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Small-Scale Chp Plant Based on a Hermetic Four-Cylinder Stirling Engine for Biomass Fuels


An efficient utilisation of biomass for energy with a minimum of environmental impact can be obtained, when biomass is used for small-scale combined heat & power (CHP) production in villages close to biomass production sites as well as in the wood processing industries. The main objective of this proposal is to develop a small-scale biomass fired CHP plant based on a 70-100 kWel hermetic Stirling engine & to erect a pilot plant where comprehensive test runs will be performed with solid biomass fuels. This new development will be based on the experiences already obtained with a 30 kWel Stirling engine that has been in operation for more than 700 hours. The further technological development is essential in order to extend the area of application & cover the large market potential of biomass CHP plants. The aim of the project is to develop a technology with high overall & electric (>20%) efficiency & low operating & maintenance requirements to achieve production costs.
A new small scale CHP plant for biofuels has been developed. The plant consists of a hermetically sealed, 8-cylinder Stirling engine and a wood chips combustion system. The project outcome includes the following:
- The first 8-cylinder Stirling engine ever made;
- The largest hermetically sealed Stirling engine ever built;
- The largest Stirling engine ever built for solid fuels;
- An electric power output of 77 kW has been obtained with wood chips as fuel which is very close to the 80 kW stated in the work plan;
- 1000 hours of operation with wood chips as fuel has newer been done before with a Stirling engine this size;
- The CHP-plant has very low emissions compared to other CHP technologies based on biofuels The results of the evaluations of test runs performed and the operating experiences gained at the CHP pilot plant based on a 75 kWel Stirling engine showed that the newly developed CHP system has already achieved a high technological standard and should be suitable for marketable solutions. Problems to be addressed regarding further development and optimisation of the technology are improvements concerning the overall electric efficiency of the CHP plant and the reduction of ash deposition on the Stirling heat exchanger by an efficient automatic cleaning system. The CHP pilot plant based on a 75 kWel Stirling engine is the first of its kind in this power range world-wide and can be considered as a major break-through regarding the utilisation of Stirling engines for small-scale CHP plants utilising wood fuels.


Technical University of Denmark
Dtu, Building 101A
2800 Lyngby

Participants (5)

Bayernwerk AG
Nymphenburger Strasse 39
80335 München
I.B. Brunn & Soen
Engboulevarden 19
4800 Nykoebing Falster
Ingenieurbüro BIOS Obernberger & Narodoslawsky
Sandgasse 47/13
8010 Graz
MAWERA Holzfeuerungsanlagen GmbH & Co KG
Neulandstrasse 30
6971 Hard
United Kingdom
Richmond Road