Energy efficiency: Still some way to go
Over 95 per cent of manufacturing plants have moved from the wet / semi-wet process to dry process of cement manufacturing and have initiated moves with a specific objective of reducing electrical and thermal energy by adopting energy-efficient technologies and products, enhanced use of alternative fuels, and alternative raw materials, enhanced use of renewable energy, and pursuing waste heat recovery systems. As per reports, the Indian cement industry, over the years, has employed the best available technology for production. Thanks to a high degree of blended cement utilisation, Indian cement producers are at the forefront of fuel and electrical energy consumption on a per tonne- of- product basis. An additional benefit in terms of sustainability is the lower per tonne CO2 emission. Stricter regulatory requirements are leading to greener technologies, and they in turn, lead to further energy efficiency.
The rising costs of energy and transport have put a heavy strain on cement manufacturers. According to Gopi Ranganathan, Senior General Manager Operations, Zuari Cement, it is an opportunity to improve the efficiency. Says Ranganathan, "We view this as an opportunity to improve our efficiency by revisiting our internal systems and processes, with the objective of making them more robust. This approach helps us to minimise the impact of the setback of rising costs. We have done a number of modifications, both major and minor, to improve the efficiency of our plants."
"The Indian cement industry, with an installed capacity of over 250 MT, is the second largest producer in the world, after China. The cement industry in India is probably the most efficient in the world, and has a well-deserved reputation for technology interventions. Most plants have thermal and electrical specific energy consumption comparable to the best in the industry. Indian cement plants have state-of-the-art technology, and energy efficient equipment; there is a sufficient focus on the plant layout design which also contributes to energy savings," Ranjan Tayal, Senior Vice President - Business Consulting, Ramco Systems. Kamal Kumar, Chief General Manager, Holtec Consulting, had this to say. "The energy consumption of the cement industry is strongly linked to the type of kiln technology used. In India, the increasing share of dry process kilns with pre-heaters and pre-calciners has had a positive impact on energy consumption in clinker production. Total energy consumption in a typical dry process cement plant is 75-80 per cent fuel (thermal energy) and 20-25 per cent electricity (electrical energy) 99 per cent of the fuel consumption is used for clinker burning or pyro-processing. Hence, pyro-processing has highest scope about 5 - 40 per cent for improvements in terms of energy efficiency. Some of the major energy efficiency improvement activities include alternative fuel utilisation and waste heat recovery, addition of stage in pre-heater."
Kumar further adds, "Even though the Indian cement industry has made a significant improvement in energy efficiency through various measures, use of alternate fuels and raw materials (AFR) is a major potential area for improvement. Present thermal substitution rate by use of AFR is in the range of 0.5 to 1 per cent whereas developed countries achieved as high as 40 per cent TSR."
Bidyut Bhattacharya, Technical Director, Sinoma International Engg Co India, says "The amount of energy saving varies on a case- to- case basis depending on the actual selection of process and equipment, quality and consistency of fuel, raw material characteristics, etc. However, it is important to understand here that long- term plant energy efficiency cannot be guaranteed based on the mere selection of the most efficient individual equipment alone. Rather, over a long term, energy (fuel and power) efficiency is largely driven by uniformity of the kiln feed chemistry, mastery of the burning zone which is primarily a kiln operation, and plant reliability factor i.e, avoiding stoppages due to incidents; all this in turn, relates to plant preventive maintenance."
According to him, utilising a vertical roller mill or roll press circuit in finish grinding mode for raw material grinding is the industry norm today, and this makes for a significant energy cost reduction when compared to the traditional closed circuit ball mill system. Likewise, for coal grinding, a vertical mill is used, and for the energy- intensive finish grinding process, the ball mill plus roll press system is widely popular. He says, "In specific cases where slag grinding is involved with high percentage moisture, the VRM technology for finish grinding is used. Only in extreme cases do we get a request for close circuit ball mill for grinding, this is inherently less energy- efficient. High efficiency separators are the standard today for all milling systems."
