The use of biomass, which is considered to produce no net CO2 emissions in its life cycle, can reduce the effective CO2 emissions of a coal-fired power generation system, when co-fired with the coal, but may also reduce system efficiency.The technical and environmental analysis of fluidised bed technologies, using the ECLIPSE suite of process simulation software, is the subject of this study. System efficiencies for generating electricity are evaluated and compared for the different technologies and system scales.Several technologies could be applied to the co-combustion of biomass or waste and coal. The assessment studies here examine the potential for co-combustion of (a) a 600 MWe pulverised fuel (PF) power plant (as a reference system), (i) co-firing coal with straw and sewage sludge and (ii) using straw derived fuel gas as return fuel; (b) a 350 MWe pressurised fluidised bed combustion (PFBC) system co-firing coal with sewage sludge; (c) 250 MWe and 125 MWe circulating fluidised bed combustion (CFBC) plants co-firing coal with straw and sewage sludge; (d) 25 MWe CFBC systems co-firing low and high sulphur content coal with straw, wood and woody matter pressed from olive stones (WPOS); (e) 12 MWe CFBC co-firing low and high sulphur content coal with straw or wood; and (f) 12 MWe bubbling fluidised bed combustion (BFBC), also co-firing low and high sulphur content coal with straw or wood.In the large systems the use of both straw and sewage sludge resulted in a small reduction in efficiency (compared with systems using only coal as fuel).In the small-scale systems the high moisture content of the wood chips chosen caused a significant efficiency reduction.Net CO2 emissions are reduced when biomass is used, and these are compared for the different types and scales of fluidised bed technologies. NOx emissions were affected by a number of factors, such as bed temperature, amount of sorbent used for SO2 capture and HCl emitted.
Bibliographical noteReference text:  L. Baxter, Biomass-coal co-combustion: opportunity for affordable renewable energy, Fuel 84 (2005), pp. 1295–1302. Article | PDF (475 K) | View Record in Scopus | Cited By in Scopus (58)
 L. Baxter and J. Koppejan, Co-combustion of biomass and coal, Euroheat Power [English edition] 1 (2004), pp. 34–39. View Record in Scopus | Cited By in Scopus (4)
 K.R.G. Hein and J.M. Bemtgen, EU clean coal technology – co-combustion of coal and biomass, Fuel Process Technol 54 (1998), pp. 159–169. Article | PDF (286 K) | View Record in Scopus | Cited By in Scopus (69)
 M. Sami, K. Annamalai and M. Wooldridge, Co-firing of coal and biomass fuel blends, Prog Energy Combust Sci 27 (2001), pp. 171–214. Article | PDF (1339 K) | View Record in Scopus | Cited By in Scopus (150)
 L.S. Pedersen, H.P. Nielsen, S. Kiil, L.A. Hansen, K. Dam-Johansen and F. Kildsig et al., Full scale co-firing of straw and coal, Fuel 75 (1996), pp. 1584–1590. Article | PDF (944 K) | View Record in Scopus | Cited By in Scopus (41)
 E. Hughes, Biomass cofiring: economics, policy and opportunities, Biomass Bioenergy 19 (2000), pp. 457–465. Article | PDF (75 K) | View Record in Scopus | Cited By in Scopus (43)
 A. Demirbas, Sustainable cofiring of biomass with coal, Energy Convers Manage 44 (2003), pp. 1465–1479. Article | PDF (150 K) | View Record in Scopus | Cited By in Scopus (53)
 M. Orjala, R. Inqualsuo, T. Patrikainen, M. Makipaa and J. Hamalainen, Cofiring of wood cocombustion, VTT Symp [Valtion Teknillinen Tutkimuskeskus] (208) (2000), pp. 87–105. View Record in Scopus | Cited By in Scopus (1)
 A.L. Robinson, H. Junker and L.L. Baxter, Pilot-scale investigation of the influence of coal-biomass cofiring on ash deposition, Energy Fuels 16 (2002), pp. 343–355. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (41)
 E.J. Anthony, E.E. Berry, J. Blondin, E.M. Bulewicz and S. Burwell, Advanced ash management technologies for CFBC ash, Waste Manage 23 (2003), pp. 503–516. Article | PDF (396 K) | View Record in Scopus | Cited By in Scopus (12)
 D.R. McIlveen-Wright, F. Pinto and L. Armesto et al., A Comparison of circulating fluidised bed combustion and gasification power plant technologies for processing mixtures of coal, biomass and plastic waste, Fuel Process Technol 87 (2006), pp. 793–801. Article | PDF (373 K) | View Record in Scopus | Cited By in Scopus (11)
 Council Directive 2001/80/EU, On the limitations of emissions of certain pollutants into the air from large combustion plants. Official J Eur Commun, 7th November 2001;L309.
