Cement is used to be seen as a kind of economic barometer: as much as the GDP increases, the use of cement usually increases in the same proportion, at least in the European environment.
In Hungary, an average of 3 million tons of cement is used annually, during economic periods this can reach up to 4.5 million tons, currently this value is well below the average of 3 million.
From the point of view of carbon dioxide emissions, it is worth distinguishing between two processes during cement production: one is from the fuel, the other is from the raw material. In the case of the latter, carbon dioxide is produced during the burning of limestone (calcium carbonate), where CO2 escapes and burnt lime (calcium oxide) remains. This is a chemical process, a natural feature, there is no way to reduce emissions here. At the same time, the capture and storage of the resulting carbon dioxide with the so-called CCS technologies (Carbon Capture and Storage) is a feasible way, so the combustion product must be captured in the chimney and stored in underground layers.
However, there are already several opportunities to reduce emissions from fuel, which the Hungarian cement industry is at the forefront of exploiting: for example, Duna-Dráva Cement Kft. (DDC) uses the most modern technologies, which are outstanding even in the European field. In the past 15 years, both the Váci and the Beremendi Cement Factory underwent complete modernization, the technology was prepared to accept alternative fuels.
We are capable of burning up to 100% alternative fuel, which is of enormous importance in the circular economy: the so-called RDF (Refuse Derived Fuel, i.e. the secondary fuel produced from residential municipal waste and the residue after sorting from selective waste collection, produced during industrial processing) and the we can utilize various industrial wastes, they do not end up in landfills, and there is no need to spend extra energy on their destruction. In addition, the advantage of utilization in the cement factory is that no ash is left behind, it is incorporated into the raw material
he told Portfolio László Szabó, Deputy Chief Technical Officer of DDC.
During production, the operating temperature is over a thousand degrees, all materials are broken down into atoms, the material coming out of the furnace is practically like lava. An artificial volcano is produced, in which materials with a completely new crystal structure are born, which have hydraulic properties, that is, if water is added to them, they harden, which gives the strength of concrete.
In order for the aforementioned wastes to provide the fuel for production, significant transformations and investments were necessary, since the released harmful substances must be 100 percent bound in order for the technology to be non-polluting. In practice, this looks like there is a gas cooling tower, where water is sprayed in for cooling, and ground limestone is countercurrent to the gas, which turns into quicklime as the temperature rises. Burnt limestone flour is technologically the most effective flue gas cleaning process.
In addition to the modernization of the energy supply, a new supply chain had to be built, and now they are in contact with dozens of companies from which they can collect raw materials suitable for alternative fuels, which can ensure consistent production. Because although it is possible to receive a wide variety of waste, the material must have a uniform calorific value and particle size due to the dosing ability, and there are also strict conditions regarding the content of harmful substances. The composition of the raw materials from the accepted, circular economy must correspond to the types of raw materials that also occur in nature. In the last 25 years, these technologies have spread not only in Europe, but also in Hungary.
Alternative fuel is the first step towards a circular economy model
A few decades earlier, these power plants operated with oil and gas, then switched to coal burning in 2003, and since then they have been constantly looking for the possibility of replacing primary fuels. Today, DDC is able to base its cement production 100% on alternative fuels, which currently mainly means the high-calorific value grindstone made from household waste with a significant plastic content, of which the company can burn between 100,000 and 200,000 tons annually. But among other things
- agricultural biowaste – for example expired or contaminated seeds,
- meat meal – products made by protein processors, from slaughterhouse waste, spoiled meat,
- plastic industry by-products, production waste, scrap generated during production
- used car tires
- but even sewage sludge
can also be used in a completely environmentally friendly way:
today, the fuel of the cement industry is not coal, but alternative materials, and much attention is also paid to the recycling of raw materials.
Although the carbon dioxide quota system basically encourages European players to reduce emissions, this trend has become global with the participation of international company groups, with differences only in the proportion of use.
It is not natural for a plant to use 100% alternative fuels, even in developed industrial countries, but the good news is that the utilization program is also spreading in China, where the annual production exceeds two and a half billion tons. (World cement production is around 4 billion tons).
This level of development is due to the fact that DDC is a member of a concern, Heidelberg Materials, where professional investors think long-term, so it was possible to experiment with new technologies, and in fact, the Hungarian subsidiary practically functions as an innovation hub within the large company. What is available in cement industry technology, and which mainly has an environmentally effective and cost-reducing effect, has been tried to be implemented in Hungary.
Zero carbon dioxide emission cement is coming
But let’s go back to emissions from raw materials, where there is less room for maneuver due to the given chemical reaction. There is not really a good alternative to the use of cement, 4 billion tons of it are consumed worldwide every year, because it cannot be replaced with another type of similarly cost-effective construction material.
As was the case in the Stone Age, Bronze Age, and Iron Age, we are now living in the era of concrete, the basis of the current infrastructure is cement
– added the experts of DDC.
At the same time, it is possible to change the composition of the cement, which can also reduce the CO2 content.
This year, the evoBuild product line will also be introduced to the Hungarian market, which is produced with at least 30% less CO2 emissions than traditional cement, but it will also be reduced by 40-50-70%. The new product line will also include concrete that contains recycled concrete, which can be used to replace primary materials such as gravel and aggregate, thereby taking a step towards a circular economy.
With this product development and fuel optimization, significant CO2 savings are possible, but
this year, they plan to introduce the evoZero product line, the cement with zero carbon dioxide emissions, which is already produced with CCS technology, to the market.
In the parent company’s Norwegian factory in Brevik, a full-scale carbon dioxide capture facility will be put into operation, which will enable the capture and transport of 400,000 tons of CO2 per year to permanent storage, i.e. it will be the world’s first industrial-scale CCS project for the cement industry.
In practice, this means that a facility of approximately the same size had to be built next to the cement factory, a flue gas treatment system, in which the flue gas is passed through an absorbing medium, the CO2 is chemically bound, from which liquid carbon dioxide can then be produced. This can then be transported by pipeline or even by ship or railway to underground storage facilities. In this case, CO2 will be injected into the underground cavities of the previously exhausted offshore natural gas deposits.
Of course, this had significant investment costs, according to the experts interviewed, the implementation of such a technology would cost at least two hundred billion forints for a cement factory in Hungary. It is therefore clear that such a project can only be realized as a result of an all-societal cooperation, as it happened in Norway: 85 percent of the cost of the entire value chain of the investment was financed by the Norwegian state.
Although cement with zero CO2 emissions can really redraw the image of the environmentally burdensome construction industry, it is also worth adding that the demand for the currently available innovative, sustainable building materials is quite subdued, which is justified by the ailing performance of the construction industry as well as the higher than traditional pricing. A good analogy for the situation is the example of the automotive industry, and within that, electric vehicles. The market for these products will start slowly, but the volumes sold will increase relatively quickly: European regulators are increasingly encouraging industrial players to use environmentally friendly solutions, as happened in the case of the aforementioned electric cars.
The publication of the article was supported by Duna-Dráva Cement Kft.
Cover image source: DDC
Tags: abandon concrete zeroemission cement year
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