Study of Biomass- and Wastewood-fired CHP Plants in the 5 to 20 MWel Power Output Range with the Goal of Improving Cost Effectiveness (Part I)

Project Number 302

The adoption of the Renewable Energies Act (EEG) in Germany has triggered the very rapid construction of a large number of combined heat and power plants fired by biomass and with a power output of up to 20 MWel. These CHP plants are mostly wood-burning stations using either grate firing or fluidised bed combustion technology. The fuel predominantly used is waste wood of types A III and A IV.

As a result of this rapid development, marked changes have occurred in both the availability and market price of the fuel supply. In many cases, the conditions for economical operation of such plants have worsened significantly.

Moreover, a large number of stoppages and plant failures are reported, caused, for example, by fuel feed problems, the occurrence of high-temperature corrosion and soiling in the steam generator, and also difficulties with purification of the flue gas. As a result of these problems, many of these plants are unable to achieve the projected annual number of full-load hours, which has a substantial impact on their cost efficiency.

There has as yet been no systematic study of the failures, faults and the remedies adopted, or performance review of the latter. Nor, at the present time, is any catalogue of potential solutions available to operators which can be consulted by them when operating problems occur.

Within the scope of this project, therefore, it is intended to

  • record in a database the plants that are already in operation in Germany or are at the approval or planning stage,
  • obtain typical plant operating data through a targeted survey of selected operators,
  • evaluate the operating data obtained and undertake further development of optimisation measures that have already proved successful.

The evaluation will focus in particular on the boiler tube corrosion, the fuel feed aspects, and a comparison of the use of grate firing or fluidised bed combustion.

The project is being supported by a group of VGB member firms who are providing much of the funding and also making the necessary operating data available:

  • Boehringer Ingelheim Pharma GmbH (Ingelheim)
  • InfraServ GmbH & Co. Wiesbaden KG (Wiesbaden)
  • BVA Hagen-Kabel GmbH (Mark-E AG)
  • OIE-Aktiengesellschaft (Idar-Oberstein)
  • Steag Saarenergie AG (Saarbrücken)
  • Standardkessel GmbH, Duisburg
  • WEP - Wärme-, Energie- und Prozesstechnik GmbH (Hückelhoven)

If the project is successfully completed, it is planned to include further plants in the evaluation in a follow-on project.

The project will be conducted from June 2007 to February 2008 under the direction of Prof. Dr. Ralf Simon of the Transfer Centre for Rational and Regenerative Energy Use at Bingen University of Applied Sciences. The study will be accompanied by the Working Panels "Industrial and Co-generation Stations" and "Biomass".