Energy 2030

Organizing Committee

Final Program

Poster Exhibition Venue 2006 Proceedings


Proceedings of the Second International Energy 2030 Conference,
November 4-5, 2008, Abu Dhabi, U.A.E.

Comparison of Engine Performance and Pollutant Emissions from Gasoline vs. Natural Gas Driven Vehicles

Mohamed Sassi

The Petroleum Institute, UAE

Sai Fok

The Petroleum Institute, UAE

Isoroku Kuobo

The Petroleum Institute, UAE

Transportation is a major contributor to air pollution. After World War II, people became aware that the exhaust emissions from vehicles can be a major cause for the increasing air pollution in congested cities. The exhaust emissions from diesel and gasoline vehicles mainly contain unburned hydrocarbons (HC), carbon monoxide (CO), Carbon dioxide (CO2), oxides of nitrogen (NOx), and a large amount of particulate matters. These gases are the main causes of the greenhouse effect and acid rain. Many illnesses had been reportedly found to be related to these pollutants.

The deterioration of the air quality and the effect of global warming had encouraged many researchers to search for “cleaner” alternative fuels. The results of many of these researches had indicated that natural gas is a “cleaner” fuel for vehicles compared with the gasoline or diesel. Natural gas is a form of petroleum produced by chemical reactions of the buried remains of organic material from earlier ages. The main constituents are a mixture of propane, butane, and methane. It is colorless, odorless and non toxic. Table 1 summarizes a general comparison of pollutant emissions from natural gas, gasoline and diesel vehicles. In general, natural gas vehicle can reduce NOx emissions by about 80% compared to gasoline and diesel vehicles. The exact emission reduction will depend on the vehicle, its state and the operating conditions.

Although natural gas is considered to be an environmental friendly fuel and has been used in some vehicles in many countries for quite some time, the commercial application of natural gas for transportation purposes is still not wide-spread. The reasons for this lack of popularity can be attributed to many factors. First, the global network for the logistic distribution of conventional fuel such as gasoline and diesel has been well established. On the other hand, there are very few refueling stations for natural gas vehicles in many countries. The lack of refueling facilities has hindered the utilization of natural gas in vehicles. Second, dominant vehicle manufacturers have been looking into the issue of alternative fueled vehicle but their current focus is still on the mass production of conventional fueled models. As a result, the evolution of natural gas vehicles is heavily dependent on retrofitting kits [1]. The lack of readily available off-the-show room models of natural gas automobiles has limited the consumer interests in this fossil fuel.

Although these two historical factors had hindered the demand for natural gas, there are strong indications that this will change in the near future. In recent years there is a growing concern on the increasing price of crude oil. This economical factor, together with the worsening environmental issues due to global warming and the increasing health problems associated with air pollution, has resulted in the growing importance of natural gas as an emerging energy resource. Economically, the natural gas market is also more stable than the oil market. The current price of natural gas is about half the price of crude oil. The reason for this economic stability is that the estimated world reservoirs for natural gas are much bigger than for oil.

The UAE government is well aware of the growing global importance of natural gas and the potential benefits in terms of environmental issues. In 2005, the UAE president had directed the Abu Dhabi National Oil Company to execute the natural gas vehicle project due to its importance in providing a safe and clean environment. It is targeted that natural gas would account for 20% of Abu Dhabi total fuel consumption by 2012. To realize this plan, the government in Abu Dhabi had prepared a strategy with the help of the concerned establishments, which include the environmental agency, the Federal Environmental Agency (FEA), ADNOC (Abu Dhabi National Oil Company), Abu Dhabi police, etc. One of the initial tasks in this strategy involved the changeover of Abu Dhabi entire taxis fleet to natural gas and to refurbish


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