The German Aerospace Center’s Solar Institute (DLR) will serve as a scientific partner. The project is funded by the German Ministry for the Environment.

Viessmann (Allendorf, Germany) and Industrial Solar (Freiburg, Germany) are developing a solar-fossil hybrid system that will generate process steam for industrial applications. 

Steam is an important heat transfer medium in the industry and is typically used at a temperature range between 100 °C and 220 °C. Many thermal processes in the food and beverage industry and chemical industry, among others, are operated with steam.

The Viessmann Group and Industrial Solar GmbH are cooperating to develop a standard solution for co-generation process steam for industrial applications combining fossil fuel and solar process heat.

Viessmann produces steam boilers that are fueled by oil or gas. At this point, the technological possibilities to increase the efficiency of these systems are largely exhausted, says Viessmann. Industrial Solar offers a concentrating solar collector, known as the Fresnel collector, which is designed especially for industrial applications for direct steam generation. The single-axis tracking mirrors of the collector concentrate sunlight onto an evacuated absorber tube, where temperatures up to 400 °C are generated.

As industry’s demand for steam around the clock, it is necessary to combine the solar collector with a fossil fuel fired steam boiler as a backup to ensure continual steam supply according to the industrial load profile. Integration of a solar collector system into an existing steam network requires a great deal of planning and is therefore costly.

The project "SolSteam" started in August 2013 and has a duration of three years. In the coming year, a demonstration plant with a collector area of 1000 m² will be implemented together with a boiler to deliver steam to a customer at a mass flow rate of about 2 t/hr.

Worldwide, industry is responsible for more than a quarter of the total primary energy consumption and associated CO2 emissions. About two thirds of this energy is in form of thermal energy, while only one third is electrical energy. Thus, the use of solar thermal collectors for industrial applications is an obvious step in the direction of energy and cost savings.