Bidyut adds, "As regards the pyro-processing area, Indian cement producers continuously strive to achieve the lowest specific fuel consumption along with high power savings. High efficiency fourth- generation grate coolers are being widely used; they provide high recuperation efficiency along with lower maintenance interventions. As the total cooling air requirement reduces from the earlier 2.2Nm3/kg clinker to say, 1.8Nm3/kg clinker, there is a lot of savings through reduced exhaust air and fans` power consumption. To achieve lower fuel consumption, six stage pre-heater systems are the popular choice, along with in- line calciners. Advanced low NOx technologies are used in many cement plants. As regards process fans, a static efficiency = 82 per cent and use of variable speed drives reduces power consumption."
According to Bidyut, however, there is scope for improvement, especially with regard to waste heat recovery systems which is slowly catching on in India. He says says, "It is imperative to make WHR a mandatory requirement for any new cement plant, as is the case in some emerging countries. A significant portion of the energy requirement can be sourced through utilisation of waste heat from the pre-heater and cooler. In this context, Indian cement producers/consultants need to do a more specific, case- to- case basis, cost- benefit analysis for the six stage vs. the five stage pre-heater system, specifically when raw material moisture is high or when civil design parameters like wind speed/seismic conditions are not favourable. Also, these days, the usage of alternate fuels in cement processing is quickly picking up. Considering the dwindling quality/supply of domestic coal and the logistic issues of imported supply, a variety of alternate fuels are being utilised cost- effectively; not only pet coke but a host of other materials from tyres to rice husk, plastic, sawdust, are all being used. Utilisation of municipal wastes/ sludge is still in its infancy in India, primarily due to supply- side bottlenecks."
Challenges are aplenty, especially when it comes to energy. With the plummeting value of currency, fuel costs are spiralling, thus raising the cost of thermal power generation. Quality coal and its availability, availability of quality raw materials like limestone, continue to be a concern. What's more, power shortages have compelled many of the players to set up captive power plants (CPP) to fulfil the energy needs. To cap it all, then, there is the increased pressure of complying with mandatory energy regulations such as Perform, Achieve, Trade (PAT), where a manufacturer must meet energy reduction targets as well as its renewable energy purchase (RPO) obligations.
PAT is the energy conservation drive launched by BEE (Bureau of Energy Efficiency) under National Mission for Enhanced Energy Efficiency. Base line figures are average of the past three years (2007-08, 2008-09 & 2009-10). Target has been given by BEE to reduce from baseline figures in a span of three years, starting April, 2012 and ending March, 2015. PAT (Perform-Achieve-Trade) is applicable for energy intensive industries. It covers 563 designated consumers in eight sectors. The energy specific improvement target would have to be unit specific. Each Designated Consumers (DC) is mandated to reduce its special energy consumption (SEC) by a fixed percentage based on its current SEC (or baseline SEC) within the sectorial bandwidth. The PAT scheme is a unique and innovative programme with no precedence anywhere else in the world. The key goal of the scheme is to mandate specific energy efficiency for the most energy efficiency for the most energy intensive industries, and further incentivise them to achieve better energy efficiency improvements that are superior to their specified specific energy consumption improvement targets. To facilitate this, the scheme provides the option to industries which achieve superior savings to receive energy savings certificates for these excess savings, and to trade the additional energy savings certificates with other energy-intensive industries, the Designated Consumers, who can utilise these certificates to comply with their own reduction targets. The Energy Savings Certificates (ESCerts) issued will be tradable on special trading platforms to be created in the two power exchanges (Indian Energy Exchange and Power Exchange India).
"The cement plant is an energy- intensive unit, where the energy cost accounts for about 30 per cent of the total manufacturing cost. Energy savings of 0.816 million tonnes of oil equivalent (Mtoe) (34PJ) per year are expected to be achieved, which is around 12 per cent of total national energy savings targets assessed under PAT," says Sumit Banerjee, Vice- Chairman, Reliance Cement. According to Banerjee, the cement industry need to focus on five broad categories of carbon emission reduction levers: thermal and electrical energy efficiency, co-processing of alternate fuels and raw materials, clinker substitution, waste heat recovery for power generation and adoption of new technologies like CCS (Carbon Capture and Storage), algal growth promotion and use of bio-fuels. He adds, "All our cement plants, either in project phase or in project development phase, will be highly energy- efficient. These plants will be designed to use alternative fuel and raw materials (AFR) and be equipped with waste heat recovery system for power generation."
