Propane the 'clean' fuel of the next century for light and heavy duty vehicles

Excise and other duty measures in Europe threaten to affect the low price of LPG as a car fuel. As a result this less polluting fuel would lose position. For this reason the Dutch LPG industry commissioned TNO to undertake a study which would clearly demonstrate the advantages of gaseous fuels. Since 1995 it seems that the LPG industry is successful in her lobby to convince the Dutch government to take LPG on as a serious automotive fuel. From an environmental point of view this lobby could be strongly supported by the latest LPG research carried out by two OEM's together with the Dutch LPG industry and TNO. Therefore two projects were carried out in the Netherlands which clearly demonstrated the advantages of LPG as an automotive fuel. One of the projects focused on the use of LPG in a Light Duty Vehicle and the other one on the use of LPG in a Heavy Duty Vehicle. The first project, commissioned by the Netherlands LPG Industry, was carried out by TNO in close cooperation with the car manufacturer Fiat. The study focused on a modern family car (Fiat Tempra 2.01) with an engine with standard compression ratio. The vehicle was equipped with a multipoint drygas LPG injection system. The paper reviews the best possible engine tuning in terms of efficiency and emissions with the target to meet 50% below the European emission legislation for 1996. Besides, a comparison of exhaust emissions, regulated and non-regulated components, for petrol as well as LPG, was made. This project was funded by the Dutch LPG industry. Fiat and the governmental agency NOVEM. In the second project a prototype heavy duty LPG vehicle was developed. With the current new heavy duty diesel engine technology it is possible to meet the proposed European 13 mode emission level of 1999. When a heavy duty diesel engine is converted to an Otto engine running on LPG these emission levels can be easily met. The extremely low emission levels currently alreadv available with such LPG engines in combination with a three-way catalyst are far from being achieved with the diesel engine. This fact, combined with the ever growing demand in particular from towns and cities for clean and silent public transport, led DAF together with Gentec to develop a horizontal LPG/CNG bus engine. The first step of this project described in this paper is the development of a bus engine on LPG. This project was sponsored by the Dutch Ministry of Transport in the framework of the governmental program Silent, Clean and Efficient.