9 September 2019, 16:20
Greenhouse gases, including carbon monoxides, nitrogen oxides, methane gas and fluorinated hydrocarbon compounds, are responsible for global warming. It is an undisputed fact that CO2 contributes to the greenhouse effect. The substance is generated when fossil fuels such as coal, crude oil and natural gas are combusted, primarily through the production of electricity and heat, in households, traffic and industrial production. Construction machinery also contributes in part, while building material plants can have a major impact too. With the Paris Agreement, 195 countries have set a clear objective for the first time: By the year 2050, the output of greenhouse gases must be reduced drastically in order for global warming to remain clearly below 2° Celsius by the end of the century.
Construction machinery – almost ideal
Manufacturers of construction machinery have been working tirelessly for the past few decades to bring their machines up to date and reduce the emissions. On the one hand, European legislation has dictated the gradual reduction of exhaust emissions since 1996 – although this only marginally affects carbon dioxide – while on the other, the cost pressures of fuels have resulted in them reducing the consumption of their machines, and in turn, their CO2 emissions.
Construction machines have a far more complex engineering architecture than a normal car or truck. There are countless types of machines which are deployed in a wide-ranging sector comprising numerous different application areas. An approach of significantly reducing CO2 emissions can therefore only be implemented holistically and must include the entire operational process, starting with the equipment, its efficiency, the operation of this equipment and alternative fuel sources. Increasing digitalization is helping to optimize these processes and make them leaner, another factor which also saves fuel. It is therefore not a viable approach to upgrade old machines (i.e. retrofit) – users should instead invest in modern and cutting-edge construction machinery which meets the increased demands and are optimally designed for the entire operational process.
An often underestimated measure is the proper use of construction machinery. An incorrectly planned job, the wrong auxiliary equipment, incorrect tire pressures and maintenance or a poorly trained operator can make even the most state-of-the-art construction machine look out of place. At this juncture, the responsibility of each individual operator is to ensure that the machine is operated by properly trained staff.
Ever more manufacturers are offering their customers the option of training and educating their staff. As part of its “Fuel Efficiency Services,” Volvo Construction Equipment not only provides tips to reduce operating costs, but also offers training courses for drivers both on real machines and in a simulator. And this is not the only company to use simulators for training purposes: Zeppelin Baumaschinen has recently introduced training courses using this technology in its in-house training center. This technology, which has long been an integral part of aviation and maritime training, is now becoming commonplace in the mechanical engineering industry thanks to the increasing level of digitalization. Liebherr even brings its own simulators to construction sites in mobile classrooms, while the Wirtgen Group operates entire training centers – Centres for Training and Technology (CTT) – to train its customers’ employees in the operation of its machines. The Paver Driver’s Licence from Vögele is just one example of a training method which is being supported by BG Bau (employers’ liability insurance association for the construction industry).
Building material plants – cement with potential
While the focus in the construction machinery sector has shifted towards the optimal planning of processes and efficient operation of machinery, things are slightly different when it comes to building material plants. After all, the production of cement alone contributes between 7 and 8 percent of global CO2 emissions! This is common knowledge amongst experts, but has not yet reached the public consciousness. Cement, water and aggregates are the main components of concrete, the most popular construction material worldwide. It is therefore a great shame that the production of this cheap and versatile construction material is one of the largest sources of CO2 emissions. For every ton of cement produced, up to one ton of CO2 is produced.
The industry has begun developing solutions which could reduce this output to almost zero through the targeted deployment of concentration and separation procedures. Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two processes which separate the CO2 produced during the manufacture of cement, enabling it to be stored or used for subsequent chemical processes. CO2 is found naturally in limestone, which is the main component of cement. The limestone is heated in large rotary kilns at high temperatures to produce Portland clinker, an intermediate product. During this process, the limestone is broken down and the carbon dioxide escapes into the air. It is therefore possible to substitute the heated cement clinker in the cement or concrete with alternative materials, resulting in a significant decrease of potential greenhouse gases. For example, approximately 30 percent of CO2 emissions can be reduced in each ton of cement by substituting calcium clays. Currently, there is no complete replacement for the raw material, as the clinker which is derived from the limestone is responsible for the strength of the concrete.