Says K N Rao, ACC, Director, Energy & Environment, "PAT scheme and the RPO obligations provide both challenges and opportunities to make manufacturing units green and self- sustainable in terms of power. Also, the continuous reduction in Specific Energy Consumption, has, to some extent, helped mitigate the rising cost of electricity generation." Rao adds, "Ten plants of ACC (nine integrated plants and the Tikaria grinding unit) have been identified as DCs under PAT. Though PAT poses a significant challenge to capex investments, we see opportunities in long term growth. To make the most of it, our twin focus should be on improving efficiencies across the industry and reducing the use of thermal and electrical energy in the manufacturing process by generating and using renewable energy.
Opportunities abound when it comes to energy efficiency. One can consider upgrading old plants, co-processing industrial and municipal waste in cement kilns, generating power from the waste heat in kilns, using waste from other industries like fly ash and slag in the manufacturing process."
"The PAT scheme is a driver for the industry to take up different important measures to reduce overall specific energy consumption. These steps will finally improve the bottom line by way of saving energy bill," says G Jayaraman, Executive President, Birla Corporation. He further adds, "BCL has taken the initiative to reduce carbon footprint by adapting energy efficiency in all units. BCL was rewarded carbon emission reduction certificate for 1 lakh tonnes of CO2 and successfully traded on the UNFCCI platform. As a roadmap for the coming three years, BCL is focusing on renewal energy, basically solar and biomass power plants.
Sandeep Shrivastava, Head, Environment, Ambuja Cement says, "The PAT scheme is focused on improving the energy efficiency in Indian industries. The cement industry is regarded as one of the most energy- efficient industry and this scheme further provides an opportunity to better the efficiency levels achieved.
We are addressing the PAT targets through a serious of initiatives in our various plants which also include implementation of ISO 50001:2011 to ensure a structured and systematic approach to energy efficiency initiatives and continual improvement." Sandeep further adds, "Cement has been long considered to be an energy- intensive sector, with energy costs making up a significant proportion of total cement production costs. Ambuja Cements well realises that climate change and energy security are global challenges and we need to adopt sustainable technologies, innovations and processes for techno- socio- economic development." According to him, renewable energy, planning for climate change mitigation as well as energy security, all of it is part of the company's long-term strategy. In order to develop the company's roadmap, three major options have been included: wind, solar and biomass.
According to Dr GVK Prasad, Executive President - Operations, KCP Limited, PAT is a very good scheme which will help cement industry for implementation of best available practices and technologies, economically viable energy efficient projects and faster adoption of low carbon technology. Prasad says, "We have a diversified portfolio of power projects in which green energy generation has an important share. We expect that, of our total energy portfolio, as much as ten percent will come from renewable energy capacities. We have successfully commissioned a 8.25 MW of hydroelectric power projects in Nekarikallu village in Guntur District of Andhra Pradesh and it is presently generating 340 lakh Kwh / year. We have set up wind power of 3.25 MW capacity in Tamil Nadu. We have also installed 2.30 MW capacity fuel less power unit using waste hot gases generated in our one of the cement units located in Macherla, Guntur District, AP. At KCP, we currently generate about 30 per cent of our electrical energy needs from waste heat recovery from this Unit. Recently, we have successfully commissioned 1.15 MW solar photovoltaic project, India's first captive such project in Muktyala, Krishna District, Andhra Pradesh."
Suman Mukherjee, Managing Director and CEO, SDCC - India, says, "We have a very strict target on reducing specific energy consumption. In line with that, we have installed various VFD/high energy efficient equipment. We have commissioned the WHR system in our plant. We are working on AFR, we are following surface mining at the quarry to achieve that. We are also part of the PAT scheme. To achieve our set targets in PAT, we are working on various fronts of SEC reduction."
Suchismita sums it up, saying there is still scope for reduction in both thermal and electrical energy consumption. And that seems to be the final word, for now.