Regasification is the process of warming LNG from -162°C back to gaseous state for pipeline delivery. Global regasification capacity in 2026 stands at ~1,100 MTPA, significantly exceeding liquefaction capacity (~520 MTPA), creating a buyer's market. Regasification terminals use specialized vaporizers that extract heat from seawater, ambient air, or combustion to safely warm LNG at rates up to 1,000 MMcf/d per terminal.
The Regasification Process
Regasification reverses liquefaction through controlled heat addition:
Process Steps
- Unloading: LNG transferred from carrier to storage tanks (6-12 hours for 174,000 m³ vessel)
- Storage: LNG held in insulated tanks at -162°C, atmospheric pressure
- Sendout: LNG pumped from storage through vaporizers
- Vaporization: Heat applied to convert LNG to gas (primary focus of this article)
- Odorization: Mercaptan odorant added (natural gas is odorless; smell aids leak detection)
- Metering & Pressure Control: Gas measured and pressurized (50-100 bar) for pipeline injection
Energy Requirements
Heat Needed per Tonne LNG:
- Sensible Heat: Warming from -162°C to 15°C: ~220 kJ/kg
- Latent Heat: Phase change (liquid → gas): ~510 kJ/kg
- Total: ~730 kJ/kg (0.2 kWh/kg)
This is far less than the 250-300 kWh/tonne required for liquefaction (cooling consumes ~100x more energy than warming).
Vaporizer Technologies
| Type | Heat Source | Efficiency | CAPEX | Market Share |
|---|---|---|---|---|
| ORV (Open Rack Vaporizer) | Seawater | 99%+ (free heat) | Low | ~55% |
| SCV (Submerged Combustion) | Natural gas combustion | ~85% (fuel cost) | Medium | ~20% |
| AAV (Ambient Air Vaporizer) | Atmospheric air | 99%+ (free heat) | Very Low | ~15% |
| IFV (Intermediate Fluid) | Propane/glycol loop | ~90% | High | ~5% |
| HOIV (Heat Exchanger) | Industrial waste heat | 99%+ (free heat) | Medium | ~5% |
1. Open Rack Vaporizer (ORV) - Industry Standard
Operating Principle:
- LNG flows through aluminum tubes arranged in vertical panels ("racks")
- Seawater cascades over tubes from top, transferring heat
- LNG vaporizes as it rises through tubes; exits as gas at ~5-10°C
- Discharge seawater is ~4-6°C colder than intake
Design Specifications:
- Tube Material: Aluminum alloy (5083 or 5052) - excellent low-temp properties
- Typical Size: 12m high × 4m wide panel; 10-20 panels per vaporizer
- Capacity: 150-250 tonnes/hour per vaporizer unit
- Seawater Flow: ~4,000 m³/h per 200 tonne/h unit
Advantages:
- Zero fuel cost (uses ambient seawater heat)
- High reliability (no moving parts in heat exchanger)
- Low operating cost (~$0.10-0.15/MMBtu)
- Proven technology (used since 1970s)
Disadvantages:
- Location-dependent: Requires coastal site with deep water access
- Environmental concerns: Discharge water 4-6°C colder affects marine life (requires mitigation)
- Cold climate issues: Seawater can freeze in extreme cold; requires SCV backup
- Corrosion: Seawater is corrosive; requires cathodic protection and regular maintenance
Seawater Intake Requirements:
Example: 1,000 MMcf/d (7 MTPA) Terminal
- LNG throughput: ~300 tonnes/hour
- Heat required: ~220 MW thermal
- Seawater flow: ~20,000 m³/h (5.5 m³/s)
- Temperature drop: 5-6°C
2. Submerged Combustion Vaporizer (SCV)
Operating Principle:
- Natural gas burned underwater in combustion chamber
- Hot combustion gases (1,800°C) bubble through water bath
- Water heated to 30-60°C
- LNG flows through submerged tubes, absorbing heat from hot water
Design Specifications:
- Fuel Consumption: ~1.5-2.0% of throughput gas
- Capacity: 100-300 tonnes/hour per unit
- Efficiency: 85-90% (some heat lost to atmosphere)
- Water Bath: 500-1,000 m³ per unit
Advantages:
- Location-flexible: Can be built inland (no seawater needed)
- Works in any climate (no freezing risk)
- Compact footprint vs. ORV
- Fast startup (15-30 minutes vs. hours for ORV)
Disadvantages:
- Fuel cost: ~$0.30-0.50/MMBtu operating expense
- CO₂ emissions: ~0.5 kg CO₂/MMBtu (climate concern)
- Water vapor plume: Visible steam discharge (aesthetic/regulatory issue)
Typical Use Cases:
- Peak Shaving: Backup to ORV during winter demand spikes
- Inland Terminals: Where seawater unavailable
- FSRU: Floating terminals use SCV for flexibility
3. Ambient Air Vaporizer (AAV)
Operating Principle:
- LNG flows through finned aluminum tubes
