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YEAR 11 - n. 1 - MAY 2010

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Natural gas vehicles


Vehicles, energy, environment Milano, May 2010 Year 11 - Issue 1 Six-monthly magazine Reg. Tribunale Milano nº 416 del 9 giugno 2000 Registro operatori di comunicazione n° 8654 Editor in chief: Alfredo Zaino Editor: Com-Media S.r.l. Via Serio, 16 - 20139 Milano Tel. +39 02-56810171 Fax + 39 02-56810131 E-mail: [email protected] Internet: Publisher: Com-Media S.r.l. Page layout by: Briefing - Milano Advertising: Com-Media S.r.l. Printed by: Multigraf S.r.l. Via Colombo, 61 20155 Gorla Minore (VA)

Circulation: 5.000 issues Copyright © by Com-Media S.r.L. Milano All rights reserved. Cover: Fiat Qubo CNG

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Long term targets Notwithstanding the zealous declarations released by the politicians of the international organisms, the atmospheric pollution in Italy and in the rest of the world is growing constantly. As all the other forms of pollution, come to that. In the last announcements on radio and newspapers, and in particular during the COP conference in Copenagen, they went so far as to pompously promise a strong reduction (e.g. by 50%) of the polluting emissions by 2050. In more than 40 years. Today’s politicians have hence taken noble commitment, which target will anyway have to be met by our descendants. Meanwhile, we keep on increasing our polluting emissions instead, on the wrong presumption that we have plenty of time. The only factor which in this very period is limiting to a certain extent the emission increase, is unfortunately enough the reduced production rate of firms, due to the financial and economic crisis. But obviously the financial economic crisis is neither a recommended nor a desirable environment protection measure. Sometimes the countries which have signed the Kyoto Protocol show strong difficulties in respecting the limits to the CO 2 emissions they have committed themselves to. Some of them, including Italy, at the end of the day will probably have to pay big penalties for this. In this situation it is obvious that we must do something very soon. We need to take profit in a rational and determined way of all the available environment friendly solutions. The

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potential of each one of them must be deployed as much as possible. Each one must be placed in the most suitable and effective application field. The use of each one of them must not impair the full application of all the other solutions equally viable. By this way only we can hope to leave our descendants a better world than the one we got from our parents, and not a just more poisoned one, only full of good intentions and of not deployed solutions. In Italy, in the transport sector, and in particular in the car sector there are two good and clean fuels which struggle to get more room, with variable results. Sometimes fighting each other undercover, rather than planning the better strategies for both. Of course we are speaking about CNG for NGV and LPG. The differences Nowadays the public opinion still tends to make confusion between the two, by adopting for both the term “gas”, with a sort of “lazy thinking” which in some instances has resulted even dangerous. The “gas” is characterised instead by a remarkable “dimorphism” on the side of the chemical and physical characteristics and on that of the applied norms. This word defines in fact two products which are extremely different from each other. One of them is always in gaseous form, except in the very rare cryogenic applications when its temperature is about minus 160 Celsius. The other one is always in liquid form except at the inlet of the engine intake manifold and in combustion chamber; and sometimes it is in liquid form even there, with the modern liquid LPG direct injection technology. CNG, imposes to the storage and management infrastructures the application of very high pressures, i.e. 200 bar. For LPG a pressure ten times lower is sufficient; thus its tank is lighter and cheaper. CNG weighs about half as much as air; if it were not flammable, it could be used to inflate children’s balloons at fairs. In gaseous form LPG weighs nearly two times as much as air; if leaking from a pipe, it vaporizes and settles down on the ground, where it will keep for long, waiting for a spark or a hot cigarette end. Natural gas is available in enormous amounts, at the same level of crude oil; and maybe far more, if it is true that the bottom of the oceans all around the world are rich of gas hydrates. LPG is just a marginal product of oil and gas production and treatment. Its availability has been estimated to be equivalent to about 5 or 6% of the proven reserves of crude oil. It is anyway a globally interesting amount of energy, which we

