Co-Combustion of Pulverised Coal/Biomass for Steam Production: e M ergy approach

1. Co-Combustion of Pulverised Coal/Biomass for Steam Production: eMergy approach C. Rahmouni, Dr - Veolia Environnement, France O. Le Corre, Ass. Prof. - Ecole des Mines de Nantes, France International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

2. Overview 1. Concept of eMergy 2. State of the art Use of eMergy concept in different industries 3. eMergy Impact of Coal or Biomass use for Steam Production Use of eMergy concept Results • What is the limit distance above which using biomass becomes • less interesting, in an eMergetic point of view, than using coal (within a specific supplying scheme)? 4. Some conclusions International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

3. Every process (natural and industrial) could be expressed as energy flow • Solar Energy is suggested to be used as a reference unit. • Emergy (spelled with an “m”) is a measure of the cumulative energy since a specific origin of time, which is different from the common measure of energy. • It represents the “memory” of the energy that was used to build a product. • Emergy, which means embodied energy, can be expressed as: • Em=t ExEx: exergy (energy availability) ; t: transformity • Transformity is defined as the emergy of one kind of available energy required directly and indirectly to make one joule of energy of another type, ie the ratio of emergy to the available energy of the product • Compare different forms, that are not usually comparable, within the same unit Howard  T.  Odum Graduate Research Professor; Director, Center for Environmental Policy Environmental Engineering Sciences University of Florida, USA 1. Concept of eMergy In 1988, Dr. Odum has suggested a new economic system based on a thermodynamic framework. International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

4. 2. State of the art • Bastianoni and Marchettini [6] : ethanol production in a sustainable point of view (1996), • Nilsson [7] : eNergy, eXergy and eMergy analysis for straw in district heating plants (1997), • - Odum [8] : eMergy evaluation of OTEC (Ocean Thermal Energy Conversion) electric power plant system (2000), • Bjöklund and al [9] : eMergy analysis for municipal wastewater treatment and generation of electricity by digestion of sewage sludge (2001), • Ulgiati and Brown [10] : environmental support for dilution and abatement of process emissions in electricity production (2002), • Yang et al. [11] : waste treatment, recycling and reuse in industrial systems in an eMergetic point of view (2003), • Carraretto et al. [12] : the impact of bio-diesel as an alternative fuel using the eMergy approach (2004), • Bargigli et al. [13] : thermodynamic and environmental indexes for natural gas, syngas and hydrogen production processes (2004), • - Wang et al. [14-15] : eMergy of Eco-Industrial Park with power plant (2005-2006) International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

5. 3. eMergy Impact of Coal or Biomass combustion for Steam Production • Case study: • Dalkia Poznań & Dalkia Łódźboth operated by DALKIA Polska International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

6. 3. eMergy Impact of Coal or Biomass combustion for Steam Production • Main assumptions: • Calculations are performed on the basis of an existing plant, i.e. eMergy of the complete power plant is not evaluated. • eMergy of the retrofitting is neglected (in fact few equipments are necessary). • Human labour is not taken into account in this paper, since new jobs are not significant. • Nominal operation is considered. Pn : nominal electric power output : nominal fuel flow-rate (at each time) : nominal eMergy (at each time) : annual eMergy (for different fuels) without transportation Global eMergy, including transportation (ex: coal by rail): International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

7. 3. eMergy Impact of Coal or Biomass combustion for Steam Production Transformities: International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

8. 3. eMergy Impact of Coal or Biomass combustion for Steam Production Global Yearly eMergy assessment for main combustibles International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

9. 3. eMergy Impact of Coal or Biomass combustion for Steam Production Global eMergy International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

10. 3. eMergy Impact of Coal or Biomass combustion for Steam Production On this basis, it is quite interesting to determine the maximum distance which is environment friendly (in an eMergetic point of view) to transport biomass by trucks versus coal by rail. This issue consists in finding the limit distance at which the annual eMergy of biomass remains lower than the annual eMergy of coal. • To calculate that distance, the following steps are necessary: • calculation of the difference between annual eMergy of coal, • including transportation by rail,and the annual eMergy of biomass • (excluding transportation) • Determination of the specific eMergy per kilometre, taking into account • the biomass flow-rate to feed at full load the burner, Q(bio) • Then, knowing the trucks transformity results in, at each time: International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

11. 3. eMergy Impact of Coal or Biomass combustion for Steam Production International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland

12. 4. Some conclusions Materials with high eMergy per mass (coal for instance) have a negative impact on the environment Transportation of fuels can have a significant impact on the environment, depending on their lower heating value / density It is worthwhile operating in co-combustion within a limit distance The limit distance was calculated at an iso-eMergy, that of coal. It depends on the lower heating value of biomasse That study has considered a specific supplying scheme: coal transported by rail and biomass by trucks. Other schemes would change the limit distance and consequently the conclusions arisen in this paper International symposium SYMKOM’08; 15 -17 September, 2008, Łódź, Poland