passengers) and London Stansted Airport (18.9 million passengers). London Heathrow Airport, located west of the capital, has the most international passenger traffic of any airport in the world and is the hub for the UK flag carrier British Airways, as well as Virgin Atlantic. Energy In 2021, the UK was the world's 14th-largest consumer of energy and the 22nd-largest producer. The UK is home to many large energy companies, including two of the six major oil and gas companies – BP and Shell. The total of all renewable electricity sources provided 38.9 per cent of the electricity generated in the UK in the third quarter of 2019, producing 28.8TWh of electricity. The UK is one of the best sites in Europe for wind energy, and wind power production is the country's fastest-growing supply; in 2019, almost 20 per cent of the UK's total electricity was generated by wind power. In 2023, the UK had 9 nuclear reactors normally generating about 15 per cent of the UK's electricity. Unlike Germany and Japan, there are currently two reactors under construction and more planned.In the late 1990s, nuclear power plants contributed around 25 per cent of the total annual electricity generation in the UK, but this has gradually declined as old plants have been shut down. The UK government is investing in Small Modular Reactors and Advanced Modular Reactors research and development. In 2021, the UK produced 935 thousand barrels per day (bbl/d) of oil (and other liquids) and consumed 1,258 thousand bbl/d. Production is now in decline and the UK has been a net importer of oil since 2005. , the UK had around 2 billion barrels of proven crude oil reserves. In 2021, the UK was the 21th-largest producer of natural gas in the world. Production is now in decline and the UK has been a net importer of natural gas since 2004. In 2020, the UK produced 1.8 million tonnes of coal falling 91% in 10 years. In 2020 it had proven recoverable coal reserves of 26 million tonnes. The UK Coal Authority has stated that there is a potential to produce between 7 billion tonnes and 16 billion tonnes of coal through underground coal gasification (UCG) or 'fracking', and based on current UK coal consumption, such reserves could last between 200 and 400 years. Environmental and social concerns have been raised over chemicals contaminating groundwater and minor earthquakes damaging