As part of the company's sustainability ambitions, HeidelbergCement is aiming to increase its alternative fuel and raw material use and at the same time reduce its stack emissions. By viewing waste as a resource, HeidelbergCement is reducing the use of natural materials such as coal and limestone. As a consequence, CO2 emissions are being reduced and an environmentally-sensitive and economically sensible waste removal service is provided to local citizens, industries and agricultural activities.
In recent years, HeidelbergCement has proven to be successful in terms of its environmental strategy. Table 1 shows the reduction of emissions to air by the whole group, while increasing the alternative fuel rate.
In all areas of the group a wide range of alternative fuels and raw materials are being used. Globally available waste streams are municipal solid waste, sewage sludge, hazardous waste and fly-ash.
HeidelbergCement is expanding the potential of these waste streams by a central coordination and exchange of learning experiences throughout the group. However it should be mentioned that achieving success in waste management requires a strong focus from the local management.
The majority of the waste used as alternative fuels is sourced in a 150km (93 mile) radius around cement plants, making stakeholder dialogues a clear responsibility of the local environmental engineers and general management. Some areas offer typical opportunities for local waste streams, such as agricultural biomass in Indonesia or animal meal in Europe.
HeidelbergCement is outperforming all the major international cement players (Figure 1) when it comes to the substitution degree of coal by waste sources. More than 10 plants in Europe have a higher substitution ratio than 70% and it should be noted that some kilns in Asia are already using more than 20% alternative fuels.
The big winner is ultimately the environment. Cement kilns do not increase their emissions when they co-process waste. This avoids emissions from incinerators and landfill. For example when incinerating sewage sludge a considerable amount of N2O (laughing gas) is released. Owing to the fact that 1t of N2O is equivalent to 300t of CO2 in terms of greenhouse gas effects and due to the high thermal efficiency of cement kilns, co-processing is by far the most environmentally-friendly disposal method for sewage sludge.
Compared to landfill, the avoidance of releasing 1t of methane (CH4), which is equivalent to 21t of CO2, is the main reason for the outstanding position of co-processing sewage sludge. In Figure 2, the LCA-results of the Institut für Energie- und Umweltforschung (IFEU) in Germany illustrate this burden and release comparison in CO2-kg equivalents per tonne of dry sewage sludge.
2010 level | Change since 2000 | |
Dust | 265g/t clinker | -0.39 |
NOx | 1354g/t clinker | -0.2 |
SOx | 418g/t clinker | -0.43 |
Waste fuel | 0.205 | 1.05 |
Table 1: Emissions are reducing, while use of waste materials is increasing.
HeidelbergCement in Asia
HeidelbergCement has been active in Asia for 15 years and now has a total clinker capacity of 28Mt/yr. Waste management systems in Asia are still under development. The large metropolises like Shanghai and Hong Kong however are already fully equipped with modern incineration plants.
Potential for waste co-processing in Asia
The cement industry, which is needed in order to build the vast infrastructure development in Asia, can at the same time contribute significantly to the developing waste treatment systems. For example if all of the 250Mt/yr municipal solid waste produced in China (with an average heat value of 4.5GJ/t) could be developed for co-processing in the Chinese cement industry, a considerable 25% of the heat demand of that enormous industry would be recovered. This would avoid the need for 750 1000t/day waste incinerators.
There is a clear relation between the level of the gross domestic product (GDP) and the amount of financial and human resources a society can afford to spend on improving waste management systems. The first step of development is from uncontrolled dumping to a well organised landfill. The next step is to create sanitary landfills that focus on maximum methane-capture for the production of electricity. A considerable amount of the mineral and calorific value is still not used and occupied land becomes more and more precious.
Co-processing is the next economically viable technology for waste recovery. Starting from a regional GDP of US$4000–5000/capita, the step to a higher level of environmental care than landfilling of municipal solid waste and sewage sludge is economically possible.
Case study - China
In 2004, Guangzhou in China reached this threshold and the technology of co-processing sewage sludge was presented to the local authorities and HeidelbergCement's local joint venture partner. In the following years, clinker capacity expansion was a clear priority. From 2007 onwards the project has been developed consistently with all related stakeholders and first production was established in 2009. Further optimisation and capacity expansion was carried out in 2010.
The plant can now recover 0.2Mt/yr of dewatered sludge. In other terms, this represents the sewage sludge generated by four million inhabitants! The sewage sludge plant uses waste heat from the kiln process avoiding any use of primary fuel for the thermal drying of the material. The design and manufacture of the equipment was all carried out in China, generating a large amount of employment during manufacturing and construction. Jobs have also been created for the expected 25 year lifetime of the new facility.
As mentioned before, the environment benefits considerably from this investment, the first of its kind in China. It saves 50,000t/yr of CO2, 25,000t/yr of coal 20,000t/yr of virgin raw materials. This clearly illustrates the benefits of the co-processing approach.
Case-study - Indonesia
In December 2005 the Indonesian HeidelbergCement company PT Indocement and German Technical Cooperation (GTZ) formed a Public Private Partnership (PPP) project. The object of the PPP was to enable the relevant Indonesian institutions and authorities to exercise the government's control function concerning the necessary emission measurements in connection with the co-processing of hazardous waste in cement kilns and other types of industrial combusters.
Extensive training on emission measurement and quality control was carried out with help from the European Cement Research Academy (ECRA), which involved representatives of the Ministry of Environment, air quality laboratory experts from the independent Institute of Technology Bandung (ITB) and the workforce of Indocement's Cirebon and Citeureup plants.
Indocement is now a front-runner in the cement industry in developing Clean Development Mechanism (CDM) projects, where CO2-reducing programmes are financially supported by EU-companies buying CO2 credits from green projects in developing countries. Extensive paperwork was elaborated, followed by in-depth audits of certifying institutions verifying the credibility of the programmes.
In Cirebon, rice husk agricultural residue now replaces more than 20% of the coal of one of its kilns, saving an emission of 0.1Mt/yr of CO2.
In the enormous cement plant at Citeureup, which operates nine kiln lines, hazardous waste, waste tyres and agricultural residual biomass are all being processed. A particularly strong point of the Citeureup plant is the processing of raw materials coming from industrial wastes, such as copper slag and paper sludge.
For the future
In the future HeidelbergCement will further expand its strategy to use waste as a resource to the plants in the vicinity of Xi'an, China, which is rapidly raising its GDP/capita. In Guangzhou the use of both industrial and municipal solid waste will be further exploited. For Indonesia the continuous growth since 2005 will be continued, based on the growing awareness and ever-lasting commitment to conquer all the challenges that are related to the use of waste as a resource.