FAQ
1. What gaseous fuels are used as vehicle propellant?
In the past, town gas, methane (fire damp, sewage gas, natural gas), wood gas and other gases (blast furnace gas, acetylene) have been used. The most widespread gaseous fuels at present are liquefied petroleum gas (LPG), compressed natural gas (CNG) and, to a lesser extent, liquefied natural gas (LNG) and biogas. In the longer term (2015-2020) there are plans to use hydrogen, both compressed GH2 and liquefied LH2, perhaps as fuel for fuel cells.2. What do the abbreviations CNG, LNG, LPG, and NGV stand for?
| CNG | compressed natural gas |
| LNG | liquefied natural gas |
| LPG | liquefied petroleum gas |
| NGV | natural gas vehicles |
3. What are the main benefits of natural gas as vehicle fuel?
Ecological benefits
Natural gas vehicles produce a much lower quantity of harmful substances. Today this applies to the emission limits of monitored harmful substances – nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), and carcinogenic substances – polyaromatic hydrocarbons, aldehydes, and aromatics, including benzene. With natural gas vehicles, there is not such an impact on the greenhouse effect compared to petrol or diesel.
When you refuel your vehicle with gas, as opposed to liquid fuels, the soil cannot be contaminated.
Economic advantages
These days natural gas is the most advantageous fuel. The current prices of compressed natural gas are about CZK 15 per m3, which is roughly half the price of petrol.
Operational advantages
The better blending of the gas with air allows for the more even filling of the cylinders and thus there is less engine stress. The high octane number of natural gas (130) means that the engine will work even in areas where there is significant fuel mixture deprivation, and resilience to engine knocking is increased.
With dual-fuel systems, the overall of vehicles is enhanced.
Greater safety
Motorists need not fear for their safety in the event of an accident, because the method used to store CNG on board the vehicle and the
properties of CNG make it the safest fuel for the propulsion of vehicles. Natural gas freely disperses; it is lighter than air and has a
high ignition temperature. The need to store it under high pressure means that it is kept in thick-walled pressure vessels which are firm
enough to withstand several times the pressure; the tanks are resilient to impact in the event of an accident. If the gas pipe is interrupted,
the tanks are protected with safety valves that close the tanks, preventing the natural gas from leaking and causing an explosive atmosphere.
If the vehicle catches fire, a tank fuse ensures that the gas is discharged and burned gradually, thus preventing an explosion.
Simple distribution of gas to the user.
Natural gas is distributed through existing gas lines, the use of which reduces the number of liquid-fuel tankers on the roads.
Greater prospects
Natural gas reserves have more than double the life of oil, which is used to make petrol, diesel and liquefied petroleum gas.
4. Will natural gas (CNG) become more expensive in the future?
The price of natural gas is derived from the price of oil, or oil products, and therefore a sustained difference can be expected between the base price (the price net of tax) of petrol and diesel on the one hand and natural gas (CNG) on the other. The prices of both commodities are interconnected; they fall and rise almost concurrently, although natural gas prices go up after a slight delay due to purchase contracts in place.
5. Will the government raise taxes on gas used for transport purposes?
Under Government Resolution No 563 of 11 May 2005, the government undertook, up to 2020, to stabilize low excise duty on natural gas used in transport (currently CZK 3.355 per kg, i.e. CZK 2.35 per m3) at the minimum level appointed by the EU.
Excise duty on refinery fuel (petrol, diesel) will rise in the future in accordance with EU proposals.
Under the ecological tax reform now being prepared, as of 1 January 2008 non-ecological vehicles (i.e. vehicles with high emissions) will be subject to charges.
6. What is the difference between natural gas and other gases used for transport purposes - liquefied petroleum gas and biogas?
Natural gas is, as the name suggests, natural; chemically, it is a mixture of gaseous hydrocarbons with a variable mix of non-hydrocarbon gases. Its main component element (96-98%) is methane (CH4).
In transport, the main gases in use are compressed natural gas (Europe) and. to a lesser extent, liquefied natural gas (USA).