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The synergies These two fuels have also some similarities, no doubt about that; and they take profit of some synergies. In both cases the combustion process is intrinsically less polluting than in the case of the other more traditional liquid fuels. Some of their management appliances are similar. The engine laboratory research can provide a benefit for both. All the component manufacturers, or most of them, offer products for both fuels, which coexistence on the market has always allowed the manufacturers higher global production rate, hence better economic turnover. During hard times, this may make the difference between keep on with the activity of shut down the firm. An interesting aspect of the synergy between

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CNG and LPG is that of norms. Usually the preparation of specific norms for one of them is just the prelude of the immediate redaction of similar norms for the other with the due technical adjustments needed because of the chemical and physic differences among the two fuels. Sometimes LPG is the first to come, immediately followed by CNG. A recent example was the decree 11 September 2008 “Modifiche ed integrazioni al decreto del Ministro dell'interno 24 maggio 2002, recante norme di prevenzione degli incendi e di progettazione, costruzione ed esercizio degli impianti di distribuzione stradale di gas naturale per autotrazione”, covering the self-service delivery mode. Some other time, the first norm is for CNG, and is followed by LPG. A recent example of this was the multi-fuel dispenser. The initiative was started by the CNG experts; and the end result was the publication of the decree 23 September 2008 which title is: “Amendments and integrations to the annex A of decree 24 October 2003, n. 340, covering safety requirements of appliances for the delivery of LPG for road transport applications”. Another example of norm replication is the result obtained by the experts with the amendment of the decree 01/02/1986: “Norms for fire protection of construction and operation of garages”, which originally forbade the underground garaging of vehicles fuelled with a gaseous fuel with relative density higher than 0.8 (i.e. LPG). That provision has been partially amended by the decree 22 November 2002 “Provisions for the garaging of vehicles fuelled with LPG in garages as a function of the relevant safety system”, which allows also to LPG vehicles the parking in underground garages, but only down to the first underground floor, and not below, and only if the LPG on-board system of the vehicle has been certified to the UN ECE Regulation R67; which means that on the vehicle are installed some particular safety devices. Maybe the rationale of this amendment is the consideration that all in all, the gaseous LPG has more or less the same physic characteristics as the gasoline vapour. So, if the garage is suitable to gasoline vehicles, it must also be so for LPG vehicles. Both CNG and LPG must rise the interest of public opinion, and remove its wait and see attitude, which is also a result of the spell of “technology mermaids” like the hydrogen easily within reach, the new light and inexhaustible


need to be able to consume. About 60% of all the LPG which is consumed today is a by-product of the natural gas production process. The remaining 40% is the by-product of the crude oil refinery process. The net heating power of CNG in gaseous from is roughly equivalent to that of a litre of diesel oil. The net hearing power of LPG in gaseous form is more than twice as much. But CNG for NGV is sold by kilogram of gas; LPG instead is sold by litre of liquid. And one kilogram of natural gas is roughly equivalent in terms of energy, to about two litres of LPG in liquid form. Natural gas, in the case of biogas can even be quite easily produced by means of the bio-chemical processes for the treatment of waste solid or liquid substances, with interesting local and global benefits for environment. And this way it becomes a renewable energy source. In the case of LPG this is not as easy. Natural gas always flows through though and well protected underground pipelines, which have no impact on road traffic, and nearly no architecture’s impact. LPG is transported by tankers, more or less as gasoline and diesel oil, with the only difference of the higher internal pressure. Natural gas never needs to be stored in large amounts by the customer, hence it must not be paid before its use. Of course we refer here to the case of the CNG refuelling station which buys natural gas from the gas company. In the refuelling station, a few cylinders are enough to efficiently damp compressors pressure pulsations. The installation of a few more cylinders is recommendable to optimise the compressor load curve, with a variable trend of incoming vehicles to be refuelled. But it is always a matter of a limited amount of stored energy. In the case of LPG instead a big high pressure underground tank is always needed, more or less as it happens with gasoline and diesel oil, still here except the higher service pressure. And the product which fills the underground tank is immediately invoiced as soon as it reaches the refuelling station, and not at months end, as it happens to natural gas. We will discuss in more depth all the differences between CNG and LNG later on in this article.


