Indian Cement Sector – A Hallmark of Energy Efficient Operations

November 25, 2021

Introduction

The Indian Cement Industry has been a front runner in adopting state of the art technology, innovative process improvements and resilient business practices. It has been building sustainable societies for the future. Cement manufacturing is an energy intensive process – any step/(s) that leads to improving energy efficiency establishes the prowess of the cement companies. Input energy represents almost 30% to 35% of the overall expenses towards manufacturing cement thereby making it critical for the industry to explore latest technologies and alternative ways of becoming energy efficient. Such transitions could be streamlined through an enabling policy environment and complementing regulations aligned to sustainable development.

Measuring Energy Efficiency

Energy efficiency in a cement plant is measured as a combination of two factors, viz., Thermal Energy Consumption and (2) Electrical Energy Consumption. The former specifically measures the kiln performance while the latter measures the overall performance of the plant.

  1. Thermal Energy Consumption (measured as MJ/t clinker)

    The fundamental process of manufacturing cement has remained consistent over a period wherein limestone is heated up to a temperature as high as 1450 degree Celsius. Most of the upcoming future prospects such as alternative binders and carbon cured cements are in initial stages of development and are not seen as a promising replacement owing to the behemoth scale of the industry. The theoretical demand of energy for clinker production varies between 1,650 to 1,800 MJ/t clinker. Additionally, about 200 to 1,000 MJ/t clinker of energy is required for drying of the raw materials before Calcination. The average annual fuel energy requirement of a representative state of the art cement kiln based on theoretical modelling and empirical data is estimated between 3,000 to 3,400 MJ/t clinker for six cyclone stages and 3,100 to 3,500 MJ/t clinker for five cyclone stages.

  2. Electrical Energy Consumption (measured as kWh/t cement)

    Figure details the electrical energy demand of the cement process as about 2% for raw material extraction, 25% for raw material preparation, 25% for clinker production plus an additional 3% for fuel grinding, 43% for cement grinding and 3% for packing and loading.3

    Electrical energy consumption in cement production
    Source: Cement Sustainability and European Cement Research Academy (2017) Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead, Available at https://ecra-online.org/fileadmin/redaktion/files/pdf/CSI_ECRA_Technology_Papers_2017.pdf; accessed on July 28, 2021

    Some of the thermal energy efficiency measures and emission control systems adopted in clinker production may inversely impact the electrical energy consumption. For example, the installation of modern coolers causes a reduction in thermal energy use but increases the consumption of electrical energy. Table details the thermal and electrical Specific Energy Consumption (SEC) in India vis a vis global peers.

    Thermal and electrical specific energy consumption
    Parameter Unit Global Top 10%1 Global Average3 India2
    Thermal SEC MJ/t clinker 3,000 3,510 3,084
    Electric SEC kWh/t cement 85 104 76.6
    Source: Cement Sustainability and European Cement Research Academy (2017) Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead, Available at https://ecra-online.org/fileadmin/redaktion/files/pdf/CSI_ECRA_Technology_Papers_2017.pdf; accessed on July 28, 2021

Levers to strengthen Energy Efficiency

The Cement Industry in India has leveraged a range of levers to strengthen its energy efficiency. Some of the prominent measures are highlighted as follows:

  1. Modern Technology

    The Indian Cement Industry is relatively young compared to its global counterparts. Around 44.0% (247 MTPA) of the total installed cement capacity has been set up over the last decade and stands at par with the best in the world.

    Decadal growth in cement installed capacity in India
    Source: Survey of Cement Industry and Directory 2019, 6th Edition and public sources such as annual report, news articles and investor presentations
  2. Process Optimisation3

    Selection of most advanced technology does not guarantee a long term sustained energy efficient operations. Over a period, energy efficiency is constantly driven by a range of process optimisation functions, such as:

    1. uniformity of the kiln feed chemistry;
    2. dexterity of the burning zone, which is a direct function of kiln operation and plant reliability factor.

    ISO 50001, voluntarily adopted by a majority of Indian cement players, also ensures implementation of a structured, systematic and continuous improvements in energy efficiency. Table highlights specific electrical energy consumption rate for selected unit processes in the Cement Industry.

    Specific electrical energy consumption for selected processes in Cement Industry
    kWh/ton of Material Technology
    0.70 Single Stage Crusher
    0.65 Double Stage Crusher
    11.10 Raw Mill - Vertical Roller Mill
    16.50 Raw Mill - Ball Mill
    23.90 Coal Mill - Vertical Roller Mill
    16.28 Five Stage Preheater - Clinkerisation
    17 05 Six+ Stage Preheater - Clinkerisation
    45.38 Five Stage Preheater - Upto Clinkerisation
    43.32 Six+ Stage Preheater - Upto Clinkerisation
    21.92 Cement Mill - Vertical Roller Mill
    27.07 Cement Mill - Ball Mill Closed Circuit
    23.20 Cement Mill - Ball Mill with HPRG
    0.65 Packing Plant
    0.67 Compressor upto clinkerisation
    0.89 Compressor Cement Griding and Packing
    Source: Confederation of Indian Industry (CII) (2019), Energy Benchmarking for Indian Cement Industry, accessed on July 28, 2021

    A majority of Indian cement plants operate at an above average installed capacity of around 1.7 MTPA, which allows optimal utilisation of resources and aids in improving energy productivity.4

  3. Product Characteristics

    Cement Industry has gradually transitioned to greener variants of Ordinary Portland Cement (OPC). Production of Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) contributing to a significant 72% (in 2017) of the total cement production in India ( Figure ). The Indian Cement Industry is the largest consumer of fly ash consuming about 28% of the total fly ash generated in the Country.5 Electrical energy demand also depends on the product characteristics. Higher the requirement for a cement’s strength development, finer it needs to be grinded, requiring significantly more energy in the grinding mills.

