Technological as well as economical optimized Biomass CHP systems with regard to state-of-the-art technologies.

Analysis and presentation of representative biomass CHP systems with an electric power output of less than 2 MW. Variation of parameters and identification of potential optimized interactions between specific units. Identification of the economically and thermodynamically most optimized interconnection based on state-of-the-art technologies.

Short Description




Initial Situation

The utilization of biomass within decentralized CHP-plants is a great opportunity to reduce greenhouse gas emissions. Due to special fees originated by the law for renewable energies in Austria, which has been in force up to the year 2007, several facilities with an electrical power up to 2 MW have been erected and are now in successful operation. Generally these plants are based on steam-cycle, resp. ORC and are integrated in different infrastructures.

Content and objectives

The unit operations of these processes are representing the state-of-the-art, which doesn't unconditionally implement, that the entire plant represents the state-of-the-art. For example the experience in operation with steam turbines is little, or opportunities to optimize the process are missed in some cases. Representative facilities will be identified and presented, to provide a basis for the examinations. The focus of this study is on the optimization of existing processes with regard to thermodynamic issues and to point out the required border conditions for an economical operation as well as to identify alternative unit operations to increase the efficiency of these power plants.
In this study, the following aspects are emphasized:

  • Selection, presentation and simulation of representative CHP plants
  • Cost Survey, variation f parameters to identify alternative operation units
  • Economic analysis of these systems
  • Development of an optimum plant design

Methodological approach

To address the target group the representative plants are presented with focus on practical experience. Due to the different operation modes, like heat or power driven operation, and the different environments where these facilities are integrated, like the size and structure of heat consumers, the influence and interaction of these parameters is highlighted. Thus a relation between these facilities should be conveyed to the audience.

Basis of the investigations are annual load lines of the district heating systems and detailed process models, which are built within the Process Simulation Environment IPSEpro, resp. the equation solver EES. Input data for the simulation are detailed operation data, which are gathered during the project, for example the isentropic efficiency of steam turbines in the observed power range.

These models are used to vary border conditions and to identify crucial parameters for an economically and thermodynamically optimized operation, especially:

  • Size and structure of district heating systems
  • Implementation of alternative unit operations, like air condenser, or evacuation unit
  • Operation during summer- or wintertime
  • Additional parameters, like steam bleeding flow for district heating

A pinch-point study is carried out to verify the configuration of heat exchangers and to optimize the maximum amount of usable energy.

To allow the comparison of the specific CHP plants the cost per kWh electric power for all these facilities is computed. This figure is independent from the specific border conditions and implements operation expenses and investment costs. The calculation is based on the assumption that the plant is transcribed during the period where the current law for renewable energies is in force.

Expected results

Relevant data from the operation experience for further simulations are gathered and presented. Existing facilities are evaluated and the potential for optimization is determined.

A Proposal for the optimized CHP plant based on existing technology is worked out and presented. The focus is on the application of alternative unit operations with high efficiency. Thus the efficiency of existing state-of-the-art CHP plants can be increased, also the entire potential of existing plants can be utilized, which could reduce the CO2-emissions with a comparatively small effort. Moreover the results from this study could be the basis for prospective biomass fired CHP plants with optimized efficiency.

Presentation of results

At May, 21st, 2008 a symposium is hosted in Güssing to present the results to the expert public and plant operators. Please don't hesitate to contact the project manager Richard Zweiler for further information or announcement. Contact address below.

Project Partners

Project management

DI Dr. Richard Zweiler
reNet Güssing GmbH

Project or cooperation partner

  • Univ. Prof. DI Dr. Hermann Hofbauer

Contact Address

DI Dr. Richard Zweiler
reNet Güssing GmbH
Europastraße 1
7540 Güssing
Tel.: +43 (5) 9010-87521
Fax: +43 (5) 9010-85012

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