Written by: Antonio Roncero @roncero_antonio January 7, 2020 9 minutes
We tell you the differences between Autogas LPG and natural gas CNG cars, which are a great solution if you are looking for a vehicle with which to save money when it comes to driving kilometers and you do not want to give up the ECO label of the DGT.
The gas cars they continue to gain followers. There is more and more supply and gas supply points increase, which means that many users are encouraged to use this solution as an alternative to hybrids to access a car with the DGT ECO label.
In addition, if you do many kilometers you recover the investment in a short time, because lGas cars have a significant cost advantage per kilometer compared to gasoline cars, diesel and even hybrids, for the lower price of this type of fuel.
We are, therefore, facing two types of ecological fuel that pollute less than conventional fuels, which allow access to the ECO label and which represent real savings when refueling. LPG and CNG cars are therefore an ECO alternative to electrified cars.
But what are the differences between LPG and CNG? What do I have to take into account when buying? We will explain it in the following points.
Fuel: differences between LPG and CNG
Although both LPG and CNG cars use the same technology as the models from which they derive in their gasoline versions, that is, they are vehicles with a gasoline engine with adaptations to run on gas, the type of fuel is different.
- LPG: It is also called Autogas, or Liquefied Petroleum Gas. They are obtained through the first step of the oil refining process and it is formed by a combination of propane and butane.
- CNG: They are the initials of Compressed Natural Gas. It is obtained mainly from natural gas fields and is basically composed of methane.
Both are clean fuels, by emitting less emissions in its combustion than gasoline, up to 95% less nitrogen oxides, also reducing hydrocarbons without burning, and hardly emitting particles. In this sense, the composition of each type of gas is not a factor to take into account when purchasing.
How is it stored in the vehicle?
The way to store LPG or CNG in the vehicle is one of the main differences between these fuels.
- The LPG it is a liquefied gas, and is stored in a liquid state in adapted tanks, at pressures that can range from 5 to 30 bar; normal are usually pressures of 10 bars.
- The CNG It is stored in the vehicle’s tanks as a compressed gas, at high pressures of about 200 bar. Therefore, the deposits in CNG cars are more sophisticated.
In neither case is security a problem, since both in LPG and CNG cars, the installation is prepared and passes a series of demands and tests far superior to those of gasoline cars.
If a leak occurs, in the case of a CNG tank, the gas will dissipate in the atmosphere, first accumulating at ground level, being denser than air. For this reason, in some very specific places there are restrictions on the parking of this type of vehicle. In the event of a leak in a CNG tank, the fuel would fall to the ground, like any other liquid fuel.
How do you refuel a LPG or CNG car?
In both cases, LPG or CNG refueling is a simple process, that we could consider equivalent to the refueling of gasoline or diesel. In fact, the Autogas supply hose is placed on the same pole as the rest of the fuels.
Gas vehicles incorporate a second socket with a nozzle or an adapter, located next to the filler neck of the fuel tank. Connecting the dispenser hose gun to the nozzle is an easy operation that requires no more effort than refueling, and refueling times are also similar.
In the following videos you can see how each of these fuels is refueled
LPG refueling
CNG refueling
How many LPG and CNG stations are there in Spain?
Undoubtedly, today this is one of the determining points, in which there are more differences when buying a LPG or CNG car.
Currently it is not difficult to find stations supplying LPG in big cities. In total they are more than 600 supply points available in Spain, of which almost 400 correspond to Repsol. It is also not difficult to find where to refill LPG during a trip, without having to plan the route.
Map of service stations with Autogas GLP
Regarding CNG, although supply points continue to grow, andn there are currently about 90 operational CNG stationss. This is the main disadvantage of CNG compared to LPG, as you can see not only by the quantity, but also by the distribution of the refueling points on the different maps.
Map of CNG service stations
To consider
One aspect to keep in mind is the autonomy with one and the other fuel. LPG cars generally keep the fuel tank intact. However, the new CNG cars that are being launched on the market, such as the Seat TGI range, have opted to increase the capacity of gas tanks, considerably reducing that of gasoline.
This, together with the lower availability of refueling points, will make you have to plan a long trip in the case of CNG cars, if you do not want to have to stop after every few kilometers to refuel gasoline if you run out of CNG, up to that you arrive at a station that supplies this type of gas.
LPG and CNG prices and consumption differences
These are the current prices of LPG, CNG and gasoline:
- LPG: 0.78 euros / liter
- CNG: 0.89 euros / kg
- Gasoline 95: 1.40 euros / liter
The consumption of a vehicle with gas is greater than running on gasoline, but the cost per kilometer is lower when the cost is translated into euros, as the fuel price is lower.
The same equation is repeated if we compare CNG with LPG, although the difference is not so great. But for putting a practical case, a compact car with a 120 hp engine can consume around 3.5-4 kg of CNG every 100 km, compared to 7.5 liters of LPG.
At the prices mentioned, traveling 100 km with CNG would cost about 3.6 euros, while with LPG the cost would be 5.85 euros. With gasoline, estimating an average consumption of 6.5 l / 100 km, the cost would be 9 euros to travel 100 km.
How do gas cars work?
Although there are brands that call this type of hybrid, in reality they are not, if we consider a hybrid car to be one that has at least two engines, and each of them can drive the vehicle on its own.
The correct thing is to refer to gas cars as bivalent vehicles, which can run on two different fuels: gasoline and LPG or gasoline and CNG. They do it with one or the other, but in no case with both at the same time.
The driver does not have to do anything. And you will not notice differences behind the wheel in terms of performance or power losses in the step of running on gasoline or gas. Yes it’s true that in the adaptation to run on gas, the original engine usually gives slightly less power official with respect to the version that works only with gasoline, a more marked difference in the case of CNG, which has less calorific value. If at all, running on gas may notice slightly more smoothness.
For practical purposes for the buyer, an important difference is that, in the case of LPG, the driver can voluntarily switch between running on gas or gasoline. For this, it has a button in the driving position, which can be operated at any time while driving.
In the case of CNG, the vehicle will always run on gas. It will only switch to gasoline mode if the gas in the tanks runs out, and it will start running on gas again after refueling, all automatically.
Differences between LPG and CNG cars: infrastructure, determining
By way of summary, we can conclude by saying that CNG has many advantages over LPG. But it has a disadvantage that, in the end, is definitive.
CNG emits less polluting emissions, as it contains less carbon. Fuel consumption is lower, and the cost per kilometer is also cheaper in a car with CNG compared to one with LPG. And as fuel, natural gas has more exploitation reserves.
However, the current infrastructure is the main stumbling block when deciding on the purchase of a CNG car, since, at least for the moment, it is not easy to fill the tank.
Others Additional advantages of LPG over CNG It is its greater autonomy considering the sum of the kilometers that can be traveled with the two fuels (gasoline and gas), and the possibility of choosing at any time which fuel to use. In the case of wanting to carry out a transformation of a vehicle from gasoline to gas after the purchase, the transition to LPG is technically easier (mainly due to the deposits) and, therefore, also more economical.
Related information of interest:
–Ten reasons to switch to LPG
–What should you know if you want to install an LPG kit in your car?
–8 things about LPG you probably didn’t know
–All SUVs on the market with LPG
Mechanics Zone E #gas cars
–
