About Dirk Lechtenberg

Dirk Lechtenberg is a pioneer in the production and use of alternative fuels. He is the founder and Managing Director of the consulting company MVW Lechtenberg & Partner (Germany). He is the recipient of the Global Fuel award 2012 by the Cement & Lime Magazine.

Energy Efficiency in Saudi Cement Industry

Saudi Arabia is the largest construction market in the Middle East, with large development projects under way and many more in the planning stage. The cement industry in the country is evolving rapidly and is expected to reach annual clinker production of 70 million tonnes in 2013 from current figure of 60 million tonnes per year. The cement industry is one of the highest energy-intensive industries in the world, with fuel and energy costs typically representing 30-40% of total production costs. On an average, the specific electrical energy consumption typically ranges between 90 and 130 kWh per tonne of cement. Keeping in view the huge energy demand of the cement industry, the Saudi Arabian government has been making efforts to reduce the energy consumption in the country towards a more sustainable.

Energy Demand in Cement Production

The theoretical fuel energy demand for cement clinker production is determined by the energy required for the chemical/mineralogical reactions (1,700 to 1,800 MJ/tonne clinker) and the thermal energy needed for raw material drying and pre-heating. Modern cement plants which were built within the last decade have low energy consumption compared to older plants.  The actual fuel energy use for different kiln systems is in the following ranges (MJ/tonne clinker):

  • 3,000 – 3,800 for dry process, multi-stage (3 – 6 stages) cyclone preheater and precalcining kilns,
  • 3,100 – 4,200 for dry process rotary kilns equipped with cyclone preheaters,
  • 3,300 – 4,500 for semi-dry/semi-wet processes (e.g. Lepol-kilns),
  • Up to 5,000 for dry process long kilns,
  • 5,000 – 6,000 for wet process long kilns and
  • 3,100–6,500 for shaft kilns.

Energy Efficiency in Cement Industry

With new built, state-of-the-art cement plants, usually all technical measures seem to be implemented towards low energy consumption. So, how to reduce it further?

Energy efficiency is based on the following three pillars

  • Technical optimization
  • Alternative raw materials for cement and clinker production
  • Alternative fuels

In Europe, the new energy efficiency directive from 2011 intends to reduce the energy consumption of the overall industry by 20%, achieving savings of 200billion Euros at the energy bill and with the goal to create 2 million new jobs within Europe. This approach will have a significant influence also on the cement industry. Saving 20% of the energy consumption is a challenging goal, especially for plants with state-of-the-art technology.

In older plants modernizations in the fields of grinding, process control and process prediction can, if properly planned and installed, reduce the electricity consumption – sometimes in a two digit number.

Alternative Fuels

Alternative fuels, such as waste-derived fuels or RDF, bear further energy saving potential. The substitution of fossil fuel by alternative sources of energy is common practice in the European cement industry.The German cement industry, for example, substitutes approximately 61% of their fossil fuel demand. The European cement industry reaches an overall substitution rate of at least ca. 20%.

Typical “alternative fuels” available in Saudi Arabia are municipal solid wastes, agro-industrial wastes, industrial wastes and some amount of crop residues. To use alternative or waste-derived fuels, such as municipal solid wastes, dried sewage sludges, drilling wastes etc., a regulatory base has to be developed which sets

  • Types of wastes/alternative fuels,
  • Standards for the production of waste-derived fuels,
  • Emission standards and control mechanism while using alternative fuels and
  • Standards for permitting procedures.

Alternative Raw Materials

The reduction of clinker portion in cement affords another route to reduce energy consumption. In particular, granulated blast furnace slags or even limestone have proven themselves as substitutes in cement production, thus reducing the overall energy consumption.

To force the use of alternative raw materials within the cement industry, also – and again –standards have to be set, where

  • Types of wastes, by-products and other secondary raw materials are defined,
  • Standards for the substitution are set,
  • Guidelines for processing are developed,
  • Control mechanisms are defined.

