LNG (liquefied natural gas) stations are also able to dispense biomethane. In this case the stations are sometimes referred to as LBM (liquefied biomethane) stations.
LNG stations consist of a cryogenic tank and a fuel dispenser. They deliver liquid fuel to the vehicles at a pressure of 30 to 120 PSI. If LNG is not regularly drawn from the stations it may suffer from very slow fuel loss as heat ‘boils off' the stored LNG and increases the pressure in the storage tank. To avoid unnecessary emissions of methane, which is a powerful greenhouse gas, modern stations have vent capture systems to avoid any unwanted release of gas. Stations are designed to ensure an optimal storage capacity that allows for regular LNG deliveries to maintain a low temperature in the storage tank. The increasing number of publically-available LNG refuelling stations in the UK is allowing more fleets to convert to LNG vehicles without the added complexity of managing onsite refuelling facilities.
CNG (compressed natural gas) stations are also able to dispense biomethane. In this case the stations are sometimes referred to as CBM (compressed biomethane) stations.
CNG stations can either have a direct connection to the national grid or have CNG delivered via a tanker. Grid connected CNG stations allow an efficient and cost effective supply of natural gas to be compressed into site storage tanks. The suitability of the station grid connection is dependent on the pressure and distance to the national gas network, low pressure or distant gas networks provide uneconomic station performance. Mother and Daughter station arrangements can also be used where a Mother-grid connected CNG station will supply a local Daughter station (via a tube trailer) with a regular supply of CNG.
A fast fill grid connected CNG station maintains sufficient site CNG storage to allow vehicles to be filled in minutes. Where vehicle use is less intensive (RCVs for example), slow fill stations can be utilised. Here the natural gas is compressed directly into vehicle tanks over a number of hours, saving the cost of site pressurised vessel gas storage.
LCNG (liquefied to compressed natural gas) stations are also able to dispense biomethane. In this case the stations maybe referred to as LCBM (liquefied to compressed biomethane) stations.
LCNG is the term used for a station that supplies both LNG and CNG. LNG is stored in and delivered from a cryogenic storage vessel as per in a dedicated LNG station. LNG is vaporised and compressed into storage tanks to add CNG functionality to the station. A sophisticated LCNG station may also utilise any ‘boil off’ from the LNG tank to compress into CNG.