The paper entitled “Solar Parabolic Trough-Biomass Hybrid Plants: A Cost-efficient Concept Suitable for Places with Low Radiation” outlines the benefits of combining solar thermal energy and biomass in a single plant to improve both efficiency and the cost of energy.
Solar thermal electric plants are usually installed in areas where annual accumulated normal direct irradiation is high enough to ensure their profitability. This is why most of the projects in the pipeline, under construction or in operation are in sunny areas such as southern Spain, MENA, Australia and California.
However, Magtel has found that if a parabolic trough plant is fitted with a biomass boiler, substantial improvements in the levelised cost of energy (LEC) and thermodynamic efficiency can be achieved, making it economically viable to install a solar thermal electric plant in places where solar radiation is not so high.
Magtel is performing a comparative analysis of three 10-MW plants operating at the same location in the Ribera del Duero, a region in northern of Spain with lower levels of irradiation but plenty of vineyards that can supply enough biomass feedstock to compensate for a moderate annual direct normal irradiation of 1,961 Wh/m2.
The three technologies being compared are a parabolic trough plant, a parabolic trough plant fitted with thermal storage, and a parabolic trough-biomass hybrid plant.
The results of the research indicate that the LEC increases with the amount of thermal storage installed and therefore, the conventional solar thermal electric plant without storage was found to have the lowest LEC.
However, the researchers also report that the LEC is directly linked to plant efficiency. The higher the efficiency, the lower the LEC and therefore, as the solar-biomass hybrid plant is the most efficient, it has the lowest LEC.
Magtel found that the hybrid plant had a LEC of 19.48 c€/kWh, assuming actual market prices of biomass, which is significantly lower than the best obtained for the choice without thermal storage (30.60 c€/kWh).
For this reason, Magtel concludes that hybridisation is a step towards solar thermal electric technology competing on the open market.
The paper will be presented on 24 September at the conference organised by SolarPACES in Perpignan (France), which will also be attended by representatives from the University of Tel Aviv, Germany's national research centre for aeronautics and space (DLR), and the US’s NREL, among others.
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