    Production of cement varieties in India
    Source: WBCSD (2018), Low Carbon Technology Roadmap for the Indian Cement Sector, Status Review 2018, Available at https://www.wbcsd.org/Sector-Projects/Cement-Sustainability-Initiative/Resources/Low-Carbon-Technology-Roadmap-for-the-Indian-Cement-Sector-Status-Review-2018; accessed on July 28, 2021

    The International Energy Agency (IEA) estimates that around 3.7 GJ of energy can be saved per tonne of clinker displaced.6 Table details the Clinker to Cement ratio in India vis a vis global peers.

    Clinker to cement ratio
    Parameter Unit Global Top 10%7 Global Average8 India9
    Clinker to Cement Ratio % 65% 75% 69.5%
    Source: Cement Sustainability and European Cement Research Academy (2017) Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead, Available at https://ecra-online.org/fileadmin/redaktion/files/pdf/CSI_ECRA_Technology_Papers_2017.pdf; accessed on July 28, 2021
  4. Ore quality

    Mineralogical and chemical characteristics of raw material/ore, such as homogeneity, removability, fragility, grindability, burnability and moisture content, affect the thermal intensity of clinker.10 Indian cement players efficiently combine high grade limestone with that of poor grade to enhance the life span of captive mines while also optimising the requirement of raw ore.

  5. Alternative fuels

    Around 4% of the total fuel requirements by the Indian Cement Industry is met through alternative fuels, primarily municipal solid waste. The inconsistency and lack of pre-treatment at the source of waste management site affects the throughput (energy efficiency) of cement kilns. A supply side segregation and pre-treatment would immensely assist in meeting higher energy productivity by the Cement Industry.

  6. Emission Norms

    The Indian emission norms calls for stringent measures for abatement of dust (Particulate Matter), SOx and NOx emissions that require additional power from corresponding ancillary equipment(s). Estimates suggest that specific electrical consumption would further increase by 5 to 15 kWh [6] to meet the increased requirements of emission reduction and product fineness.

Future Outlook

Energy efficiency can be streamlined through collaborative efforts amongst the Cement players, State bodies and academic institutions. Financial incentives towards adoption of state of the art technologies and energy management systems would increase the speed and scale of transition.

Perform Achieve Trade (PAT) initiative by the Government of India has been a successful driver behind transition to higher energy efficiency within the industry sector. The Cement Sector has surpassed the prescribed efficiency targets in both the cycles of PAT, which demonstrates its proactiveness and partnership in achieving cleaner growth pathways. Future PAT cycles are expected to further strengthen the energy efficiency targets for the Cement Industry ( Table ). Presently the integrated cement plants with a threshold annual energy consumption of more than 30,000 toe are included under the PAT scheme.

Timeline for upcoming PAT cycles
Initiative Target Set
PAT Cycle III 0.096 Mtoe
PAT Cycle IV 0.004 Mtoe
PAT Cycle V 0.087 Mtoe
Source: Bureau of Energy Efficiency, Available at https://beeindia.gov.in/content/pat-notifications; accessed on July 28, 2021

The Indian Cement Industry has been able to leverage on the energy efficiency levers to optimise its energy requirement and is poised to play a critical role in transition towards sustainable development.

References
  1. Global Top 10%: Cement Sustainability and European Cement Research Academy (2017) Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead, Available at https://ecra-online.org/fileadmin/redaktion/files/pdf/CSI_ECRA_Technology_Papers_2017.pdf; accessed on November 26, 2020
  2. India: India’s performance is computed for the top five players (by installed capacity) representing 241 MT of installed capacity, which is equivalent to 45% of the total installed capacity.
  3. Loading, Global Average, Process Optimisation: CII (2019); Energy benchmarking exercise for Indian Cement industry; accessed on November 26, 2020
  4. Productivity: CMA compilation based on Survey of Cement Industry and Directory 2019, 6th Edition and public sources such as annual report, news articles and investor presentations
  5. Country: Report on Fly Ash Generation and Utilisation, Central Electricity Authority; Available at https://cea.nic.in/wp-content/uploads/tcd/2021/03/Half_Yearly_Ash_Report-2020-21_Full-Final.pdf; Accessed on September 23, 2021
  6. Displaced: International Energy Agency (2017), Energy Technology Perspectives, Available at https://www.iea.org/reports/energy-technology-perspectives-2017; accessed on November 26, 2020
  7. Global Top 10%: Cement Sustainability and European Cement Research Academy (2017) Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead, Available at https://ecra-online.org/fileadmin/redaktion/files/pdf/CSI_ECRA_Technology_Papers_2017.pdf; accessed on November 26, 2020
  8. Global Average: Ibid
  9. India: India’s performance is computed for the top five players (by installed capacity) representing 241 million tonnes of installed capacity, which is equivalent to 45% of the total installed capacity.
  10. Clinker: Abdul VahapKorkmaz (2019), Evaluation of chemical, mineralogical and clinker burnability properties of mudstones as cement raw materials, Available at https://www.sciencedirect.com/science/article/pii/S2214509518304054, accessed on November 26, 2020