12 December 2006 DISTRIBUTED GENERATION OPTIONS Lu Aye International Technologies Centre (IDTC) Department of Civil and Environmental Engineering The University of Melbourne, Victoria 3010 lua@unimelb.edu.au Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 1 of 45 Outline • • • • • • • Introduction: Distributed generation (DG) Cogeneration Microturbines (MT) Photovoltaics (PV) Gas Engines Greenhouse gas emissions benefits Conclusion Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 2 of 45 1 12 December 2006 Distributed Generation (DG) • DG is a any small-scale (< 10 MWe) electrical power generation technology that provide electric power at or near the load site; it is either interconnected to the distribution system, directly to the costomer’s facilities, or both (Borbely & Kreider 2001). • Terms like distributed power, distributed energy, distributed energy resources, embedded generation, decentralized power, dispersed generation, and onsite generation can also be found in the literature. Although some of those terms may be used with a different meaning, typically they de facto refer to distributed generation (Wikipedia 2006). Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 3 of 45 Problems with electricity • The rate of production must balance the rate with which it is consumed at all times. • Demand for electricity does not remain constant and fluctuations in load occur: – at different times of the day, – on different times of the week, – in different months of the year. • Sufficient ‘generation capacity’ must be constructed to meet demand at its highest point. Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 4 of 45 2 12 December 2006 Average life cycle cost of electricity in Australia (Australian cents/kWhe) c/kWhe Energy source Coal 2.8 – 3.5 Natural gas 3.8 – 6.5 Diesel 22 – 50 Biomass 5 – 15 Wind 5.5 – 10 Photovoltaic 40 – 80 (Source: Fung et al. 2002) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 5 of 45 Conventional generation (Typical Australian data) Type Overall efficiency Net CO2 (%) (t/MWh) 40 - 70 0.00 Combined Cycle Gas Turbine 48 0.39 Thermal - Natural Gas 38 0.49 Thermal - Black Coal 35 0.93 Thermal - Brown Coal 29 1.23 Hydropower (Source: ACA 1997) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 6 of 45 3 12 December 2006 Potential benefits of DG • Less or no distribution losses (typical distribution losses 4 to 9%) • Better power quality and consistent power supplies (i.e. no voltage dips, interruptions, transients, and network disturbances from other loads) • Enable on-site waste heat recovery (i.e. cogeneration) • Reduce grid demand during peak • Can provide emergency power • Can increase diversity of energy sources Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 7 of 45 DG technologies • Internal combustion reciprocating engines (ICRE) and generators • Small combustion turbine generators (including microturbines) • Photovoltaic (PV) modules • Fuel cells • Solar thermal conversion • Stirling engines • Biomass conversion Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 8 of 45 4 12 December 2006 Status of DG technologies Capacity IC Engine Turbines PVs Fuel Cells 50 kW – 5 MW 25 kW – 25 MW 1 kW – 1 MW 200 kW – 2 MW Efficiency 25 – 45 % 29 – 42 % 6 – 19 % 40 – 57 % Capital cost ($/kW) 200 – 350 450 – 1000 6000 – 10000 3750 – 5000 O&M cost* (¢/kWh) 1.00 0.50 – 0.65 0.10 – 0.40 0.17 Commercial Commercial in large sizes Commercial Commercial scale demos Technology status * O&M costs do not include fuel. (Source: Adapted from Borbely & Kreider 2001) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 9 of 45 Definition of “Cogeneration” • Cogeneration is the sequential production of thermal and electric energy from a single fuel source. • Heat is recovered that would normally be lost in the production of one form of energy. • That heat is then used to generate the second form of energy. • The overall fuel utilisation efficiency is typically 70-80% versus 30-40% for electric power plant. Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 10 of 45 5 12 December 2006 Traditional industrial energy supply (Source: Cogen3 2004) ELECTRICITY P R TRANSFORMER O C E STEAM E FUEL BOILER HEATERS DRYER Lu Aye, IDTC S S AIR S Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 11 of 45 Cogen industrial energy supply (Source: Cogen3 2004) ELECTRICITY P R O C E Fuel Flue gases (~ 550 ° C) FUEL Air Exhaust heat (~150 ° C) STEAM Fuel S S E HRSG S Elect ricit y Generat or GAS TURBINE WITH HRSG Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 12 of 45 6 12 December 2006 Components • Prime mover produces mechanical energy through combustion. • Generator converts the mechanical energy to electrical energy. • Waste heat recovery system captures exhaust heat or engine coolant heat and converts that heat to a useful form. • Operating control systems insure that the individual system components function together. Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 13 of 45 Types of prime mover • Steam turbine systems – Consist of a boiler and turbine – Boiler can be fired by a variety of fuels (oil, natural gas, coal, wood, MSW, etc.) • Combustion gas turbine systems – Made up of one or more gas turbines and a waste heat recovery unit – Fuelled by natural gas or light petroleum products • Internal Combustion Engine systems – Utilise one or more reciprocating engines together with a waste heat recovery system – Fuelled by natural gas or distillate oils (petrol & diesel) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 14 of 45 7 12 December 2006 Energy balance of a typical power plant 7% 33% Electrical output Condenser losses Exhaust stack losses Radiation losses 30% 30% Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 15 of 45 Potential heat recovery • 100 % of Condenser/cooling losses • 40% of Exhaust stack losses Ein = Eout Q = E electricity + Econdenser + Eexhaust + Eradiation Eelectricity = 0.33Q, Econdenser = 0.3Q, Eexhaust = 0.3Q Eavailable = Econdenser + 0.4 Eexhaust = 0.42Q Eavailable = 1.273Eelectricity Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 16 of 45 8 12 December 2006 Topping cycle (Brayton & Rankine) Waste Heat Heat Exchanger Fuel Lu Aye, IDTC Prime Mover Electric Generator Thermal Energy (Steam, Hot Water) Electric Power Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 17 of 45 Bottoming cycle Waste Heat Heat Recovery Boiler Fuel Lu Aye, IDTC Lu Aye, IDTC Turbine Electric Generator Electric Power Prime Boiler Thermal Energy (Steam, Hot Water) Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 18 of 45 9 12 December 2006 Combined cycle • Rankine cycle on the “topping” portion and Brayton cycle on the “bottoming” portion of the combination. • Ideal mix of power delivered from Brayton and Rankine portions: 70 % and 30 %. • There are many variations and options available. Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 19 of 45 Combined cycle variations • Gas turbine exhaust is used to produce low pressure steam (200 kPa) for steam turbine with no additional fuel burnt. • Gas turbine exhaust is used directly for a boiler (1.5-18 MPa). • Gas turbine exhaust is fired in the duct with additional fuel for a steam turbine (6-9 MPa). Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 20 of 45 10 12 December 2006 Cogeneration technologies (Source: Cogen3 2004) Steam turbines Gas turbines Engines (N. gas, Diesel) Combined cycles Microturbines Lu Aye, IDTC Fuel cells Stirling engines Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 21 of 45 Cogeneration fuels (Source: Cogen3 2004) • Cogeneration can be done from a variety of fuels – also Municipal Solid Waste (MSW) • Installations may be designed to accept more than one fuel Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 22 of 45 11 12 December 2006 Prime mover selection criteria • Hours of operation – Continuous: steam turbine (ST) & gas turbine (GT) – Intermittent: reciprocating engines (RE) • Maintenance requirements – RE: highest maintenance requirement; GT: require less frequent maintenance; ST: require less maintenance than gas turbines • Fuel requirements – RE: fix fuel quality required, GT: fuel may be switched, ST: limited only by the fuel for their steam source • Capacity limits – RE: 40 kW-3 MW, GT: 0.5-30 MW, ST: >1 MW Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 23 of 45 Typical energy production (%) GT <2 MW GT with after burner CC G&ST ST Electricity 28 32 22 18 40 12 960 kPa Steam 18 21 50 66 37 0 200 kPa Steam 0 0 0 0 0 68 82°C Hot water 33 27 0 0 0 0 Waste 21 20 28 16 23 20 Lu Aye, IDTC Lu Aye, IDTC RE Diesel RE Gas Output Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 24 of 45 12 12 December 2006 Environmental advantages & disadvantages • Better fuel utilisation efficiency: 70-80% versus 30-40% for conventional electric power plant • Need to look at from fuel life cycle point of view • Depend on the nature of the fuel used – Impacts on global air pollutants – Impacts on local air pollutants Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 25 of 45 Microturbines • One of the best short-term DG options – because of their simplicity and – because no major technological breakthroughs are required for their deployment. • • • • Capacity: 25 – 500 kWe power output Single-stage compressor and single-stage turbine Pressure ratio: 3 – 4 (Conventional: 13 – 15) Rotor: short drive shaft with generator on one end with a bearing in the middle Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 26 of 45 13 12 December 2006 Discussion • Roles of cogeneration Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 27 of 45 Capestone microturbine (Source: Gillette 2006) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 28 of 45 14 12 December 2006 Example microturbine specifications Manufacturer N krev/min Power kWe Efficiency %(LHV basis) Recuperated Capstone 30 96 28 Yes Honeywell 75 75 30 Yes 116 45 17 No Elliott (Source: Rodgers et al. 2001) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 29 of 45 Recuperated microturbine (Source: http://www.grc.nasa.gov/WWW/RT2002/5000/5960weaver.html) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 30 of 45 15 12 December 2006 MT overview Fuel Natural gas, hydrogen, propane, diesel Efficiency 15 % (unrecuperated) 20 – 30% (recuperated) up to 85 % (with heat recovery) Cost ($/kW) 700 – 1100 (+ 75 – 350 with heat recovery) O & M costs (¢/kWh) 0.5 – 1.6 < 9 – 50 ppm NOx Other features Cogen (50 – 80°C water) Commercial status Small volume production, commercial prototypes now (Source: CEC 2006) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 31 of 45 PV background • Photovoltaics generate electricity without no moving parts from the renewable source of sunlight. • Can be installed on or at the building. • PV modules are well proven with an expected service life of at least 30 years. • It is a modular technology, viable and cost effective option in many stand alone applications. Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 32 of 45 16 12 December 2006 Typical cell, module & array • A typical crystalline silicon solar cell is 100 cm2 and produces about 1.75 peak watts (Wp) at 0.5V & 3.5A under full sun at standard test conditions (STC: AM 1.5, 1 kW/m2 and 25ºC cell temperature). • Modules are typically available in ratings from less than 50 Wp to greater than 250 Wp. • Crystalline silicon modules deliver approximately 100-120 W/m2 at STC. • Amorphous silicon (a-Si) thin-film modules deliver 40-50 W/m2 at STC. Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 33 of 45 Efficiency records Theo (%) Cell (%) Module (%) Si (crystalline) UNSW PERL (3/99) 29 24.7 ± 0.5 22.7 ± 0.6 Si (multicrystalline) UNSW/Eurosolare (2/98) 27 19.8 ± 0.5 15.3 ± 0.4 CdTe NREL, on glass (9/01) 31 16.5 ± 0.5 10.7 ± 0.5 Classification Source: Green et al. 2003, Prog. Photovolt: Res. Appl. 11:347-52 Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 34 of 45 17 12 December 2006 Typical I-V and P-V curves (Source: Duffie & Beckman 1991) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 35 of 45 Effect of solar radiation level (Source: Duffie & Beckman 1991) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 36 of 45 18 12 December 2006 Effect of temperature (Source: Duffie & Beckman 1991) [ ] η = η ref (1 + β Tref − Tcell ), β = 0.004 C −1 E = ηAI Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 37 of 45 Life cycle emission factors (g/kWh) Energy Source SOx NOx Coal 3.400 1.800 Energy input (kWh/W installed) 322.8 12 Oil 1.700 0.880 258.5 18 Natural Gas 0.001 0.900 178.0 6 Nuclear Photovoltaic 0.030 0.003 0.020 0.007 7.8 5.3 4 2 CO2 (Source: NREL 2001) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 38 of 45 19 12 December 2006 Gas engines overview Methane content (%) 30 – 90 Landfill to natural gas Efficiency (%) 37 – 40 3 CO (mg/Nm ) 25 – 45 NMHC (mg/Nm3) 37 – 58 NOx (mg/Nm3) 250 – 500 (Source: Hüchtebrock, B 2003) Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 39 of 45 Status of DG technologies IC Engine Turbines PVs Fuel Cells 50 kW – 5 MW 25 kW – 25 MW 1 kW – 1 MW 200 kW – 2 MW Efficiency 25 – 45 % 29 – 42 % 6 – 19 % 40 – 57 % Capital cost ($/kW) 200 – 350 450 – 1000 6000 – 10000 3750 – 5000 Capacity O&M cost* (¢/kWh) Technology status 1.00 0.50 – 0.65 0.10 – 0.40 0.17 Commercial Commercial in large sizes Commercial Commercial scale demos * O&M costs do not include fuel. (Source: Adapted from Borbely & Kreider 2001) Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 40 of 45 20 12 December 2006 Discussion • Roles of DG technologies – Gas engines – Microturbines – PV Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 41 of 45 Conclusion • MT: fuel, ambient condition, load • PV: solar radiation, cell temperature • GE: fuel, load Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 42 of 45 21 12 December 2006 References ACA 1997, Profiting from Cogeneration, Australian Cogeneration Association. Borbely, A-M & Kreider, JF 2001, ‘Distributed generation: An introduction’, in Distributed Generation The Power Paradigm for the New Millennium, Eds A-M Borbely & JF Kreider, CRC Press. CEC 2006, California Energy Resource Guide, California Energy Comission Cogen 3 2004, EC-ASEAN COGEN Programme Phase 3 Workshop, AIT, Bangkok, 13 January. Duffie JA & Beckman WA 1991, Solar Engineering of Thermal Processes, 2nd Ed, John Wiley & Sons, Inc. Fung, PYH; Kirschbaum, MUF; Raison, RJ & Stucley, C 2002, ‘The potential for bioenergy production from Australian forests, its contribution to national greenhouse targets and recent developments in conversion processes’ Biomass and Bioenergy, 22 (4) 223-236. Gillette 2006, ‘CHP case studies – Saving money and increasing security’ http://www.capstoneturbine.com/_docs/WCEMC04.pdf. Hüchtebrock, B 2003, Stationary gas engine development trends, CHAPNET Workshop, Brussels, 16. September 2003. NREL 2001, Solar Electric Power – The U.S. Photovoltaic Industry Roadmap, National Renewable Energy Laboratory Rodgers, C; Watts, J; Thoren, D; Nichols, K & Brent, R 2001 ‘Microturbines’, in Distributed Generation The Power Paradigm for the New Millennium, Eds A-M Borbely & JF Kreider, CRC Press. Wikipedia 2006, http://en.wikipedia.org/wiki/Distributed_generation. Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 43 of 45 Acknowledgements I wish to thank: • Dr Martin Cope and Dr Tom Beer, CSIRO Energy Transformed Flagship for inviting me to give this talk • Ms Fiorella Chiodo, IDTC for providing administrative assistance Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 44 of 45 22 12 December 2006 Thank you! For more information contact: Lu Aye International Technologies Centre (IDTC) Department of Civil & Environmental Engineering The University of Melbourne Vic 3010 lua@unimelb.edu.au Lu Aye, IDTC Lu Aye, IDTC Distributed Energy and the Intelligent Grid Workshop, Melbourne, 12-13 December 2006 45 of 45 23