NOL CH OG E Y T • • R E E C S N E E Concentrated solar power and circulating fluidized A I 296 R VTT TECHNOLOGY C C bed power plant hybrids S H • S H N Final results of the COMBO-CFB project 2 9 6 I G O I H S L I I V G • H S Concentrated solar power (CSP) is a renewable energy technology, T which is able to provide dispatchable power according to demand. Dispatchability is typically achieved by decoupling solar thermal collection and power production with a thermal energy storage system. Hybrid system, in which solar field is integrated to a conventional power plant, is another option to produce renewable load-following power. The main idea in a hybrid system is to compensate the variation in solar thermal production with the steam boiler. The project "Combination of Concentrated Solar Power (CSP) with Circulating Fluidized Bed (CFB) power plants" (COMBO-CFB) aimed at developing innovative, flexible and high-efficient hybrid concept, which is able to balance the distributed intermittent production. The research focused on the capacity building in terms of different CSP technologies, hybrid concepts and thermo- chemical processes, and in technical feasibility of the hybrid concepts, including the benefits provided by different concepts, challenges and possible future improvements. C oncentrated solar po w er and circulating... Concentrated solar power and circulating fluidized bed power plant hybrids Final results of the COMBO-CFB project ISBN 978-951-38-8531-1 (URL: http://www.vttresearch.com/impact/publications) Elina Hakkarainen | Suvi Suojanen | Matti Tähtinen ISSN-L 2242-1211 ISSN 2242-122X (Online) | Toni Pikkarainen | Antton Tapani | http://urn.fi/URN:ISBN:978-951-38-8531-1 Teemu Sihvonen | Markus Hurskainen | VTT TECHNOLOGY 296 Concentrated solar power and circulating fluidized bed power plant hybrids Final results of the COMBO-CFB project Elina Hakkarainen, Suvi Suojanen, Matti Tähtinen, Toni Pikkarainen, Antton Tapani, Teemu Sihvonen, Markus Hurskainen, Hannu Mikkonen, Jari Lappalainen & Heidi Saastamoinen VTT Technical Research Centre of Finland Ltd ISBN 978-951-38-8531-1 (URL: http://www.vttresearch.com/impact/publications) VTT Technology 296 ISSN-L 2242-1211 ISSN 2242-122X (Online) http://urn.fi/URN:ISBN:978-951-38-8531-1 Copyright © VTT 2017 JULKAISIJA – UTGIVARE – PUBLISHER Teknologian tutkimuskeskus VTT Oy PL 1000 (Tekniikantie 4 A, Espoo) 02044 VTT Puh. 020 722 111, faksi 020 722 7001 Teknologiska forskningscentralen VTT Ab PB 1000 (Teknikvägen 4 A, Esbo) FI-02044 VTT Tfn +358 20 722 111, telefax +358 20 722 7001 VTT Technical Research Centre of Finland Ltd P.O. Box 1000 (Tekniikantie 4 A, Espoo) FI-02044 VTT, Finland Tel. +358 20 722 111, fax +358 20 722 7001 Cover image: Elina Hakkarainen, VTT Technical Research Centre of Finland Ltd Preface Combination of Concentrated Solar Power with Circulating Fluidized Bed Power Plants (COMBO-CFB) project was a joint project to develop hybrid power plant concepts combining concentrated solar power and circulating fluidized bed power plants. The goal of the project was to increase the knowledge on the CSP tech- nology and its opportunities to enhance the renewable centralized power produc- tion. This work was carried out in the COMBO-CFB (Combination of Concentrated Solar Power with Circulating Fluidized Bed Power Plants) research project (40066/14) coordinated by VTT Technical Research Centre of Finland Ltd with funding from Tekes – the Finnish Funding Agency for Innovation. VTT Technical Research Centre of Finland Ltd and the University of Oulu were the research partners in the project. VTT was the coordinator of the project. Participating companies were Amec Foster Wheeler, Vaisala Oyj and Telog Oy. Pöyry Finland Oy, Energiateollisuus ry and Teknologiateollisuus ry participated to the steering group work as expert members. International collaboration was con- ducted with DLR (Deutsches Zentrum für Luft- und Raumfahrt e.V.) as a research exchange. Project participated actively to the events organized by SolarPACES (Solar Power and Chemical Energy Systems, A technology collaboration pro- gramme of the International Energy Agency). 8.3.2017 Authors 3 Contents Preface ................................................................................................................. 3 List of symbols..................................................................................................... 7 1. Introduction .................................................................................................. 11 1.1 Novel concentrated solar power and conventional solid fuel-fired hybrid power plant concepts .............................................................................. 11 1.2 Key drivers for the development of hybrid CSP concepts ......................... 