Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

WP(6) Environmental analysis of heat and power production

- This work organized within the WP6, was tackled at first by conducting a theoretical consideration of environmentally relevant aspects which occur along the energy wood chain within the energy plant.
- The spectrum of consideration includes the actual conversion process, up- and downstream as well as auxiliary processes.
- Based upon this set of information a questionnaire was developed (cf. Report on Environmental Aspects D19 /SCHRADER et al. 2005/).
- By means of the questionnaire a survey was conducted in order to quantitatively and qualitatively evaluate the current status of energy plants throughout Europe.
- Within these nine countries 45 energy plant operators were cooperative in providing data, which presentation and discussion is subject of this Report on Emissions/Reduced Emissions D18.

- The interviewed energy plants are mainly new (< 10 years), equipped with a small and medium sized combustion units.
- They function either as decentralized energy units (< 20 MW) implemented into wood-working production plants, or to a smaller extent as industry scaled energy plants (> 100 MW), selling steam and power to clients.
- Main focus of the survey was directed to emissions with the result, that almost all energy plants would comply with e.g. German limit values.
- Here, especially newer energy plants show no problems.
- Two of three energy plants have installed a flue gas treatment for dust reduction, some insert additives to reduce NOx, while over 90% have applied water treatment facilities.
- Only very few energy plants emit noise to a level higher than the location specific value, again with regard to German standards.
- To high noise emissions are not process immanent to energy plants as they can easily be counteracted by effective containment / isolation etc.
- According to fuel proportion, ash residues accumulate to 3 wt.% of fuel input, being very low compared to solid fossil fuels.
- Concerning the output parameters, their values e.g. the rate of plant utilization show a wide variation among the energy plants included in the study, mainly due to application characteristics and expressed in different maintenance periods and downs times correlating to wood-working applications.

Key innovative results:
- Compared with fossil fuels, the environmental compatibility of the thermal utilization of energy wood fares far better.
- Hence, the goal is to study relevant environmental aspects of the utilization of wood for energy in conversion plants.
- Relevance of individual processes in thermal utilisation of wood is analyzed and evaluated including delivery, preparation, storage of biomass and ash disposal / ash recovery.

Current status:
- Almost all of the plants utilize a mixture of residual and waste woody biomass with a net calorific heat value between 10 and 15 MJ/kg.
- The generally used combustion technology is grate firing, predominantly executed as pusher grate.
- Other technologies, such as fluidized bed and pulverized combustion, are sporadically found too.
- Gasification of woody biomass was not present at the survey, despite of the high degree of conversion efficiency. Its technology still needs further development to reach more operating experience.
- Just half of all energy plants are constructed as combined heat and power plants.
- The investigation of process losses and power consumption by auxiliary drives brought up values comparable to conventional energy plants.

Use potential:
- In the future, number decentralized energy plants using woody biomass will increase.
- Additionally, an increasing energetic utilization of wood in energy plants (> 50 MW) is going to be encountered in regions with vast resources (e.g. Sweden, Finland, Russia).
- In the medium time range perspective the utilization of gasification gas in engines will be realized with on-going plant technology development, while the long-term utilization of fuel gas seems achievable in high efficiency fuel cells, thus consequently leading to lower emission.

Expected benefits:
- It could be shown, that the energetic utilization of woody biomass is becoming more and more important to provide process heat and power, mainly in decentralized CHP energy plants.
- Although, predominantly encountered in wood-working countries like Sweden and Finland, energy plants extend their capability of firing different types of woody biomass, and therefore, become attractive in other regions too.
- Their compliance with legislative emission regulations is achieved due to applying state-of-the-art combustion technology.
- They are characterized by high energy conversion efficiency at affordable investment costs.
- Energy plant operators relay on a secured fuel supply (< 50 km) under cost effective conditions (substituting high priced fossil fuels).

Informazioni correlate

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