Comparative Study of Battery and Hydrogen Storages to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden Yang Zhang , Anders Lundblad, Pietro Elia Campana, Jinyue Yan KTH-Royal Institute of Technology April, 20 th , 2016
Introduction • PV capacity in Europe and Sweden • PV capacity in Italy, Greece and Germany can meet more than 7% of electricity demand[1]; • 0.06% in Sweden[2] • Reasons at end user side • Local weather condition; • Low incentives; • PV intermittence; • Daily Mismatch; • Seasonal Mismatch; • etc. [1] IEA, Snapshot of Global PV Markets. 2015. [2] National Survey Report of PV Power Applications in SWEDEN. 2014 .
Introduction • Reasons at end user side • Local weather condition; • Low incentives; • PV intermittence; • Daily Mismatch; US$0.13/kWh • 1,2 Seasonal Mismatch; 1 • Electricy Price, SEK/kWh etc. 0,8 0,6 0,4 US$0.03/kWh 0,2 0 Self-Consumed Electricity Surplus Electricity Elspot Price Grid charge, Energy Tax, etc. Revenue from PV panels
Introduction Averaged Daily Consumption in Different Months • Reasons at end user side • Local weather condition; • Low incentives; • PV intermittence; • Daily Mismatch; • Seasonal Mismatch; • etc. Averaged Daily Production in Different Months
Introduction • PV capacity in Europe and Sweden • PV capacity in Italy, Greece and Germany can meet more than 7% of electricity demand[1]; • 0.06% in Sweden[2] • Reasons at end user side • Local weather condition; • Low incentives; • Battery Storage PV intermittence; • Daily Mismatch; Storage • Seasonal Mismatch; Hydrogen Storage [1] IEA, Snapshot of Global PV Markets. 2015. [2] National Survey Report of PV Power Applications in SWEDEN. 2014 .
System schematic layout
System schematic layout: Battery Storage System Electricity Weather Profile Load Profile Price Profile Battery PV model Operation Strategy characterizing parameter Battery V-I Hourly PV PV Size Simulation Battery Size Production Model Battery Lifetime PV LCC Battery LCC Model Saving & Income Self Sufficiency Ratio Net Present Value
System schematic layout: Hydrogen Storage System Electricity Weather Profile Load Profile Price Profile PV model Operation Strategy Fuel Cell Fuel cell Size Electrolyzer Hourly PV PV Size Simulation Electrolyzer Production Size Hydrogen Tank size System LCC PV LCC Saving & Income Self Sufficiency Ratio Net Present Value
System schematic layout • Cost o Investment Cost o Replacement Cost PV Size o Maintenance Cost Battery Size System Electrolyzer Size • Performance Revenue Fuel Cell Size Hydrogen Tank Size o Self Consumption Revenue o Export Revenue t 2 max( ( ),0) G t ( R C C ) t 25 SSR 1 100% 1 y OM y , R y , t NPV I 2 L t ( ) y 1 (1 d ) t 1 y 1 r Self Sufficiency Net Present Value Trade Off Ratio Optimization Genetic Algorithm
Net Present Value & Self Sufficiency Ratio • Cost Component Cost Life Time O&M Reference PV Panels 12900 SEK/kW 25 Years 0.01 [1] 4000 USD/kW 30000 Working Hours 0.005 [14] Fuel Cell Electrolyzer 5000 USD/kW 15 Years 0.005 [14] Hydrogen Tank 570 (USD/kg) 15 Years 0.005 [14] Lithium ion battery 469 USD/kWh 746 @ 80% DOD 0.005 [9] • Revenue Item Cost Self Consumption Elspot Price+0.84 (SEK/kWh) Revenue Elspot Price (SEK/kWh) Export Revenue t 2 max( ( ),0) G t ( R C C ) 25 t y OM y , R y , SSR 1 1 100% NPV Inv t 2 y 1 L t ( ) (1 d ) 1 y t r 1 Net Present Value Self Sufficiency Ratio
System Input Values • Load profile (from Wallenstam AB ) • Hourly load profile of a residential building that comprises of 140 apartments in 2014; • Located in Gothenburg; • Weather profile (from Meteonorm) • Global horizontal radiation (W/m 2 ) • Diffuse horizontal radiation (W/m 2 ) • Wind speed (m/s) • Ambient temperature ( ° C) • Provided by Meteonorm, generated from recorded weather data through a stochastic model • Elspot Price (from Nordpool) • Hourly Price in 2014 • SE3
