Optimization of Power Supply Systems with Large-Scale Solar and Wind Energy in Zambia

ザンビアにおける大規模太陽エネルギーと風力エネルギーを用いた電力供給システムの最適化

○ Biness LUKWESA*1, Yutaka TABE*1, and Takemi CHIKAHISA*1

*1 Division of Energy and Environmental System, Hokkaido University

▪ Power storage systems are cost-effective auxiliary equipment necessary forthe effective deployment of large-scale Solar PV and Wind power;

▪ Pumped hydropower storage is more effective than battery storage due to ahigher efficiency and higher energy to power ratio;

▪ Power storage effective in mitigating the effect of reduced hydropowergeneration during a dry year;

Discussion and Conclusion

J05317P

ResultsObjective

Analytical Model

北海道大学工学院、エネルギー環境システム部門、エネルギー変換システム研究室 日本機械学会2019年度年次大会、2019年9月8日（日）～11日（水）、秋田大学手形キャンパス

Power Generation Cost

Power Capacity

Power generation

Cost minimization

Model

Constraints• CO2 emission reduction rate

• Charge and discharge rate• Output of hydro power

Hourly Time-series data▪ Electricity demand▪ Output (Wind and Solar

power)

Parameters▪ Thermal efficiency▪ Cycle efficiency and hourly

self-loss of storages▪ Life time

Costs▪ Construction cost▪ Maintenance cost▪ Running cost▪ Fuel cost

Simulation Cases

(B) Scenario B with Pumped hydropower storage;

▪ Power fluctuation of Solar PV and Wind;

▪ Power storage options introduced to mitigate power fluctuations;

• NaS storage batteries

• Pumped Hydropower storage

Current power generation mix only

consists of hydro, coal and fuel oil This study focuses on 2050

▪ Need for diversification of power supply options by introducing

large scale solar PV and wind to meet increasing power demand;

Item Unit Hydro Coal Biomass Geothermal Fuel Oil Solar PV Wind Battery

Capital Cost [US$/kW] 2679 2869 2500 3501 2600 2671 1970 1200

Capital Cost [US$/kWh] - - - - - - - 40

Fixed O&M [US$/kW/yr] 8.72 20.00 15.00 15.00 12.00 27.00 35.00 12

Variable O&M [US$/MWh] 6.00 14.30 20.00 5.00 15.00 20.10 17.40 2.10

Lifespan [Years] 50 35 25 25 25 25 20 15

Maximum Capacity [MW] 7000 2000 150 50 - - - -

CO2 Emission [kg/MWh] 0.013 0.850 0.270 - 0.625 - - -

Charge loss factor - - - - - - - 0.92

Self-discharge loss factor - - - - - - - 0.99

Capacity Factor 0.70, 0.55* 0.80 0.50 0.60 0.80* 0.20* 0.29* -

C-rate - - - - - - - 0.16

Key Input Parameters;

Scenario B Case A Case B Case C Case D

[Dry Year Effect] 〇 〇 〇 〇

NaS Battery Storage × 〇 × 〇

Pumped Hydro Storage × × 〇 〇

Hydropower load-following 〇 〇 〇 〇

Scenario A Case 1 Case 2 Case 3

Seasonal variation of Hydropower

[Dry Year Effect]× 〇 〇

NaS Battery Storage × × 〇

Hydropower load-following × × ×

(A) Comparison of power Capacity, generation and cost;