Integrated Wind-Solar Hybrid Power Solution for Remote Islands

Abstract​

This proposal presents an innovative integrated energy solution that deeply combines wind power, photovoltaic power generation, pumped hydro storage, and seawater desalination technologies. It aims to systematically address the core challenges faced by remote islands, including difficult grid coverage, high costs of diesel power generation, limitations of traditional battery storage, and scarcity of freshwater resources. The solution achieves synergy and self-sufficiency in "power supply - energy storage - water supply," providing a reliable, economical, and green technological pathway for the sustainable development of islands.

​I. Technical Field and Background Challenges​

1. ​Technical Field​

This solution is a cross-disciplinary, comprehensive technology, primarily encompassing:

• Renewable Energy Generation: Wind power and solar photovoltaic power generation.
• Large-Scale Physical Energy Storage: Pumped hydro storage technology.
• Comprehensive Water Resource Utilization: Reverse osmosis seawater desalination technology.
• Efficient Intelligent Control: Multi-energy cooperative control and energy management.
1. ​Background Challenges​
• ​Energy Supply Dilemma:​​ Remote islands are far from mainland grids and typically rely on high-cost diesel generators. Subject to international oil price fluctuations and difficulties in fuel transportation, this results in high electricity prices and unstable supply, severely restricting local economic development and residents' quality of life.
• ​Limitations of Traditional Storage:​​ Conventional wind-solar complementary systems rely solely on battery storage, which faces four major bottlenecks: short lifespan (requiring frequent replacement), high cost, potential environmental pollution risks, and limited storage capacity. These limitations make it difficult to support the large-scale, long-term stable energy demands of islands.
• ​Resource Demand Contradiction:​​ Islands suffer from scarce freshwater resources. Daily water supply depends on external transportation or small, high-energy-consumption desalination units, both extremely costly. Existing power generation systems and freshwater production facilities operate in isolation, failing to achieve synergistic use of energy and resources.

​II. Core Technical Solution and System Composition​

The system consists of three core modules, organically coordinated through an intelligent controller.

​III. System Operating Principles (Three Core Processes)​​

1. ​Intelligent Power Distribution and Control Logic (Controller-Led)​​

The system core is the intelligent controller, which continuously compares "total wind-solar power generation" with "total load demand (resident consumption + desalination unit consumption)":

• ​Scenario 1: Generation ≥ Load Demand​
• Priority is given to charging the small-capacity batteries to replenish their charge.
• Once batteries are full, the pumped storage unit is automatically activated in pumping mode, converting surplus electricity into potential energy.
• If excess power remains, the seawater desalination unit is prioritized to operate at full capacity, converting electricity into valuable freshwater resources.
• ​Scenario 2: Generation < Load Demand​
• The pumped storage unit is automatically activated in turbine mode for hydroelectric generation.
• Simultaneously, the batteries discharge to handle instantaneous peak loads, working together to cover the generation shortfall and ensure continuous power supply.
1. ​Pumped Hydro Storage Operation Process​
• ​Energy Storage Phase (Low Load / High Renewable Generation):​​ Utilizes low-cost or zero-cost surplus wind/solar power to pump seawater from the lower reservoir (e.g., sea level) to the elevated upper reservoir. This achieves large-scale, long-duration, lossless energy storage.
• ​Energy Release Phase (Peak Load / No Wind or Sun):​​ Utilizes the height difference to release water, which flows down to spin the reversible pump-turbine and generate electricity. This process starts quickly and responds rapidly, effectively smoothing the randomness and intermittency of renewable power output.
2. ​Seawater Desalination Synergistic Process​

Seawater is intake d and passed sequentially through a multi-media filter (removing large particles) and a cartridge filter (fine filtration). It is then pressurized by the high-pressure pump and sent to the reverse osmosis membrane modules to produce freshwater, which is stored in the product water tank. This entire process is driven by system electricity. Acting as an interruptible, adjustable, high-quality load, it perfectly realizes the synergistic concept of "producing water with electricity, using water production for implicit storage."

​IV. Benefits of the Solution​

• ​Maximized Resource Utilization:​​ Fully exploits the island's abundant wind and solar resources, completely replacing or significantly reducing dependence on imported diesel, lowering energy costs at the source, and achieving energy self-sufficiency.
• ​Revolutionary Optimization of Storage Solution:​​ The hybrid storage model, "Pumped Hydro Storage as primary + Small-Capacity Batteries as auxiliary," fundamentally overcomes the four major drawbacks of traditional batteries. It offers absolute advantages: massive storage capacity, long lifespan (decades), environmental friendliness, and low comprehensive cost.
• ​Significantly Enhanced System Power Supply Stability and Reliability:​​ Pumped hydro storage can rapidly respond to load changes, providing strong peak shaving and frequency regulation capabilities. Combined with batteries handling instantaneous fluctuations, it gives the island grid stability and power quality comparable to traditional grids.
• ​Synergistic Satisfaction of Multiple Needs, Killing Multiple Birds with One Stone:​​ Innovatively integrates seawater desalination as a system load, simultaneously solving the two critical survival and development challenges of "lack of electricity" and "lack of water" on islands. It achieves a high degree of integration in "power generation - energy storage - freshwater production," yielding significant comprehensive benefits.
• ​Prominent Environmental and Green Low-Carbon Advantages:​​ The entire process is based on renewable energy, resulting in zero carbon emissions. It drastically reduces the use and pollution associated with lead-acid batteries. It provides a sustainable green development path for island communities, offering substantial ecological benefits.