Dear Editor,
ExxonMobil recently announced that they can supply 50 Million standard cu ft of gas per day
(mmscfd) to Guyana. Of course, the naysayers had a field day claiming that the Government would be forced to enter a take or pay contract which would be detrimental to the country. This was in addition to previous claims that natural gas would be harmful to the environment and it would be better to invest in alternative energy instead of landing the pipeline and using the gas to generating power.
The fact of the matter is that Guyana’s potential gas production of 50 Million standard cu ft of gas per day is miniscule when compared to the 3.110 Billion standard cubic feet per day (Bscf/D) of neighbouring Trinidad and Tobago. To put this in context, Trinidad’s lowest daily natural gas production in 2020 was more than six thousand percent (6,000%) of Guyana’s maximum potential natural gas production. Of course, there is a difference between the gas produced in Trinidad and Guyana. Trinidad produces dry natural gas or non-associated gases which does not require any further processing. In the case of ExxonMobil Guyana, the gasses are produced together with the oil and as such are called associated or wet gas. Dry natural gas is at least 85% methane, while wet natural gas contains methane, but also contains ethane, propane, butane and pentane.
Neither ExxonMobil nor the Government of Guyana has published the composition of the associated gasses which are being produced, as such it is difficult to project how the various gas components can best be used. It is doubtful if it would be economical to process the ethane because of the expected small volume. Propane and butane would be separated as Liquified Petroleum Gases (LPG). Butane is normally present as Normal Butane and Iso Butane. If there is as significant quantity of Iso Butane, it may be economical to recover it for use as a refrigerant (R600a) and also as a propellant for aerosol cans. LPG is mainly used as cooking gas in Guyana. If there is an excess quantity available, it can be used as Autogas, a fuel for internal combustion engines in vehicles – cars, buses, and trucks.
It is today the most accepted alternative fuel in the automotive sector with more than 21 million vehicles operating worldwide. Pentane or natural gasoline can be used to blend ethyl alcohol to make Ethanol fuel (E85). The remaining natural gas can be used to generate cheap electricity, and the excess can be used as feedstock for a small Ammonia plant to produce urea fertilizer for local use. The plant required to separate the 50 mmscfd of associated gases in Guyana would be microscopic compared to the Atlantic LNG plant in Trinidad. It is estimated that the LPG plant in Guyana would require less than 2 MW of power to operate while the four LNG trains in Trinidad are powered by a fleet of 28 GE Frame 5 Gas Turbines rated at 25 MW each for total installed capacity of 700 MW. It is obvious, therefore, that the Guyana LPG plant would have a significantly lower environmental footprint than the Trinidad LNG plant and the concomitant environmental issues would be correspondingly less.
Yours truly,
Tara Singh