Conclusions

To reduce the energy consumption, an energy efficiency program, focusing on “production-related energy efficiency” has to be developed. Substantial potential for energy efficiency improvement exists in the cement industry and in individual plants. A portion of this potential will be achieved as part of (natural) modernization and expansion of existing facilities, as well as construction of new plants in particular regions. Still, a relatively large potential for improved energy management practices exists and can be exhausted by determined approaches.

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Agricultural Scenario in MENA

Agriculture plays an important role in the economies of most of the countries in the Middle East and North Africa.  The contribution of the agricultural sector to the overall economy varies significantly among countries in the region, ranging from about 3.2 percent in Saudi Arabia to 13.4 percent in Egypt.  Large scale irrigation is expanding, enabling intensive production of high value cash and export crops, including fruits, vegetables, cereals, and sugar.

Egypt is the 14th biggest rice producer in the world and the 8th biggest cotton producer in the world. Egypt produced about 5.67 million tons of rice and 635,000 tons of cotton in 2011. The area of cotton crop cultivation accounts for about 5% of the cultivated area in Egypt. The total amount of crop residues is about 16 million tons of dry matter per year. Cotton residues represent about 9% of the total amount of residues. These are materials comprising mainly cotton stalks, which present a disposal problem.

Although the Kingdom of Saudi Arabia is widely thought of as a desert, it has regions where the climate has favored agriculture. By implementing major irrigations projects and adopting large scale mechanization, Saudi Arabia has made great progress in developing agricultural sector. The Kingdom has achieved self-sufficiency in the production of wheat, eggs, and milk, among other commodities, though it still imports the bulk of its food needs. Wheat is the primary cultivated grain, followed by sorghum and barley. Dates, melons, tomatoes, potatoes, cucumbers, pumpkins, and squash are also important crops.

Despite the fact that MENA is the most water-scarce and dry region worldwide, many countries across the region, especially those around the Mediterranean Sea, are highly dependent on agriculture.  For example, the Oum Er Rbia River basin contains half of Morocco’s public irrigated agriculture and produces 60 percent of its sugar beets, 40 percent of its olives, and 40 percent of its milk.

Agricultural output is central to the Tunisian economy. Major crops are cereals and olive oil, with almost half of all the cultivated land sown with cereals and another third planted. Tunisia is one of the world's biggest producers and exporters of olive oil, and it exports dates and citrus fruits that are grown mostly in the northern parts of the country.

Agriculture in Lebanon is the third most important sector in the country after the tertiary and industrial sectors. It contributes nearly 7% to GDP and employs around 15% of the active population. Main crops include cereals (mainly wheat and barley), fruits and vegetables, olives, grapes, and tobacco, along with sheep and goat herding.

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Sustainability in MENA Cement Industry

The population in the MENA countries has doubled during the last 30 years (from ca. 110m in 1980 to almost 220m in 2010). As per conservative estimates, the rate of urbanisation in the MENA countries will exceed 70% five years from today (average for all developing countries: 54%). The proceeding urbanisation and the population increase involve several problems and challenges for the national governments and also for the cement industry. The cement production of countries in the MENA region has almost tripled during the last 15 years up to approximately 500m tons  Since the start of national revolts and demonstrations in MENA countries in 2011 the problems of especially young Arabs have attracted the attention worldwide.

Environmental problems that accompany a fast growing population and increasing urbanisation are, among others, increasing consumption of energy and raw materials, increasing land use in order to satisfy the increasing food demand, infrastructure development, disposal of increasing amounts of waste and development of sewage systems. Solving these generation spanning problems is a challenging task for the national governments.

Naturally, such high growth rates also affect the cement industry. In the MENA countries it consists of various companies, part of them listed on the stock exchange. A number of cement companies has, partly for cost aspects, responded to the negative consequences of the rapid population growth. The following paragraphs describe the cement industry’s approaches to push a sustainable development in certain sectors. They are partly driven by own responsibility and partly by regulations of the national governments. In this context it should be mentioned that the growth of the cement industry is already partly limited by factors that are directly connected with sustainability and raw material supply.

Although the factors differ from country to country and cannot be generalised, there are a few major concerns, for example:

  • Fuel shortage
  • Dependence on oil
  • Lack of investment in innovations

Let’s have a closer look on the limiting factors and innovation potential based on practical examples.

