CSP Today has just published a comprehensive report entitled “CSP Parabolic Trough Report—Costs and Performance”.

The authors interviewed more than 45 senior executives at companies involved in CSP, including developers, component manufacturers, EPCs and research labs.

The team also collected data on costs from the interviewees and input information such water costs, insurance and labor necessary to calculate costs of CSP. The collated data was then run through a model called the Solar Advisory Model (SAM), developed by NREL, and the final results and report analysis were peer reviewed by leading scientists at CIEMAT, developers (Abengoa) and industry associations (Protermosolar).
Planned CSP capacity per country (in MW). Where are parabolic troughs being installed? There are 26 plants in total with 12 in the USA and 11 in Spain. Spain leads in capacity with 1200 MW plus 600 under construction, followed by the USA with 800 MW and 1200 under construction—but the planned future capacity in the USA stands at an impressive 10.9 GW, larger than the next 10 nations combined.

Why are they being installed?

The levelized cost of energy (LCOE) is significantly lower than that of conventional solar PV: 0.15-0.24 €/kWh vs. 0.25-0.325 €/kwh for solar PV. Also, thermal energy can be conveniently stored to help to balance supply and demand.

What is LCOE and how was it calculated?

The LCOE was calculated according to the simplified IEA method (Ref. International Energy Agency (IEA), Guidelines for the economic analysis of renewable energy technology applications, (1991)) using euro as the currency. Equation 1 shows how the LCOE was calculated.

Renewable energy overview. (Note: Emission costs have been neglected for the PTC LCOE estimation.) How do these costs work out relative to other energy sources? And what is the optimum plant size?

A major challenge to CSP plants is their inherently high capita cost. However, conventional power plants suffer from high fossil- fuel-dependent running costs, and thus the running costs of parabolic trough plants were found to be very competitive. The optimum plant size derived from the model used in this report was found to be around 150 MW.

How do parabolic troughs work?

The electricity is generated using by transferring the heat generated from solar collection to a heat transfer fluid and then to a steam heat exchanger, and then converting it into electricity using a conventional steam turbine.

The solar collector assembly (SCA) is a central component of parabolic trough solar thermal power plants. The solar field is made up of a combination of many parallel rows of SCAs, normally aligned on a north-south horizontal axis. Each SCA has a linear parabolic-shaped reflector capable of tracking the sun from sunrise to sunset, concentrating the sun’s irradiation onto the absorber tube along the focal line. Within this absorber tube a heat transfer fluid, usually synthetic oil, is circulated and heated to an approximate temperature of 400°C.

Parabolic trough collector designs are split into three groups: torque-box, torque- tube and space-frame, which each represent about a third of capacity—350 MW, 370 MW and 454 MW of installed capacity respectively. While torque-box and torque-tube designs use steel to provide rigidity, the space-frame designs are fabricated of extruded aluminum profiles.