Natural Gas: The Global Underestimated Gold

The last decade witnessed the glory of crude oil: high price and high production. However, it has been postulated that the production of crude oil in the coming fifteen years is going to drop drastically due to reservoirs drain of Middle East producers. Figure 1 illustrates this fact with insight on the future production.

Crude oil is a fossil fuel; it is a major source of pollutants, i.e. COx, NOx, HC…etc., which contributed to climate change problem. From environment point of view, natural gas doesn’t produce smoke when it burns. It is a popular fuel choice because it burns cleaner, hotter, and brighter than coal and oil. British petroleum statistical data for 2009, presented in Figure 2, shows that natural gas represents the third source of global energy after oil and coal. Currently, natural gas is used for industrial purposes, generation of electricity, residential, and transportation.

In the transportation sector, natural gas is used as compressed natural gas (CNG) or liquefied natural gas (LNG). The CNG is the currently used fuel storage technique for natural gas vehicle. In this system, natural gas is compressed at pressure up to (21-25) MPa in order to be stored compactly on-board and dispensed quickly. Figure 3 gives an example how the natural gas fuel system looks like.

However, this storage method requires expensive and heavy high-pressure compression technology in the refuelling stations. Also, there is a perception of damage associated with high pressure system as well as some real potential problems, such as cylinder corrosion and the possible explosive release of compressed gas. The LNG is the conventionally large-scale natural gas storage. In this method, natural gas is cooled to ~109 K (cryogenic temperature). The LNG cooling requirement is an inconvenience to its use as a fuel. The cost of the requirements is such as to make it unsuitable for use on a small scale. These difficulties are the reason behind the limited utilization of natural gas as a potential transportation fuel.

This fact is clearly seen in Figure 4 (from the long-term outlook report of the European union of the natural gas industry EUROGAS, 2007) where the amount of natural gas used in the transportation sector (NGV) is very low compared to other sectors.

When natural gas is charged into a vessel packed with a porous media, i.e, activated carbon, the energy density stored will be greater than that of the same vessel without the porous solid (empty vessel) at the same pressure. Therefore, the amount of natural gas that can be stored is 2/3 (67%) of the amount that could be stored with an empty vessel (CNG system) but at 1/6 of its pressure. The giant vehicle manufacturer FORD has produced a light truck using this technology. For passenger service, the natural gas vehicle should have a 400 mile driving range and its fuel storage system should cost about US$2000-3000 per vehicle. According to them, vehicles running on natural gas using this technology are slightly more expensive than vehicles with the conventional petrol fuel system.

This technology is a promising option to move away from our strong dependence on oil, and use the huge reservoirs of natural gas that have not been fully utilized yet. Although this technology has been known for over two decades by now, the progress is hindered by the limited attempts to engage this fuel system in vehicles and subject them to real driving tests under real conditions. It is more obvious than ever before that it is time to secure energy sources for of the near future. Natural gas could be of greater help and benefit than just being used for heating and cooking…! Don’t you agree?

 

 

To cite this article, please use following information:

(use the given format or any standard citation format)

Ridha, F., Natural Gas: The Global Underestimated Gold, ChE Thoughts 2 (1), 12-13, 2011.

 

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