Natural Gas and Renewable Methane for Powertrains

As fuels, natural gas (CNG) and renewable methane (biomethane) can make a major contribution towards achieving the Federal Government’s energy and climate change objectives. In a first step, we want to reduce final energy consumption in the transport sector by 10 % by 2020, and we want to do this with the aid of natural gas, among others.

Mobility is an important prerequisite for economic exchange and individual prosperity and good transportation systems fulfil the mobility needs of the population. Not only has the passenger car assumed a dominant role within the domain of private transport, road transport is the mainstay of freight traffic. Motorized traffic, as it exists today, has many negative effects on the environment and also on people: greenhouse gas emissions, air pollution, noise, land consumption and the use of resources for the construction of infrastructure, the vehicles themselves and the fuels (see also [1]). The focus of this contribution lies on the greenhouse gases caused by motorized traffic.

The rise of combustible gases as relevant energy sources began as early as in the “First Industrial Revolution.” At that time it was synthetic city gas that served as the basis for the development of the market in various areas of application and for which the construction of the initially purely city-oriented supply infrastructure was completed. With the discovery of rich natural gas reserves in first half of the 20^th century and the development of a suitable long-distance transport technology, most notably in the form of natural gas pipelines, the rise of natural gas as a high-value fossil fuel began, particularly from the 1930's on. Today it is employed by commercial and private users most notably for heating purposes as well as in gas power plants. Especially in the last three decades natural gas has also begun to play an important role as a fuel for motor vehicles. The following chapter will focus on the history of natural gas in general and on the history of natural gas vehicles in particular.

According to current thinking, natural gas is a fossil energy carrier that, just like oil, underwent organic transformation under high pressure and in the absence of oxygen in the interior of the earth and therefore its composition as a naturally occurring product varies according to its geological source. The main component is always methane, which varies between 75 and 98 %. Other components include nitrogen, ethane and carbon dioxide.

Natural gas vehicles are a mature technology already available today for solving the environmental problems caused by the automobile. The advantage is based on the features of the main fuel content methane. While keeping a minimum fuel quality standard, it is doesn’t matter to the vehicle technology whether the Methane is several million years old or just a few days. There is complete compatibility between fossil and renewable sources for this most simple of all hydrocarbons. Its highest possible ratio between hydrogen and carbon and the resulting features considering production/availability (fossil & renewable), the justifiable effort in the fuel system and the engine and environmental features make methane an ideal vehicle fuel.

Gas engines currently have an extremely diverse range of applications. Off-highway gas engines—i.e. engines that are not intended for road vehicles—are increasingly also being used for applications that just a few years ago were the exclusive preserve of diesel engines.

We have known this statement for so long now that probably no one knows anymore, which inspired person formulated it first. The meaning the statement conveys is that methane, as the main constituent of natural gas, enables a practically completely particulate-free, i. e. “deposit-free” combustion and its high octane rating leads to high knock resistance, which enables high compression ratios and hence high degrees of efficiency.