The COMBO-CFB project led by VTT Technical Research Centre of Finland Ltd. has developed a new innovative concept to increase solar energy production in the energy system.

According to its research, the concept can reduce fuel consumption and emissions stressing the climate by more than 33 percent. The concept is based on the combination of concentrated solar power (CSP) technology and a traditional power plant process into a hybrid plant which produces electricity on the basis of consumption.

Research partners: VTT Technical Research Centre of Finland, the University of Oulu, Amec Foster Wheeler, Vaisala, Telog, Pöyry, Finnish Energy and the Federation of Finnish Technology Industries. Courtesy of VTT.

If part of the fuel used by a power plant is replaced with solar energy, power plant emissions will be reduced. This is also required in order to meet the emission reduction targets. The COMBO-CFB project examined how various types of hybrid plant solutions can produce power flexibly according to demand, without the need for energy storage. It then analyzed and compared different hybrid plant concepts.

The concept in which steam generated by a solar field was fed directly into the power plant’s high-pressure turbine brought a reduction in emissions and fuel consumption which, at best, exceeded 33 percent. Furthermore, a reasonable dimensioning of the hybrid plant and process optimization can bring efficiency benefits as compared to the use of separate power production methods. In the aforementioned case, the plant’s net efficiency improved by 0.8 percent. In addition to positive climate effects, good hybrid plant planning can also bring financial benefits since part of the power plant components are shared by two power production methods.

The COMBO-CFB project applied the Finnish project partners’ high-level expertise in boiler technology. In a hybrid power plant, solar energy production which varies with weather is balanced by using a steam boiler. The production concepts developed through this project will expand the application possibilities of the CSP technology.

The implementation of the CSP technology in power production is reasonable in areas with an abundance of sunlight. In Europe, this means, for example, the countries bordering the Mediterranean. However, this technology can also be implemented in areas with less sunlight by using hybrid power plants in which solar power is supported by another form of energy. For the time being, Finland is not applying this technology, whereas Denmark is already using a CSP-bio hybrid plant to produce district heating.

VTT Technical Research Centre of Finland is a state-owned and controlled research and technology company.