due to higher power demand and lower mine output this year.


India is an agricultural country with huge untapped potential for using agricultural waste as biomass for producing biofuels to replace conventional fuels such as coal and petroleum. Solid biofuels, such as briquettes and pellets, are considered carbon-neutral and used in industrial boilers, which typically run on coal.


Can biofuels produced from agricultural waste be the new coal? How do they compare in terms of efficiency and cost? Read the article to find out.


How are Biofuels Produced from Agri-waste Briquetting?

Briquettes and pellets are made by compressing biomass material under high pressure and converting them into blocks of various uniform sizes and shapes. These are energy-dense and burn with little or no smoke depending upon the type of biomass used in making them.

The process of briquetting converts loose biomass sourced from various crop residues, agro-waste, and industrial raw biowaste into dense energy-rich bricks of uniform shape and sizes. Briquettes burn without emitting smoke, so they are also known as white coal or biocoal.


The calorific value of solid biofuels, such as briquettes, varies depending upon the type of biomass used in the manufacturing process. The various type of raw organic waste used in briquette and pellet making include (but are not limited to):


● Sugarcane Bagasse

● Wood chips, shavings, sawdust

● Groundnut and Cashew Seed shells

● Rice husk and paddy straw

● Coir dust

● Wheat straw

● Sunflower waste


The calorific value of quality briquettes is substantially higher than loose biomass and is slightly lower in comparison to coal. However, there may be exceptions.


How do Briquettes and Pellets Compare with Coal?


1. Calorific Value


Calorific value is a measure of the amount of heat generated from the combustion of a specific quantity of a substance. The calorific value of coal ranges between 25–35 MJ/kg. Anthracite has the highest calorific value among different types of coal. The calorific value of high-quality briquettes ranges between 18 and 24 MJ/kg.


A Comparison of Essential Quality Parameters of Common Biomass Commodities

Commodity

Commodity Residue

GCV (Kcal/kg)

Moisture (%weight)

Ash (%weight)

Wood

Saw Dust

4025

8

4

Groundnut

Shell

4108

8

7

Soyabean

Husk

4000

7

4

Groundnut and Wood

Shell/ Saw Dust

3813

10

9

Sugar cane and Wood

Bagasse/ Saw Dust

3830

10

9

Sugar cane and Wood

Trash/ Saw Dust

3657

10

11

Sugar cane and Coffee

Trash/ Husk

3754

10

10

Corn

Cob

3511

12

20

Soyabean and Wood

Husk/ Saw Dust

3666

9

11


Above mentioned values may vary from case to case.

2. Pricing

The price of biomass briquettes depends on the burning efficiency, quality, and availability in a particular location and time of the year. Briquettes with higher GCV than coal are likely to be priced higher than coal when the demand is high, and supplies are short. The ongoing surge in coal prices has fueled the demand for locally manufactured briquettes and pellets at competitive prices.


Below is an example of a change in the pricing trend of Groundnut Sawdust briquettes from June ‘21 to June ‘22 observed on BiofuelCircle, India’s 1st online marketplace for biomass and biofuels:





3. Availability:


India’s domestic coal production in financial 2021-22 was at a record high of 780 million tons and is projected to grow in FY 2022-23. And yet, each year, India depends on imported coal to meet its domestic requirements. This has been attributed to the boost in the economy after the pandemic which has led to surplus energy demands.


It is estimated that if the current installed capacity for biomass-based power plants is fully utilized, it could bring down the demand for coal by close to 230 million tons.


India being an agricultural country, there is immense scope for creating a solid biofuel reserve from agricultural waste and biowaste generated from industries to ensure a continuous supply of fuels such as briquettes and pellets in place of coal.


Currently, there are limitations such as the lack of a steady supply of agricultural waste and quality suppliers of biofuels, which can create challenges in terms of biofuel availability throughout the year. A scattered marketplace is a major challenge that needs to be addressed to accelerate the sourcing of biomass to make solid biofuels for replacing coal.


4. Emissions


It is a well-known fact that coal and other fossil fuels are major sources of greenhouse gas emissions, such as CO2, affecting climate change on a massive scale. Co-firing coal with briquettes and pellets is an effective way to cut down emissions from thermal plants.


The debate on whether or not briquettes and pellets are an eco-friendly alternative is still ongoing. However, burning fossil fuels has a negative impact on the environment whereas emissions from briquettes and pellets are comparatively lower.


Is Replacing Coal with Briquettes Economical?


The transition from coal to biofuels for industrial boilers depends on various factors. This needs careful consideration of certain parameters such as


● Gross calorific value

● Availability and ease of handling

● User’s readiness to modify their boilers

● Adapting to changes in boiler equipment

● Cost considerations


Co-firing is a viable option implemented by industries, where coal and an additional fuel source such as briquettes are used to power a boiler. This process results in lower emission of greenhouse gases, which is an advantage over burning coal.


Can Briquettes and Pellets Replace Coals?


Our massive dependency on coal to generate electricity makes it highly unlikely that a complete transition to solid biofuels will be immediate. But the fact that coal reserves are depleting but the energy requirements continue to rise makes it necessary that we move towards cleaner fuels.


In developing countries, the use of briquettes and pellets to fire industrial boilers has seen an upward trend. Rising coal prices and limited fossil fuel reserves are likely to further contribute to this shift in the coming years. A positive environmental impact works in favour of using biofuels as a substitute for coal.


The Ministry of New and Renewable Energy is set to achieve 500 GW of electricity from non-fossil fuels by the year 2030. A total of 152.90 GW of renewable energy projects have been installed as of January 2022, of which 10.63 GW is from Bio-power. This presents a great opportunity for use of biofuels in place of coal.


The attributes of briquettes and pellets such as calorific values and energy efficiency make them an ideal fuel source to power industrial boilers. Although there are several bottlenecks in realizing their full potential as a replacement for coal, the shift in this direction is evident. The need for economical and eco-friendly alternative fuels is likely to drive this shift in the near future.


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