Saudi Arabia

In many industrialised countries the continuous and tailored supply of the industry with fossil fuels is only a question of price.  But the fact that of all countries, it was cement plants in the own country that repeatedly reported shortages of fossil fuel supply (heavy fuel oil), was certainly an important reason for the government to get closely involved in this matter.

Cement producers in the Kingdom of Saudi Arabia obtain state-subsidised natural gas at a price of US$ 0.75/mmbtu from the state-owned oil company “Saudi Aramco”. Formerly, the cement production costs resulting thereof were on average US$ 28.8/ton of cement (costs in neighbouring countries: Kuwait US$ 59.2/ton, UAE US$ 47.8/ton, Oman US$ 37.0/ton) which made it redundant to deal with the topic of energy. In India, a country with one of the highest energy costs in the world, the production of one ton of cement costs US$ 70.0/ton in 2010.

Due to such low energy prices and a steadily growing demand the production capacities grew constantly. Currently, the industry accounts for approximately 40% of the overall energy demand of the country. Analysts estimate that this demand will even double within the next 15 years. However, it is planned to reduce this disproportionate energy demand of the industry.

Under the patronage of HRH Prince Abdulaziz bin Salman, the state-owned oil company “Saudi Aramco” is developing a so-called “Mandatory Energy Efficiancy Program” (MEEP) for the entire Saudi-Arabian industry. The plan of MEEP is to “establish mandatory policies and regulations with the objective of reducing existing and future energy consumption levels in the industrial sector”.

For the national cement industry this approach implies investments in energy-saving measures. Key points for an energy-efficient industry are identified as

  • Use of alternative raw materials
  • Use of alternative fuels
  • Training and education in energy efficiency

As the use of alternative fuels and raw materials is not yet common in the Kingdom of Saudi Arabia, guidelines and a regulatory framework have to be defined which set standards for the use of alternative or waste-derived fuels like municipal solid wastes, dried sewage sludge, drilling wastes and others. It has to include:

  • Types of wastes and alternative fuels that may be used by the cement industry
  • Standards for the production of waste-derived fuels
  • Emission standards and control mechanisms while using alternative fuels
  • Standards for permitting procedures

Appropriate standards also need to be established for alternative raw materials that are to be used for clinker and cement production. In order to achieve an energy-efficient production special education, further training and workshops for the involved staff have to be carried out.

Egypt

The current political developments in Egypt influence the local cement industry significantly. The government expects additional sources of revenue on the one hand from selling licences for the construction of new cement plants and on the other hand from a reduction of subsidies for fossil fuels. Since these news are not a surprise for the local cement plants, they started to invest in the implementation of alternative – mostly biomass-derived fuels. One of them is CemexAssiut that not only started using different kinds of biomass, but also, most notably and exemplary, established plantations for the production of biomass (here: “Casuarina”) that are irrigated with pretreated sewage water from the city Assiut.

Egypt is the 14th biggest rice producer in the world and the 8th biggest cotton producer in the world. Egypt produced about 5.67 million tons of rice and 635,000 tons of cotton in 2011. The area of cotton crop cultivation accounts for about 5% of the cultivated area in Egypt. The total amount of crop residues is about 16 million tons of dry matter per year. Cotton residues represent about 9% of the total amount of residues. Such high production rates should be welcomed by the cement industry since these materials comprise cotton stalks, rice husks and rice straw which serve ideally as alternative fuels.

The use of waste-derived alternative fuels is, however, more complicated. Although for example Cairo produces some 15,000 tons of waste each day, it is not easy for the cement plants to obtain this waste since they are in direct competition with the informal sector that controls approx. 60% of the local waste total. So-called Zabbaleen or scavengers – mostly young people who do not have other options – make their living by collecting and selling waste-derived recyclables.