An alternative solution for reducing emissions must therefore be found. To this end, thyssenkrupp has been researching a new oxyfuel combustion process in which the combustion air is replaced by pure oxygen. The emissions would then almost completely consist of pure CO2 and steam, thus radically simplifying the complicated separation process and enabling the CO2 to be stored or processed. The first experimental plants for the cement industry in the USA and Europe were introduced from 2010, but the project has not yet moved beyond the experimental phase.
Operators can retrofit their existing plants to the oxyfuel process. For older concepts (from around 2005 onwards), exhaust gas recirculation systems can be retrofitted to existing plants. This requires additional equipment, which in turn significantly increases the complexity and the operating costs. Engineers at the research center of thyssenkrupp Industrial Solutions AG are therefore working on an improved process, and success is within reach. The new polysius® pure oxyfuel procedure uses pure oxygen as a combustion gas and does not require exhaust gas recirculation, thus significantly reducing the effort required to separate CO2. For all known CCS or CCU procedures, retrofitting represents a notable change in plant operation.
thyssenkrupp Industrial Solutions is also researching processes to convert the separated CO2 into reusable materials such as methane or methanol. Methane can be fed into the natural gas network, while methanol is a base for synthetic fuels such as kerosene. This process enables CO2 to be used in a sensible way while also reducing the demand for fossil fuels.
The “Low-Carbon Transition in the Cement Industry”1 technology roadmap from the OECD / International Energy Agency has calculated that using new technologies such as carbon capture and storage or carbon capture and utilization would result in a substantial reduction of CO2 emissions.
“Innovative technologies including carbon capture (CO2 emissions reduction of 48%) and reduction of the clinker to cement ratio (CO2 emissions reduction of 37%) lead the way in cumulative CO2 emissions reductions in cement making in the roadmap vision compared to the RTS by 2050.”2
Global cumulative CO2 emissions reductions by applying the roadmap vision (2DS – 2 Degrees Scenario) compared to the RTS2
Note: Cumulative CO2 emissions reductions refer to the period from 2020 to 2050 and are based on the low-variability case of the scenarios.2
So far, so good.
What is missing, however, is the infrastructure required to transport the carbon dioxide and an approval framework covering how it can be reused or stored.
Responding to a query from VDMA Construction - Equipment and Plant Engineering, the Federal Ministry for Environment, Nature Conservation and Nuclear Safety (BMU) stated that separating CO2 with the goal of storing it is currently not an option. This means that the only currently viable options are to utilize carbon dioxide, or preferably to avoid it altogether. The BMU is currently developing a funding program for decarbonization in emissions-heavy industries, with implementation planned for the coming year. In November 2019, the ministry will open a Center of Expertise for Climate Protection in Energy-intensive Industry in Cottbus with the target of supporting the industries which are facing particular challenges regarding the goal of neutral greenhouse gas emissions, as well as retaining jobs in the German industrial sector in the future.
In the view of VDMA Construction Equipment and Plant Engineering, it is conducive to promote the standardization of alternative cements, as well as the approach of the BMU of developing a sales market for cements produced using greenhouse gas-neutral procedures. It is, however, necessary to create an approval framework quickly, and therefore also the requisite infrastructure for transporting and reusing the separated CO2. Policymakers need to act.
What to do with the CO2?
A key technology in this scenario is power-to-X, with which both synthetic gas and liquid fuels can be manufactured. Alternative energy sources can be used as seasonal storage in electricity or transport applications, such as in heavy-duty transport or in shipping and aviation. One significant benefit is that the infrastructure which is in place to transport and fill fossil fuels can continue to be used for the synthetic gases and fuels. As research projects have shown, these synthetic fuels can also be admixed to fossil fuels in almost any ratio, thus contributing to the quick reduction of greenhouse gases.
VDMA views power-to-X as a guarantor of the energy transition. As CO2 is required to convert hydrogen into alternative energy sources, cement plants could therefore contribute to the reliable and permanent generation of energy.
The work by VDMA and its member companies makes a significant contribution towards achieving the goals set out in the Paris Agreement, while simultaneously safeguarding Germany’s standing as an industrial location, its jobs, its leading technological position and its social cohesion and prosperity. This is a task which requires all involved parties to act. Companies which wish to contribute are invited to join VDMA and take on an active role here.
1The roadmap is the result of a collaborative effort between the International Energy Agency (IEA) and the World Business Council on Sustainable Development (WBCSD) Cement Sustainability Initiative (CSI).
2 IEA (2018). Technology roadmap: Low-Carbon Transition in the Cement Industry. All rights reserved. P.22