More than two billion people currently live under water stress, with one in four lacking access to safe drinking water.

Global water scarcity is a critical issue facing the world today. Projections suggest that by 2050, the number could rise to five billion, driven by climate change and increasing water demands from agriculture and industry. Sustainable Development Goal (SDG) Target 6.1 is to: “achieve universal and equitable access to safe and affordable drinking water for all” by 2030.

Asia have been exploring the potential of deep-sea water farms for sustainable desalination as part of efforts to meet growing freshwater demands, improve food security, and address environmental challenges in coastal regions. Deep-sea water farms, which involve using water from deeper ocean layers (typically below 200 meters), offer distinct advantages over traditional desalination methods. Here’s how deep-sea water farms can contribute to sustainable desalination in Asia:

What Are Deep-Sea Water Farms?

Deep-sea water farms involve the extraction of water from deeper layers of the ocean, where it is typically colder and more mineral-rich. This water is often referred to as “deep ocean water” (DOW). The water can be used in various applications, including desalination, aquaculture, and agriculture.

Asian Examples of Deep-Sea Water Farms for Desalination

1. Japan
   • Japan has been a leader in using deep-sea water for various purposes, including desalination, aquaculture, and cooling systems. The Nagasaki Marine Resources Center is an example of how Japan uses deep-sea water for desalination and energy generation.
   • The Okinawa Institute of Science and Technology (OIST) is also involved in deep-sea water desalination research, working on technologies that could scale sustainable desalination for coastal communities in Japan.
2. Taiwan
   • Taiwan has been exploring the use of deep-sea water for desalination and aquaculture through projects like the Taiwan Ocean Water Corporation, which taps into the cold, nutrient-rich deep ocean water to support sustainable aquaculture and freshwater production.
   • The Kaohsiung Deep-Sea Water Desalination Plant uses deep-sea water to produce potable water, supporting the local economy by providing freshwater for industries and households.
3. South Korea
   • South Korea has started to develop deep-sea water farms to address water scarcity and promote sustainable agriculture. The Jeju Island Deep Ocean Water Research Center focuses on extracting cold deep-sea water for desalination and to support fish farming and crop irrigation in this water-scarce region.
   • South Korea has also looked into utilizing ocean thermal energy and desalination systems that leverage the temperature gradients between deep ocean water and surface waters.
4. China
   • China has shown increasing interest in using deep-sea water for sustainable desalination, especially for coastal regions like Shandong, Fujian, and Guangdong. In these areas, deep-sea water is seen as a way to supplement freshwater supplies and integrate it into existing marine industries.
   • The Dalian Deep-Sea Water Desalination Project in Liaoning Province is one of the more notable efforts, where deep-sea water is being used to provide freshwater for industrial and agricultural purposes.
5. Philippines
   • The Philippines, an archipelago with many coastal and island communities, is looking into deep-sea water desalination as a potential solution for providing freshwater to remote areas. The government is exploring deep-ocean water resources to support both desalination and sustainable aquaculture, given the country’s growing demand for freshwater and seafood.
6. Indonesia
   • Indonesia is actively researching the use of deep-sea water desalination, particularly in regions like Bali and the Sulawesi Islands, which face water shortages and environmental degradation. These projects are exploring how deep-sea water can be harnessed for both drinking water and agricultural purposes.

Deep-sea water farms for desalination typically focus on:

1. Extracting deep ocean water (DOW) for use in reverse osmosis desalination systems.
2. Utilizing natural temperature gradients for energy-efficient desalination processes, such as Ocean Thermal Energy Conversion (OTEC).
3. Integrating aquaculture and agriculture to create multi-use systems that maximize water and energy efficiency.

Key Benefits of Deep-Sea Water Farms for Desalination

1. Energy Efficiency: Deep-sea water farms can be combined with energy-efficient technologies like OTEC, where temperature differences between the cold deep ocean water and warm surface water are used to generate power. This reduces reliance on fossil fuels for desalination.
2. Freshwater Production: Deep-sea desalination can provide a sustainable, reliable source of freshwater in water-scarce regions, such as many coastal areas of Asia.
3. Environmental Impact: Unlike traditional desalination, which relies heavily on energy-intensive processes, deep-sea water farms can reduce the environmental impact by using renewable energy sources, minimizing brine discharge, and integrating with sustainable aquaculture systems.
4. Enhanced Aquaculture: Cold deep-sea water can be used in aquaculture for species that require specific temperature conditions, and the nutrient-rich water can promote the growth of fish and other marine organisms, contributing to food security.