 Williams BC. The development of the ECLIPSE simulator and its application to the techno-economic assessment of clean fossil fuel power generation systems. DPhil thesis, Energy Research Centre, University of Ulster, Coleraine, N.I., 1994.
 J.T. McMullan and B.C. Williams, Development of computer models for the simulation of coal liquefaction processes, Int J Energy Res 18 (2) (1994), pp. 117–122.
 B.C. Williams and J.T. McMullan, Techno-economic analysis of fuel conversion and power generation systems – the development of a portable chemical process simulator with capital cost and economic analysis capabilities, Int J Energy Res 20 (2) (1996), pp. 125–142. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (25)
 B.C. Willams and J.T. McMullan In: Imariso and Bemtgen, Editors, Progress in synthetic fuels, Graham and Trotman, London (1988), pp. 183–189.
 ECLIPSE process simulator, Energy Research Centre, University of Ulster, Jordanstown, N.I., 1992.
 Gramelt S. Deutsche Babcock Anlagen GMBH. FGD system for 600 MWe coal fired power plant – process description, PFD, Mass and energy balance, Equipment specifications, Private Communication 1994.
 Breihofer D, Mielenz A, Rentz O. Emission Control of SO2, NOx and VOC at stationary sources in the Federal Republic of Germany, Karlsruhe, 1991.
 S. McCahey, J.T. McMullan and B.C. Williams, NOx reduction technology in PF boilers, Develop Chem Eng Mineral Process 7 (1999), pp. 115–130. View Record in Scopus | Cited By in Scopus (2)
 EPZ Reports, (1998), op.cit.
 H. Rudiger, A. Kicherer, U. Graul, H. Spliethoff and K. Klein, Investigations in combined combustion of biomass and coal in power plant technology, Energy Fuels 10 (1994), pp. 789–796.
 A. Asai and K. Azaki et al., System outline and operational status of Karita Power Station New Unit 1 (PFBC), JSME Int J Series B: Fluids Thermal Eng 47 (2004), pp. 193–199 [Operational Problems, Trace emissions and by-product management for industrial biomass co-combustion. Contract No. JOR3-CT95-0057 – OPTEB, Joule-Thermie programme of the European Commission, 1998.]. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (3)
 S. Rajaram, Next generation CFBC, Chem Eng Sci 54 (1999), pp. 5565–5571. Abstract | PDF (2543 K) | View Record in Scopus | Cited By in Scopus (8)
 Jacquet L, Jaud J, Ratti G, Klinger JP. Scaling up of CFB boilers the 250 MWe GARDANNE CFB project. In: Proceedings of the american power conference 1994;56:930–6.
 M.J. Fernandez Llorente, R. Escalada Cuadrado, J.M. Murillo Laplaza and J.E. Carrasco Garcia, Combustion in bubbling fluidised bed with bed material of limestone to reduce the biomass ash agglomeration and sintering, Fuel 85 (2006), pp. 2081–2092. Article | PDF (839 K) | View Record in Scopus | Cited By in Scopus (18)
 D.C. Liu, C.L. Zhang, B. Mi, B.K. Shen and B. Feng, Reduction of N2O and NO emissions by co-combustion of coal and biomass, J Inst Energy 75 (2002), pp. 81–84. View Record in Scopus | Cited By in Scopus (6)
 H. Spliethoff, W. Scheuer and K.R.G. Hein, Effect of co-combustion of sewage sludge and biomass on emissions and heavy metal behaviour, Process Saf Environ Prot 78 (2000), pp. 33–39. Abstract | PDF (376 K) | Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (12)
 H. Liu and B.M. Gibbs, The influence of limestone addition at different positions on gaseous emissions from a coal-fired circulating fluidized bed combustor, Fuel 77 (1998), pp. 1569–1577. Article | PDF (294 K) | View Record in Scopus | Cited By in Scopus (14)
 S. Julien, C.M.H. Brereton, C.J. Lim, J.R. Grace and E.J. Anthony, The effect of halides on emissions from circulating fluidized bed combustion of fossil fuels, Fuel 75 (1996), pp. 1655–1663. Article | PDF (850 K) | View Record in Scopus | Cited By in Scopus (20)
 Coda B. Studies on ash behaviour during co-combustion of paper sludge in fluidised bed boilers. PHD thesis, IVD, University of Stuttgart, 2004.
 W.A. Helmer and D.D. Stokke, A case study of fluidized-bed combustion of wood/coal mixtures. Part B. The effect of wood moisture content, Forest Prod J 48 (1998), pp. 51–54. View Record in Scopus | Cited By in Scopus (1)
 B.M. Jenkins, L.L. Baxter, T.R. Miles Jr. and T.R. Miles, Combustion properties of biomass, Fuel Process Technol 54 (1998), pp. 17–46. Article | PDF (638 K) | View Record in Scopus | Cited By in Scopus (239)