Liquefied petroleum gas is a mixture of liquefied refinery gases – hydrocarbons, mainly containing propane C3H8 and butane C4H10, along with a smaller quantity of higher hydrocarbons. The key raw material in the acquisition of liquefied petroleum gas is petroleum.
Under normal atmospheric conditions, liquefied petroleum gas occurs in gaseous form. It is relatively easy (through cooling or compression) to convert into a liquid state. It is pumped into vehicle tanks and stored there in liquid form. It is converted into gas in the carburettor, and is mixed with the air into a fuel mixture in the mixing unit.
In transport, biogas is fuel generated through biological processes from organic matter, which for the purposes of propelling motor vehicles has undesirable foreign materials removed (especially carbon dioxide and hydrogen sulphide) in order to comply with natural gas requirements. In particular, purified landfill gas is used. The disadvantages of biogas are its limited quantity and the fact that only local use is possible.
According to the experts, another gas – hydrogen – should become the fuel of the future.
7. What is more advantageous – natural gas or liquefied petroleum gas?
Advantages of liquefied petroleum gas over natural gas:
- relatively wide network of filling stations in the Czech Republic and Europe,
- with most vehicles, there is a greater range per full tank,
- lower price of gas equipment,
- smaller pressure tank.
Advantages of natural gas over liquefied petroleum gas:
- lower price of natural gas,
- better engine starting properties at lower temperatures,
- safety – unlike liquefied petroleum gas, natural gas is lighter than air, and is therefore safer to operate and handle; liquefied petroleum gas has stricter parking conditions. Storage in pressure vessels is protected several times more,
- vehicles can park in secured underground car parks,
- stable fuel quality,
- good prospects for use – natural gas reserves will last longer than oil reserves (the production of liquefied petroleum gas relies on oil).
8. Can natural gas be used in vehicles running on liquefied petroleum gas?
Definitely not. The gases and technologies are different. Be careful not to confuse natural gas with liquefied petroleum gas! Several tragic accidents have already occurred due to the use of compressed natural gas in a vehicle designed to run on LPG. As the pressure of CNG is several times higher than that of LPG, the LPG tank ruptures, which is followed by an explosion. LPG is held in storage as a liquid.
9. In which countries is natural gas most widely used for transport purposes?
More than 3.5 million vehicles in 50 countries run on natural gas today.
Most CNG vehicles can be found in Argentina (more than a million), Brazil (550,000), Italy (380,000), Pakistan (280,000), India (137,000), and the USA (126,000).
The largest number of gas-run vehicles in the world is operated by the US post office. Of the 208,000 vehicles in the US Postal Service fleet, 7,400 run on compressed natural gas.
Most buses and coaches running on natural gas can currently be found in the USA, Columbia, Australia, France and Sweden.
In Europe, 400,000 vehicles run on natural gas and there are almost 900 filling stations.
Besides Italy, most natural gas vehicles are in operation in Germany (20,000), France (4,500) and Sweden (2,000).
Natural gas is used for cars and commercial vehicles, bus and coaches, and light and heavy freight vehicles. Considering the ecological properties of natural gas, the use of gas propulsion is particularly topical in conurbations with high levels of congestion, e.g. for delivery vans, refuse collection vehicles, taxis, police cars, post office vans and other municipal vehicles. In particular, natural gas is used by public transport buses in larger towns, industrial conurbations, at spas, and in recreational areas.
10. How many natural gas vehicles are there in the Czech Republic?
In the Czech Republic about 460 vehicles run on natural gas, of which:
- 160 cars and vans (gas companies)
- 120 cars and vans (company and private vehicles)
- 165 buses (Havířov, Frýdek-Místek, Prostějov, Ústí nad Labem, Teplice, Česká Lípa, Litoměřice, Znojmo, Podkrkonoší, …)
- 8 freight and refuse collection vehicles
The largest operators of natural gas vehicles are:
- Pražská plynárenská, a.s. (50 cars and vans),
- Dopravní podnik Havířov (42 buses),
- Dopravní podnik Ústeckého kraje (90 buses).