System Input Values • Elspot Price
Photovoltaic Model • Five parameter single diode model V IR V IR s s a I I I e 1 l l R sh V-I curve, P-I curve and MPPT
PV model • Five parameter single diode model Source: NREL System Advisory Database
PV model Ambient Temperature, 25 °C Radiation, 100 W/m 2 V-I curve with different radiation and ambient temperature
PV model • Azimuth and Tilt Angle PV Production at Azimuth angle of 0° and Tilt Angle of 36°
Battery Model • Battery Voltage-Current Model • Charge and discharge characteristics under different SOC and current • Take into account the influence of SOC and current on the round trip efficiency • V=f(SOC,I) • Battery Lifetime Model • Estimate the batter life time with the consideration of operation condition • Lifetime=g(SOC)
Battery Voltage-Current Model Charge Q Q * V E K i K it A exp( ) t iR 0 Q it Q it Discharge Q Q * V E K i K it A exp( ) t iR 0 0.1 Q it Q it Lead Acid Battery Lithium ion Battery Charge and discharge performance of two batteries
Battery Lifetime Model • Battery life cycle numbers and cycle depth Lead Acid Battery LiPFO 4 Battery Cycle Cycle DOD DOD 𝐷 life life 𝑂 = 𝐸𝑃𝐸 − 𝑒 𝑛 100% 250 80% 700 Three Parameter 80% 300 50% 1440 N-S Curve Function 50% 500 20% 2900 30% 1200 10% 6300 Calender Battery C d m R-square @ 80% DOD life Lithium ion 594.3 -7.703e-12 1.022 0.9988 746 8Years Lead Acid 209.1 -3.335e-10 1.448 0.9951 289 3Years
Battery Lifetime Model • Rainflow Counting Method It decompose the complex cycles to microcycles of different DOD Decomposed Microcycles with Different DOD Half or Cycle Cycle Cycle Full No. Path Depth Cycle 1 ACDE 60% 0.5 Rainflow 2 EFGI 65% 0.5 3 BCD 20% 1 4 FGH 20% 1 𝑀 𝑑𝑧𝑑𝑚𝑓 = 𝑂 𝑡𝑢 𝑂 𝑡𝑢 = 𝑛 𝑂 𝑠𝑓𝑒 𝐸𝑃𝐸 𝑗 − 𝑒 𝑀 = min 𝑀 𝑑𝑧𝑑𝑚𝑓 , 𝑀 𝑑𝑏𝑚𝑓𝑜𝑒𝑏𝑠 × 𝑆 𝑗 𝐸𝑃𝐸 𝑇𝑈 − 𝑒 Cycle lifetime
Hydrogen Storage Model • Power-Current Curve • Experimental Data • Interpolate in the simulation P-I Power Current Hydrogen Curve SPE Electrolyzer H 2 Storage PEM Fuel Cell P-I Power Current Hydrogen Curve P-I curve for Fuel Cell and Electrolyzer
Genetic Algorithm PV Size Battery Size Createa population Electrolyzer Size of chromosomes Determine the Fitness Function fitness of each NPV and SSR individual Generations 200 Termination Criterion? Population size 50 Variant of NSGA II Algorithm Select next generation Heuristic Crossover function Crossover rate (%) 50 Perform reproduction using crossover Mutation function Uniform Mutation Mutation rate (%) 5 Result
Results and Discussion • Comparison between battery storage and hydrogen storage • Sensitivity Study of the component cost of the hydrogen storage system • Hybrid battery and hydrogen storage system
Battery storage vs. Hydrogen storage Higher storage capacity Battery Storage Hydrogen Storage No Storage Pareto Front from GA SSR vs. NPV of battery storage and hydrogen storage
Sensitivity study with hydrogen storage system PV Capacity Electrolyzer Cost 200 kW p Fuel Cell Cost Hydrogen Tank Cost
Hybrid battery and hydrogen storage system Comparison between hybrid storage system with single battery or hydrogen storage system
Conclusion • Battery storage system is superior to the hydrogen storage system since it has higher NPV with the same achieved SSR; • Electrolyzer cost is the most sensitive factor in the hydrogen storage system for achieving higher SSR and NPV; • Hybrid battery and hydrogen storage system can take advantages of both individual system and achieve much better system performance.
Thank you! Tack!
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