Tunisia

Some years ago, Tunisia already invested in the establishment of an organised waste management system in form of a state-owned agency named “ANGED”. Funded by the national German KfW development bank, numerous waste collection points as well as organised landfills have been built. Additionally, a special collection centre for hazardous waste was erected in Jradou. This centre was operated by MVW Lechtenberg’s Partner Nehlsen AG, the German Waste Management Group, collecting and processing wastes like used oils and solvents. Such wastes are ideal alternative fuels. A fact that is also known to the local cement companies that planned to use them in their plants. Unfortunately, due to public opposition the centre was closed and the projects for the processing of alternative fuels have been suspended since then.

Tunisia is one of the biggest producers and exporters of olive oil in the world. It also exports dates and citrus fruits that are grown mostly in the northern parts of the country. It seems paradox that for example olive kernels – the waste from Tunisian olive production – is exported to European power plants in order to save fossil fuel-derived CO2 emissions there, while Tunisia imports approximately 90% of its energy demand, consisting of fossil fuel.

Morocco

The Moroccan cement industry has already achieved a greater success regarding the use of alternative fuels. Cement plants, mostly owned by the international companies Lafarge, Cimpor, Holcim and Italcimenti, already invested years ago in the environmentally friendly use of alternative fuels and alternative raw materials due to the development of world market prices. Also the only local competitor, CIMAT, has started preparing for the implementation of alternative fuels immediately after completion of its new plant (a 5-stage double string calciner from Polysius) in Ben Ahmed, near Casablanca.

In the year 2003 an agreement on the use and import of alternative fuels (used tyres at the time) was made between the Association Professionelle de Ciment and Moroccan government. Since last year attempts are being made to agree on an industry regulation that sets standards for the use of all appropriate special waste available in Morocco.

United Arab Emirates

The United Arab Emirates, represented by Dr. Rashid Ahmad Bin Fahd, Minister of Environment and Water, recently issued a decision streamlining the activities of cement plants all over the country. The resolution will affect all existing and new cement factories across the country. Its provisions obligate the industry to prepare a report assessing the impact of cement plants on the environment.

According to the decision, this report has to be prepared by a consulting firm having expert knowledge regarding environmental protection in the cement industry. This is certainly the first step to evaluate the current situation which will be followed by an investigation of alternatives towards a sustainable development. Interest in the implementation of alternative fuels already exists among the national cement industry which is proven not least by the numerous planned investment projects.

Conclusions

The cement industry in the MENA region will change significantly within the next years. This change will focus on the improvement of energy efficiency and on the increased use of alternative raw materials and alternative fuels. This will include high investments in technology and in the human resources sector where the creation of new jobs, especially in the field of environmentally friendly and sustainable development, provides a perspective for the growing, young population of the MENA countries.

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Use of Sewage Sludge in Cement Industry

The MENA region produces huge quantity of municipal wastewater which represents a serious problem due to its high treatment costs and risk to environment, human health and marine life. The per capita wastewater generation rate in the region is estimated at 80-200 litres per day. Sewage generation across the region is rising by an astonishing rate of 25 percent every year.

Municipal wastewater treatment plants in MENA produce large amounts of sludge whose disposal is a cause of major concern. For example, Kuwait has 6 wastewater treatment plants, with combined capacity of treating 12,000m³ of municipal wastewater per day, which produce around 250 tons of sludge daily. Similarly Tunisia has approximately 125 wastewater treatment plants which generate around 1 million tons of sewage sludge every year. Currently most of the sewage is sent to landfills. Sewage sludge generation is bound to increase at rapid rates in MENA due to increase in number and size of urban habitats and growing industrialization.

Use of Sewage Sludge in Cement Industry

An attractive disposal method for sewage sludge is to use it as alternative fuel source in a cement kiln. The resultant ash is incorporated in the cement matrix. Infact, several European countries, like Germany and Switzerland, have already started adopting this practice for sewage sludge management. Sewage sludge has relatively high net calorific value of 10-20 MJ/kg as well as lower carbon dioxide emissions factor compared to coal when treated in a cement kiln. Use of sludge in cement kilns can also tackle the problem of safe and eco-friendly disposal of sewage sludge. The cement industry accounts for almost 5 percent of anthropogenic CO2 emissions worldwide. Treating municipal wastes in cement kilns can reduce industry’s reliance on fossil fuels and decrease greenhouse gas emissions.

