Mobility Solutions

Gas-powered cars: CNG is not LPG The operating costs, service station networks, and conversion
costs for compressed natural gas and liquefied petroleum gas

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  • July 29, 2014
  • Mobility Solutions
  • Press releases

press release

What are the advantages of gas-powered vehicles?
Both CNG and LPG powertrain systems are cheaper and more eco-friendly in cars than diesel or gasoline systems. Their combustion is comparably cleaner, reducing emissions of particulates and nitrogen oxides. Both fuels are also cheaper than gasoline or diesel. Thanks to low production costs and tax incentives, compressed natural gas (CNG) costs drivers up to 50 percent less. However, gas-powered vehicles are a little more expensive to buy than gasoline-powered ones, because they are generally equipped with two fuel systems (gasoline and CNG/LPG). More and more automakers are offering CNG vehicles ex works, with the difference in price comparable to that between diesel and gasoline variants. In Germany, CNG powertrains in passenger cars pay off as soon as annual mileage exceeds 7,000 kilometers. Compared with a conventional gasoline engine, a gas-powered vehicle generating the same power will emit 25 percent less CO2. This is due to the chemical properties of this fuel source. The CO2 savings offered by liquefied petroleum gas (LPG) are somewhat lower – but then it is somewhat cheaper to convert a vehicle to LPG than it is to buy a CNG system ex works.

Quotation: “Naturalgas systems already have the potential to reduce CO2 emissions at little extra cost. Technologically, this is an area in which Bosch components lead the way. However, CNG-powered vehicles will become more popular in the market only if the infrastructure is significantly expanded.” (Dr. Volkmar Denner, chairman of the board of management of Robert Bosch GmbH, responsible for research and development)

LPG or CNG – which fuel is cheaper?
In Germany, both fuels enjoy tax incentives, which will last until 2018. On the sign outside a service station, LPG can often seem cheaper than CNG. But that is only half the story. CNG, a gas, is priced in kilograms, while LPG, a liquid, is priced in liters. “If all you go on is the prices advertised at service stations, then you’re comparing apples with oranges,” says Heiko Kaiser, a gas systems expert at Bosch. After all, one kilogram of CNG contains the same energy as around two liters of LPG. Expressed another way, it is around a third cheaper to obtain one kilowatt-hour of energy from CNG than it is from LPG.

Is it better to convert or buy ex works?
While a number of automakers are now offering CNG systems ex works, LPG systems often still come as retrofit solutions. This involves taking the vehicle to a workshop and having it fitted with a second fuel system. Since these retrofit systems generally offer nothing like the quality or durability of an OEM system, additional costs and visits to the workshop are almost guaranteed. It’s a different story with CNG cars, since these systems are almost always integrated into the vehicle ex works. The Volkswagen Group, Fiat, and Opel, for instance, all offer new vehicles fitted with Bosch CNG systems. These vehicles leave the same impression of quality and longevity as comparable variants equipped with gasoline systems. They can switch back and forth between CNG and gasoline whenever necessary, without the driver noticing. The Bosch system can start on CNG even when it is cold, which means that customers can practically always drive on the more cheaply priced CNG. Other systems have to use expensive gasoline to warm up in the start-up phase.

Where can I fill up on LPG and CNG?
Currently, the LPG network in Germany stretches to some 6,500 service stations. CNG service stations are also becoming more widespread; there are already around 1,000 of them. What’s more, virtually all vehicles fitted with a CNG system ex works also feature a small reserve tank for gasoline. “The gasoline reserve tank guarantees mobility even if there is no CNG service station nearby,” says Heiko Kaiser. Apps and navigation systems can also help locate the nearest service station.

CNG or LPG – what’s the difference?
Compressed natural gas – CNG for short – is made up of molecules of CH4. This combination of one carbon atom with four hydrogen atoms carries a lot of energy. Natural gas is also used in heating systems and in gas ranges. Liquefied petroleum gas – LPG for short – is a mixture of propane (C3H8), propylene (C3H6), butane (C4H10), and butylene (C4H8). This is the mixture often found in camping stoves. LPG’s exact composition varies from region to region. In Germany, for instance, LPG is largely made up of propane and propylene. In France, however, it is largely made up of butane and butylene. It is the composition of a given blend of LPG that determines its antiknock quality and the rate at which fuel is consumed. For instance, LPG rich in butane carries a lot more energy than LPG rich in propane. In winter, drivers of LPG vehicles must be sure to fill up with what is known as “winter gas,” which contains a higher proportion of propane, since it is much more difficult to vaporize butane in the cold.

Video animation:
CNG powertrains

Mobility Solutions is the largest Bosch Group business sector. In 2015, its sales came to 41.7 billion euros, or 59 percent of total group sales. This makes the Bosch Group one of the leading automotive suppliers. The Mobility Solutions business sector combines the group’s expertise in three mobility domains – automation, electrification, and connectivity – and offers its customers integrated mobility solutions. Its main areas of activity are injection technology and powertrain peripherals for internal-combustion engines, diverse solutions for powertrain electrification, vehicle safety systems, driver-assistance and automated functions, technology for user-friendly infotainment as well as vehicle-to-vehicle and vehicle-to-infrastructure communication, repair-shop concepts, and technology and services for the automotive aftermarket. Bosch is synonymous with important automotive innovations, such as electronic engine management, the ESP anti-skid system, and common-rail diesel technology.

The Bosch Group is a leading global supplier of technology and services. It employs roughly 375,000 associates worldwide (as of December 31, 2015). The company generated sales of 70.6 billion euros in 2015. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers some 150 countries. The basis for the company’s future growth is its innovative strength. Bosch employs 55,800 associates in research and development at 118 locations across the globe. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.”

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PI8649 - July 29, 2014

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