Reducing the clinker factor in the final cement reduces CO2 both from the calcination of carbonates and from combustion of coal, but the fuel substitution rate has to go up. Facilitation is required to allow cement kilns to utilise large quantum of wastes as AFRs. Ulhas Parlikar of Geocycle India elaborates on what can happen with appropriate policy framework.
India is the second largest producer of cement next to China. The Indian cement industry is consolidated, organised and mature. The top 20 cement companies account for almost 70 per cent of the total cement production of the country (IBEF, 2014). Actual production of 250 Mt cement in 2013, meant that the industry consumed approximately 300 Mt of virgin raw material, 24 Mt of coal (MoC, 2015), 20 billion kWh electricity and emitted nearly 175 MtCO2. Due to reducing coal linkages over the years, the Indian cement industry imports over 30% of its total coal requirement, adding to the cost of producing cement.
The Indian industry´s average thermal energy consumption is estimated to be about 725 kcal/kg clinker and the average electrical energy use is about 80 kWh/t cement, much lower than the global average of 934 kcal/kg clinker and 107 kWh/t cement. The best levels achieved by the Indian cement industry, at about 680 kcal/kg clinker and 66 kWh/t cement, are comparable with the best achieved levels in the world (WBCSD CSI, 2013). The cement industry is currently using 45 Mt of fly ash from coal-based power stations and around 10 Mt of blast furnace slag from the production of pig iron (WBCSD, 2013).
The mineral waste fractions are substituting the Portland cement clinker by grinding it together in the cement mill (or separate pulverisation prior to blending). Reducing the clinker factor in the final cement reduces the CO2 both from the calcination of carbonates and from combustion of coal.
However, the Thermal Substitution Rate (TSR) or Fuel Substitution of the Indian cement industry with the utilisation of wastes from agricultural, industrial and municipal sources as alternative fuels and raw materials (AFRs) is only in the range of 1 - 2 per cent.
Waste generation scenario and cement kiln option for its gainful disposal
India generates large quantum of wastes from agricultural, Industrial and municipal sources and currently the entire waste is disposed without any recovery process. Several countries globally have utilised cement kilns as an effective option for their country´s industrial, municipal and hazardous waste disposal. This creates a win-win situation for both the local administration and the cement plants: the administration utilises the infrastructure already available at cement kilns, thereby spending less on waste management, and the cement kilns are paid by the polluter for safe waste disposal, as well as having their fuel requirements partly met.
The Cement Vision of India 2025 prepared by AT Kearney/CII has projected that the TSR of the Indian cement industry would be about 12% by 2025 and the study of the Low-Carbon Technology Roadmap for the Indian cement industry prepared by the International Energy Association, in collaboration with WBCSD, has projected the same to be 19% in 2030 and 25% in 2050.
Opportunity for resource conservation and GHG mitigation through co-processing
If the Indian cement industry is also able to move towards large-scale use of AFRs and is able to achieve the TSR as envisaged in the low carbon technology roadmap, there will be a substantial contribution that the cement industry will be able to make towards resource conservation and GHG mitigation.
The projected output of this exercise is presented in the Table-1
It can be observed that if wastes are utilised as AFRs, there is potential to conserve coal of about 11 to 16 Mio TPA in the year 2030 and about 17 to 30 Mio TPA of coal in the year 2050. In 2020 and 2030, for every Mt of cement produced, 7 000 tonnes and 25 000 tonnes of AFs need to be co-processed, respectively. This means that we will be saving an amount of coal that we are consuming at present. This also helps in mitigating an amount of GHG emissions that we are letting into the environment. India´s industrial waste is growing in volume. Out of current generation of 4 Mt of landfillable and incinerable wastes, 2.5 Mt (60%) is awaiting disposal. Studies conducted by the Ministry of New and Renewable Energy (MNRE) have estimated surplus biomass availability at about 120-150 Mt per annum covering agricultural and forestry residues. As per the Planning Commission task force report on waste to energy, of the 62 Mt of MSW generated in urban India, 12 Mt is a combustible fraction, which can be potentially converted to RDF, thereby replacing 8 Mt of coal.
Current regulatory processes are not aligned to tap this opportunity
The cement industry prefers uniform emission standards for co-processing rather than case-by-case permits. In India, it normally takes more than a year for a waste stream to get regular permits for co-processing. This is because the law and guideline mandates trial runs to be conducted for each new waste streams, requiring approvals for trial and regular usage from both state and central pollution control boards. For some special and difficult to treat hazardous wastes (pesticides, PCB, CFC, etc.), however, it is important and necessary to carry out trial burns to ensure compliance to environment and occupational health and safety.
In India itself, co-processing technology has also been used to destroy hazardous chemicals. A trial conducted at ACC-Kymore cement works, in SINTEF´s and CPCB´s supervision, demonstrated destruction and removal efficiency (DRE) of 99.9999% for concentrated CFC (chlorofluorocarbons) gases at high feeding rate in an Indian cement kiln. This shows the potential of the technology with regard to safe and sound destruction of hazardous chemicals in existing infrastructure.
The major categories of wastes that can be used by the cement industry as alternative fuels and raw materials are hazardous wastes, non-hazardous wastes, Refuse Derived Fuel (RDF), Municipal Solid Waste (MSW), shredded tyres and biomass. The major constraints in implementing large-scale co-processing of these kinds of wastes in the Indian cement industry along with the support required are elaborated in detail in the low carbon technology roadmap document.
