Deep Sea Technology Could Revolutionize San Diego's Water Future

By San Diego Tech Staff
May 14, 2025

SAN DIEGO — A revolutionary approach to seawater desalination could provide San Diego County with drought-proof water while cutting energy costs in half, according to a new engineering study released today by water experts.

The technology, known as deep sea reverse osmosis (DSRO), would place desalination equipment hundreds of meters beneath the ocean surface to take advantage of natural water pressure — potentially transforming how the region sources its drinking water.

"This isn't just an incremental improvement — it's a fundamental reimagining of desalination," said Dr. Elena Martinez, lead water engineer at the San Diego County Water Authority, who was not involved in the study but reviewed its findings. "If the projections hold up in real-world testing, this could be a game-changer for coastal communities throughout California."

Beyond Carlsbad

San Diego County is already home to the nation's largest seawater desalination plant — the Claude "Bud" Lewis Carlsbad Desalination Plant — which provides about 10% of the region's water supply. While the plant has been a reliable source since opening in 2015, its energy consumption has drawn criticism from environmental groups.

The Carlsbad facility, like most desalination plants worldwide, requires massive amounts of electricity to create the high pressure needed to force seawater through specialized membranes that filter out salt and impurities.

Deep sea desalination circumvents much of this energy demand by utilizing the natural pressure that exists at ocean depths.

"At 500 meters below the surface, you've already got about 50 atmospheres of pressure — approximately 735 psi — which approaches what conventional systems need to generate artificially," explained Dr. James Chen, one of the engineering study's authors. "It's essentially free energy provided by nature."

Cutting Costs, Reducing Emissions

The study estimates that a deep sea desalination facility could produce water using 40-50% less energy than conventional surface plants. For a facility the size of the Carlsbad plant, this could mean savings of millions of dollars annually in operational costs and a substantial reduction in carbon emissions.

"Water and energy are inextricably linked in California," said County Supervisor Maria Rodriguez. "Any technology that can reduce the energy intensity of our water supply strengthens our climate resilience and helps meet our carbon reduction goals."

The reduced operational costs could potentially lower the price of desalinated water, though the study notes that the initial capital investment would likely be higher than conventional plants due to the challenges of building and maintaining subsea infrastructure.

Environmental Questions Remain

While the energy benefits are clear, the potential environmental impacts of deep sea desalination require further study, according to marine biologists.

"We know relatively little about ecosystems at these depths compared to shallow coastal environments," said Dr. Thomas Wong, marine ecologist at Scripps Institution of Oceanography. "Before proceeding with large-scale implementation, we need careful assessment of how intake systems and brine discharge might affect deep sea communities."

The concentration of salt-laden brine — a byproduct of all desalination processes — is of particular concern. However, proponents suggest that deeper waters may actually provide better dilution capabilities than shallow coastal areas, potentially reducing environmental impact if properly managed.

The Path Forward

The San Diego County Water Authority has expressed interest in the findings and is considering funding a small-scale pilot project to test the technology off the coast of La Jolla, where the continental shelf drops relatively quickly to desirable depths.

"We're always investigating innovative approaches to water security," said Robert Johnson, SDCWA Board Chair. "With climate change increasingly threatening our imported water supplies, locally controlled, drought-proof options are more valuable than ever."

The proposed implementation would follow a phased approach, beginning with a small demonstration project before scaling to commercial production. Full implementation could take 7-10 years, according to the study.

For a region that imports roughly 80% of its water from the Colorado River and Northern California, the promise of another local supply is compelling. But experts caution that deep sea desalination represents just one piece of a diversified water portfolio.

"Conservation, recycling, stormwater capture — we need all tools in the toolkit," said Rebecca Nelson of the California Water Conservation Coalition. "But innovations like this remind us that water challenges can drive creative solutions when we think beyond conventional approaches."

If successful, San Diego could once again find itself at the forefront of water innovation, potentially creating a model for coastal communities worldwide facing similar water security challenges.

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Editor's Note: The San Diego County Water Authority will hold a public information session on deep sea desalination technology next month at the Water Conservation Garden. Details will be announced on the Authority's website.

