Within the LNG distribution chain, one challenge is nearly impossible to avoid: Boil-Off Gas (BOG). Even though LNG is transported in tanks at around −162°C, evaporation can still occur.
At first glance, this might seem like a weakness in the LNG storage and transportation process, but with the right management strategies, BOG can actually be transformed into a profitable opportunity.
What Is Boil-Off Gas (BOG)?
Boil-Off Gas (BOG) refers to a small portion of Liquefied Natural Gas (LNG) that evaporates into gas form as it absorbs heat during various handling stages, including:
- Loading
- Storage
- Transportation
- Unloading
In simple terms, BOG is the vapor generated from LNG evaporation.
The formation of BOG is primarily driven by three factors:
- Heat ingress through the tank walls
- Rising gas pressure inside the tank
- Liquid agitation during marine transport
As BOG accumulates, tank pressure increases, so it must be controlled to remain within safe limits.
In operational practice, BOG is not always vented or wasted. It is commonly reused as fuel for ship engines or reliquefied back into LNG to maintain energy efficiency.
Read More: Does FSRU Make LNG Cheaper: Fact or Myth?
What Are the Risks of Poor BOG Management?
If BOG is not handled with proper systems, the resulting risks can span multiple dimensions.
Economic and Commercial Losses
Every cubic meter of evaporated LNG represents lost cargo, and in global markets, that loss translates directly into financial value.
When BOG is vented into the atmosphere, shipping or terminal operators lose product volume that could have otherwise been sold.
If large-scale evaporation occurs across the entire supply chain, from liquefaction facilities to LNG carriers and regasification terminals, the potential economic losses can reach millions of dollars annually.
Read More: Are LNG Terminals No Longer Efficient? Here Are the Facts
Environmental and Safety Hazards
When Boil-Off Gas (BOG) is not properly managed, it accumulates and increases pressure within cryogenic tanks.
If this excess pressure is not controlled, it can damage the tank, cause safety valve failures, or even trigger explosions that endanger personnel and surrounding facilities.
BOG also poses significant environmental risks. Because it is primarily composed of methane (CH₄), uncontrolled release of BOG into the atmosphere contributes heavily to climate change.
Read More: 5 Advantages of Floating LNG You Won’t Find in Onshore Terminals
Strategies to Make Boil-Off Gas More Beneficial
Turning BOG from a liability into a valuable resource requires smart and effective management strategies. Below are several practical solutions:
Re-Liquefaction (Turning Gas Back into LNG)
Re-Liquefaction technology is designed to recover evaporated LNG that has turned into Boil-Off Gas.
The goal is to capture most of the BOG and convert it back to liquid form. The recovered LNG is then returned to the main storage tank.
This system drastically reduces LNG losses, preserves product value, and minimizes methane emissions to the atmosphere.
Read More: 5 Key Roles of Small-Scale LNG
Utilization as Fuel
Boil-Off Gas can also be used as an energy source for operational needs, both at terminals and aboard LNG carriers.
Compressed BOG can be directed to the ship’s engine system to serve as the primary fuel, replacing conventional oil-based fuels.
This approach enhances operational cost efficiency by utilizing what would otherwise be wasted gas, while simultaneously reducing the need for additional fuel.
Read More: Understanding LNG Hub, The Infrastructure Backbone of Gas Distribution
Integration with Gas Networks
Integrating BOG into existing gas infrastructure is another effective way to transform it into a regional energy asset.
Instead of venting or using it only locally, compressed and purified BOG can be injected directly into onshore gas pipeline systems.
This practice is common in regasification terminals, where BOG is fed into city or industrial gas distribution networks, supporting supply continuity and operational efficiency.
Through these strategies, BOG, once considered a byproduct, is now evolving into a stable, reliable, and strategically valuable supplemental energy source for local markets.
References:
- EJP. Accessed 2025. Modelling of Boil-Off Gas in LNG Tanks: A Case Study
- Timera Energy. Accessed 2025. Getting to Grips with LNG Shipping Costs
- Howarth and Marino Lab. Accessed 2025. The Greenhouse Gas Footprint of Liquified Natural Gas (LNG) Exported from the United States
- ENTSOG. Accessed 2025. Gas Quality Monitoring Report
