Liquefied Natural Gas (LNG)
We use methane for cooking and heating and generating electricity. It can also form the raw material for manufacture of a variety of products (clothing fibres and plastics for healthcare, computers and furnishings). When methane – a natural gas – is cooled to a temperature of approximately -160°C, at atmospheric pressure, it condenses to form a liquid: Liquefied Natural Gas (LNG). This process reduces the volume of gas by 600:1 enabling large quantities to be transported economically over long distances and to be sourced from many producing countries.
Methane is composed of one carbon and four hydrogen atoms, forming one of the cleanest, simplest and most abundant hydrocarbon fuels. In its liquefied form (LNG) it is colourless, odourless and non corrosive. LNG is a clean fuel that, when burned, is virtually free of nitrogen dioxide and sulphur dioxide.
LNG has to be converted to gas and mixed with air in the right ratio for it to burn. LNG vapours are only flammable within an approximate concentration of 5 – 15% gas in air. Outside this range it cannot burn as either the fuel or air ratios are too low. LNG, as a liquid, will not explode or burn.
History of Liquefied Natural Gas (LNG)
Natural gas was first liquefied (cooling natural gas to form Liquefied Natural Gas) in the 19th century by Michael Faraday and Karl Von Linde. However, the industry, as it is known today, commenced in the UK in 1961 when Britain signed a 15-year contract to take just under 1 million tonnes per annum (mtpa) from Algeria. Imports of gas to the UK stopped in the early 1970’s when the North Sea started production of natural gas.
The first liquefaction plant in the World was commissioned at Arzew, in Algeria, and the gas to supply this contract came from the huge gas reserves found in the Sahara.
LNG in the UK today
Over 18 million homes in the UK use natural gas. We use natural gas to heat our homes, cook food and enjoy a hot shower. Over 40% of all electricity produced in the UK comes from natural gas.
Over the next few years, as North Sea gas declines and the UK needs to import increasing amounts of gas, some of it will come through pipelines but these are dependent on one particular source of supply. LNG (liquefied natural gas) has become a viable alternative to oil or piped gas (natural gas transported from its country of origin through pipelines). Indeed, LNG is increasingly being seen as the best technology for large-scale movement of natural gas over long distances. LNG terminals provide flexibility: the gas can come from anywhere in the World, especially countries too far away to supply gas by pipeline.
Diversity and security of supply are closely linked to each other. Diversity can increase the security of supply by reducing the impact of disruption from any one source, thereby reducing the likelihood of sudden shortages. LNG has been used for many years in countries such as the USA, Korea and Japan. There is increasing use worldwide as advances in technology make LNG more economical to produce, transport and store, opening up a wider market for its use.
The UK has already been home to LNG for over 40 years. Dragon LNG’s facilities can supply a significant part of the UK’s current energy needs. There are also LNG import facilities at the Isle of Grain (Rochester, Kent) and South Hook (Pembrokeshire).