 

Deep Sea Reverse Osmosis for Sustainable Freshwater Supply to Coastal California: Engineering Analysis and Economic Feasibility

Abstract

This paper investigates the potential application of deep sea reverse osmosis (DSRO) technology for freshwater production in coastal California, with specific focus on San Diego County. As California faces increasing water scarcity due to climate change, population growth, and depleting traditional water sources, innovative desalination approaches like DSRO present promising alternatives. DSRO leverages the natural hydrostatic pressure available at ocean depths to reduce energy consumption in the reverse osmosis process. Through comprehensive literature review and engineering analysis, this paper evaluates the technological feasibility, energy efficiency, financial considerations, and environmental impacts of implementing DSRO systems. Compared to conventional surface reverse osmosis (SRO), DSRO could potentially reduce energy consumption by up to 50%, thereby decreasing operational costs and environmental footprint. The paper concludes with recommendations for pilot projects and identifies key research needs to facilitate commercial deployment of DSRO technology in California's coastal regions.

Keywords: Desalination, Deep Sea Reverse Osmosis, Water Supply, California, Energy Efficiency, Environmental Impact

1. Introduction

1.1 Water Challenges in Coastal California

California's coastal communities, including San Diego County, face increasing challenges in securing reliable freshwater supplies. The region has historically relied on imported water from the Colorado River and Northern California, as well as limited local groundwater resources. However, these traditional sources are becoming increasingly strained due to persistent drought conditions, climate change, population growth, and competing demands (DWR, 2023).

San Diego County imports approximately 80% of its water supply, making it particularly vulnerable to disruptions in the water delivery system, including potential seismic events affecting major aqueducts (San Diego County Water Authority, 2025). This dependency has motivated local water agencies to pursue supply diversification strategies, including conservation, water recycling, groundwater management, and seawater desalination.

1.2 Current Desalination Efforts in California

Seawater desalination has emerged as a significant component of California's water supply portfolio. The Claude "Bud" Lewis Carlsbad Desalination Plant, operational since 2015, represents the largest seawater desalination facility in the United States. With a capacity of 50 million gallons per day (MGD), it provides approximately 10% of San Diego County's water supply (Poseidon Water, 2023).

Conventional desalination plants like Carlsbad employ surface reverse osmosis (SRO) technology, which requires substantial energy to generate the high pressure (approximately 800-1,200 psi) needed to overcome the osmotic pressure of seawater. This energy intensity contributes to both high operational costs and environmental concerns related to greenhouse gas emissions.

1.3 Emergence of Deep Sea Reverse Osmosis Technology

Recent technological innovations have led to the development of deep sea reverse osmosis (DSRO), a promising approach that could substantially reduce the energy requirements of desalination. DSRO systems leverage the natural hydrostatic pressure available at ocean depths to drive or supplement the reverse osmosis process, potentially reducing energy consumption by up to 50% compared to conventional SRO plants (Fasano et al., 2021).

This paper explores the potential application of DSRO technology for sustainable freshwater production in coastal California, with particular focus on San Diego County. The analysis encompasses technological feasibility, energy efficiency, economic considerations, environmental impacts, and potential implementation strategies.

2. Principles of Deep Sea Reverse Osmosis

2.1 Fundamentals of Reverse Osmosis

Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane to remove ions, molecules, and larger particles from drinking water. In seawater desalination, RO systems typically operate at pressures of 800-1,200 psi to overcome the natural osmotic pressure of seawater (approximately 400-500 psi) and generate adequate water flux through the membranes.

Conventional surface-based RO plants require substantial electrical energy to power high-pressure pumps, which represents the largest operational cost component. Recent advances in energy recovery devices, such as pressure exchangers, have improved efficiency, but the fundamental energy requirement remains significant.

2.2 Deep Sea Reverse Osmosis Concept

Deep sea reverse osmosis exploits a fundamental physical principle: hydrostatic pressure increases linearly with depth in a water column (approximately 1 atmosphere or 14.7 psi per 10 meters of depth). At a depth of 500 meters, for example, the ambient pressure is approximately 50 atmospheres (735 psi), approaching the operational pressure required for seawater desalination.

