10. CO₂ Scrubber Implementation
This section provides a detailed guide to building and deploying an ocean-based CO₂ scrubber device. It covers the required materials (with cost estimates and suppliers), tools, step-by-step construction, and guidelines for operation, maintenance, and scaling. The design is based on the latest ocean carbon capture research, combining proven methods (like electrodialysis-based CO₂ extraction) with practical engineering.
The ocean CO₂ scrubber functions like a "mechanical tree" planted in the ocean, but working much faster: it continuously "inhales" CO₂ from seawater (which the ocean then replenishes from air) and collects that CO₂ for storage or utilization. Unlike traditional carbon capture, our design requires no consumable chemicals and operates on minimal energy, making it ideal for scaled deployment.
Overview of the CO₂ Scrubber Device
Purpose: The ocean CO₂ scrubber extracts carbon dioxide directly from seawater. By doing so, it indirectly pulls CO₂ out of the atmosphere, as the ocean naturally absorbs more CO₂ to replace what's removed. The captured CO₂ gas can then be stored or utilized, while the treated seawater is returned to the ocean with slightly enhanced alkalinity.
Key Design Principles
- Self-contained system with no consumable chemicals
- Acids and bases generated internally through electrochemical processes
- Minimal environmental footprint with no waste streams
- Modular design allows for scaling from small to industrial units
Process Flow
Filtered seawater enters the system
Electrical process acidifies water, releasing CO₂
Vacuum extracts released CO₂ gas
Water neutralized with base and returned to ocean
System Diagram
Seawater Intake
Electrochemical Cell
Base & Acid Streams Generated
Degassing Chamber
CO₂ Collection
Neutralization Mixing
Materials and Components
Building an ocean CO₂ scrubber requires a combination of off-the-shelf industrial parts and some specialized components. All materials should be marine-grade or corrosion-resistant, since they will contact saltwater or acidic/alkaline solutions.
| Component | Description & Function | Example Source | Est. Cost (USD) |
|---|---|---|---|
| Intake Pump & Piping | Seawater pump (centrifugal or submersible) to draw water; PVC/HDPE piping (5–10 cm diameter) to route flow. Needs ~50–100 L/min capacity for a small unit. | Pump: marine supply (e.g. Xylem, Grundfos); PVC pipe: plumbing supply. | Pump $2,000; Piping $200 |
| Intake Screen Filter | Pre-filter/strainer to remove debris & marine life from intake water (e.g. coarse screen or self-cleaning filter). Protects the downstream equipment from fouling. | Industrial water treatment suppliers or aquarium stores (for smaller strainers). | $500 – $1,000 |
| Electrochemical Reactor | The heart of the system: a bipolar membrane electrodialysis stack that splits water into H⁺ (acid) and OH⁻ (base) with electrodes, ion-exchange membranes, and a cell frame that creates flow channels. | Membrane manufacturers (e.g. Fumatech, DuPont); Electrodes from electrochemical suppliers (e.g. Magneto); Cell stack hardware from lab equipment suppliers. | Total ≈ $8,500 |
| DC Power Supply | Heavy-duty DC power source (0–10 V at up to 200–300 A) to drive the electrolysis in the reactor. Can be an adjustable lab power supply or a rectifier. | Electrical supply (e.g. TDK-Lambda, XP Power) or high-current lab PSU. | $2,000 – $5,000 |
| Gas–Liquid Contactor & Vacuum | Degassing chamber under vacuum where acidified water releases CO₂ gas. Could be a packed column or spray chamber with a two-stage rotary vane or liquid ring vacuum pump. | Vacuum pump: industrial suppliers (e.g. Busch, Edwards); Contactor: chemical equipment supplier or custom chamber with packing material. | Total ≈ $4,300 |
| CO₂ Capture System | Gas separator/dryer to remove moisture, compressor to store CO₂, and storage tanks or cylinders for collected gas. | Gas drying: refrigeration supplier; CO₂ compressor: gas equipment companies; CO₂ cylinders: welding gas suppliers. | Total ≈ $5,000 |
| Sensors & Controls | pH sensors, flow meters, pressure gauges, gas flow meter, and a PLC/controller system to automate operation. | Sensors from industrial suppliers (e.g. Hach, Emerson); PLC from Siemens, Allen-Bradley, or Arduino/Raspberry Pi for prototypes. | Total ≈ $2,600 |
| Structure & Miscellaneous | Frame, enclosure, valves, fittings, wiring, and safety equipment. | Local metal fabrication; plumbing and electrical suppliers; safety gear. | Total ≈ $3,800 |
| Total Prototype Materials Cost: | $20,000 – $30,000 | ||
Costs are approximate for prototype quantities; bulk/industrial purchases could be cheaper per unit. Large-scale systems will cost more in absolute terms but less per unit of CO₂ captured due to economies of scale.
Tools and Required Expertise
Workshop Tools
Basic Hand Tools
Wrenches, screwdrivers, pliers, pipe cutters, hacksaw, and measuring tape for assembly of pipes, fittings, and general construction.
Power Tools
Electric drill with bits for metal and plastic, jigsaw or angle grinder for cutting, and potentially a welding machine for custom frames.
Electrical Tools
Wire strippers, crimping tool, multimeter, and soldering iron for electronics and sensor wiring work.
