Indian cement industry needs to gradually shift from coal to biogas
Vivek Taneja, Business Head – Waste to Wealth & Integrated Utility Solutions, Thermax Ltd.

Indian cement industry needs to gradually shift from coal to biogas

The cement sector can achieve environmental goals by using the ash from coal-based power plants through more innovative ways than just OPC to PPC conversion. Usage of all fly ash for greener cement with emerging geopolymer technologies will make the sector far greener, says Vivek Taneja, Business Head – Waste to Wealth & Integrated Utility Solutions, Thermax Ltd.

What are your thoughts on lowering carbon footprint/emission rate in the cement industry? How do you look at this problem in India? What can be done to meet this challenge?

The cement sector is probably one of the top largest carbon contributors with a carbon intensity of about one-ton carbon per ton of clinker produced. If the Cement sector is really serious about lowering the carbon footprint they have to look within and adopt some very easy practices to start greening the sector.

These solutions are not something of the future but here and now, commercially viable and not just environmentally friendly but also help the local rural economy in the vicinity of cement plants flourish.

What solutions do you think are apt for the cement industry in reducing carbon footprint?

Some easy solutions are already being looked at by the cement sector like energy efficiency and waste heat recovery. Infact, the Indian cement sector has set some benchmarks in terms of energy efficiency and has some of the lowest power and fuel intensity. However, they still are very big contributors to the carbon pool and that is not sufficient to impart even a green tinge on the sector. The sector has to look at solutions that are out of the box. Solutions that have no precedence in the globe and be the role model for the global cement industry to follow.

Could you explain how can cement plants reduce power consumption by using alternate sources?

There is no single solution but a suite of solutions that need to be deployed by the industry.

They would fall in two buckets:

a) To reduce the power and energy consumption – where energy efficiency comes in and PAT scheme works as an incentive for the sector to reduce the consumption.

b) To use less carbon and water-intensive energy sources or alternate sources – this is something which needs to increase dramatically in the sector.

What best practices and technology would you suggest in reducing carbon footprint?

Apart from solar and wind the sector needs to look seriously at the other emerging alternate technologies. The next decade will be focused on the shift from coal and liquid fossil fuels-based energy sources to gaseous fuels. Unfortunately, India does not have large gas reserves and needs to import them. Hence, inspite of gas being comparatively lower, carbon-intensive fuel does not make commercial sense just yet.

This is where renewable gas usage comes into the picture – Biogas has been around for decades but the technology so far had been primitive and focused on easy-to-digest organic and wet wastes. The breakthrough in the technology which allows ever 2G bio residues like tough to digest ligno cellulosic bio waste is something that can be commercially viable source of not just carbon neutral but carbon negative energy.

Apart from this, the cement sector can do wonders by using the ash from coal-based power plants in more innovative ways than just OPC to PPC conversion and usage of the cenosphere the potential is much larger. Usage of all fly ash for greener cement with emerging geopolymer technologies will make the sector far greener. Apart from that usage of bottom ash into high-end building products will reduce the overall carbon intensity of the building sector, not just initial carbon content but making the buildings more energy efficient with lower thermal conductivity. This will go on reducing the operating carbon intensity of the building over its lifetime.

Could you tell a bit more about the carbon negative alternate energy source and how it will benefit local communities in the vicinity of the cement plants?

Many Cement companies do a lot under the CSR activities. However, they can fortify their CSR with some enhanced holistic growth in the local economy.

This is where a gradual shift from coal to biogas options comes in. Conventionally the bio residue is left on the fields to rot or converted to bio compost thereby emitting methane which is more than 20 times more dangerous GHG in terms of CO2 equivalence. If the cement companies were to shift to biogas usage they will be helping the farmers increase their income by the sale of biowaste. Utilising the latest technology that is feedstock agnostic and uses no water can help some entrepreneurs in the local vicinity to develop aggregate bio residue or even do further value addition of producing biogas in lieu of coal.

This will ensure that the biowaste like stubble is not burnt on fields, nor is it left to rot or just converted to compost while emitting methane. This route will ensure that methane or CO2 emission is avoided which makes the solution carbon negative. Being bio residue energy is carbon neutral. The Digestate has two usage – either the industry can decide to be part of circular economy and return the digestate to the farmers as high-quality organic compost sans any chemicals after utilising the methane as an energy source or use the digestate as green coal in kilns to further reduce the coal usage and making the entire process greener by a few more notches. The excess raw Bio Gas, if any ca be converted to Compressed Bio Gas ( CBG) and the complete logistics of the cement plant can be shifted from Diesel to CBG. CBG has high calorific value of over 12000 Kcal/ kg and can directly replace all CNG/ LPG application being Methane of over 90% purity.

This route will not just make the process and transport Greener but a lot economical as well as the cost of running on CBG is almost half that of Diesel.

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