Differentiate between LNG and CNG.
CNG (Compressed Natural Gas): Natural gas (primarily methane) stored at high pressure (200-250 bar / 2900-3600 psi) in gaseous state at ambient temperature.
LNG (Liquefied Natural Gas): Natural gas cooled to extremely low temperature (-162°C / -260°F) converting it to liquid form, reducing volume by approximately 600 times.
| Parameter | CNG (Compressed Natural Gas) | LNG (Liquefied Natural Gas) |
|---|---|---|
| Physical State | Gas (compressed) | Liquid (cryogenic) |
| Storage Condition | High pressure: 200-250 bar at ambient temperature | Low temperature: -162°C at atmospheric pressure |
| Volume Reduction | ~1/200 of natural gas volume | ~1/600 of natural gas volume |
| Energy Density | Lower (~9 MJ/liter) | Higher (~22 MJ/liter) |
| Storage Tanks | Heavy, thick-walled steel/composite cylinders | Double-walled insulated cryogenic tanks |
| Production Process | Compression using compressors | Liquefaction requiring cooling plants |
| Infrastructure Cost | Lower (compression stations) | Higher (liquefaction, regasification terminals) |
| Transportation | Pipelines, cascades for short distances | Ships, tankers for long distances; trucks for distribution |
| Primary Applications | Light vehicles (cars, buses, auto-rickshaws) | Heavy vehicles (trucks), ships, industrial use, long-distance trade |
| Vehicle Range | Limited (150-300 km) due to lower energy density | Longer (500-1000 km) due to higher energy density |
| Refueling Time | Fast (3-5 minutes) | Slower (10-15 minutes for trucks) |
| Safety Concerns | High pressure risk; lighter than air (disperses quickly) | Cryogenic burns; boil-off gas management |
| India Infrastructure | 3500+ CNG stations; expanding CGD network | 6 LNG import terminals; limited LNG dispensing stations |
| Application | CNG | LNG |
|---|---|---|
| Cars & Light Vehicles | ✓ Preferred | ✗ Not practical |
| City Buses | ✓ Widely used | ○ Emerging |
| Auto-rickshaws | ✓ Preferred | ✗ Not used |
| Long-haul Trucks | ✗ Limited range | ✓ Preferred |
| Ships/Marine | ✗ Not practical | ✓ Growing rapidly |
| Industrial Use | ○ Limited | ✓ Power, heating |
| International Trade | ✗ Not feasible | ✓ Primary method |
CNG in India: 35+ lakh CNG vehicles; 3,500+ stations; Major cities - Delhi NCR, Mumbai, Gujarat, Pune
LNG in India: 6 import terminals (42.5 MMTPA capacity); Growing LNG trucking pilots; GAIL's LNG distribution network
CNG and LNG are both forms of natural gas but differ fundamentally in their physical state, storage method, and applications. CNG (compressed gas at high pressure) is ideal for light vehicles and urban transport where refueling infrastructure exists. LNG (liquefied at cryogenic temperatures) offers higher energy density, making it suitable for heavy-duty, long-distance transport and international trade. In India's transition to cleaner fuels, CNG dominates urban transport while LNG is emerging for long-haul trucking and as an import fuel to meet growing gas demand. Both play important roles in reducing transport emissions compared to traditional petroleum fuels.