Deep-Sea Technological Innovations

• Ocean Thermal Energy Conversion (OTEC): OTEC uses the difference in temperature between warm surface water and cold deep-sea water to generate electricity. This process can power desalination plants, making deep-sea water desalination more energy-efficient and sustainable. Several Asian countries, including Japan and the Philippines, are exploring OTEC for integrated energy and desalination systems.
• Reverse Osmosis: Deep-sea water desalination systems use reverse osmosis (RO) to filter out the salt and minerals from the deep-ocean water, producing clean, potable water.
• Energy from Deep Ocean Water: Cold deep-sea water is also used for cooling purposes in large-scale industrial operations, which can reduce energy consumption and further improve the environmental sustainability of desalination systems.

Challenges

1. High Initial Costs: Establishing deep-sea desalination systems requires significant upfront investments in infrastructure, technology, and research.
2. Environmental Impact: While deep-sea desalination is more environmentally friendly than traditional methods, the extraction of large volumes of deep-sea water could potentially disrupt marine ecosystems.
3. Technological Development: As deep-sea desalination is still an emerging field, continuous research and development are needed to improve the efficiency and reduce the costs of these technologies.

Deep-sea water farms for sustainable desalination in Asia hold great potential for addressing water scarcity and supporting aquaculture. By combining renewable energy sources like OTEC and integrating sustainable practices, these projects offer a promising solution for future-proofing freshwater resources while minimizing environmental impact. Countries like Australia, Japan, Taiwan, South Korea, and China are leading the charge in developing and implementing deep-sea water desalination systems, with the possibility of scaling these technologies across other regions facing water shortages.

AUSTRALIA

Australia is particularly vulnerable to the impacts of climate change, including droughts and water scarcity pioneering the field of desalination –  particularly due to its status as the driest inhabited continent on Earth with approximately 70% of Australia’s landmass is classified as arid or semi-arid, with an average annual rainfall of less than 600 > 250 millimeters.

Background

Australia’s desalination efforts began in the early 20th century, with the first plant constructed in 1903 to treat saline groundwater in Kalgoorlie, Western Australia. However, it wasn’t until the severe drought from 1997 to 2009 that the country significantly ramped up its desalination capacity.

Modern Desalination Plants

Some of the notable large-scale plants include:

– Perth Seawater Desalination Plant: Completed in 2006, it was the first modern large-scale desalination plant in Australia using seawater from Cockburn Sound to produce potable water, drawing seawater from the ocean and converting it into drinking water through a reverse osmosis process.

– Victorian Desalination Plant: Located in Wonthaggi, seawater from Bass Strait through intake structures and processes it using reverse osmosis technology to produce potable water producing up to 150 billion liters of water per year with the capacity to provide water for 33% of Melbourne’s population. (Source)

– Adelaide Desalination Plant: Located in Lonsdale, it can supply 50% of Adelaide’s water needs using reverse osmosis to convert seawater from the Gulf St Vincent into potable water.

– Sydney Desalination Plant: Although not a deep-sea water farm specifically, the Sydney Desalination Plant is one of the largest desalination projects in Australia. It uses seawater from the ocean (not deep-sea water) to produce about 15% of the city’s drinking water requirements using reverse osmosis technology to convert seawater into potable water.

Australia’s Challenges and Future Directions

While desalination provides a reliable source of freshwater, it is considered expensive compared to traditional water sources. Research is ongoing to develop more cost-effective and energy-efficient desalination technologies.

Australia’s deep sea desalination efforts are a testament to the country’s commitment to addressing water scarcity and ensuring a sustainable water supply for its population.

Tasmania is also a hub for renewable energy research, and future deep-sea desalination projects could combine OTEC and deep-sea aquaculture systems in the state.

Australian Renewable Energy Agency (ARENA): ARENA has supported several research projects in Australia focused on offshore renewable energy technologies. These include studies into wave energy, tidal power, and offshore wind, all of which could complement deep-sea water desalination systems powered by renewable energy.