The proposal of AEGPL aims to introduce modifications to bi-fuel vehicle definitions in order to permit the simultaneous use of gas and petrol in the gas mode:

• • To avoid over-use of petrol, provisions are provided to limit its use in duration (60 seconds maximum in starting-up) and/or amount (minimum limit to gas energy ratio);
• • A calculation method for gas energy ratio is provided basing on the conservative assumption that only gas is burned during the driving cycle (see GFV-16-02 for technical details); this assumption is in line with the present requirements for fuel consumption (FC) as well as for pollutant emissions, even if a certain use of petrol is already allowed (max 60 seconds over the cycle);
• • As for pollutants, no adaptation of correction factors are needed just in force of the conservative hypothesis that the test cycle is driven only on gas; the errors committed are also negligible (see GFV-16-02 for technical details).

TNO believes that the combined application of a maximum timeframe for starting-up the engine and a minimum limit to the gas energy ratio over the cycle is clearer and more stringent, closing the loopholes that the present regulations offers when setting only a time limit.

During the discussion it is highlighted that, according to the proposals, the requirement on the gas energy ratio would be applied to all the system types, so even to those that do notneed to use petrol beyond the start-up phase: the addition of a safeclause derogating such systems is evaluated;

With regard to the involvement of NG vehicles in the proposed adaptation of the two regulations, it is noted that also NG bi-fuel vehicles – factory built or retrofit – basically equipped with a direct injection petrol engine requires the use of a gas system capable to keep the petrol injectors cool, as with the LPG systems. The result can be achieved either by NG direct injection with the same petrol injectors (LNG direct injection is under development) or managing a limited use of petrol in the gas mode under certain circumstances, i.e. the solution in question;

Question for GFV: Do we have a positive feeling about the proposal to make it an informal document for the next GRPE or as a second option, to make it a formal document for the GRPE in June.

After discussion about the procedural aspects of introducing this new approach advocated by AEGPL and having been considered in-depth by the GFV, it is decided that the document will be presented as a GFV informal document in the next GRPE. It is intended, therefore, to involve more input from others not participating in the GFV directly and attempt to explain the new approaches to achieve support for it. The informal document should be provided to the GFV in the next weeks for final approval; Mr. Rijnders will send it to the GRPE secretariat to submit to the GRPE January meeting.

Mr Rijnders indicated that the documents GRPE 63-5 (R.83) and 63-06 (R.115) are informal documents for this GRPE.

Mr. Piccolo indicated that the group decided to look at a re-definition of bi-fuel vehicles to include new technologies making a more intensive use of gasoline in gaseous fuel vehicles, instead of providing ad-hoc provisions for gas systems intended to be fitted on direct injection petrol engines, in retrofit or new applications.

A common requirement for all types of systems has been defined: the use of petrol simultaneously with gas during the Type I test cycle is permitted provided that the energy consumption of the gaseous fuel is higher than 80% of the total amount of energy consumed during the test.

A gas energy ratio has been preferred to a petrol one since gas consumption measurement has been considered easier and more accurate.

Mr. Rijnders indicated that the proposals were agreed in the last GFV meeting but ask again if there are additional comments. Mr. Tappe (CLEPA/Bosch) notes that the present paragraph 3.2.5. of Annex 12 permits, within the maximum time frame of 60secs, the use of petrol during the entire test, while the proposed amendments would allow the use of pure petrol exclusively in the start-up phase;

Mr. Tappe pointed out that there are systems using the 60 seconds of petrol split over the cycle and not necessarily only in the starting phase.

He proposes to re-extend this possibility also to the rest of the driving cycle, adding the wording “only or” in the paragraph 3.2.5 of Annex 12 just after the first part of the sentence: “Without prejudice to paragraph 6.4.1.3. of Annex 4a, during the Type I test it is permissible to use petrol….”.

TUV remarks that recalculation of dilution factors might be needed because they do not take into consideration the use of different fuels.

Mr. Rijnders indicated that presently recalculation the use of petrol up to 60 seconds is not considered because the effect is negligible. Only for simultaneous use of the fuels is a recalculation is introduced. The dilution factors as well as fuel density of gas only are used in the calculations of the final emissions in gram/km, since these represent the “worst case” conditions. This basic assumption generates emission values (g/km) higher than those that would be generated by weighted factors and a mean density.

Mr. Piccolo brings forth document GFV-16-02, where there are detailed explanations on why the present calculation procedures of emissions, based only on gas parameters are not affected by the proposed amendments and do not need to be adapted.

Oliver Eberhardt (BMU, Germany) asked why extend the possibility to increase the use of petrol.

Mr. Rijnders explained the technical reason: in the gas mode, petrol injectors placed directly in the combustion chamber (direct injection) could be over-heated if not cooled by the passage of some petrol.

Mr. Erario asked if there will be an amendment from CLEPA because he is concerned there already is a document on the table for GRPE.

Mr. Rijnders indicates that if this point should be agreed here, it can be included in the informal document as proposed by GFV. Otherwise it would have to be included as an amendment from CLEPA.

It is decided that CLEPA and AEGPL will work together to create amended language that will be included in the GRPE document as a GFV ‘amendment’.