11. How do you refuel a vehicle with natural gas?
Natural gas from the gas pipeline network is compressed to a pressure of 20-30 MPa with the aid of a compressor. The compressed natural gas is stored in interconnected pressurized containers. The actual refuelling merely entails the release of compressed natural gas from the pressurized containers via a dispensing pump into the vehicle’s pressure vessel. The gun of the dispensing pump’s hose is connected to the vehicle’s refuelling valve via a quick-fastening system.
Depending on the refuelling method, the following are used:
a) fast filling station
The refuelling principle is described above.
The refuelling time is the same as for pumping liquid fuel (3-5 minutes).
b) slow filling station
Refuelling takes place via a small compressor directly into the vehicle tank, i.e. without pressurized containers.
Refuelling takes between 5 and 8 hours. This type of station is suitable for homes and smaller companies.
12. What units are used for natural gas?
Compressed natural gas is reported as volume (m3) or weight (kg).
13. How does one litre of petrol, diesel or LPG compare to 1 m3 of natural gas?
Each motor fuel has a different energy content.
| 1 kg CNG | = | 1,4 m3 CNG |
| 1 l petrol | = | 1.0 m3 CNG |
| 1 l diesel | = | 1.2 m3 CNG |
| 1 l LPG | = | 0.8 m3 CNG |
14. Where can natural gas filling stations be found in the Czech Republic?
There are 16 compressed natural gas filling stations in the Czech Republic, nine of which are public and seven private (these are mainly at the depots of bus companies).
| Public stations: | Private station: |
|
Prague – SHELL, Švehlova ul Prague – Michle, at the Pražská plynárenská complex Hradec Králové – at the Východočeská plynárenská complex Frýdek – Místek Horní Suchá – OKD Doprava complex Prostějov – FTL complex Liberec – at the ČSAD Liberec complex Plzeň – ZČP, a.s. complex České Budějovice – JČP, a.s. complex Znojmo |
Ústí nad Labem – ČSAD complex Teplice – Krupka – ČSAD complex Teplice – Dubí – ČSAD complex Česká Lípa – ČSAD complex Roudnice – ČSAD complex Prunéřov – ČSAD complex |
By the end of 2006, further public filling stations will be built in Ústí nad Labem, Brno, Ostrava and, evidently, Mladá Boleslav. In future years, the number of filling stations should rise; based on an agreement with the Czech government, the gas companies will build a network of 100 filling stations.
15. What is the principle for the operation of natural gas vehicles?
Vehicles are filled with compressed natural gas (pressure of 20 MPa, 200 bar) at CNG filling stations by means of a refuelling valve. The CNG fuel tank is a gas pressure vessel which is usually made of steel, although lighter composite vessels are becoming more popular. In modern cars, pressure vessels are generally located outside the luggage area (on the bottom of the vehicle); in buses (especially low-floor buses), they tend to be positioned on the roof. When the vehicle is in operation, the CNG makes its way through a high-pressure gas tube to the high-pressure regulator, where the gas pressure is reduced to the required operating pressure. The stepper motor, based on signals from the controller, continuously adjusts the quantity of gas entering the mixing unit to ensure the optimum performance, fuel consumption and level of emissions. The fuel is mixed in the mixing unit, i.e. the natural gas is mixed with the air to create an explosive gaseous mixture. The mixing unit has the same function as a carburettor or injection in petrol-run vehicles. The electronic part of the gas equipment – the controller and emulator (the injection breaker) – is used to ensure the proper running of a natural gas vehicle; it interrupts the petrol injection and controls the gas dosing. A gas quantity indicator is located by the dashboard (including a gas/petrol switch in dual-fuel vehicles).
16. Is it safe to drive a natural gas vehicle?
Some people are worried about gas, especially as natural gas in transport is used under very high pressure. In reality, natural gas vehicles are safer than vehicles run on petrol, diesel or LPG. This is because of the physical properties of natural gas and the method used to store CNG.
