Air pollution prevention
The production of vehicles at Daimler plants creates several air pollutants, most notably in the form of solvents (volatile organic carbon compounds, or VOCs) that are released in the paint shops. Other pollutants, such as sulfur dioxide (SO2), carbon monoxide (CO), nitrogen oxides (NOx), and particulates, are emitted into the atmosphere primarily through combustion processes in furnaces and at engine test rigs. We will strive to maintain the low level of emissions achieved to date and to reduce emissions even further wherever possible.
Our Quick Analyser (absolute figures and specific figures) will provide you with further information about our air borne emissions. In addition, it will enable you to compile data from the past few years, in a targeted manner and in accordance with your specific needs. This data can be output in graphic or table form, or downloaded as an Excel file.
Painting technology for passenger cars has already reached a very high standard that makes it possible to achieve only minor additional reductions in emissions. The introduction of water-based paints in the 1990s enabled us to reduce solvent emissions by some 70 percent at the passenger car plants. We are also striving to significantly cut solvent emissions in the Commercial Vehicles division. Examples of progress in this area include the UV painting area for truck axles in the Gaggenau plant and the new paint shop at EvoBus in Ulm.
In 2009 an especially innovative system was put into operation at the paint shop of the Gaggenau plant, where it substantially reduces solvent emissions, energy consumption, and CO2 emissions. The innovative paint shop uses special paints that dry within just 90 seconds under ultraviolet light. By contrast, normal paints take 30 minutes to dry at a temperature of 80 degrees Celsius. We were able to further optimize this solvent-free technology under production conditions last year. The experience gained in this way will benefit the development of future painting applications.
Quick and environmentally friendly: UV light is used to harden paint in series production for the first time
One of the main factors influencing air pollution in automobile production is the generation of volatile organic compounds (VOCs) during the painting process. In response to legal stipulations regarding the reduction of these pollutants, the Mercedes-Benz plant in Gaggenau set itself the goal to not only cut emissions below the limits, but also to use innovative technology to improve other environmental aspects related to the painting process. As a result of the project, which was launched in 2005, the Gaggenau plant now operates a VOC-free UV paint shop — and has been doing so since 2009. This facility completely replaced the former paint shop in January 2011.
The project first addressed the painting of truck hub-reduction axles, because this process was responsible for 80 percent of all the solvent emissions at the Gaggenau plant. In 2008, these emissions still amounted to about 78 tonnes. An interdisciplinary team of experts examined two variants for reducing emissions of the pollutants: the aqueous coatings known as hydro-paints and the so-called UV-hardening paints. The crucial breakthrough was achieved by switching to UV-hardening paints that also combine the properties of a primer and a top coat in a single layer. Whereas conventional paints take about 30 minutes to dry at a temperature of 80 degrees Celsius, UV paint can harden in less than 90 seconds thanks to a photochemical process that relies on ultraviolet radiation. This technique drastically reduces the amount of energy consumed and the associated CO2 emissions.
The project team had to overcome a series of major challenges in order to adjust the painting processes, since it had to develop a painting facility for very large components, which were also geometrically very complex. In addition, the coat of paint had to conform to the highest standards with regard to corrosion protection, weather resistance, and the prevention of stone chipping. In cooperation with the paint supplier and the machinery manufacturer, the project team came up with a globally unique painting process that met all of these requirements. Following the successful implementation of the new process at the Gaggenau plant, further possibilities for its application have opened up within the Group.
As a result of a comprehensive lifecycle assessment, it was determined that UV painting technology offers the following advantages over the current series-production process and alternative water-based painting technology:
- It cuts VOC production to a level far below the legal limits and creates zero emissions in the UV painting area
- Energy consumption is reduced by about 24 percent lower than with alternative techniques
- The amount of contaminated waste water is reduced by around 900 cubic meters per year
- The new process does not directly generate or emit CO2 as is the case with the conventional painting process, which involves thermal drying of the paint and requires exhaust air treatment
- Less time is needed for the process, because the coat hardens in 90 seconds
- The facility’s size and area are reduced
- The quality of the paint is optimized
- Unit costs are reduced in comparison to the alternative water-based paint
