Natural gas vehicles

In the USA, there is a powerful movement afoot to encourage companies to trade in their diesel-powered big rigs in favour of ‘alternative-fuelled’ vehicles. Natural gas – either compressed natural gas (CNG) or liquefied natural gas (LNG) – is part of the new technology. Several of the major heavy-duty truck builders, including Freightliner, Peterbilt and Volvo, already build heavy-duty trucks that run on natural gas. Federal and state governments are putting up taxpayers’ money to encourage companies to purchase heavy-duty ‘natgas’ trucks.

The sales pitch for natural gas-powered trucks in the USA is that it is clean, cheap, abundant and domestic. CNG is cheap at the present time. In Oklahoma City, you can fill up at a CNG station for the gasoline (petrol) equivalent of $1.50 per gallon (£1.30 per imperial gallon).

Compressed natural gas seems to have the upper hand at present over LNG. There are more CNG filling stations and CNG is easier to pump and store. LNG is a more energy-dense fuel than CNG, meaning your truck can go further on one fill up. LNG is a 260°F liquid, which must be stored in heavily-insulated tanks. A truck filled with LNG without the engine running will vent LNG, ie pure methane, a greenhouse gas that is 24 times worse than carbon dioxide.

Another solution may be on the horizon. A company called Primus Green Energy made an announcement on 2 February 2016 that it has developed a gas-to-liquids technology, STG+TM, that transforms methane and other hydrocarbon gases into 100 octane gasoline (petrol) at its demonstration plant in Hillsborough, New Jersey.

“This accomplishment demonstrates the advantages of Primus technology STG+TM,” said Sam Golan, CEO of Primus Green Energy. “Primus technology can also use a range of natural gas feedstock, including gas that would otherwise be stranded or flared.”

The process starts with natural gas (CH4) and then reforms it with steam (H2O) into a stream of hydrogen and carbon monoxide (H2 + CO2), which are then chemically synthesised into methanol (CH3OH). It is further dehydrated over a catalyst to yield gasoline (petrol).

With the huge amount already invested in petrol-powered cars and the existence of a coast-to-coast network to keep them filled up, it would make sense to integrate natural gas into the existing system rather than create a whole new one for LNG or CNG.

For companies such as ours, which conduct a significant amount of NDT in petroleum refineries, it behooves us to be aware of new and significant technologies that can affect our markets.

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