Two primary DSRO configurations have been proposed:

1. Submarine RO Systems: These involve placing the entire RO system at depth, with only the product water and control systems connected to the surface. The natural hydrostatic pressure is used directly to drive or supplement the RO process.

2. Pressure-Assisted RO Systems: These capture the high-pressure deep seawater and transport it to surface-based RO systems, reducing the supplemental pumping requirements.

2.3 Theoretical Energy Advantages

From a thermodynamic perspective, DSRO offers significant potential energy savings compared to conventional SRO. The minimum theoretical energy requirement for seawater desalination (assuming 35,000 mg/L TDS and 50% recovery) is approximately 1.07 kWh/m³ with perfect energy recovery systems (Kim et al., 2019). However, real-world SRO plants typically consume 3-4 kWh/m³ due to inefficiencies in pumps, energy recovery devices, and other components.

DSRO systems could potentially operate at energy consumption levels of 1.5-2.0 kWh/m³, representing a 50% reduction compared to conventional SRO plants. This improvement stems from utilizing "free" hydrostatic pressure rather than electrically generated pressure.

3. Technical Feasibility Analysis

3.1 Bathymetric Assessment of California Coast

The feasibility of DSRO in coastal California depends significantly on offshore bathymetry—the underwater depth profile. Ideal DSRO sites would have relatively steep bathymetric gradients, allowing access to sufficient depths within a reasonable distance from shore.

The continental shelf off San Diego extends approximately 15-30 km offshore before reaching depths of 500 meters. This moderate shelf width presents neither the ideal nor worst-case scenario for DSRO implementation. Sites with narrower continental shelves, such as parts of central California coast near Monterey, might offer more favorable conditions.

3.2 System Configuration Options

Several DSRO system configurations could be applicable to San Diego's coastal profile:

1. Fixed Seabed Installations: Permanent RO modules installed on the seabed at optimal depths (400-600m), with product water and brine pipelines connecting to shore facilities.

2. Floating DSRO Plants: Surface vessels or platforms with deep water intake pipes reaching sufficient depths to exploit hydrostatic pressure advantages.

3. Hybrid Systems: Combining partial depth advantages with supplemental high-pressure pumping to optimize system performance across varying bathymetric conditions.

4. Batch DSRO Systems: Operating on cyclical pressure-volume cycles to maximize energy efficiency, particularly suitable for moderate depth applications.

3.3 Key Technical Challenges

Several technical challenges must be addressed for successful DSRO implementation:

1. Materials and Structural Integrity: All subsea components must withstand long-term exposure to high-pressure marine environments, corrosive seawater, and potential biofouling.

2. Membrane Performance Under High Pressure: While RO membranes are designed for high-pressure operation, the continuous high ambient pressure in deep sea environments may affect membrane performance and lifespan.

3. Maintenance and Operation: Subsea installations present significant challenges for routine maintenance, membrane replacement, and system monitoring compared to surface installations.

4. Power Supply and Control Systems: Reliable power and control systems must be established between surface facilities and subsea components.

5. Intake Design: Proper design of deep water intakes is essential to minimize entrainment and impingement of marine organisms while ensuring reliable water supply.

6. Brine Discharge Management: Environmentally responsible discharge of brine concentrate remains a challenge, though deep discharge may offer dilution advantages.

4. Energy Analysis and Efficiency

4.1 Energy Requirements Comparison

A comparative energy analysis between conventional SRO and proposed DSRO systems for a hypothetical 50 MGD plant (equivalent to the Carlsbad facility) yields the following estimates:

Conventional SRO:

• High-pressure pumping: 3.0-3.6 kWh/m³
• Pretreatment and post-treatment: 0.5-0.8 kWh/m³
• Other processes: 0.2-0.4 kWh/m³
• Total energy consumption: 3.7-4.8 kWh/m³

DSRO (500m depth):

• Supplemental pumping: 0.8-1.2 kWh/m³
• Pretreatment and post-treatment: 0.5-0.8 kWh/m³
• Deep water intake/delivery: 0.2-0.4 kWh/m³
• Other processes: 0.2-0.4 kWh/m³
• Total energy consumption: 1.7-2.8 kWh/m³

These estimates suggest potential energy savings of 40-50% for DSRO systems compared to conventional SRO plants. The precise savings would depend on specific site conditions, system configuration, and technological implementation.