The use of sewage sludge as alternative fuel in clinker production is one of the most sustainable option for sludge waste management. Due to the high temperature in the kiln the organic content of the sewage sludge will be completely destroyed. The sludge minerals will be bound in the clinker after the burning process. The calorific value of sewage sludge depends on the organic content and on the moisture content of the sludge. Dried sewage sludge with high organic content possesses a high calorific value.  Waste coming out of sewage sludge treatment processes has a minor role as raw material substitute, due to their chemical composition.

The dried municipal sewage sludge has organic material content (ca. 40 – 45 wt %), therefore the use of this alternative fuel in clinker production will save fossil CO2 emissions. According to IPCC default of solid biomass fuel, the dried sewage sludge CO2 emission factor is 110 kg CO2/GJ without consideration of biogenic content. The usage of municipal sewage sludge as fuel supports the saving of fossil fuel emission.

Sludge is usually treated before disposal to reduce water content, fermentation propensity and pathogens by making use of treatment processes like thickening, dewatering, stabilisation, disinfection and thermal drying. The sludge may undergo one or several treatments resulting in a dry solid alternative fuel of a low to medium energy content that can be used in cement industry.

Conclusions

The use of sewage sludge as alternative fuel is a common practice in cement plants around the world, Europe in particular. It could be an attractive business proposition for wastewater treatment plant operators and cement industry in the Middle East to work together to tackle the problem of sewage sludge disposal, and high energy requirements and GHGs emissions from the cement industry.

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Energy Sector in Arab Countries

The Arab energy sector has played and will continue to play an important role in the regional as well as global economy. In addition to satisfying energy needs for economic and social development, it is the source of oil and gas export revenues contributing to economic development. The Arab oil and gas sector represents the largest economic sector in the region. Increase of oil revenues were the main drivers for economic development in most of the Arab oil producing countries.

Due to the remarkable recent increases of the oil prices and the escalated levels of oil production in some Arab countries, the Arab oil revenues have witnessed a parallel unprecedented growth. The Arab economies, as well, are heavily dependent on oil and gas to meet their domestic energy demand. Oil contributes about 53.6 % of the total demand and the share of gas represents about 43.9 %, while other resources such as hydro power, coal, and renewable resources represent only about 2 %

The energy sector in the Arab word has been struggling in recent years to find ways to tackle existing and anticipated shortfalls in resources and investments. In many cases, the efficiency of energy production and consumption patterns in the region requires improvement. Though the per capita energy consumption in the GCC sub-region are among the world’s top list, more than 40 percent of the Arab population in rural and urban poor areas do not have adequate access to energy services. It is also noted that almost one-fifth of the Arab population relies on non-commercial fuels for different energy uses.

Energy Consumption in Arab Countries in 2003

  • The average primary energy consumption reached 1196 kgoe per capita, compared to the world average of 1523 kgoe. Wide disparities exist in the levels of energy consumption within and between Arab countries.
  • The average electricity consumption reached 1445 kwh per capita regionally, compared to the world average of 2271 kwh per capita, and
  • The average primary energy intensity in the region is 0.51 kgoe per US$ compared to a world average of 0.27 kgoe, reflecting the low economic returns on energy consumption in the region

Electricity Consumption in Arab Countries in 2005

  • Installed capacity in 2005 was 124 GW compared with 13 GW in 1975.
  • Electricity consumption in 2005 was 480,000 GWh (480 TWh) compared  with 22,000 GWh (22 TWh) in 1975.
  • Half of the installed capacity exists in Arab Gulf countries.
  • Population in 2005 was 313 million compared to 140 million in 1975.
  • Annual per capita consumption increased from 160 KWh in 1975 to 1530  kWh in 2005.

Relying heavily on fossil fuels, it is evident that the current trends in the Arab energy sector are unsustainable. The move towards achieving the objectives of energy for sustainable development requires policies and measures to address such problems, while maintaining the effective contribution of the sector to the region’s prosperity.

