The Canary Islands paradox - Desalination plants: Curse or blessing? | DW Documentary

Key Concepts

• Desalination: The process of removing salt and minerals from seawater to produce freshwater.
• Reverse Osmosis: A specific desalination technology using pressure to force water through a semi-permeable membrane.
• Brine: The highly concentrated saltwater byproduct of desalination, posing environmental risks.
• Galleras: Traditional tunnels dug to access groundwater, representing historical water management practices in the Canary Islands.
• Horizontal Rain: Condensation of moisture from clouds onto laurel forest leaves, a natural water source.
• Membrane Bioreactors (MBR): Technology used to treat wastewater, producing reusable water and fertilizer for agriculture.
• Water Scarcity: The lack of sufficient available water resources to meet water needs.
• Sustainable Water Management: Practices aimed at balancing water use with environmental protection and long-term availability.

The Canary Islands: A Case Study in Desalination and Water Management

Introduction: The Global Water Crisis & Desalination as a Solution

The video opens by highlighting the growing global water crisis, predicting that by 2050, half the world’s population may face difficulty accessing drinking water. Desalination – removing salt from seawater – is presented as a promising, though complex, solution gaining traction worldwide. The Canary Islands serve as a focal point for examining the benefits and drawbacks of this technology.

Historical Context: Water Scarcity and Early Adoption of Desalination

The Canary Islands, located off the coast of Africa, have historically struggled with water scarcity due to their arid climate and limited rainfall (less than the Spanish average). This led to the islands becoming the first European region to adopt desalination technology over 60 years ago, initially in 1964 with a plant on Lanzarote. Prior to desalination, traditional methods were crucial:

• Laurel Forests & Horizontal Rain: UNESCO-protected laurel forests played a vital role in capturing moisture from the “sea of clouds,” condensing water on leaves (horizontal rain) and replenishing groundwater aquifers.
• Indigenous Water Collection: The indigenous Tenneref people collected fog water in carved basins.
• Galleras (Tunnels): From the 1850s, over 1,700 km of tunnels (galleras) were dug to access groundwater, representing a significant engineering effort. Haime Kouo Bravo’s work maintaining these tunnels underscores their continued importance, supplying up to 80% of Tenneref’s drinking water.

The Rise of Tourism and the “Illusion of Abundance”

The video details how desalination enabled a massive expansion of tourism in the Canary Islands, beginning in the 1960s after WWII. This led to an “illusion of abundance” and a water-intensive economy. Today, the archipelago receives around 17 million tourists annually, heavily reliant on desalinated water for hotels, golf courses, and swimming pools. Juan Ramon’s personal account of a severe drought in 1947 highlights the stark contrast between past scarcity and present-day access, albeit dependent on desalination.

Desalination Technology & Current Infrastructure

The Canary Islands now boasts 330 public and private desalination plants, among the highest concentration per square kilometer globally. A modern plant in Tenneref treats approximately 30,000 cubic meters of water daily (equivalent to 15 Olympic swimming pools), supplying 60% of Santa Cruz de Tener’s water needs.

• Reverse Osmosis Process: The core technology is reverse osmosis, where seawater is forced through semi-permeable membranes under high pressure. For every 100L of seawater, approximately 45L of freshwater and 55L of brine are produced.
• Post-Treatment: The freshwater undergoes remineralization and disinfection before distribution.
• Consumer Preference: Despite being potable, many Canarians prefer bottled water due to taste, smell, and concerns about the processing.

Environmental Impacts of Desalination

The video critically examines the environmental consequences of desalination:

• Energy Consumption: Desalination is energy-intensive, consuming over 10% of the islands’ electricity, largely generated by fossil fuels. The weekly electricity consumption of all plants is equivalent to a 120,000-ton oil tanker’s cargo. This results in approximately 2,000 tons of CO2 emissions daily.
• Brine Discharge: The discharge of hyper-concentrated brine back into the ocean poses a significant threat to marine ecosystems.
  • Impact on Marine Life: Diver Fernando Espino’s research demonstrates the devastating effects of brine on marine flora and fauna, creating “dead zones” devoid of life within a 50m radius of discharge points. The invasive cyanobacterium Lingia majuscula thrives in these areas, destroying seagrass beds.
  • Chemical Contamination: Brine often contains chemicals like sodium metabisulfite used for pipe cleaning, which are toxic to marine life.
• Carbon Footprint: The reliance on fossil fuels exacerbates the carbon footprint of desalination.

Towards Sustainability: Renewable Energy & Water Recycling

The video explores efforts to mitigate the environmental impacts of desalination:

• Eliero’s Renewable Energy Initiatives: Eliero is striving for energy self-sufficiency through a combination of wind turbines (Gona Delviento) and a pumped hydro storage system. While ambitious, the island still relies on 60% fossil fuels.
• Wastewater Recycling with Membrane Bioreactors (MBR): Researchers at the University of La Lagona, led by Louisa Vera, are developing membrane bioreactors to treat wastewater, producing reusable water for agriculture and valuable fertilizers. This reduces the demand for desalinated water. The system utilizes bacteria to remove pollutants and ultrafiltration membranes to purify the water.

Traditional Water Management & Laomera as a Model

The island of Laomera stands out as an exception, largely relying on traditional water management practices and natural freshwater resources.

• Reservoir Network: A sophisticated network of dams and pipes distributes water efficiently across agricultural zones.
• Adaptive Agriculture: Farmers adapt their cultivation practices to water availability, employing techniques like mulching and drought-resistant seeds.
• Sustainable Tourism: Laomera prioritizes sustainable tourism, limiting visitor numbers to align with available resources.

Conclusion: A Call for a Holistic Approach

The video concludes that desalination is a tool, not a magic bullet. A fundamental shift in mindset is needed, recognizing that water is not an unlimited resource. Sustainable water management, renewable energy integration, wastewater recycling, and a commitment to responsible consumption are crucial for ensuring long-term water security in the Canary Islands and beyond. The future requires a holistic approach that balances technological solutions with traditional practices and a deep respect for the environment.