ARTICLE / MAKALE alized everywhere. note most sites wi ll have other gas loads an site which means that these sizes give a rough approxi mation. ►►► THE SITUATION iN UK GENERAL Up to 2 200 000 kWh per year Connection to L TS at Low Pressure Up to 100 kWe CHP 2 200 ooo to Privatisation of the UK's gas market started with the Gas Act 1986 which created a competitive market for gas i nitially for customers consumi ng over 73 275 kWh per year and from 1998 all customers were able to select thei r gas suppliers. in 1995 amendments to the Gas Act split the 58.6 rnillion kWh per year Connection to LTS either at Mediurn or lnterrnediate Pressure 100 kWe to 3 Mwe CHP 58.6 rnillion to 1 465.5 rnillion kWh per year Connection to LTS either at Mediurn or lnterrnediate Pressure 3 MWe to 75 MWe CHP Over 1 465.5 rnillion kWh per year Connection to the NTS Over 75 MWe CHP i ndustry into gas transporters, gas shi ppers and gas suppliers. Gas transporters own and operate gas pi peli ne networks, gas shippers contract with the transporters for gas to be shipped through the transport networks usually from the beach to the customers of a gas supplier. Gas suppli ers seli gas to customers, and if they are not themselves a shipper contract with a shipper. Over 60 gas supply companies compete for i ndustrial and commercial customers, and i n 1998 competition was extended to all residenti al customers. The largest gas transporter is Transco which operates the National Transmission System as well as loca! networks, a further 6 transporters have l icences for local networks. AII transporters are responsible for transmission and meteri ng of gas and safety issues and for faci litati ng connection to thei r network. As the domi nant transporter the following concentrates on the procedures and costs of connecti ng to Transco's system. Network Description Transco's network of 270 000 km of pipeli nes extends from the delivery of gas at the beach to the meters at nearly 20 mi l l ion customers premises. The mai n network zones are: in each case the regulations, connections and options are sl ightly different. For connections under 2 200 000 kWh Transco has a statutory duty to connect premises if they are withi n 23 metres of a relevant gas mai n-subject to a charge for supplyi ng and layi ng the pipe. For single premises the fi rst 1 O meters of pipeli ne outside the premises is free of charge. For higher volume connections the options and requi rements are more complex, and as most cogeneration· capacity comprises schemes over 100 kWe the followi ng secti ons concentrates on the issues for connection of cogeneration schemes over 1 00 kWe to the higher pressure networks. Transco's 'Connection Guideli nes' explai ns the approach to each different type of connection separate Connections Chargi ng Statement provides detai ls of the methods used to charge for connection. Connections over 2 200 000 kWh For these connections Transco has a duty to comply with requests to connect - where economical. Connections under 5 860 000 per year can only be connected on a firm (uni nterruptible) basis, connecti ons for volumes greater than this can be on a fi rm or an i nterruptible basis. Sites can contract with Transco to provide siteworks - where Transco bui lds and owns the pipeline, with excavation Network Zone Pressure Network size of trenches either by Transco or the site's contractor. The connection costs include the pipeli ne, Nationaı Transrnission System (NTS) Local Distribution Zones (LDZ) - 12 areas cornprising: Local Transmission System (LTS) lntermediate Pressure Mediurn Pressure Low Pressure Connections 38 to 75 bar 24 to 38 bar, but can cycle as low as 1 O bar as this network is used to bufler daily gas demand 2 to 7 bar 75 mbar to 2 bar 19 to 75 rnbar 6000 km connected pressure reduci ng equipment, a safety isolati on to 12 LDZs 1 1 891 km with 2 400 pressure reducing stations 3 500 km 31 000 km 215 000 km with 98% of customer connections valve, volume conversion and data loggi ng equipment and the supply meter. in these cases Transco's terms and conditions for siteworks would apply - except for high value connection costs where a special construction agreement may apply. Alternatively the site can opt for self-lay. The i nstaller and Transco will have to exchange design i nformation to enable an appropriate connection to the network. The i nstaller will also be responsi ble The procedures for connection to the Transco gas system depend on the annual volume of gas, which wi ll be taken from the system. The followi ng table l ists the different volume l imits and converts these i nto approxi mate size of cogeneration plant based on the esti mated annual gas usefor prepari ng a safety case for the pipeli ne. Transco wi ll provide a supply meter once a gas shipper has been appointed. Subject to a number of conditions such as safety issues Transco may take ownership of the pi pel ine once bui lt. For self-lay connections and i n some special cases Transco may requi re a NExA(Network Exit Agreement) COGENERATION WORLD & Reneable Energy �ı
RkJQdWJsaXNoZXIy MTcyMTY=