contact us

In the heavy vehicles, the LNG is stored at low pressure and in thermally insulated tanks with capacities that vary from 174 to 511 liters. LNG is stored in liquid state at the evaporation temperature. In the case of boiling water (100 ° C), the temperature remains constant during the change from liquid to gas, even if it continues to supply heat. This is due to evaporation. Similarly, the LNG remains practically a constant temperature (-162ºC) if it is kept at a same pressure, and since the steam is released from the reservoir.

The only difference between a gasoline vehicle and a vehicle with CNG fuel system is:
1 CNG is injected into the vehicle through a valve which leads to the storage cylinder.
2 In these cylinders, the gas is initially stored at about 200 bar. As the gas is consumed, the pressure goes down, and below 15 bar it is necessary to refuel.
3 If the vehicle is bi-fuel, at the dashboard must be installed a switch that allows the driver to select between natural gas and gasoline. When the driver selects the natural gas, it leaves the cylinders and flows through the rigid pipe for high pressure to the engine compartment.
4 The gas accesses the throttle, device that reduces the pressure to values that allow overcome the losses to the engine intake (at near atmospheric pressure).
5 The output of the pressure regulator for the gas injection system is controlled by a solenoid valve. This also suspends the gas flow, when the driver makes switching to gasoline.
6 Natural gas blends with the air in the injection system and enters the combustion chambers.

Economy: The use of a natural gas vehicle (NGV) provides a very significant saving at two levels. According to data from the Portuguese Natural Gas Vehicle Association (APVGN), on the basis of an equivalent liter, natural gas costs about 70% less than diesel. On the other hand, a NGV consume a clean-burning fuel, which reduces the maintenance requirements as regards the oil exchanges or spark plugs, for example.
Environment: Natural gas is the cleanest of the fossil fuels currently used as alternative. NGVs emissions of carbon dioxide are about 20% lower, the non-methane hydrocarbon emissions are 80% lower, and the nitrogen oxides are 40% less than gasoline-powered vehicles. Furthermore, NGVs emit significantly lower quantities of greenhouse gases and toxins. Plus, natural gas is not corrosive and does not contaminate the soil.
Security: NGVs are as safe as vehicles that run on conventional fuels. The excellent safety record of NGVs is due, mainly, to the structural integrity of the fuel system and the physical qualities of natural gas. The NGVs safety requirements powered are quite demanding, which ensures the user unquestionable levels of security.
Abundance: World reserves of natural gas are almost the double of the oil, according to official information available on the site Association for the Study of Peak Oil and Gas. Another strong argument of this energy source is that it can be achieved through systems pullers applied in dumps and landfills, extracting bio-methane (also known as biogas). The bio-methane can be converted to natural gas and compressed, to be used as a power source for vehicles. Thus, it appears as a renewable energy.

NGV is made up of natural gas while LPG is made up of propane and a small quantity of butane. And in addition to pass all tests relating to environmental impact, NGV is also the most economical option.

According to the national association of natural gas vehicles (APVGN), installation in light vehicles cost around € 2,000, being the higher value for heavy vehicles. A heavy vehicle powered by natural gas costs about 25% higher than a diesel counterpart. Although in Portugal there is no official table for the compressed natural gas, the APVGN advances with an estimated 70% savings compared to the price per liter of diesel, which leads to a rapid recovery of the initial investment.

Dourogás has filling stations to the fleets of heavy vehicles at Urjais, Loures, Picoto and Escariz. Alternatively, there are filling stations for private vehicles in Braga, Loures and Porto. In these last location, the supply is only possible through an affiliation to the Portuguese Association of Natural Gas Vehicle (APVGN), once the gas station is for private use of STCP (Porto) carrier.

Previously, gasoline vehicles converted to natural gas were subject to small power losses, what no longer happens due to the electronic control units. Vehicles designed specifically to operate on natural gas do not show power losses because they are optimized in origin. In addition, natural gas has a high octane number (about 120), which allows the engine to operate at higher compression ratios than petrol (octane number between 95 and 98), increasing the effective power of the motor.

The Law-Decree nº40/93 of February 18, Article 1, at 24:13, benefits, with exemptions from 50% of the Automobile Tax (IA), passenger vehicles using exclusively natural gas; and with exemption from 40% those using natural gas and other fuel (bi-fuel). This legislation is available on the website of the General Directorate of Customs and Special Taxes on Consumption.

The European Union has focused efforts on the project "Blue Corridors". This aims to establish liquefied natural gas (LNG) as an effective alternative to conventional fuels for the medium and long distance transports. To this end, the project has set an LNG filling stations roadmap, creating four halls covering the area of the Atlantic, the Mediterranean and connecting the south with the north of Europe, the west with the east.

For further information, please consult:
›   Portuguese Natural Gas Vehicle Association
›   International Association for Natural Gas Vehicles
›   Natural Gas Vehicle Association-Europe
›   LNG Blue Corridors