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electric batteries, the emission killing hybrids, the ultimate alternative energies. Both CNG and LPG must struggle hard to map out and settle their growth and development path, to enlarge their niche in the automotive market, still ruled (and it will be so for long) by traditional liquid fuels.


A pill of history The first to come on the market was CNG, before the Second World War. To take more profit of the one and only domestic fossil energy source which was available on the national territory with inherent abundance, and which was to be used for house heating and industry, but also for vehicles. It did allow the country some self-sufficiency, imposed by the hard political situation of that time, when Italy acted as ambitious colonial power and was punished with the embargo. Then, on more recent times, with the far and wide spread of oil and its derivates, LPG has joined in. It is produced by condensation from natural gas, but it is mainly produced by oil refinery as top gas from the distillation tower. Finally, it was also found in limited amounts in its own underground reservoirs in the country (e.g. the wells of Malossa, near Treviglio, at a depth of some kilometre). Since its entry of the market, LPG has succeeded in quickly developing an automotive market share. Even if keeping at the level of niche, it has firmly settled on a prevailing position over CNG, and today its market share is about three times as that of CNG, in terms of vehicles in circulation, number of refuelling stations, and amount of fuel consumed by the light duty vehicle sector. Opposite, its penetration of the heavy duty vehicle sector, a niche of the niche, has always been harder. Here CNG is absolutely prevailing. In the residential and commercial sector, in some cases the opposite process has occurred. Here in fact LPG has often been the pioneer one in the marginal areas, with the installation of tanks for isolate locations, such as rural settlements, restaurants or hotels too far from cities and towns and their gas networks. And often it has also allowed to build small local pipe networks for the distribution of a mixture of propane and air, having more or less the same net heating power as natural gas, in areas still not connected to the natural gas national pipeline system. This way LPG made thus possible in many places the application of the technologies, and the diffusion of the culture of a gaseous fuel, waiting for the natural gas national pipeline network to reach those areas in a subsequent time, at which point natural gas would inexorably suppress the pioneer LPG. For example in Sardegna at present there are only propane air mixture pipeline systems in operation as in that region the natural gas pipeline system do not yet exist at all. But in the future a submarine one, the Galsi, will reach the region, carrying natural gas from the near Algeria. The development of natural gas pipelines, which

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in the past were more intense compared to the present situation, has thus progressively displaced those initial applications of LPG, causing a surplus, hence a gradual increase of the relevant offer as automotive fuel. It is a process quite similar to that of the substitution of diesel oil and fuel oil for natural gas in the heating plants in the urban areas affected by the development of the natural gas city network. The process was driven by the energy market rules, but mostly so by the need for environment safeguard. In the recent past, the increasing availability on the market of new diesel vehicle models had created some sale problems to the gaseous fuels, and in particular to LPG, which, opposite than the case of CNG, is burdened by not negligible excise duties, even if lower than those applied to gasoline and diesel (excise duty in application since 1/5/2008: gasoline 0.564 €/l; diesel 0.423 €/l; LPG 0.125 €/l; CNG 0.00291 €/ m3). The diesel oil, also the amount displaced by natural gas in the heating plants, was available in large amounts and was offered at competitive prices. The concurrent entry to the market of a number of car models offered by all OEM with more than acceptable performance, made diesel oil suddenly very attractive for all kinds of customer. With diesel, far longer specific running range is allowed by the remarkably higher Diesel engine efficiency compared to the Otto engine, and there are no difference in acceleration and power. These features had for some time put in jeopardy the market share of CNG, and even more so that of LPG, in a frightening way. But the market is a living thing, which reacts promptly to any stimulation. And it has reacted quickly enough to the strong rise of the demand for diesel oil as fuel, with a consequent sharp increase of the prices at the pump. Also because a part of the diesel oil demanded by market must be imported from abroad, as exceeding the maximum possible production rate of national refineries. This has substantially restored the former market balance, based on the price competitiveness of LPG, let alone CNG. Furthermore, meanwhile the average pump price of LPG has kept low, even if slightly higher than the average pump price of CNG, and the offer on the market of OEM LPG vehicle models has also widened, quickly dwarfing the offer of OEM CNG vehicle models, growing as well, but at slower pace. The market Nowadays there are on the market in Italy more than 90 models of LPG private passenger cars, whereas just about 20 CNG car models are on sale. Many models are then available in a number of different version and arrangement, which further widens the choices offered to customers, as well as the spread between the LPG vehicles choices and the NGV choices.

