Australian Solar Cooling Interest Group (ausscig) Conference Financial analysis of solar cooling systems in Australia

Transcription

1 Financial analysis of solar cooling systems in Australia Dan Wu, Lu Aye, Priyan Mendis & Tuan Ngo Presenter: Dan Wu Renewable Energy and Energy Efficiency Group Melbourne School of Engineering, The University of Melbourne 1 Overview Introduction Solar cooling technologies investigated - Solar electric cooling - Solar thermal cooling (thermo-chemical & thermo-mechanical cooling) Simulations of the cooling systems - System descriptions - System sizing Financial analysis - Cost assumptions - Financial parameters: annualised life cycle cost (ALCC) and unit cooling cost (UCC) Conclusions Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 2 of 18 2

2 Introduction In Australia, heating, ventilation and air-conditioning (HVAC) of commercial buildings account for 40-50% of electricity consumption and 80% of electricity is generated from fossil fuels (Fong et al. 2010). Cooling demand in Australia has high sensitivity to global warming (Wang, Chen & Ren 2010). SOLAR COOLING Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 3 of 18 3 Introduction Market share Solar cooling << Conventional cooling Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 4 of 18 4

3 Solar cooling technologies Aim: To investigate the life cycle costs of solar cooling systems which can be designed and assembled with commercially available system components. Solar electric cooling system Solar thermo chemical cooling system VS Conventional cooling system Solar thermo mechanical cooling system Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 5 of 18 5 Solar electric cooling system PV panels + scroll chiller Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 6 of 18 6

4 Solar thermo chemical system PTC + absorption chiller PTC: Parabolic Trough Collector Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 7 of 18 7 Solar thermo mechanical system ETSC + ORC + scroll chiller ETSC: Evacuated Tube Solar Collector ORC: Organic Rankine Cycle Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 8 of 18 8

5 Simulations Simulation tools: TRNSYS, STEC library, TMY data files (Morrison & Litvak 1999) Locations: Darwin, Brisbane, Perth, Sydney, Adelaide, Canberra and Melbourne Building characteristics: - 2 storeys office building with 3000 m 2 floor area and 2.7 m ceiling height - East and west walls: 33% double-glazing windows - North and South walls: 60% double-glazing windows Target solar fraction: ~75% Location Darwin Brisbane Perth Sydney Adelaide Canberra Melbourne Cooling season Jul - Jun Aug - Jun Sep - May Sep - Apr Oct - Apr Nov - Mar Oct - Apr Latitude (deg S) Tilt angle (deg) Max. cooling load (kw r ) Total cooling (kwh r ) Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 9 of 18 9 Simulations Specifications for main components Component Parameter Value Module area of PV panel (m 2 ) 1.61 PV panel Maximum output (W) 250 Maximum voltage (V) 30.4 Module efficiency (%) AC output voltage (V) 400/230 Inverter DC input voltage (V) 300~450 Efficiency (%) 98 Cell voltage (V) 2 Battery bank Depth of discharge (%) 65 Charging efficiency (%) 92 Absorber area (m 2 ) 24 Demand outlet temperature (Celsius degree) 150 PTC Heat loss coefficient A 70 Heat loss coefficient B Heat loss coefficient C Heat loss coefficient D Absorber area (m 2 ) ETSC Intercept efficiency based on gross area Negative of first order efficiency coefficient (WK -1 m -2 ) Negative of second order efficiency coefficient (WK -1 m -2 ) Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 10 of 18 10

6 Simulations Part load performance of scroll chiller and absorption chiller Rated compressor COP for scroll chiller: 4.0 Rated COP for absorption chiller: 1.2 Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 11 of Simulations Assumptions: Quasi steady state Peak cooling load = Design capacity of chiller All solar collectors and PV panels are placed facing north Two-days energy storage (electricity and heat) for all solar cooling systems Location Darwin Brisbane Perth Sydney Adelaide Canberra Melbourne PV area (m 2 ) Battery capacity (kwh e ) PTC area (m 2 ) PTC tank volume (m 3 ) ETSC area (m 2 ) ETSC tank volume (m 3 ) Location Darwin Brisbane Perth Sydney Adelaide Canberra Melbourne Conventional, electricity (kwh e ) PV + VCC, electricity (kwh e ) PTC + Absorption, gas (MJ h ) PTC + Absorption, electricity (kwh e ) ETSC +ORC + VCC, gas (MJ h ) ETSC + ORC + VCC, electricity (kwh e ) Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 12 of 18 12

7 Life cycle cost (LCC) Annualised life cycle cost (ALCC) Unit cooling cost (UCC) LCC ALCC = Pa ALCC ($/year) UCC = Cooling supplied (kwh r/year) t n t 1+ i 1 LCC = C + Cr = C + Cr = + n n 1 1 D n= 1 ( 1+ d ) t Pa = d 1+ d 1+ d C = Initial cost of the system ($) Cr = Single future cost ($) D = Nominal discount rate d = Real discount rate i = Real inflation rate t = Project life time Pa = Present worth factor Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 13 of Financial parameter used Project life time: 20 years Land costs were not included Social and environment benefits & costs were not considered Loss of efficiency in PV system over time was neglected Parameter Value Real discounted rate 8 % Electricity cost ($/kwh) 0.26 [1] Real escalation rate of electricity price 3 % Natural gas cost ($/MJ) 0.02 [1] Real escalation rate of natural gas price 2 % [1] Office of the Tasmanian Economic Regulator Comparison of 2012 Australian Standing Offer Energy Prices, pp.1-31, Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 14 of 18 14

8 Results Item System Darwin Brisbane Perth Sydney Adelaide Canberra Melbourne Initial cost ($) Conventional PV + VCC PTC + Absorption ETSC +ORC + VCC Conventional Specific cost PV + VCC ($/kw r ) PTC + Absorption ETSC +ORC + VCC Conventional ALCC PV + VCC ($/year) PTC + Absorption ETSC +ORC + VCC UCC ($/kwh r ) UCC ($/kwh r ) w/o storage Conventional PV + VCC PTC + Absorption ETSC +ORC + VCC PV + VCC PTC + Absorption ETSC +ORC + VCC Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 15 of Conclusions Under current technical and financial conditions, solar cooling systems investigated are less competitive compared to conventional cooling system. Among the solar cooling systems with storage components the solar absorption system has the lowest life cycle cost. If the storage components are not included in the system, the PV solar electric system would have the lowest life cycle cost. Initial estimations showed that the UCCs for all solar cooling systems investigated in this study become closer to that of conventional systems. Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 16 of 18 16

9 Acknowledgement The authors would like to acknowledge and extend their gratitude to the followings: Anonymous reviewers for providing feedbacks; Permasteelisa Group and Australian Research Council (ARC) for supporting the research; The University of Melbourne for providing a scholarship to Dan Wu. Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 17 of Dan Wu Australian Solar Cooling 2013 Conference, Sydney, 12 April 18 of 18 18