A key pillar of Volkswagen’s drive system strategy is compressed natural gas (CNG) propulsion technology which the company says it is using to shape the transition to sustainable mobility. Signalling its impetus, the German auto manufacturer is presenting an innovative, compact three-cylinder TGI engine for natural gas propulsion for the VW Polo at the 38th Vienna Motor Symposium this week.
Dr Wolfgang Demmelbauer-Ebner, Head of Volkswagen Petrol Engine Development, outlines the subject in his symposium speech as follows: “Due to its chemical composition, natural gas as a fuel already reduces CO2 emissions if it comes from fossil sources. If, however, it is produced in a sustainable way, for instance as biomethane from agricultural waste, then looked at from well-to-wheel it facilitates a form of mobility that produces appreciably less CO2. We use the term e-gas to describe synthetically produced CNG that is made out of water and CO2 from renewable power generation’s excess current. e-gas is ideal for making renewable power usable for the transport sector and for storing it. It is in practical terms a partner in the switch to renewable forms of energy.”
Volkswagen has been represented in the marketplace with CNG engines since 2002. A special feature of the new three-cylinder turbocharged engine with a cubic capacity of 1.0 litre and high torque of 66 kW (90 PS) that is being shown at the Vienna Motor Symposium is its bivalent concept: it can be run on petrol or CNG. In gas-powered mode it works in a particularly low-emission manner – and that applies both to CO2 and NOx particulate emissions. The compact 1.0 TGI is a new engine specification for the small car class in the Volkswagen Group.
A key factor in its low emissions is the optimum conversion of the methane in the exhaust gas. In order to bring the catalytic converter quickly up to operating temperature and keep it there, Volkswagen has developed a lambda split process. During warm running and under low load two cylinders are fired using a rich mixture and one using a lean mixture. An important component of the technology here is the so-called lambda probe with no dew-point end. Thanks to electric heating, it is able to take up its regulating function within no more than ten seconds of a cold start, even if the exhaust gas and exhaust system still contain certain amounts of condensation.
The activities promoting CNG drive systems go well beyond technical solutions. In addition to the Group’s extensive range of models, Volkswagen is also conducting an intensive dialogue with other market participants and political players. In collaboration with energy providers, the gas industry, other OEMs and federal government ministries, the company is driving forward activities that continue to make CNG known and attractive as a fuel.
Volkswagen is thus pursuing every path leading to CO2-neutral mobility. In addition to systematic optimisation of the existing powertrains, alternative forms of drive system are being introduced into the portfolio. Looked at overall, the fuels’ CO2 relevance is a key factor. In this regard, CNG in the form of e-gas is playing an increasingly important role.
(Source: Volkswagen AG)