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KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.ORCID iD: 0000-0001-9923-4189
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
2013 (English)In: American Solar Energy Society (ASES) - SOLAR2013, 2013Conference paper (Refereed)
Abstract [en]

A desired feature of solar power systems would be to continue producing at high output a few hours after sunset in order to cover local peak loads. An energy storage system would be able to help with solving this problem. The simplest and most cost-effective energy storage method is a thermal accumulator, where hot water or another fluid is stored at a given temperature higher than the surroundings. Conversion of thermal energy into mechanical power when compared to photovoltaic systems, however, is limited in efficiency and requires comparatively complex equipment, which might not be as cost-effective as desired, suffer from low reliability and require frequent maintenance.

The thermal path of converting solar energy into electricity is certainly promising but has largely been underestimated and underutilized. Several thermal-to-electricity energy conversion technologies already exist in either conventional form or at close-to-commercialization phase and can be further optimized and adapted to low-cost low-temperature solutions. Combined heat and power (cogeneration) facilities at small scales can be attractive for a quicker and wider deployment in solar-rich locations.

This study evaluates and compares several candidates for the conversion of low-temperature solar thermal energy into power and examines their technical feasibility and thermodynamic performance, as well as their potential for low-investment strategies and integration with thermal energy storage. With temperatures in the solar collectors limited to 150

oC (300 oF), the suggested energy conversion techniques include flat plate and evacuated tube solar collectors combined with low-parameter steam Rankine cycles or turbocharger derivative Brayton cycles, organic Rankine cycles and novel thermoelectric solutions.

Results show that common steam, organic, or air expansion cycles optimized for low parameter applications are feasible for further development and deployment in the near future, based on established components featuring turbines derived from commercial products. Thermal-to-electricity efficiency of around 5% - 12% and solar-to-electricity efficiency of around 4 – 8% can be achieved by some of the cycle alternatives at their best operational conditions.

Place, publisher, year, edition, pages
Keyword [en]
solar thermal electricity, low-temperature, low-enthalpy, thermal storage, energy conversion
National Category
Energy Engineering
URN: urn:nbn:se:kth:diva-128443OAI: diva2:647548
American Solar Energy Society (ASES) - SOLAR2013, Baltimore, April 2013

QC 20130924

Available from: 2013-09-11 Created: 2013-09-11 Last updated: 2013-09-24Bibliographically approved

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