Unlike liquid fuels, natural gas is lighter than air.
The ignition temperature of natural gas is double that of petrol.
The thick-walled gas pressure vessels made of steel, aluminium or composite materials are safer and more impact-resilient than the thin-walled tanks used for liquid fuels. Pressure vessels undergo a number of tests that are much more stringent than the tests required for liquid-fuel tanks. In particular, they are tested for resistance to shock, fire and pressure rises. In the vehicle, the pressure vessels are fitted with safety valves with a number of safety elements (automatic closure if the vehicle is involved in an accident, gradual discharge of gas and the burning-off of this gas if the vehicle catches fire) to prevent the tank from rupturing and being destroyed. Even in real cases where gas vehicles have been written off in accidents and, in one case, where there was blaze in a garage of gas-run buses, the pressure vessels were found not to have suffered significant damage.
A number of periodic inspections of the gas equipment are prescribed to ensure long-term safety.
17. What types and makes of vehicle are run on natural gas?
Gas can be used as a fuel based on one of the following variants:
a) A mass-produced vehicle with gas propulsion and full guarantees applicable to a new vehicle.
b) The model (en-masse) conversion of a vehicle as part of conversion homologation.
Most types of Škoda (Favorit, Felicia, Pick-up, Octavia, Fabia) in the Czech Republic currently have homologations based on which vehicles run on conventional fuel can be converted en-masse to natural gas.
c) Individual conversion of a vehicle and subsequent approval of roadworthiness.
Conversion is gradually waning; it is most common among older types of cars and lorries, usually at the expense of user comfort (the tanks occupy part of the luggage space).
Mass-produced original CNG cars:
- Opel (Zafira, Combo, Astra),
- Fiat (Punto, Multipla, Doblo, Marea, Ducato),
- Citroën (Berlingo, C3)
- Volvo (V70, S80, S60),
- Mercedes
- Ford (Ka, Focus),
- VW (Golf Variant),
- Honda (Civic),
- Toyota (Crown, Corola),
- Mazda (Demio) …
Škoda Auto, a.s. Mladá Boleslav does not offer mass-produced models running on CNG or LPG.
Mass-produced original CNG vans and lorries:
Mercedes-Benz, Ford, Toyota, Nissan, Mitsubishi, Citroën, Fiat and others
Mass-produced CNG buses:
In the Czech Republic – Karosa, Ekobus, TEDOM; abroad: all major producers, e.g. Mercedes Benz, Iveco, MAN, Volvo, Neoplan, Nissan, Isuzu, Renault, Van Hool, Scania.
18. How much does the conversion of a vehicle to natural gas cost?
Who carries out the conversion?
The subsequent conversion of a vehicle to CNG requires the incorporation of a set comprising a CNG pressure vessel, a regulator, a refuelling valve, a controller and interconnecting material to ensure the proper propulsion of the vehicle on compressed natural gas in accordance with valid legislation. The conversion of a vehicle includes registering a change to the form of propulsion (as specified in the roadworthiness certificate) at the Traffic Inspectorate of the Czech Police Force, which is a requirement for operation on public highways.
It costs approximately CZK 60,000 inclusive of VAT to convert a Škoda Fabia or similar car. This price includes the cost of material and labour, plus the registration of the vehicle at the Traffic Inspectorate.
The following companies in the Czech Republic are authorized to convert cars, i.e. they hold a ‘Certificate of the Ministry of Transport of the Czech Republic on the approval of the technical capability of vehicle fittings and components’ and a ‘Decision of the Ministry of Transport of the Czech Republic on approval to carry out en-masse vehicle conversions’:
Škoda Fabia:AG Autogas Systéme
EKO GAS AUTO
Beranových 130, 199 05 Praha 9 – Letňany
Škoda (Favorit, Felicia, Pick up, Octavia), Renault:
EKOSS-CNGS-ČR, spol. s r.o.