4.2 Energy Recovery Considerations

Energy recovery devices (ERDs) play a crucial role in both conventional SRO and DSRO systems. State-of-the-art pressure exchangers can recover up to 97% of the energy from high-pressure brine streams, significantly improving overall system efficiency.

For DSRO systems, specialized ERDs could be developed to optimize performance under the unique operating conditions of deep sea operations. These might include advanced isobaric systems specifically designed for the pressure profiles encountered in DSRO applications.

4.3 Renewable Energy Integration

DSRO systems present intriguing opportunities for integration with renewable energy sources, particularly offshore wind and wave energy. The California coast offers substantial renewable energy potential, including:

• Offshore wind resources, especially in northern California
• Wave energy potential along the entire coastline
• Solar potential at surface facilities

Integrated renewable energy systems could further reduce the carbon footprint of DSRO operations while providing complementary benefits such as grid stabilization and energy storage.

5. Economic Analysis

5.1 Capital Expenditure (CAPEX)

Developing DSRO facilities would involve significant capital investment, potentially exceeding that of conventional SRO plants due to the challenges of marine construction and specialized equipment. Key CAPEX components include:

1. Intake and Outfall Infrastructure: Deep water intake pipes, brine discharge systems, and associated marine infrastructure represent major capital costs.

2. RO System Components: Pressure vessels, membranes, pumps, and energy recovery devices scaled for the desired production capacity.

3. Marine Construction: Subsea structures, anchoring systems, and installation services requiring specialized vessels and equipment.

4. Land-Based Facilities: Product water storage, post-treatment systems, and connection to municipal water infrastructure.

5. Control Systems: Advanced monitoring and control systems to ensure reliable remote operation of subsea components.

Based on current industry benchmarks, a 50 MGD DSRO facility might require capital investment of $1.2-1.5 billion, compared to approximately $1 billion for the Carlsbad SRO plant of equivalent capacity.

5.2 Operational Expenditure (OPEX)

DSRO's primary economic advantage lies in reduced operational costs, particularly energy expenses. For a 50 MGD facility:

Conventional SRO:

• Energy costs: $0.55-0.70/m³ (assuming $0.15/kWh)
• Membrane replacement: $0.10-0.15/m³
• Chemical treatment: $0.08-0.12/m³
• Labor and maintenance: $0.20-0.30/m³
• Total OPEX: $0.93-1.27/m³

DSRO (500m depth):

• Energy costs: $0.25-0.40/m³ (assuming $0.15/kWh)
• Membrane replacement: $0.12-0.18/m³ (potentially higher due to access challenges)
• Chemical treatment: $0.08-0.12/m³
• Labor and maintenance: $0.25-0.40/m³ (higher due to subsea operations)
• Total OPEX: $0.70-1.10/m³

These estimates suggest potential operational cost savings of 15-25% for DSRO systems compared to conventional SRO plants, primarily driven by energy efficiency.

5.3 Levelized Cost of Water (LCOW)

The levelized cost of water (LCOW) provides a comprehensive metric for comparing different water supply options, incorporating both capital and operational expenses over the project lifetime. Preliminary LCOW analysis yields:

Conventional SRO: $1,800-2,200 per acre-foot DSRO (500m depth): $1,600-2,000 per acre-foot

For context, imported water in San Diego County currently costs approximately $1,100-1,300 per acre-foot, while recycled water costs approximately $1,600-1,800 per acre-foot (San Diego County Water Authority, 2025).

While DSRO appears to offer modest cost advantages compared to conventional SRO, both technologies remain premium water supply options. However, the reliability and drought-resistance of desalinated water provide additional value beyond direct cost comparison, particularly in water-stressed regions like Southern California.

