But let’s start with precision. Chemically, LNG is similar to natural gas transported by gas pipelines. Its particularity is that it must be liquefied in order to allow its transport by boats. On arrival, LNG must also be rewarded in order to be injected into the local gas network.
It is these specific LNG operations (liquefaction, transport by Lightners, Regazéification, etc.) that make it more intensive in carbon than gas transported by gas pipelines. But in what proportions? The study of the IAI actually focuses on part of the carbon impact of LNG: the extraction and purification of natural gas; its transport to the liquefaction plant; liquefaction operations; Transport by Lightners; and regzéification in the arrival port.
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The study therefore does not take into account carbon emissions related to transport on the gas network of the country of consumption, nor those linked to the combustion of gas in boilers or factories. But, a priori, these emissions are identical for LNG and classic gas. There is therefore no need to take it into account to compare the carbon impact of the two kinds of gas.
LNG more polluting than conventional gas
What are the results of the study? According to the IAI, LNG production and trade have a 62 % higher carbon impact than natural gas in general. We are 12 grams of CO₂ equivalent (by mega joule) for gas in general, against 19.5 grams for LNG.
In addition, there are enormous differences according to the countries of production. Some LNG exporters from Africa and Southeast Asia are 26 grams, against barely 6 grams for Norway. Note that North America is the third worse student worldwide. The carbon impact of North American LNG is thus greater than that from Russia.
The majority of the carbon impact of LNG (47 %) comes from methane and CO₂ leaks on natural gas extraction sites (but these emissions also exist for gas transported by gas pipelines). Then come the very energy -consuming Liquefaction of LNG (33 %), transport by boats (18 %), and re -arrival on arrival (1 %).
If LNG has a more important carbon impact than conventional gas, the AIE refutes the idea that it is worse than coal. When we take into account the complete life cycle of the two energies (extraction, transport, combustion), the AIE estimates that the carbon impact of LNG is 25 % less than that of coal. And the difference is even 40 %, in favor of LNG, when we talk about electricity production. “”This is explained by the fact that gas power plants are more effective than coal electric power plants “advance the aie.
“However, comparing the LNG with coal amounts to putting the bar too low”adds the IEA. The organization believes that LNG must do much better than a reduction in emissions by 25 % compared to the worst energy that exists.
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The AIE also believes that it is possible to greatly reduce carbon emissions associated with LNG production and trade. By electrifying the liquefaction factories and certain extraction sites close to an electrical network, by attacking methane leaks, and installing CO₂ capture systems on certain extraction sites.
While the LNG sector emits approximately 350 million tonnes of equivalent CO₂ per year, it would be possible to drop to 130 million tonnes (-63 %), according to the IAI. For this, measures must be put in place for an amount of $ 100 billion. But that would be profitable, assures the IAIE.