Dukelská 10, 680 01 Boskovice
Škoda (Favorit, Felicia, Pick up, Octavia):
Autoservis Černý
Na Zvoničce 1145/11a, Praha 4 - Podolí
19. How far can you travel on a full tank of CNG?
In general, the range depends on the size and number of pressure vessels and on the gas consumption of the specific vehicle, as well as on the method of use (urban, non-urban) and type of journey.
Mass-produced cars with larger tanks (e.g. FIAT Multipla, Opel Zafira) have a range of up to 550 km.
Converted cars fitted with a 70-litre pressure vessel have the following average range:
- Škoda Fabia: 220-260 km
- Škoda Octavia: 190-220 km
The average range for buses is 450 km in urban traffic and more than 500 km on non-urban roads.
20. How much do gas pressure vessels weigh and how much space do they take up in a vehicle?
The manufacturers of original gas cars preserve the vehicle’s value in use, i.e. the tanks are not placed in the luggage area; instead a larger number of smaller tanks (usually three or four) are located under the vehicle, under the rear seats or in other suitable spaces inside the vehicle.
In a converted vehicle, the pressure vessel for compressed natural gas is a cylinder shape and generally holds between 70 and 100 litres. Steel vessels weigh (expressed in kg) approximately the same as their volume (expressed in litres), i.e. a 70-litre vessel will weigh about 70 kg). Lighter vessels made from aluminium or composite materials weigh up to three times less. In these cars, the pressure vessel is usually located in the vehicle’s luggage area; in buses it can be found in the luggage area or on the roof (in the case of low-floor buses); in lorries it is under the chassis.
21. Is it possible to park a natural gas vehicle in an underground car park?
The entry of CNG vehicles into garages and similar areas is regulated in an Informational Document of the Ministry of Transport of the Czech Republic, in Article 61(d) and (e):
d) it is prohibited to enter closed warehouse, garage and similar areas where the entry of vehicles propelled by CNG or LPG is not expressly permitted,
e) before a vehicle enters a repair workshop or communal garage, the responsible member of staff at this structure must be informed that the vehicle is run on CNG or LPG.
Entry to secured underground garages is permitted, i.e. the garage must be ventilated and detectors must be installed that indicate any gas leak.
22. How long will it take for me to recoup my investment in gas propulsion?
The recoverability of funds spent on the higher cost of a vehicle run on natural gas depends on several factors, the most important of which are:
- the number of kilometres travelled,
- the mutual relationship between the selling prices of natural gas, petrol and diesel,
- the higher cost of purchasing a gas vehicle (approximately CZK 60-80,000), or the cost of converting a vehicle to natural gas.
In March 2006, the fuel prices were CZK 28.50 per litre and CZK 15 per m3 of CNG (i.e. CZK 21 per kg), which means you would recoup your outlay on converting a car to natural gas after 55-73,000 km with (with consumption of 8 l/100 km or 8 m3/100 km).
From what is mentioned above, we can infer that natural gas is advantageous primarily in cases where vehicles clock up a high number of kilometres every year. With these vehicles, the cost of converting a vehicle or the extra cost of acquiring a gas version is recouped quickly, and then the operating costs are approximately half those of liquid fuels. The vehicle is more economical to run and, in particular, it is environmentally friendly.
23. How does natural gas consumption for transport purposes compare to consumption for heating purposes?
The annual gas consumption per company car is approximately 2,000 3 of natural gas per year (average consumption of 8 m3/100 km, an average distance covered of 25,000 km/year) = natural gas consumption used to heat one flat, the annual gas consumption per bus is approximately 28,000 m3 of natural gas per year (average consumption of 40 m3/100 km, an average distance covered of 70,000 km/year) = natural gas consumption used for eight houses, one bus depot with 50 buses = professional user with an annual natural gas consumption of 1.4 million m3.
24. Can I refuel a natural gas vehicle with gas from the gas service line on my land?
Yes. You will need a ‘domestic refuelling device’, i.e. equipment for slow refuelling. The official international name is a VRA (vehicle refuelling appliance). Another commonly used term is FuelMaker, taken from the Canadian producer with a dominant market position. Cars are refuelled with natural gas directly via a compressor; several vehicles may be refuelled at the same time. Refuelling usually takes place over five to six hours at a time when the vehicle is not in use – during the night or breaks in a journey.
