Every day, liquefied natural gas receiving terminals around the world warm LNG from cryogenic temperatures back into a gaseous form so it can be delivered to homes, power plants, and industrial users. This routine process underpins the global gas supply, yet it also produces a largely overlooked by-product. As LNG is heated, vast amounts of cold energy are released, most often into seawater, where its potential value is discarded. A new study suggests that this “wasted cold” could instead be harnessed to recover valuable hydrocarbons such as ethane and liquefied petroleum gas, delivering both economic and environmental benefits.

The research, carried out by engineers from The University of Western Australia, examines how LNG regasification systems could be redesigned to make productive use of cold energy rather than losing it. The team developed and evaluated three alternative process configurations that integrate hydrocarbon recovery directly into LNG regasification. All of the designs use seawater as the heat source, which is already common practice at LNG terminals, meaning the proposed concepts could potentially be applied without introducing fuel combustion or high-temperature heating utilities.

LNG arrives at import terminals at temperatures close to –160 degrees Celsius, yet, under conventional operation, this extreme cold is neutralised and released with little regard for its value. Lead author Shing Hon Wong explains that this cold energy can instead be exploited to separate ethane and LPG from the LNG stream. These components are often significantly more valuable than natural gas itself, particularly in regions with strong petrochemical industries. Recovering them at the point of regasification could therefore increase the overall value of imported LNG without increasing upstream production.

Ethane and LPG are essential feedstocks for chemical manufacturing and a wide range of industrial applications. In many markets, their prices exceed those of pipeline natural gas, making on-site recovery economically attractive. To test this potential, the researchers used advanced process simulation software to model three system designs and assess their technical performance and profitability. Two of the designs focused on maximising the use of LNG cold energy by re-condensing methane-rich streams, allowing pumps to replace more energy-intensive compressors. The third design operated at lower temperatures to maximise ethane recovery, but required additional compression and higher operating costs.

The results were encouraging across all configurations. Ethane recovery ranged from about 91 to 96 per cent, while LPG recovery exceeded 90 per cent in every case. When economic performance was compared, one design stood out. For a typical LNG receiving terminal processing around 3.15 million tonnes of LNG per year, this configuration was estimated to generate an annual net profit of approximately 97 million US dollars. Further analysis showed that the economics remained robust under a range of LNG compositions, terminal sizes, and market conditions.

In addition to financial gains, the study highlights environmental advantages. Using seawater as the sole heat source avoids direct combustion and reduces associated carbon dioxide emissions. The discharge of cooled seawater is similar to that of existing LNG vaporisation systems and can be managed with standard thermal controls. Although the authors stress that their work is conceptual rather than site-specific, the findings clearly show that cold energy recovery at LNG terminals is an underused opportunity. With the proper process design, LNG regasification can move beyond simple energy loss and become a source of higher-value products and improved efficiency.

More information: Shing-hon Wong et al, A technoeconomic analysis of cryogenic recovery of heavy hydrocarbons from LNG using seawater as the heat source, Energy & Environment Nexus. DOI: 10.48130/een-0025-0013

Journal information: Energy & Environment Nexus Provided by Biochar Editorial Office, Shenyang Agricultural University