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The OEM cars fuelled with gaseous fuel on the market in Italy

CNG models

Gran Picasso

dr5 Panda Punto 5 porte Grande Punto Punto Evo

Qubo Doblò Multipla Focus berlina Focus S.W.


Classe B

Manufacturer LPG models Micra Nissan Note Corsa Opel Astra Astra S.W. Meriva Zafira 207 Peugeot 207 S.W. Renault Twingo Clio Storia Clio berlina Megane Modus Grand Modus Kangoo Scenic Espace Koleos 9-7x Saab Seat Ibiza 3 porte Ibiza 5 porte Leon Altea Altea XL Shuanghuan Ceo Skoda Fabia Fabia S.W. Octavia berlina Octavia S.W. Roomster Subaru Justy Impreza Forester Nuova Legacy Nuova Outback Suzuki Alto Swift Splash Tata Indica Indigo Toyota Yaris Aygo Volkswagen Fox Polo 2001 Golf Touran V50 Volvo Totale modelli 96

CNG models



Manufacturer LPG models Chevrolet Matiz Aveo Lacetti Nubira Cruze Epica Captiva Nuova C3 Citroen C3 berlina Sandero Dacia Logan berlina Logan MCV Daihatsu Sirion Materia Terios DR dr5 Panda Fiat Punto 3 porte Punto 5 porte Grande Punto Punto Evo Bravo Idea Ford Fiesta Focus berlina Focus S.W. Mondeo berlina 4 p. Mondeo berlina 5 p. Mondeo S.W. C-Max Hyundai i10 i20 i30 berlina i30 S.W. Tucson KIA Picanto cee'd 5 porte cee'd S.W. cee'd Soul cee'd Sportage Lada Niva Lancia Ypsilon Musa Mazda Mazda 2 Mercedes Mini Ray G Mitsubishi Colt Nissan Pixo



Indica Indigo

Caddy Touran Passat berlina Passat S.W. 21


It is worth outlining that practically all the CNG models on the market are real OEM, i.e. they are designed and manufactured in CNG version by the manufacturer. Instead, almost all the LPG models offered to the market as OEM, and as

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that considered by the norms covering the grant of incentives, in real terms are something quite different, which is less “valuable” than a real OEM. In fact, they can be considered as QVM (qualified vehicle modifiers). They are built by

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the manufacturer in gasoline version, more or less prepared for a subsequent conversion, then they are converted to LPG by special workshops, anyway under the direct control of the manufacturer. So they are some sort of good compromise between a real OEM and a mere retrofit conversion done in one of the 2,000 conversion workshop disseminated over the national territory. But for the end customer all this is not so important. All he knows is that if he wants an LPG car he is bound to find one on the price-list, choosing among the models he mostly likes, and those which are more suitable to his need, without any compromise on the side of brand and style, while this is not the case sometimes for those who want to buy a CNG car. He will take profit of the incentives offered by the government for the purchasing of OEM gaseous fuel cars; if available. Even if to be true, the last incentive of 1,500 Euro offered by DL 10 February 2009 n 5, which has expired in December 2009, was offered only to OEM CNG cars. And he will be offered the full warranty of the manufacturers, as if nobody had ever put the hands on his car after the original manufacturing. For the manufacturer instead, things are a lot different. The design and construction of a real OEM requires an investment far higher that that required by the QVM option, which also results in higher sale prices. This over-cost sums up to the


