Bioenergy Agreement Task XI11 Biomass Utilization Technologies for Small Scale WOOd-FUdled Combined Heat and Power Systems Henrik Houmann Jakobsen Serren Houmerller Lars Thaaning Pedersen dk-TEKNIK, Energy & Environment Gladsaxe Msllevej 15 dk-2860 Sarborg Denmark dk-TEKNIK . GLADSAXE MBLLEVEJ 15. DK-2860 S0BORG . TEL t45 39 69 65 11 . FAX t45 39 69 60 02 DISCLAIMER Portions of this document may be illegible electronic image products. Images are produced from the best available original document. Introduction The aim of this study is to describe and compare different technologies for small cogeneration systems (up to 2-3 We),based on wood as fuel. For decentralized cogeneration, i.e. for recovering energy from saw mill wood wastes or heat supply for small villages, it is vital to know the advantages and disadvantages of the different technologies. Also, for the decision-makers it is of importance to know the price levels of the different technologies. A typical obstacle for small wood cogeneration systems is the installation costs. The specific price (per kW) is usually higher than for larger plants or plants using fossil fuels. For a saw mill choosing between cogeneration and simple heat production, however, the larger installation costs are counterweighed by the sale of electricity, while the fuel consumption is the same. Whether it is profitable or not to invest in cogeneration is often hard to decide. For many years small wood cogeneration systems have been too expensive, leading to the construction of only heat producing systems due to too high price levels of small steam turbines. In recent years a great deal of effort has been put into research and developing of new technologies to replace this traditional steam turbine. Among these are: e Steam engines e Stirling engines e Indirectly fired gas turbines e Pressurized down draft combustion. Along with the small scale traditional steam turbines, these technologies will be evaluated in this study. When some or all these technologies are fully developed and commercial, a strong means of reducing the strain on the environment and the greenhouse effect will be available, as the total efficiency is high (up to 90%)and wood is an energy source in balance with nature. The study has been performed by dk-TEKNIK, Denmark, within the framework of the IEA Bioenergy Agreement Task X, Combustion activity. All countries represented in the Technical Committee of the task have contributed with guidelines, facts and informations to the project. In this version more detailed economical calculations including a sensitivity analysis is presented compared to previous versions. Authors are Henrik Houmann Jakobsen Lars Thaaning Pedersen / Ssren Houmller EA Task X - Technologies for Small Wood Co-Generation Systems Page 1 TABLE OF CONTENTS 1. Scope of Work .......................................................................................................... 4 2 . Watch Out! .............................................................................................................. 5 3 . Steam Turbines ......................................................................................................... 6 3.1 Basic Principles .................................................................................................. 6 3.1.1 The Rankine cycle .................................................................................. 6 3.1.2 The Steam Turbine ................................................................................. 7 3.2 Sites of R&D ..................................................................................................... 8 3.3 Stage of Development ........................................................................................... 9 3.4 Economy .......................................................................................................... 9 3.5 Feasibility ......................................................................................................... 10 3.6 Major Barriers for Technical Adaptability to Existing Energy Infrastructure.......................... 10 4. Steam Engines .......................................................................................................... 11 4.1 Sites of R&D ..................................................................................................... 11 4.1.1 Traditional Engines ................................................................................. 11 4.1.2 Modified Traditional Engines..................................................................... 12 4.1.3 Diesel Based Systems.............................................................................. 13 4.1.4 Modern Steam Engines ............................................................................ 14 4.2 Stage of Development........................................................................................... 14 4.3 Economy.......................................................................................................... 14 4.4 Feasibility ......................................................................................................... 15 4.4.1 Advantages and Disadvantages of the Steam Engine.......................................... 15 4.4.2 Necessary Innovations.............................................................................. 16 4.5 Major Barriers for Technical Adaptability to Existing Energy Infrastructure.......................... 16 r m .. .. 3 . stirling mgmes......................................................................................................... W 5.1 Sites of R&D . .................................................... ............................................. 19 ?an e- . 3.~stage or ueveiopment ........................................................................................... LL"1 5.3 Economy .......................................................................................................... 22 5.4 Feasibility ......................................................................................................... 23 5.4.1 Advantages and Disadvantages of the Stirling Engine ........................................ 23 5.4.2 Necessary Innovations .............................................................................. 25 5.5 Major Barriers for Technical Adaptability to Existing Energy Infrastructure.......................... 25 6 . Indirectly Fired Gas Turbines ....................................................................................... 26 6.1 Sites of R&D ..................................................................................................... 26 6.2 Stage of Development........................................................................................... 27 6.3.1 Canadian investigation ............................................................................. 28 6.3.2 Belgian investigation ............................................................................... 28 6.4 Feasibility ......................................................................................................... 29 6.4.1 Advantages and Disadvantages of the Indirectly Fired Gas Turbine 29 1 ........................ 6.4.2 Necessary Innovations .............................................................................. 30 6.5 Major Barriers for Technical Adaptability to Existing Energy Infrastructure.......................... 30 IEA Task X - Technologies for Small Wood Co-Generation Systems Page 2 7 . Direct Fired Pressurized Gas Turbines ............................................................................ 31 7.1 Sites of R&D ..................................................................................................... 31 7.2 Stage of Development........................................................................................... 32 7.3 Economy.......................................................................................................... 32 7.4 Pressurized Direct Fired Gas Turbine. The PGI Concept ................................................. 33 7.4.1 Stage of development............................................................................... 34 7.4.2 Economy ............................................................................................. 34 7.5 Feasibility ......................................................................................................... 34 7.5.1 Advantages and Disadvantages of Pressurized Down Draft Combustion .................. 34 7.5.2 Advantages and Disadvantages of Pressurized Direct Fired Gas Turbine ..................35 7.6 Major Barriers for Technical Adaptability to Existing Energy Infrastructure.......................... 36 8 . Economical comparison of different technologies ............................................................... 37 8.1 Introduction ....................................................................................................... 37 8.1.1 Definition of economical optimum size ......................................................... 37 8.2 Duration graph ................................................................................................... 38 8.3 Introduction ....................................................................................................... 39 8.4 Example ........................................................................................................... 39 9 . Economical calculations .............................................................................................