Since 1992, Arab countries have been moving towards the sustainability of the energy sector to achieve the goals and targets relevant to the key energy issues. Several Arab declarations have been issued in recent years emphasizing concerns and commitment of regional powers to achieve sustainable developmentSome progress has bee achieved; however, more steps are required to achieve the desired objectives.

Drilling Waste Management and Cement Industry

During the exploration and production of oil, huge amounts of drilling wastes are produced in the form of mud and cuttings.  As per conservative estimates, around 0.37 kg of drilling wastes is generated for every barrel of oil produced. The American Petroleum Institute (API) has estimated that approximately 1.21 barrels of total drilling wastes are generated for every foot drilled.

The Middle East oil and gas industry has made a lot of effort in order to reduce the environmental impact of their activities; modern drilling methods such as horizontal drilling, navigating the drill bits three dimensionally through the earth, contacting and economically producing resources while minimizing surface disruption. Drilling wastes must be properly managed to prevent negative impact on human health as well as on the environment.

Drilling Waste Management

Drilling waste management technologies and practices can be grouped into three major categories: minimization, recycle/reuse, and disposal. The first step in managing drilling wastes is to separate the solid cuttings from the liquid drilling mud. Once solid and liquid drilling wastes have been separated, companies can use a variety of technologies and practices to manage the wastes. For some applications, drilling wastes are solidified or stabilized prior to their ultimate management practice.

Drilling wastes, such as cuttings, are indifferent and not of specified quality. The cuttings separated from the mud at the shale shakers may be coated with so much mud that they are unsuitable for the next reuse or disposal step or are difficult to handle or transport. Constituents of the cuttings or the mud coating them (e.g., oil, metals) may leach from the waste, making them unsuitable for land application or burial approaches.

Various materials can be added to cuttings to solidify and stabilize them. Still this can be an opportunity for cement plants to use uncontaminated cuttings as substitute raw material, even in a lower substitution. The use of such raw materials will be more environmental friendly then the common practice of oil companies to spread such cuttings on the land.

Several different approaches are used for injecting drilling wastes into underground formations for permanent disposal. Slurry injection technology, which involves grinding or processing solids into small particles, mixing them with water or some other liquid to make slurry, and injecting the slurry into an underground formation at pressures high enough to fracture the rock. As these muds could be used as fuel resource and substitute other fossil fuels, it is preferred to process the muds and use them.

Use of Drilling Wastes in Cement Industry

Thermal technologies use high temperatures to reclaim or destroy hydrocarbon-contaminated material. Thermal treatment is the most efficient treatment for destroying organics, and it also reduces the volume and mobility of inorganic such as metals and salts. Additional treatment may be necessary for metals and salts, depending on the final fate of the wastes. Waste streams high in hydrocarbons (typically 10 to 40%), like oil-based mud, are good candidates for thermal treatment technology.

The use of drilling wastes and muds is most preferable in cement kilns, as a cement kiln can be an attractive, less expensive alternative to a rotary kiln. In cement kilns, drilling wastes with oily components can be used in a fuel-blending program to substitute for fuel that would otherwise be needed to fire the kiln.

Cement kiln temperatures (1,400 to 1,500 degrees C) and residence times are sufficient to achieve thermal destruction of organics. Cement kilns may also have pollution control devices to minimize emissions. The ash resulting from waste combustion becomes incorporated into the cement matrix, providing aluminum, silica, clay, and other minerals typically added in the cement raw material feed stream.

Recent studies have shown that it is feasible to use such drilling waste as substitute fuel in a cement plant. The drilling mud can be processed by a centrifuge to separate remaining water, compressed by a screw into a solid pump and conveyed.

The cement industry can play a significant role in the sustainable development in the Arab countries, e.g. by reducing fossil fuel emissions with the use of refused derived fuels (RDF) made from municipal solid waste (MSW) or hazardous waste such as oil spilling. 

The cement companies in the Middle East can contribute to sustainability also by improving their own internal practices such as improving energy efficiency and implementing recycling programs. Businesses can show commitments to sustainability through voluntary adopting the concepts of social and environmental responsibilities, implementing cleaner production practices, and accepting extended responsibilities for their products.