NET4GAS, s.r.o. is the holder of an exclusive gas Transmission System Operator (TSO) licence in the Czech Republic. Under this licence it carries out the transit of natural gas across the Czech Republic, imports gas to the Czech Republic from suppliers abroad, and transports gas at the national level to its domestic partners. In accordance with the Czech Energy Act (Act No. 458/2000 Coll., as amended), it grants access to the transmission system in line with the principle of third party access. NET4GAS also transports natural gas from underground gas storage (UGS) facilities. It is a member of the Czech Gas Union and Gas Transmission Europe (GTE), the European association of gas transmission system operators.
The unbundling of gas transmission and gas trading activities was required by EU directives and under an associated amendment of the Czech Energy Act. As of 1 January 2006, gas companies were therefore divided into two independent legal entities – in our case, the transmission system operator NET4GAS and the gas trader RWE Transgas. This made room to allow the entry of further traders who had decided to sell natural gas on the Czech energy market.
Czech customers consume around ten billion cubic metres of gas each year, but domestic resources can cover only one percent of that volume. The rest of the country’s gas must be imported - at the present time 75 percent of imports come from Russia and the remaining 25 percent from Norway. The Czech Republic’s transmission system has been in operation since 1973, and over the entire period of this cooperation with foreign partners there has not been a single serious failure of supply. Even if one were to occur, thanks to its underground gas storage facilities, whose total capacity amounts to almost three billion cubic metres, the Czech Republic has a sizeable reserve supply.
NET4GAS has a transit system composed of gas pipelines with a total length of 2,455.5 km. It is connected together by a system of five compressor stations and twenty-two national transfer stations. The pipes of the network have a nominal diameter ranging from DN 800 to DN 1400, and transport gas at nominal pressures of 6.1 MPa, 7.35 MPa and 8.4 MPa.
A set of national transfer stations connect the transit system to the national network, which consists of pipes of sizes DN 80 to DN 700, with a total length of 1,183 km. During transport, the gas pressure ranges from 4 MPa up to a maximum of 6.1 MPa, which is the pressure that 85 % of the pipes are designed for. From this national network, gas is then transferred via a further 75 transfer stations to the distribution systems of regional distribution companies and to direct customers. Custody transfer metering of the quantity of gas is installed at all these transfer stations, and the quality of the gas is measured at 15 junction points of the system.
When it enters or exits the Czech Republic gas is transferred from one operator to another. This is carried out at four border transfer stations. Two of these are on the Czech side of the border, at Hora Svaté Kateřiny and Lanžhot, and the other two are situated in Germany, at Waidhaus and Olbernhau. During the transfer of gas, measurements are also made of its quantity and quality.
Compressor stations ensure that the gas in the pipeline has the required pressure. On the Czech Republic’s transmission system they are spaced at approximately 100 km intervals, at the towns of Kralice nad Oslavou, Kouřim, Břeclav, Hostim and Veselí nad Lužnicí. Their total installed capacity is 351 MW.
Natural gas is a naturally occurring, colourless, tasteless and odourless gas, with a high calorific value and excellent properties for its use. It consists of a mixture of gaseous hydrocarbons and non-flammable components (in particular nitrogen and carbon dioxide), and is characterised by its high methane content.
There are several theories about this topic. Since natural gas is most frequently found together with oil (associated petroleum gas) or with coal (coal bed methane), it is generally thought that gas was released during the formation of these other minerals as a result of the gradual decomposition of organic matter. Natural gas may therefore have been produced by the decay of plant and animal remains. According to another theory, however, it was created from inorganic materials by a series of chemical reactions. In recent times, American scientists have also put forward an “abiogenic” hypothesis, according to which natural gas results from the cracking of hydrocarbons which accumulated on our planet during its formation from cosmic material. Over time, these higher hydrocarbons gradually broke down into methane, which then rose through the mantle to the surface of the Earth.
This is mainly due to the positive effect of natural gas use on improving the state of the environment. Without exaggeration, it can be called a truly environmentally-friendly fuel. It does not pollute the air with sulphur dioxide (SO2) or ash and dust particles to which carcinogenic substances attach, and during its combustion natural gas produces only thermal nitrogen oxides, so that its NOx emissions are just 25-30 % of those for coal, or 30-40 % of those for liquid fuels. In terms of carbon monoxide, emissions from burning natural gas are two orders of magnitude lower than in the case of coal, and its CO2 emissions are also 40-50 % less than those of solid fuels, and 30-35 % lower than for liquid fuels.
Gas pipelines run underground, so they have no impact on the appearance of the landscape. The metre-wide pipes are laid a metre below the surface, and the width of the construction corridor can be limited to a mere thirty metres. In optimal conditions, the land above the pipeline can be returned to its original use two years after the first trench was dug.
Natural gas is on-hand for users 24/7 and 365 days a year. Gas appliances make the regulation of heating very quick and easy. Operation is simple – all that is needed is to switch the appliance on at the start of the heating season and switch it off at the end. Customers are directly connected to the distribution network, so they do not have to build up stocks or arrange for fuel supplies. Natural gas thus offers savings on investment costs.
Because natural gas must cover thousands of miles to get from the well to the customer, its long-distance transportation is the most difficult stage in the whole process. There are two possible means for doing this - by pipeline, or by tankers carrying gas in compressed or liquefied form. Pipelines run not only over dry land, but also across the beds of seas. Tankers are used for transportation by sea when the distances are very large - e.g. compressed natural gas (CNG) and liquefied natural gas (LNG) are supplied to Europe this way from Algeria, Nigeria and even Australia. Although LNG is not yet used in the Czech Republic, RWE is participating in the construction of terminals on the Croatian island of Krk and at Rotterdam in the Netherlands, and believes that LNG could be a potential future source of natural gas for Czech customers. Both terminals should start operation around 2010.