Despite making several strides in the overall energy efficiency, the industry is yet to tap 60 per cent of the potential in WHRS.
Indian cement industry has already crossed several milestones on energy efficiency and sustainability parameters. Itáhas emerged as one of the most energy-efficient industries globally with the lowest carbon footprint in the world and it is among few large scale modern industries that do not produce any hazardous solid or liquid discharge. Since 2015, the industry is taking a number of measures aimed at further improving its performance on parameters like specific heat consumption, setting up of waste heat recovery systems and use of alternate fuels (This issue is dealt with exclusively in the cover story in this edition).
Increasing competitive pressures, rising energy prices, coupled with stricter regulations for environmental protection are making energy efficiency and sustainable use of resources a top priority for the manufacturers in the recent years, and the cement industry is no exception.
The industry has reduced its overall specific electrical energy consumption (SEC - Electricity), in cement production from 80 kilowatt hour/tonne of cement (kWh/t cement) in 2010 to 76 kWh/t cement in 2017, according to the report - Low Carbon Technology Roadmap (LCTR) for the Indian Cement Sector: Status Review 2018 released by World Business Council for Sustainable Development (WBCSD). The steady increase in the production of blended cements (72 per cent) in 2016 and 2017 and improvements in the clinker factor have mostly driven this reduction. A decrease in clinker quantity in cement implies lower energy consumption for grinding. Despite increased use of petcoke and alternative fuels, frequent stop-starts due to market conditions and low capacity utilisation, the specific electrical energy use of clinkerisation (kWh/t clinker) decreased by nearly 1 kWh/t clinker compared to the baseline (2010).
The thermal SEC increased to 744 kcal/kg clinker in 2017 compared to 725 kcal/kg clinker in 2010. The increase in thermal SEC can be attributed to increased petcoke use, increase in alternative fuel use and frequent start/stops due to low market demand.
Several segments in the cement manufacturing process have seen several changes/ improvements with respect to electrical and thermal energy-efficiency improvements during 2010-2017 - preheater and kilns, latest generation high-efficiency clinker coolers, grinding systems, process fans and auxiliary equipment.
The challenge in India today is that there is large variation in energy intensities of different units, ranging from the best in the world to extremely inefficient units.
"Therefore, there is a lot of room to improve energy intensity with right deployment of technologies and best in class practices. With the adoption of massive modernisation and the state-of-the-art technology, Indian cement plants can become energy-efficient and environment-friendly, as compared to the best in the world in all respects, whether it is size of the kiln, technology, energy consumption or environment-friendliness," says Meenu Singhal, Vice President, Industry Business, Schneider Electric.
The Indian government announced Perform, Achieve and Trade (PAT) scheme, an innovative, market-based trading scheme, in 2008 under its National Mission on Enhanced Energy Efficiency (NMEEE) in the National Action Plan on Climate Change (NAPCC). PAT aims to improve energy efficiency in industries by trading in energy-efficiency certificates in energy-intensive sectors.
The first PAT cycle period ran from 2012 to 2015 and included 85 cement plants. The target allocated to these plants was to reduce energy consumption by 0.815 million tonnes of oil equivalent (MTOE). The plants in PAT cycle-1 surpassed the energy saving targets and achieved savings of 1.48 MTOE, which is around 81 per cent higher than the savings target.
PAT cycle-2 will cover 111 cement plants. The average reduction target for the sector in cycle-2 remains similar to that in cycle-1 (4-5 per cent). It will be challenging for the sector to achieve these targets since most of the easy changes have already been made. The appropriate pricing of Energy Saving Certificates (ESCerts) is crucial for ensuring the continued effectiveness of the PAT scheme.
The adoption of waste heat recovery system (WHRS) in Indian cement plants offers several benefits, such as mitigating greenhouse gas emissions and achieving PAT cycle targets. This may ultimately contribute to long-term energy security in India. According to the latest Confederation of Indian Industry (CII) data, the total waste heat recovery potential in India is 800 MW, of which the major cement plants across the country are currently tapping 43 per cent.
The country has seen a three-fold increase in WHRS installations, from 110 MW in 2010 to 344 MW in 2017, says according to the WBCSD report. Growing energy costs, including that of coal and grid electricity, have been the primary drivers for cement manufacturers to opt for WHRS. Since its introduction in 2010, the Clean Energy Cess on coal had increased 700 per cent by 2017. By 2017, 25 cement plants have installed WHRS in some 47 kilns across the country. Given the surging input costs and rising emphasis on adopting environmentally friendly production techniques, the importance of WHRS for the cement sector is increasing. All such systems installed in Indian cement plants are self-financed and use a Rankine cycle, except one which uses an Organic Rankine cycle. Cement Sustainability Initiative (CSI) member companies had 62 per cent of the total WHRS installed capacity in 2017.
The key barrier that most of the large cement manufacturers in India that opt for WHRS face is the capital expenditure required for installation and maintenance. Limited indigenous suppliers and service providers and lower cycle efficiency adds to the overall operational costs of WHRS.
Additionally, there are no policy drivers that incentivise the co-generation of power from waste heat. A policy initiative to consider WHRS under the Renewable Purchase Obligation (RPO) could significantly scale up capacities, says WBCSD in its report.
- BS SRINIVASALU REDDY