over-cost of the CNG on-board system, which is burdened by the cost of the high pressure (200 bar) CNG cylinder. For example, a Grande Punto has a price of 15,400 € in the CNG version, and 14,150 in the LPG version; a Ford Focus costs 19,400 € in the CNG version, and 17,900 in the LPG version. One might ask himself why in the world the car manufacturers don’t adopt the cheaper QVM option also in the case of CNG models. At least when the room required for the installation on-board of the CNG cylinder don’t penalise too much the load space. This market could get some benefit for sure from this. And the resulting solution would be acceptable on the technical and legislative side, as it is in the case of the LPG vehicles. There is a big difference in favour of LPG also on the side of the “aftermarket” conversions done by the workshops operating on the territory, which are all able to make both CNG and LPG conversions. Nearly 90% of the conversions done in 2009, and the relevant incentives granted by the government have been LPG conversions. In 2009 as much as 167,000 cars have been converted to LPG, whereas a ridiculously smaller number of cars have been converted to CNG: 17,500 units. Another explanation of this is that the normal cost of the CNG conversion is twice as much that of the conversion to LPG, applying the same level technology.

The market of the gaseous fuels in the automotive sector in Italy



Car registrations 2006

~ 29.200 (1,10%)

~ 6.400

Car registrations 2007

~ 64.000

~ 28.400

Car registrations 2008

~ 86.000 (~ +33% vs. 2007)

~ 74.000

Car registrations 2009

~ 141.000 (~7% on the total car registrations; ~+64% vs. 2008)

~ 340.000 (~14% on the total car registrations; ~+400% vs. 2008 )

Conversions 2008

~ 38.000

~ 170.000

Conversions 2009

~ 17.500

~ 167.000

Total vehicles 2008

~ 536.000 (1,3%)

~ 1.100.000 (2,7%)

Total vehicles 2009

~ 640.000 (estimate)

~ 1.500.000 (estimate)

Refuel. stations 2000

~ 340

~ 1950

Refuel. stations 2009

~ 750 (of which ~20 on motorways)

~ 2.350 (of which ~200 on motorways)

[fonte dati: elaborazioni Federmetano, Assogasliquidi, Ecogas]

National consumption of natural gas and LPG


total NG billion m3 (thousand TEP)(*)

CNG million m3 (thousand TEP)(*)

total LPG thousand ton (thousand TEP)(*)

automotive LPG thousand ton (thousand TEP)(*)


68,83 (56.440)

448 (367)

3.719 (3.942)

1.313 (1.392)


75,89 (62.220)

442 (362)

3.714 (3.937)

1.209 (1.282)


78,75 (65.570)

442 (362)

3.549 (3.762)

1.106 (1.172)


84,27 (69.100)

436 (358)

3.528 (3.740)

1.029 (1.091)


82,53 (67.670)

376 (308)

3.301 (3.499)

989 (1.048)


82,95 (68.020)

515 (422)

3.140 (3.328)

944 (1.001)


85,00 (69.700)

610 (500)

3.194 (3.386)

1.004 (1.064)

2009 (stima)

78,00 (63.960)

740 (607)

3.199 (3.391)

1.087 (1.152)

(*) net heating power: NG = 8,200 kcal/m3; LPG = 10,600 kcal/kg; TEP = 10,000,000 kcal source: Ministry of Industry; Oil & Gas Journal

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this time on the side of the refuelling station network. Comparison between the chemical and phisical characteristics


CNG (methane)



LPG (50% propane-50% butane)






Molecular weight of fuel





Molec. weight of required oxygen





Molec. weight CO2 emissions





Molec. weight H2O emissions





Emissions CO2 kg/kg





Emissions CO2 g/MJ





Emissions CO2 g/kWh





density Kg/Nm in gaseous conditions






density Kg/l in liquid conditions





Main components % mass

75C, 25H

82C, 18H

83C, 17H


Ratio H/C of atoms





Nhp MJ/Nm3 in gaseous conditions





Nhp MJ/l in liquid conditions

21,1 (GNL)




Nhp MJ/kg





Nhp kWh/kg





Boiling Temperature °C





air fuel mixture Nhp MJ/m3





Self ignition temp. °C (*)





theoretic combustion air kg air / kg fuel





Ignition limits in air % vol. of vapour, at atmospheric pressure (upper ÷ lower)










Cethane Number





Evaporation heat J/kg








-187 ÷ -138

-187 ÷ -138

-187 ÷ -138

Spec. heat of liquid kJ/kg°K Flash point °C (**)