Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - CAPTure (Competitive SolAr Power Towers – CAPTure)

Teaser

The world\'s power demand is currently of about 15 terawatts. Most of it is provided by burning fossil fuels, which has a severe impact on the environment and on the world’s climate. Given the fact that the sun provides roughly 85 petawatts, available for terrestrial solar...

Summary

The world\'s power demand is currently of about 15 terawatts. Most of it is provided by burning fossil fuels, which has a severe impact on the environment and on the world’s climate. Given the fact that the sun provides roughly 85 petawatts, available for terrestrial solar collectors, makes solar-energy-based technologies a highly promising research area. Especially the concentrated solar power (CSP) sector, also known as solar thermal electricity (STE), with the potential of storing thermal energy, is expected to play a key role regarding the integration of large fractions of renewable energy in the power grid.

The principal aim of the CAPTure project is to bring the central receiver technology to the next level, introducing the combined cycle technology to concentrated solar power. In particular, the CAPTure project tends to combine highest thermal-to-electric conversion efficiencies (typically known from modern combined-cycle plants that are in the order of magnitude of 58%), with the concentrated solar power technology with the highest cost-reduction potential and also best potential for advanced solar combined cycles (the solar power tower technology).

The global objective of the CAPTure project is to increase plant efficiencies and reduce levelized cost of electricity (LCOE) by developing all relevant components that allow implementing an innovative plant configuration. This plant configuration is based on a multi-tower decoupled advanced solar combined cycle approach that not only increases cycle efficiencies but also avoids frequent transients and inefficient partial loads, thus maximizing overall efficiency, reliability as well as dispatchability, all of which are important factors directly related to cost competitiveness on the power market.

In order to achieve this global objective, the specific developments in the project are the following:

-The development of an advanced and innovative pressurized air solar receiver unit, composed of an open volumetric receiver, and a network of highly efficient fixed-bed regenerative heat exchangers working in alternating modes that allow to reach a thermal receiver overall efficiency of more than 80%.

-The development of small-area downsized heliostats that will contribute to an improved solar flux control at the solar receiver mainly in two ways, namely (i) via an advanced and effective automatic heliostat field calibration and (ii) via an innovative dynamic multi-aiming-point strategy.

-The theoretical assessment and optimization of the CAPTure concept as a whole: The modular multi-tower decoupled solar combined cycle concept (DSCC)

Work performed

The main deliverable of the CAPTure project will be a prototype of the solar-driven hot-air turbine and prototypes of the small-area heliostats, both tested at the solar research facility PSA in the south of Spain.

In order to achieve these goals:

WP1 has focused on the general specifications of the solar-driven hot-air turbine. On the other hand, WP1 has focused on the optimization of the CAPTure plant concept, the decoupled solar combined cycle.

WP2 has focused on the solar receiver development. At the current project stage (end of first reporting period), the first design iteration on cup level has been finished. A first set of prototypes has been manufactured and assembled.

WP3 has focused on the design of the regenerative beds that connect the solar receiver to the hot-air turbine. At this stage, the conceptual modelling, sizing and the definition of operational modes is finished.

WP4 has focused on the design of the hot-air turbine. At this stage, the conceptual design and the requirement specifications of key components are finished. The detailed design is ongoing.

WP5 has focused on the development of downsized heliostats, optimized for mass production. Two designs are being developed in parallel. Also a smart calibration system is under development.

WP6 has focused on the system integration of the final prototype. At this stage, the testing modes of the prototypes have been defined.

WP7 has been focusing on risk management.

Finally, WP8 is responsible for dissemination, WP9 for exploitation, and WP10 deals with the general project management.

Final results

PROGRESS BEYOND THE STATE OF THE ART:

The development and application of solar combined cycles is the obvious step to boost conversion efficiencies of solar termal power plants. The CAPTure concept, represents here clearly a huge breakthrough
regarding state-of-the-art technology. Solar-to-electric peak efficiencies of up to 38% are possible, and this in dispatchable form due to the intermediate thermal energy storage system – CAPTure’s decoupled solar combined cycles.


IMPACT:

- Replicability: The CAPTure consortium includes two companies with expertise in high temperature materials (both ceramic and metallic), companies with expertise in receivers and turbo-compressor development, companies with expertise in high volume manufacturing (especially in drive systems), companies specialized in flow control solutions at different temperatures and finally reference Engineering, Procurement and Construction (EPC) partners and promoters like EDF and FLAG ensuring strong industrial links with major European players and easily deployable technologies for quick market transfer.

- Socio-economics: The CAPTure project strengthens the European industrial technology base since key and more costly components (not only main heliostat components like drives, but also receivers, turbines, high temperature valves, etc.) of the system will be produced in Europe, implying a quite important demand of different employee skills, representing an intense integration of European enterprises and thereby contributing to creating growth and jobs in Europe.

- Environment: The CAPTure project will allow reducing the total amount of water consumed. On one hand due to the implementation of a combined cycle which demands less water per kWh produced, and on the other hand, because of increased efficiency which leads to an equivalent solar field size reduction for a given power and hence the need of water for cleaning can be reduced.

- Market Transformation: One of the key aspects of CSP tower power plants is the integration of thermal energy storage systems which make them a much more reliable and predictable source of electricity compared to other renewable energy sources. Utilizing stored thermal energy to operate a conventional synchronous generator, CSP plants with thermal energy storage can support power and provide ancillary services including voltage support, frequency response, regulation and spinning reserves, and ramping reserves – services that would otherwise be provided, at least in part, by conventional fossil-fuel generation.

- Policy: Concentrated solar power with its key advantage of thermal energy storage and/or hybridisation in combination with an abundant availability of solar energy, forms the obvious solution for providing clean, renewable, 100% safe and dispatchable electricity all at once. Hence, developing highly efficient and thus cost competitive solar thermal power plants is one of Europe’s strategic goals. The central receiver technology addressed in CAPTure is highly suitable for Europe’s “sun belt” (e.g. Spain, Italy and Greece) with the potential of providing a considerable amount of renewable and clean electric energy in the near future.

Website & more info

More info: http://www.capture-solar-energy.eu.