- Natural air convection (or fans) transfers ambient heat to tubes
- No external energy input required (passive system)
Design Specifications:
- Tube Array: Vertical or horizontal configuration with extensive fin area
- Capacity: 10-50 tonnes/hour per unit (smaller than ORV/SCV)
- Footprint: Large - requires 10-20x more space than ORV for same capacity
Advantages:
- Zero operating cost (no fuel, no pumps in passive design)
- Extremely simple and reliable
- No environmental discharge (no seawater, no emissions)
- Ideal for small-scale LNG (trucking terminals, peak shaving)
Disadvantages:
- Large land requirement (prohibitive for large terminals)
- Climate-dependent: Capacity drops significantly in cold weather
- Icing: Frost/ice buildup on fins reduces efficiency; periodic defrosting needed
- Scaling limitation: Not practical above ~100 MMcf/d due to footprint
Best Applications:
- Small-scale LNG terminals (trucking, satellite stations)
- Peak shaving facilities (seasonal use)
- Remote locations where simplicity valued over efficiency
4. Intermediate Fluid Vaporizer (IFV)
Operating Principle:
- Closed-loop system using propane or glycol as heat transfer fluid
- Intermediate fluid heated by seawater, combustion, or waste heat
- LNG vaporized in separate heat exchanger (no direct contact)
Advantages:
- Prevents LNG contact with seawater (safety/environmental benefit)
- Can use multiple heat sources simultaneously
- Better temperature control than ORV
Disadvantages:
- High CAPEX: Requires additional equipment (pumps, heat exchangers)
- Maintenance: More complex than ORV
- Efficiency loss: Two-stage heat transfer reduces overall efficiency
Import Terminal Operations
Typical Terminal Layout
A modern 7 MTPA (~1,000 MMcf/d) import terminal includes:
- Ship Unloading Berth: Jetty with 4-6 unloading arms (1,200-1,500 m³/h per arm)
- Storage Tanks: 2-4 tanks, each 180,000-200,000 m³ capacity
- Sendout Pumps: High-pressure cryogenic pumps (150-300 bar discharge)
- Vaporizers: 4-8 ORV units + 2-3 SCV (backup/peak)
- Metering & Odorization: Gas quality adjustment and measurement
- Pipeline Connection: High-pressure (50-100 bar) tie-in to transmission grid
Unloading Process
| Phase | Duration | Description |
|---|---|---|
| Berthing & Connection | 2-3 hours | Ship moors; loading arms connected; safety checks |
| Cooldown | 1-2 hours | Pipelines pre-cooled with LNG vapor to prevent thermal shock |
| Cargo Transfer | 10-14 hours | LNG pumped at 8,000-12,000 m³/h (174,000 m³ cargo) |
| Disconnection | 1-2 hours | Arms drained, disconnected; ship prepares to depart |
| Total Port Time | 14-20 hours | Varies by cargo size and terminal efficiency |
BOG Handling at Import Terminals
Boil-off gas generated during unloading and storage must be managed:
- BOG Compressor: Compress BOG to 50-80 bar, inject into sendout pipeline
- Reliquefaction: Some terminals have small reliquefaction units to return BOG to storage
- Flare (Emergency): Burn excess BOG if system capacity exceeded (avoided due to emissions)
Sendout Flexibility
Modern terminals can modulate sendout from 10% to 110% of design capacity:
- Base Load: Continuous sendout at ~70-80% capacity
- Peak Mode: 100-110% during winter demand or pipeline maintenance
- Minimum Sendout: 10-15% to maintain system operability
Cold Energy Recovery
LNG at -162°C contains significant cold energy (~830 kJ/kg) that is typically wasted during regasification. Some terminals capture this for value-added applications:
Cold Energy Applications
| Application | Energy Use | Value | Adoption |
|---|---|---|---|
| Power Generation | Cryogenic turbine (Rankine cycle) | 5-7 kWh/tonne LNG | ~15% of terminals |
| Air Separation | Liquefy air to separate N₂/O₂ | High (co-located with industrial users) | ~5% |
| Cold Storage | Refrigerate warehouses | Medium (logistics hubs) | ~5% |
| Desalination | Freeze desalination process | Medium (water-scarce regions) | <5% |
| CO₂ Capture | Liquefy CO₂ for sequestration | High (with CCS infrastructure) | Pilot stage |
Power Generation Example
Direct Expansion Turbine:
- LNG pumped to high pressure (80-100 bar)
- Expanded through turbine while vaporizing (like steam turbine)
- Generates ~5-7 kWh per tonne LNG
- Economic Value: $0.30-0.50/MMBtu at $0.10/kWh electricity price
Challenge: High CAPEX ($50-100M for 7 MTPA terminal); payback 10-15 years.