The major constraint is the current regulatory framework that is built on the principle of disposal rather than the principle of sustainability. A permitting system resembling international best practice will probably stimulate broader interest. A revision and update of the existing guidelines and permitting requirements (addressing issues such as interstate transportation, emission limits, standard approach for utilisation of alternative sources of de-carbonated materials and mineralizers, etc.,) is regarded to be of crucial importance in order to stimulate increased co-processing practice.
Desired changes in the Indian regulatory framework
The desired changes are provided below.
1)Amendment in Hazardous Waste (Management, Handling & Transboundary Movement) Rules, 2008 to:
1.Recognise co-processing in cement kiln as a preferred technology for disposal because it is a resource recovery option over landfill and incineration operation. (By this provision, the wastes that can be co-processed will not get disposed through landfill and incineration process. In fact, restrictions or limits on landfill (or inclusion of externality charges or future liability costs to landfill charges) will give impetus to co-processing initiative in India).
2.Authorise cement plants to receive, store, pre-process and co-process wastes based on the availability of required infrastructure to handle and store hazardous wastes as specified in the HWM Rules and based on prescribed emission standards.
The current waste by waste permitting process through co-processing trial is not a relevant process of approval for co-processing for following reasons: (a)The concern of the impact of the chemical constituents present in the waste on the emissions/ product quality.
(b)There are more than 20,000 waste streams that are co-processed globally. In the past 10 years, we have been able to complete trial of less than 100 waste streams. By the waste by waste trial approval process, we will never be able to move ahead.
(c)Even if a waste stream is approved for co-processing through trial, its waste characteristics are never constant. They vary from batch to batch and from time to time.
(d)While undertaking the co-processing of approved waste streams, they get blended to a new chemical composition which is completely different from all individual ones.
(e)The very purpose of implementing waste stream approval based on trial gets completely defeated.
Hence, the trial based waste by waste permitting process is not relevant at all.
Based on experience gained in India and international best practices, the desired regulatory process of approval needs to be based on (i) emission standards for cement kilns conducting co-processing, (ii) adequate infrastructure to safely handle and store wastes, (iii) appropriate laboratory facility to achieve desired input control, (iv) proper systems to monitor & control the input rates and (v) well established operational procedures for health and safety. These processes will secure the same level of environmental protection at Indian cement plants as the current EU and US regulations.
3.Allow interstate movement of hazardous wastes for cement kiln co-processing with letter of intimation to concerned SPCBs.
With this provision, waste can be moved at economically attractive distances across the states.
The pricing of waste management services is a key factor, both to ensure waste minimisation at source (to reduce disposal costs for waste generators) as well as to ensure low cost to cement manufacturers (encouraging them to install the infrastructure needed for proper handling, storage and firing at their premises) for increased TSR. The ´polluter-pays´ principle should be the basis for the economic and financial analysis of waste utilisation.
To allow cement kilns, that are complying with the prescribed emission standards for co-processing, to co-process of all kinds of non-hazardous wastes in cement kilns through intimation to SPCBs.
III.RDF from MSW
To implement amendment in draft Municipal Solid Wastes (Management and Handling) Rules, 2015 to ensure that the segregated combustible fraction is not allowed to be landfilled but is converted into Refused Derived Fuel (RDF) that is suitable for use as alternate fuel in cement plants and other suitable thermal processes. Also, to institute fiscal measures that will facilitate building large number of pre-processing facilities to convert wastes into AFRs and MSW into RDF.
Shredded tyres are used extensively in the cement industry as a supplementary fuel and MoEFFCC/CPCB may want to consider ways to increase the availability in India.
Co-processing of biomass leads to complete energy recovery and this process is much more energy efficient, even compared to biomass-based power plants. Incentives should be given for biomass utilisation in cement kilns akin to that given for biomass-based power plants.
International co-operation for assimilating Technology, Skills and Policy (TSP) framework to leap-frog
Co-processing in cement kilns is a widely practiced activity in many countries for management of wastes. The technological infrastructure required for implementing large scale co-processing is well established and operated. The skills are well developed with the operating teams to operate the kilns with large quantum of wastes and produce the right quality cement product. In these countries, the legislative processes are also designed and practiced with preference to recovery technologies such as co-processing. The TSR in these countries is therefore very high.
Our experience in the country of the past 10 years suggests to us that AFR co-processing growth takes place with a reasonable learning curve and support available from the international co-operation helps a lot. The Indian cement industry is already collaborating with several knowledge partners in utilising this lever for using large amount of wastes as AFRs in the cement kilns. Several international cement players that are implementing large scale co-processing in their plants in different countries, such as LafargeHolcim, Hiedelberg, CRH, VICAT, Italicement, etc are already operating in India and several Indian cement players such as Ultratech, Dalmia, etc., are also sourcing international co-operation in bridging the technical and skill gap in implementing large scale utilisation of AFRs.
CPCB has been closely working with the Norwegian research organisation SINTEF for the last few years and has been able to contribute towards building capacity and confidence among various stakeholders on the viability of safe and sound co-processing. We consider that co-operation of Indian policy-making bodies with agencies like SINTEF, who have been working closely with the authorities and industries in such countries, can facilitate quicker assessment of the policy level hurdles encountered in implementing large scale management of wastes as AFRs through co-processing and implementing fitting solutions to deal with them from the policy and operational considerations.
Low carbon technology roadmap