5.4 Financing Considerations

DSRO projects would likely require innovative financing mechanisms similar to those employed for the Carlsbad facility, which utilized a public-private partnership model. Potential approaches include:

1. Public-Private Partnerships: Long-term water purchase agreements between private developers and public water agencies.

2. Green Bonds: Sustainable infrastructure financing specifically targeting water security and climate resilience.

3. Federal and State Grants: Funding support for innovative water supply projects that advance sustainability objectives.

4. Water Infrastructure Finance and Innovation Act (WIFIA): Low-interest federal loans for qualifying water infrastructure projects.

The higher capital costs of DSRO facilities would need to be balanced against long-term operational savings to establish financial viability.

6. Environmental Impact Assessment

6.1 Energy-Related Environmental Benefits

The reduced energy consumption of DSRO systems offers significant environmental benefits compared to conventional SRO plants:

1. Greenhouse Gas Emissions: A 50% reduction in energy consumption would translate to proportional reductions in GHG emissions, assuming similar energy sources. For a 50 MGD plant in California, this could represent approximately 30,000-40,000 metric tons of CO₂ equivalent annually.

2. Air Quality: Reduced energy demand would contribute to improved regional air quality by decreasing reliance on fossil fuel generation, particularly during peak demand periods.

3. Renewable Energy Compatibility: The lower energy intensity of DSRO makes integration with renewable energy sources more feasible, potentially enabling carbon-neutral operation.

6.2 Marine Environmental Considerations

DSRO systems present both advantages and concerns regarding marine environmental impacts:

1. Intake Effects: Deep water intakes may reduce entrainment of sensitive nearshore marine organisms but could affect deep-water communities that are less well-studied. Site-specific assessments would be required.

2. Brine Discharge: Deep discharge of brine could potentially benefit from greater dilution capacity but might impact sensitive deep-water ecosystems. The density of brine presents particular challenges for effective mixing.

3. Construction Impacts: Installation of subsea infrastructure would cause temporary disturbance to benthic communities, requiring careful site selection and construction practices.

4. Operational Impacts: Continuous operation could create localized changes in current patterns, temperature, and salinity that might affect marine life, particularly in semi-enclosed basins with limited circulation.

6.3 Regulatory Framework

Implementation of DSRO in California would require navigation of complex regulatory frameworks involving multiple agencies:

1. California Coastal Commission: Responsible for coastal development permits and enforcing compliance with the California Coastal Act.

2. Regional Water Quality Control Boards: Oversight of water quality impacts, particularly related to brine discharge.

3. State Water Resources Control Board: Implementation of the Ocean Plan Amendment governing desalination facilities.

4. California State Lands Commission: Management of state-owned submerged lands.

5. U.S. Army Corps of Engineers: Permitting for structures in navigable waters.

6. National Marine Fisheries Service: Consultation regarding potential impacts to marine species.

The 2015 California Ocean Plan Amendment established specific requirements for desalination facilities, including best available technology for intakes and rigorous monitoring requirements. These would need to be adapted for the unique aspects of DSRO systems.

7. Comparative Case Study: Carlsbad Desalination Plant

7.1 Facility Overview

The Claude "Bud" Lewis Carlsbad Desalination Plant provides a valuable reference point for assessing DSRO potential in San Diego County. Key characteristics include:

• Capacity: 50 million gallons per day (56,000 acre-feet annually)
• Technology: Surface reverse osmosis (SRO)
• Energy consumption: Approximately 3.6 kWh/m³
• Capital cost: Approximately $1 billion (2015)
• Operational since: December 2015
• Water cost: $2,125-2,368 per acre-foot (2017 figures)

The plant provides approximately 10% of San Diego County's water supply and serves about 400,000 residents.