Why Cold Recovery Isn't Universal
- Low value: 5-7 kWh/tonne only worth ~$0.50-0.70/tonne
- High CAPEX: Equipment costs $50-150M for large terminal
- Complexity: Adds operational risk and maintenance burden
- Location: Requires nearby customer for cold energy or grid connection for power
Safety Systems
LNG Rollover Prevention
Rollover is rapid vaporization caused by density stratification in storage tanks:
- Cause: Different LNG compositions (e.g., Qatar heavy LNG layered over Australian light LNG)
- Risk: Sudden BOG surge can overpressure tank
- Prevention: Blend incompatible cargoes slowly; use multiple fill points; recirculation pumps
Emergency Shutdown (ESD) Systems
Triple-redundant safety systems at import terminals:
- Level 1: Automated process shutdown (leak detection, overpressure)
- Level 2: Tank isolation (emergency valves close in <30 seconds)
- Level 3: Ship quick-release couplings (vessel can disconnect in emergency)
Fire Protection
- Water Curtains: High-pressure spray to disperse LNG vapor clouds
- Dry Chemical: Powder suppression for confined fires
- Foam Systems: Cover LNG pools to prevent vaporization
Regasification Economics (2026)
Terminal Construction Costs
| Component | Cost (7 MTPA Terminal) | % of Total |
|---|---|---|
| Storage Tanks (3×180,000 m³) | $300-400M | 40-50% |
| Vaporizers & Sendout Equipment | $150-200M | 20-25% |
| Jetty & Unloading Arms | $100-150M | 15-20% |
| Utilities, Piping, Instrumentation | $100-150M | 15-20% |
| Total CAPEX | $650-900M | 100% |
Operating Costs
- Vaporization (ORV): $0.10-0.15/MMBtu
- Vaporization (SCV): $0.30-0.50/MMBtu (fuel cost)
- Labor & Maintenance: $0.05-0.10/MMBtu
- Total Regas Fee: $0.30-0.60/MMBtu (typical terminal tariff)
Comparison: Land-Based vs. FSRU
| Parameter | Land-Based Terminal | FSRU |
|---|---|---|
| CAPEX | $650-900M (7 MTPA) | $200-350M (5 MTPA) |
| Development Time | 4-6 years | 12-18 months |
| Operating Cost | $0.30-0.50/MMBtu | $0.50-0.80/MMBtu (lease + opex) |
| Flexibility | Permanent | Relocatable |
| Capacity | Up to 30+ MTPA | 3-6 MTPA typical |
Key Takeaways
- Regasification requires ~730 kJ/kg heat input, ~100x less energy than liquefaction
- Open Rack Vaporizers (ORV) dominate (55% share) due to zero fuel cost
- Typical terminal: $650-900M CAPEX for 7 MTPA capacity
- Regasification fee: $0.30-0.60/MMBtu (ORV-based terminal)
- Global regasification capacity: ~1,100 MTPA vs. 520 MTPA liquefaction (2026)
- Cold energy recovery adds $0.30-0.50/MMBtu value but high CAPEX
- FSRUs offer 3x faster deployment than land terminals (12-18 months vs. 4-6 years)
- Ship unloading: 14-20 hours for 174,000 m³ cargo