Safety Gear
Protective eyewear, insulated electrical gloves, chemical-resistant gloves for handling acid/base, and ear protection for power tools.
Required Expertise
Mechanical Engineering
Knowledge of fluid systems, pump selection, piping design, and structural assembly. Ability to prevent leaks and ensure proper flow.
Electrical Engineering
Experience with DC power supplies, high-current circuits, sensor wiring, and electrical safety in wet environments.
Chemistry Knowledge
Understanding of CO₂ in water chemistry, electrochemistry principles, acid-base reactions, and safe handling of chemicals.
Controls Systems
Ability to program PLCs or microcontrollers, implement sensor feedback loops, and create automated operation sequences.
Step-by-Step Construction Guide
Build the Frame/Skid
Start by assembling the structural frame that will hold all components. Layout the major components on the floor first to determine optimal arrangement for minimal piping runs and easy maintenance access.
Mount the Seawater Pump and Intake Assembly
Install the intake pump at the frame's base and secure with bolts. Attach intake piping with a foot-valve or strainer. Mount the intake filter upstream or immediately after the pump. Include isolation valves for servicing.
Install the Electrochemical Reactor
Assembly Steps
- Layer cation/anion exchange membranes and bipolar membranes between gaskets
- Insert electrodes at the stack ends with correct polarity orientation
- Tighten stack assembly uniformly using a torque wrench
- Mount cell stack vertically to help avoid trapping bubbles
Connection Details
- Connect main seawater flow loop to be acidified
- Route the brine loop through membranes for acid/base production
- Create pathway for base readdition to neutralize water
- Connect DC power to electrodes with appropriate gauge cables
Set Up the CO₂ Degassing Chamber
Install the gas-liquid contactor after the reactor. Mount it above the reactor outlet so acidified water can flow in by gravity. Add packing material inside to increase surface area for gas release. Connect a vacuum pump to the gas outlet and ensure proper hosing.
Integrate Neutralization and CO₂ Collection
Neutralization System
Connect the base outlet from the reactor to mix with the acidic water after degassing. Add a static mixer or sufficient pipe length to ensure thorough mixing. Install a pH sensor after this point to verify neutralization.
CO₂ Collection System
Install a gas dryer or condenser on the vacuum pump output to remove moisture. Connect the dried CO₂ output to a compressor and storage tank. Include a check valve and pressure gauge for safety monitoring.
Install Sensors and Controls
Mount pH probes in flow-through holders after acid injection and after base addition. Install flow sensors, pressure gauges, and temperature sensors at key points. Mount the control panel and wire all sensors to the PLC or microcontroller.
Testing and Commissioning
Perform leak tests with fresh water before using seawater. Test electrical systems at low voltage. Run initial operation with real seawater, gradually ramping up power while monitoring all parameters.
Leak Test
Check all joints for water leaks
Electrical Test
Verify current flow and sensor readings
Safety Test
Confirm emergency shutdown works
Build Timeline
Operation Guidelines
Startup Procedure
- Power on controllers and sensors
- Verify valve positions (intake/discharge open, drains closed)
- Start seawater pump and confirm flow
- Turn on vacuum pump for degassing
- Gradually ramp up electrolysis power to target current
- Monitor and adjust to reach operating setpoints
Shutdown Procedure
- Turn off electrolysis power
- Continue running seawater pump briefly to flush system
- Turn off vacuum pump
- Turn off seawater pump
- Close isolation valves
- Consider fresh water flush to prevent salt crystallization
Performance Monitoring
- Monitor pH levels at key points to ensure proper operation
- Track flow rate and adjust as needed for optimal performance
- Measure CO₂ collection rate to quantify carbon removal
- Watch for temperature rises in electrochemical cell
Maintenance Schedule
- Daily: Visual inspection, filter check, sensor verification
- Weekly: Biofouling check, pH sensor calibration
- Monthly: Vacuum pump service, system cleaning
- Quarterly: Electrode and membrane inspection
Cost Scaling and Implementation Considerations
Prototype Scale
One-off Custom Build
High unit cost reflects R&D investment. Not economical at scale but essential for learning and refinement.
Small Production
Batch Production & Larger Units
Economies begin with bulk material purchases, design optimization, and fixed cost distribution across multiple units.
Industrial Scale
Mass Production & Gigaton Deployment
Massive cost reductions through automated manufacturing, design improvements, renewable energy integration, and co-location with existing infrastructure.
Site Selection
- Deploy where easy access to seawater exists (coasts, piers, or offshore platforms)
- Co-locate with desalination plants to leverage existing seawater handling
- Install on ships to "scrub" CO₂ while in transit across the ocean
- Ensure appropriate permits for water intake and discharge operations
Energy Considerations
- Use renewable energy sources to maximize climate benefit
- For offshore deployment, integrate with wind or solar power
- Small units require ~5kW continuous power; large units scale up from there
- Implement backup power or safe shutdown procedures for outages
Implementing an ocean CO₂ scrubber is an engineering challenge that is entirely feasible with today's technology. By carefully selecting materials, following sound construction practices, and scaling wisely, one can build devices that reliably remove CO₂ from ocean water. The path from prototype to industrial scale involves continuous refinement and cost reduction—a journey already being pursued by innovative companies worldwide. With each iteration, these systems become more efficient and cost-effective, ultimately providing a powerful tool for climate restoration.