7.2 Performance Assessment

After nearly a decade of operation, the Carlsbad plant has demonstrated both the benefits and challenges of large-scale seawater desalination:

Benefits:

• Reliable, locally controlled water supply independent of imported sources
• Drought-resistant supply unaffected by climate variability
• High water quality meeting or exceeding all standards
• Protection from seismic risks affecting imported water infrastructure

Challenges:

• Higher cost compared to traditional water sources
• Significant energy consumption and associated carbon footprint
• Periodic operational issues, including temporary closures due to red tides
• Environmental impacts from intake and discharge

7.3 Potential DSRO Improvements

Implementing DSRO technology for a similar-sized facility in San Diego County could potentially address several of the challenges experienced at Carlsbad:

1. Energy Efficiency: Reducing energy consumption by 40-50% would address a key sustainability concern while lowering operational costs.

2. Deep Water Quality: Drawing intake water from deeper ocean layers might reduce vulnerability to surface phenomena like red tides and algal blooms.

3. Discharge Dilution: Deep brine discharge could potentially benefit from improved mixing and dilution compared to nearshore discharge, though site-specific studies would be required.

4. Operational Resilience: Decreased dependence on electrical pumping could improve reliability during grid disturbances.

8. Implementation Strategy for San Diego County

8.1 Site Selection Criteria

Optimal sites for DSRO implementation in San Diego County would balance multiple factors:

1. Bathymetric Profile: Areas with relatively steep offshore slopes providing access to 400-600m depths within reasonable distance from shore.

2. Proximity to Demand: Locations near existing water distribution infrastructure and major demand centers.

3. Environmental Sensitivity: Avoidance of marine protected areas, sensitive habitats, and areas with concentrated marine activities.

4. Existing Infrastructure: Potential co-location with existing marine infrastructure (e.g., power plant outfalls, piers) to minimize new construction impacts.

5. Land Availability: Sufficient onshore space for post-treatment, storage, and distribution facilities.

Preliminary analysis suggests that areas off La Jolla, Point Loma, and south of Carlsbad might offer suitable conditions for DSRO implementation.

8.2 Phased Development Approach

Given the innovative nature of DSRO technology, a phased development approach would be prudent:

Phase 1: Pilot Testing (1-2 years)

• Small-scale prototype (1-5 MGD) to validate technological concepts
• Comprehensive environmental monitoring program
• Collection of operational data to refine designs

Phase 2: Demonstration Project (2-3 years)

• Mid-scale facility (10-20 MGD) incorporating lessons from pilot phase
• Integration with existing water infrastructure
• Validation of economic models and environmental performance

Phase 3: Full-Scale Implementation (4-5 years)

• Commercial-scale facility (50+ MGD) based on proven technology
• Comprehensive integration with regional water management systems
• Potential for multiple facilities along the California coast

8.3 Stakeholder Engagement

Successful implementation would require engagement with diverse stakeholders:

1. Water Agencies: San Diego County Water Authority and member agencies would be primary partners in developing and utilizing DSRO facilities.

2. Regulatory Agencies: Early engagement with permitting agencies to address novel aspects of DSRO technology.

3. Environmental Organizations: Collaboration with conservation groups to ensure robust environmental protection measures.

4. Research Institutions: Partnerships with universities and research institutions to advance technological development and monitoring.

5. Community Groups: Engagement with coastal communities affected by facility siting and operation.

6. Industry Partners: Collaboration with technology providers, marine construction firms, and other specialized service providers.

9. Research Needs and Future Directions

9.1 Technology Development Priorities

Several key research areas would accelerate DSRO implementation:

1. Membrane Technology: Development of pressure-tolerant membranes optimized for deep sea conditions, potentially with integrated anti-fouling capabilities.

2. Energy Recovery Systems: Specialized energy recovery devices designed for the pressure profiles encountered in DSRO applications.

3. Materials Science: Advanced corrosion-resistant materials for long-term subsea deployment.

4. Intake/Outfall Design: Innovative intake structures minimizing marine life impacts while ensuring reliable operation.

5. Monitoring Systems: Remote sensing and automated monitoring technologies for subsea components.

9.2 Environmental Research Needs

Critical knowledge gaps in marine environmental impacts must be addressed:

1. Deep Ocean Ecology: Better understanding of biological communities at potential DSRO operating depths.

2. Brine Dilution Modeling: Advanced models of brine dispersion and dilution in deep water environments.

3. Long-term Ecosystem Effects: Studies of prolonged exposure to altered salinity in deep water environments.

4. Climate Resilience: Assessment of DSRO vulnerability to climate change effects, including sea level rise and ocean warming.

