Eco-Friendly Advancements in Foam Insulation: Embracing HFO Gas for Sustainable Solutions
Foam insulation has played a crucial role in the transportation and storage of liquefied natural gas (LNG) for the past three decades. Among the leading innovators in this field is GTT, whose technologies have continuously evolved to ensure optimal conditions for LNG containment. In recent years, GTT has further embraced environmentally-friendly practices by transitioning to low Global Warming Potential (GWP) foam insulation.
For three decades, GTT has continuously evolved its technologies to optimize LNG containment conditions. Reinforced Polyurethane Foam (R-PUF) remains a key factor in this success due to its low thermal conductivity and cost-effectiveness. Specifically, it allows the Mark III, NO96 and future NEXT1 technologies to limit the passive boil-off rate of LNG at -163°C. R-PUF production is well mastered by GTT's approved suppliers, and has been historically located near shipyards in South Korea and China.
To give an idea of the order of magnitude, around 28,000 m2 of insulation surface area are required for the four tanks of a 174,000 m3 LNG Carrier. In this scenario, GTT's Mark III Flex+ technology, with a 480 mm thick insulation, generally requires a net volume of R-PUF of around 13,500m3. To produce R-PUF with a typical density of around 130 kg/m3, approximately 5 kg of blowing agent is needed per cubic meter. This means that for a ship that requires around 13,500 m3 of R-PUF, over 75 tonnes of blowing agent would be needed.
The blowing agent allows the liquid polyurethane to foam and expand during a cross-linking chemical reaction, resulting in a lightweight cellular material with small gas-filled cavities. Traditionally, hydrofluorocarbons (HFCs) have been used as the blowing agent, as they are highly effective at foaming. To enhance the thermal insulation properties and reinforcement, around 10% glass fibre is incorporated into the polyurethane foam in the form of continuous filament mat layers. The addition of this glass fibre is essential, as it allows the R-PUF to withstand the considerable thermal gradient of over 180°C that exists between the extremely cold LNG cargo at -163°C and the warmer vessel surfaces.
Acknowledging regulatory efforts to curb high-GWP refrigerants, GTT is proactively seeking lower-emission blowing agent alternatives to future-proof its industry-leading insulation technologies in the face of increasingly stringent climate policies while, at the same time, maintaining optimal LNG cargo performance.
Like all gases, blowing agents are refrigerant gases characterized by coefficients indicating their impact on the ozone layer and on global warming.
GTT has been diligently complying to regulations and proactively anticipating industry changes for several years. For over 30 years, GTT has been constantly improving mechanical, thermal and environmental performance. Until today, all GTT technologies delivered use foam with a blowing agent with an Ozone Depletion Potential (ODP) of 0. However, starting 1 July 2024, GTT will only approve R-PUF with blowing agents that have a very low global warming potential - at least 800 times lower than the majority of blowing agents used today.
The first low-GWP foam to receive approval in 2016 used a Hydro Fluor-Olefins (HFO) blowing agent with an OPD of 0 and a global warming potential of 1. The transition to low GWP R-PUF gained significant momentum in 2019 with the production of the first HFO foam for a Floating Storage Regasification Unit. This pioneering foam leveraged a blend of HFO and CO2 in a 40/60% ratio, maintaining the same ODP and GWP standards. Thus, the use of HFO emerged at the time as a more sustainable solution for reinforcing polyurethane foam. In comparison, according to a reference from the Intergovernmental Panel on Climate Change, the global warming potential of HFCs in use is 858.
In 2020, GTT achieved another milestone with the production of the first low-GWP R-PUF designed for land storage. Notably, this foam relies on pure HFO, demonstrating GTT's dedication in pushing the boundaries of environmentally friendly insulation solutions.
Last but not least, the production facilities of GTT's approved R-PUF suppliers are well-equipped for the utilization of HFO. This strategic alignment ensures seamless integration into the manufacturing process.
Understanding the key factor of thermal conductivity in insulation performance, GTT recognizes that the thermal conductivity of R-PUF is intrinsically tied to the gas present in the closed cells. In pursuit of optimal thermal performance, GTT emphasizes the utilization of HFO over CO2, given HFO's superior thermal conductivity. This strategic approach aligns with the company's dedication to maximizing efficiency in LNG transportation and storage.
GTT will officially inform its suppliers and future suppliers, specifying the details of GTT's decision to qualify only low-GWP foams from July 1st, 2024. They have already been made aware of this and they are focusing their development towards this type of blowing agent.
