This project deals with R&D for compressed natural gas (CNG) and biogas vehicles. CNG and biogas (upgraded to CNG equivalent quality) consist mainly of methane. Therefore, the terminology "methane vehicles" will be used in the subsequent text for these vehicles. Methane vehicles have the potential to reduce the local traffic based air pollution problems (ozone, NO2, particulate matter) as well as the greenhouse gas emissions (CO2-equivalent) significantly. The use of methane as motor vehicle fuel assists the effort for a diversification of the transport fuel market (that has today an 98% crude oil dependency) and allows the usage of preprocessed biogenic methane, produced waste (organic waste, sewage sludge, liquid manure, unburned wood).To use this potential, the methane vehicle technolgoy needs to be improved.

The traditional gasoline-to-CNG-coversion technology was often disapointing regarding reliability, efficiency, costs, functions and so on. Due to the development of methane-powered vehicles by the automotive industry, a strong improvement was initiated. Besides engine optimization, the main R&D aspects for methane vehicles are the optimization of the catalytic converter's methane conversion ability with (cost driven) low loading of platin group metals (PGM) and the simultaneous improvment in durability.

As methane is a potent greenhouse gas, the technology to assure methane emissions near zero is not only important to fulfill the demanding hydrocarbon emission limits given by the emission legislation but it is also crucial for the superb overall ecological performance of methane vehicles.

In the first phase, the actual project included the evaluation of the catalytic converter specification on the dynamic engine dynamometer (Fig. 1 and 2). Thereby, fresh and aged catalytic converters were systematically investigated and evaluated regarding their conversion efficiency and their dynamic oxygen storage and oxygen release behaviour. With the knowledge this first phase, technical specifications for optimized catalytic converters were eleborated and prototypes of such catalytic converters were produced.

In the second phase, three prototype vehicles for field testing were equipped with these optimized catalytic converters. The vehicles were (and still are) operated in cooperation with Novatlantis, a sustainability network in the ETH-domain, in the so called "Pilotregion Basel" at different administration offices and companies. The emission behavior of the vehicles is monitored every 5'000 km for emissions stability in the official European driving cycle as well as in the real world driving cycle CADC on a chassis dynamometer (Fig. 3). The surface of the catalytic converters is analysed regarding poisoning, sintering and phase transformation after the field testing for further improvements.

Results:The conversion efficiency of the catalytic converters could be increased while the coating with PGM elements could be significantly reduced (reduced costs) and the emission stability was strongly improved (no deterioration visible until the actual mileage of 20'000 km). Conventional high-PGM technologies showed a clear worsening of emissions within this mileage.

The necessarily high methane conversion ability of catalytic converters for methane vehicles was typically achieved yet by increased coating with PGM elements. This, however, is very costly, a waste of limited resources and was possibly one reason for the bad emission stability due to PGM particle size gowing on the surface of the catalytic converters.The improvement of the conversion efficiency and emission stability of catalytic converters for natural gas vehicles at lower costs is one main result, which improved also the acceptance of decision makers of the automotive industry, because the compliance with emission standards (including durability requirements) is crucial.

Individuals
Individuals, driving natural gas vehicles equipped with this catalytic converters benefit an improved emissions stability and reduced system costs.SocietySociety benefits an enhanced use of methane vehicles by a fuel prize stabilization as a result of a the fuel market diversification.Economy
Economy benefits stabilized transportation fuel prize and the access to vehicles with significantly reduced CO2 emissions, which is an important competion criteria for tenders. Furthermore, the local production of purified biogas out of organic waste, sewage sludge, liquid manure, unused wood creates an added value. EnvironmentThe environment benefits durably verly low exhaust pollutants of methane vehicles equipped with this technology, less use of PGM elements and the reduced greenhouse gas (CO2, methane) emissions.

The project was performed in close cooperation between Empa (research institution), Volkswagen AG and Umicore AG (industry), Novatlantis (sustainability network in the ETH domain) and the partner (administraion offices, natural gas supplier) in the "Pilotregion Basel" (field testing) and the Swiss federal office for energy (funding).This project layout with the integration of all relevant stakeholders (industry, enduser, authority, politians, fuel supplier, research institution) allows to consider the different requirements for the development of a technology with a high potential for an implementation in mass production.

Supporting the greening of the individual mobility by reducing the emissions and the use of biofuels as well as the reduction of the crude oil dependecy are main drivers for the implementation of natural gas vehicles.The impact of the nominees on individuals comprises the support for the evaluation of suited vehicle concepts with "real world" data and experience and, at the end, to make clean technology at affordable costs available to customers. The impact of the nominees on the society is given by several communication actions (including a TV and a radio broadcast), where information about the advance in advanced methane vehicle technology was given.The impact of the nominees on the economy is given due to the participation of the industry in the projects which is interested in selling cost-efficient technologies to customers.The impact of the nominees on the environment is based on the teardown of one barrier for alternative fueled clean vehicle technology at affordable costs. CNG vehciles have a CO2 advantage (compared with gasoline) of about 25% bececause of the low carbon content of methane. If biogas is used, the carbon cycle is completely closed. Biogas is the regenerative fuel with the best production efficiency of all biogenic fuels. Additionally, it does not compete with the production of human food products. Supporting this technology can lead to important CO2 reductions in the individual mobility sector.

The main advantage of the project is the technological step on catalytic converters for natural gas vehicles with the described impact.

Methane vehicles are broadly accepted as an important piece of a puzzle for cleaner transport. In many countries, CNG and biogas vehicles are part of actual visions for a cleaner transports and such vehicles are supported in different ways. The political will to support this technology exists widely but the technical barriers (durability, limited range, dedicated engine technology), the psychological barriers (gaseous fuel) and the economical barriers (higher costs) have to be lowered. This project lowered an important technical barrier (other technical barriers were lowered by the project team in an award-winning predecessor-project* and will be lowered in future projects). The advantages of methane-based mobility for certain application was and is communicated by the project partners using several communication channels to stakeholders, to political and industrial decision-makers and to the public.

* Clean Engine Vehicle Project: a common project of Empa and ETH with Volkswagen and Bosch. The project won in October 2006 the "Innovation Price of the German Gas Industry".