9.3 Policy and Regulatory Development

Regulatory frameworks will need adaptation to address novel aspects of DSRO:

1. Subsea Infrastructure Permitting: Streamlined processes for innovative marine technologies.

2. Deep Water Discharge Standards: Science-based regulations for deep brine discharge.

3. Financial Incentives: Policies supporting water supply diversification and energy-efficient desalination.

4. Integrated Planning: Frameworks connecting water supply, renewable energy, and marine spatial planning.

10. Conclusion and Recommendations

Deep sea reverse osmosis technology presents a promising approach for enhancing freshwater supply reliability in coastal California, particularly San Diego County. By leveraging the natural hydrostatic pressure available at ocean depths, DSRO could substantially reduce the energy intensity and environmental footprint of seawater desalination while providing a climate-resilient water source.

Key advantages include potential energy savings of 40-50% compared to conventional surface reverse osmosis plants, reduced operational costs, and corresponding reductions in greenhouse gas emissions. These benefits must be weighed against higher capital costs, technical challenges of subsea operations, and potential impacts to deep marine environments.

Based on this comprehensive analysis, we recommend:

1. Pilot Project Development: Initiation of a small-scale DSRO pilot project offshore of San Diego County to validate technological concepts and gather operational data.

2. Research Program Establishment: Creation of a coordinated research program addressing key knowledge gaps, particularly regarding membrane performance in deep sea environments and marine ecological impacts.

3. Regulatory Framework Advancement: Engagement with regulatory agencies to develop appropriate guidelines for DSRO technology that balance innovation with environmental protection.

4. Public-Private Partnership: Formation of collaborative ventures between water agencies, technology providers, and research institutions to share development costs and risks.

5. Integrated Planning: Consideration of DSRO within broader regional water supply and energy planning efforts, potentially linking with offshore renewable energy development.

DSRO represents one component of a diversified approach to water security that should include continued advancement of conservation, recycling, stormwater capture, and watershed management. The technology's promise of more energy-efficient desalination aligns with California's climate goals while addressing critical water security needs.

Figures

The figures in the paper are currently using placeholder URLs since I can't generate actual images. Below is a list of all figures with their placeholder URLs:

1. Cover Image: Deep Sea Reverse Osmosis for California Water Supply

   • URL: https://via.placeholder.com/800x400?text=Deep+Sea+Reverse+Osmosis+for+California+Water+Supply

2. Figure 1: Hydrostatic Pressure vs Depth and DSRO Principle

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3. Figure 2: Conventional Surface RO vs Deep Sea RO Configurations

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4. Figure 3: Bathymetric Profile of San Diego Coastal Region

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5. Figure 4: Energy Consumption Comparison Between Conventional SRO and DSRO

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6. Figure 5: Comparative Levelized Cost of Water for Different Supply Options

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7. Figure 6: Environmental Considerations for Deep Sea Brine Discharge and Dilution

   • URL: https://via.placeholder.com/800x500?text=Figure+6:+Environmental+Considerations+for+Deep+Sea+Brine+Discharge+and+Dilution

8. Figure 7: Carlsbad Desalination Plant Aerial View and Schematic

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9. Figure 8: Proposed Phased Implementation Timeline for DSRO

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10. Figure 9: Conceptual Design of Integrated DSRO Facility for San Diego

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These URLs point to placeholder images that would need to be replaced with actual figures if you were to publish the paper. In a real engineering paper, these would be custom-created diagrams, charts, photographs, or schematics specific to deep sea reverse osmosis technology and its implementation in coastal California.

 

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19. California Coastal Commission. (2015). Seawater Desalination and the California Coastal Act.

20. State Water Resources Control Board. (2015). Final Amendment to the Water Quality Control Plan for Ocean Waters of California Addressing Desalination Facility Intakes, Brine Discharges, and Incorporating Other Nonsubstantive Changes.