20120430-IRENA-Electricity_Storage_and_Renewables_for_Island_Power_A_Guide_for_Decision_Makers_48页_1mb

electricity storage and renewables for island power: a guide for decision makers

abstract:
This report by the International Renewable Energy Agency (IRENA) examines the role and implementation of electricity storage technologies in island and remote electrification systems. Storage facilitates renewable energy integration, enhances grid stability, and optimizes energy management, but its selection and deployment must align with system-specific requirements.

1. Introduction:
Electricity storage addresses the challenge of balancing variable renewable generation with fluctuating demand in isolated systems. Technologies like pumped hydro, batteries, flow batteries, and flywheels offer solutions tailored to different scales and needs.

2. Overview of Storage Technologies:

• Lead-Acid Batteries: Mature and modular; ideal for small systems (5–10 kWh modules). Moderate costs ($300–$800/kW) but short lifespans (3–10 years).
• Lithium-Ion Batteries: Higher costs ($400–$1,000/kW) but longer lifespans (10–15 years) and better efficiency (85–95%). Suitable for larger scales.
• Flow Batteries (VRB, ZBB):
• Flywheels: High power but short duration; useful for grid stabilization ($2,000–$4,000/kW).
• Compressed Air Storage (CAES): Large-scale, mature technology matching pumped hydro.
• Hydrogen Storage: Inefficient (~20–30% roundtrip efficiency) but scalable for long-term backup.

3. Optimizing Storage Deployment:
Key lessons from model scenarios and case studies:

• Storage supplements renewables by reducing diesel dependency (e.g., 35% diesel savings in Bonaire).
• Technological synergy matters—integrating PV, wind, and storage can lower costs (e.g., 42.4¢/kWh vs. 53.9¢/kWh with diesel alone).
• Cost-efficiency hinges on proper sizing, integration, and maintenance. OverRSized diesel generators exacerbate inefficiencies.

4. Applications and Case Studies:
Case Study: Apolima Island (Samoa) achieved 70% diesel reduction with PV/lead-acid storage.
Case Study: Bonaire transitioned from diesel to hybrid (wind/PV/storage), reducing fuel costs by $550/km/year.
Case Study: King Island (Australia) faced VRB failure due to technical mismatches, highlighting the need for robust testing.

Common themes:

• Local conditions (geology, climate, funding) require tailored solutions.
• Training local operators is critical for system resilience.

5. Lessons Learned:

• Integration is paramount: Storage alongside renewables form a powerful combination.
• Costs dominate decisions: Higher upfront costs must yield long-term savings.
• Failures teach caution: Case studies reveal the importance of robust designs and mature technologies.
• Oversimplification risks failure: Rules of thumb must be validated through modeling (e.g., HOMER software).

Conclusion:
Electricity storage presents a viable path toward sustainable island energy, but success depends on informed design, local context, and lifecycle management.

Key Terms: Capacity, roundtrip efficiency, Levelised Cost of Energy Storage (LCOS), balance-of-system (BoS) costs.
Relevant Links: IRENA Publications (@IRENA.org), HOMER software (www.homerenergy.com).