In recent years, several projects have been developed to explore alternative energies. Among the main requirements for these new energy sources are that they be widely available and low in environmental emissions. Natural gas is one of the most promising candidates.
Within these projects, Linde Gas has performed numerous activities, both in terms of technology and the construction and operation of plants and the supply of industrial gases.
Clean energy and immediate application
Together with hydrogen, considered a promising future source of energy, the use of natural gas as fuel has been attracting increasing interest, both in terms of use and mobile or stationary units. This is because, while the infrastructure for the widespread use of hydrogen will only be available in the medium to long term, natural gas today already represents an ecological and economic alternative to the use of refined oil, even as a source of fuel for vehicles. Additionally, large natural reserves of this gas guarantee its long-term availability.
Natural gas is composed primarily of methane (CH4), which ensures combustion with very low emissions. Compared with the petrol engine, emissions resulting from the burning of natural gas contain up to 80% less CO and NOx. Moreover, the release of carcinogens, such as benzene and carbon particles, is practically nil. For these reasons, natural gas significantly reduces air pollution caused by vehicles in major population centres.
High concentration of energy in liquefaction
In vehicles, natural gas may be used in compressed form (CNG = Compressed Natural Gas) or in liquid form (-162°) (LNG = Liquefied Natural Gas). The latter alternative leads to a drastic reduction in gas volume, therefore offering the advantage of providing more efficient use of tank capacity, significantly increasing autonomy.
Against this background, a natural gas liquefaction plant has been operating for three years in the town of Gablingen, Germany, the result of a partnership with “Bayernwerk AG” and “Erdgas Südbayern GbmH (ESB)”. In this plant, natural gas is collected from the ESB pipeline network, purified by absorption and cooled with liquid nitrogen (-196°C) to a temperature of -162°C, which transforms it into a clear liquid. The LNG is then stored in a 30 ton tank, from which customers are supplied using tankers suitable for transporting this type of product. The annual production capacity of this plant is 6.000 tonnes of LNG.
Combined CNG/LNG gas station
For several pilot projects where natural gas is used as fuel for engines, Linde Gas has developed an appropriate filling station. Within the ESB company in Wolfratshausen (Bavaria), the first combined CNG / LNG gas station started operating, which, after a period of several months of testing, was incorporated into the public network of service stations belonging to ARAL in Munich in November 2000. At this station, customers may refuel directly either with LNG or CNG obtained through compressing and subsequently vaporising the liquid. A patented cooling technology ensures no methane vapour escapes into the environment during the storage and supply of LNG provided by Linde from the Gablingen liquefaction plant.
Natural gas for forklifts
An interesting refuelling station project has been developed by Linde Gas in Austria, in partnership with Steirischen Ferngas AG. On the premises of the Brauerei Puntingam Brewery in Graz, a CNG station was installed, which used a connection to the existing natural gas network to compress it at high pressure. Currently, this station supplies CNG for 30 forklifts that until now were working on propane. Advantages of this alternative:
Operational savings, since the fuel is cheaper
CNG-powered forklifts may also be used in closed environments without having to comply with the stringent regulations enforced for propane engines
The time taken to refuel the forklifts is very short: 30 to 40 seconds for gas tanks of 60 litres/200 bar
Measuring the fuel level is simple, i.e., through the use of a pressure gauge.
Natural gas-powered locomotives
Natural gas is not only recommended for use with light vehicles. Under a project developed by Linde Gas in partnership with “Deutsche Bahn”, a "Kof 360877" shunting locomotive was converted to operate using LNG. For this project, Linde installed an LNG fuelling station at a site near the main railway station in Munich, providing a steady supply of natural gas.
All the above projects have one thing in common: they show that natural gas, both in liquid form and in compressed form, is competitive with petroleum-based fuels, even surpassing them in terms of low emissions.