25. By how much per cent is the performance of a gas vehicle lower than that of a petrol vehicle?
Natural gas has an octane number of 130; therefore an engine designed to run on natural gas has a higher compression ratio than a petrol engine and hence better parameters. However, at this stage we still mainly come across petrol engines which have been modified to run on natural gas, which is hardly the ideal solution for natural gas. In these cases the performance of an engine using natural gas is approximately 5-8% lower than an engine running on petrol.
26. Why isn’t natural gas more widespread in the Czech Republic?
The main obstacles preventing the faster development of natural gas use in transport are:
- Insufficient information for potential users of natural gas vehicles
- Insufficient infrastructure – there are currently only a small number of CNG filling stations. Gas companies have pledged to construct a network of 100 filling stations.
- Insufficient funding to build new filling stations or purchase new gas buses.
- A lack of interest among vehicle operators, especially urban transport companies.
- The current restricted range of gas cars (Citroen, Opel, Fiat); Škoda cars can only be converted
- In cases where vehicles are converted, the vehicle users have to surrender some of the comfort they have enjoyed:
- smaller luggage space
- lower range of CNG vehicles
- more stringent safety measures.
- Public disinterest as regards environmentally friendly fuel.
27. How does the European Union view the use of natural gas in transport?
A European Commission action plan from the end of 2001 is reckoning on 20% replacement of petrol and diesel with alternative fuels by 2020.
According to EU experts, only three alternative fuels/technologies have a chance of replacing more than 5% of engine fuel consumption in the next 20 years:
a) biofuels, already in use,
b) natural gas in the medium term,
c) hydrogen and fuel cells in the long term.
- energy security and supply strategy,
- environmental protection (a reduction in the greenhouse gas CO2).
| Year | Biofuels (%) |
Natural gas (%) |
Hydrogen (%) |
Total (%) |
| 2005 | 2 | 2 | ||
| 2010 | 6 | 2 | 8 | |
| 2015 | (7) | 5 | 2 | 14 |
| 2020 | (8) | 10 | 5 | (23) |
In absolute figures, the percentages above are equal to:
- 23.5 million natural gas vehicles,
- consumption of natural gas as an engine fuel of 47 billion m3,
- 20,000 natural gas filling stations.
28. Does natural gas have a future in the transport sector?
Automotive operations are currently one of the largest environmental polluters. At the outset of the 21st century, new, more stringent emission regulations are due to enter into force that will force car manufacturers to develop more sophisticated drive units and refineries to improve the quality of engine fuel. Although the traditional fuels, petrol and diesel, have by no means come to the end of their historical role, the development of energy for vehicle propulsion has been headed in other directions in the last few years. Gaseous fuels, especially liquefied petroleum gas and natural gas, are among the most commonly used alternative fuels. Gas propulsion is becoming more popular among motorists; it is more environmentally friendly than the currently predominant petrol and diesel, and is more efficient economically. Practical experience of natural gas vehicles to date has underlined the competitiveness of this fuel with liquid fuels. It offers an ecological, economically advantageous, proven, technically resolved, safe, immediately usable solution.
Natural gas therefore definitely has a future in the transport sector.
29. What does the term ‘alternative fuel’ or ‘alternative technology’ mean?
This term covers all fuels replacing today’s dominant oil-based fuels (petrol and diesel) and technology replacing today’s internal combustion engines (diesel engines and spark ignition engines).
Gaseous fuels- natural gas, compressed (CNG) or liquefied (LNG),
- liquefied petroleum gas (LPG) – this is not an alternative fuel to oil products,
- biogas,
- hydrogen, compressed (GH2) or liquefied (LH2).
- electricity from fuel cells (methanol, natural gas, hydrogen),
- electricity from conventional accumulators.
- alcohols – methanol, ethanol,
- biodiesel (e.g. rapeseed oil methylester)
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