12 1.3 Structure of the COMBO-CFB project ...................................................... 15 2. Stand-alone and hybrid concentrated solar power technologies ............... 17 2.1 Stand-alone concentrated solar power technologies ................................ 18 2.1.1 Parabolic trough technology ......................................................... 20 2.1.2 Linear Fresnel technology ............................................................ 21 2.1.3 Central receiver technology .......................................................... 24 2.2 Hybrid concentrated solar power technologies for electricity production .... 27 2.2.1 Direct hybridisation of concentrated solar power and solid fuel-fired power plants ................................................................................ 28 2.2.2 Indirect hybridisation of concentrated solar power and solid fuel- fired power plants......................................................................... 34 2.3 Thermochemical processes and applications ........................................... 35 2.3.1 Solar thermal reforming of methane .............................................. 39 2.3.2 Solar thermal cracking of methane................................................ 40 2.3.3 Solar gasification ......................................................................... 40 2.3.4 Thermochemical splitting of water and carbon dioxide ................... 41 2.3.5 Economics of the thermochemical applications ............................. 44 3. Effects of CSP integration on CFB combustion dynamics .......................... 46 3.1 Circulating fluidized bed boilers ............................................................... 46 3.1.1 Benefits of CFB boilers................................................................. 47 3.1.2 Process requirements and restrictions of CFB boiler in CSP hybrid plant ............................................................................................ 48 3.2 Pilot-scale CFB combustion tests ............................................................ 50 4 4. Development of virtual CSP and CSP hybrid power plants ......................... 57 4.1 Dynamic simulation software Apros ......................................................... 57 4.2 Defining solar field performance .............................................................. 59 4.3 Defining CSP hybrid plant performance ................................................... 60 5. Virtual stand-alone CSP concepts ............................................................... 62 5.1 Direct steam generating linear Fresnel solar field ..................................... 62 5.1.1 Modelling approach of the direct steam generating linear Fresnel solar field ..................................................................................... 62 5.1.2 Results of simulation cases .......................................................... 65 5.1.3 Importance of irradiance forecast accuracy for production estimates ..................................................................................... 67 5.2 Molten salt solar field with two-tank thermal energy storage system.......... 70 5.2.1 Modelling approach of the direct molten salt linear Fresnel solar field ............................................................................................. 71 5.2.2 Results of simulation cases .......................................................... 73 5.3 Direct-heated supercritical carbon dioxide CSP concept........................... 77 5.3.1 Modelling approach of the direct-heated sCO2 CSP concept.......... 78 5.3.2 1-day simulations at different dates and results ............................. 81 5.3.3 Simulation of irradiance disturbances and results .......................... 83 5.4 Comparison of line-focusing CSP concepts based on supercritical carbon dioxide ................................................................................................... 85 5.4.1 Modelling approach of the indirect sCO2 CSP concept .................. 85 5.4.2 Results of the comparative simulation of two sCO2 CSP concepts . 87 5.5 Central receiver solar field....................................................................... 89 5.5.1 Collector model ............................................................................ 89 5.5.2 Receiver model ............................................................................ 90 5.5.3 Apros model for the central receiver power plant ........................... 90 6. Virtual CSP hybrid concepts ........................................................................ 93 6.1 Subsystems of the hybrid concepts ......................................................... 93 6.1.1 Linear Fresnel solar field .............................................................