In Qatar, a desert state, fresh water is scarce. Most of the water used in homes and businesses comes from the sea and must pass through energy-intensive desalination plants.
Shell engineers had to ensure that the Pearl GTL complex in Qatar – the world’s largest GTL plant – could operate without the need for a fresh, external water source. They designed what is believed to be the largest industrial complex to have a self-sufficient water system.
The GTL process itself helps by creating water. Natural gas is partly oxidised at high temperature and pressure to produce synthesis gas, a mixture of hydrogen and carbon monoxide.
This synthesis gas then reacts with a Shell-developed catalyst to make liquid products. Water is a by-product.
The water is cleansed using live microorganisms that remove chemical impurities. Then it is processed to remove salts. Most of the treated water is used to absorb the heat generated in the GTL process.
In turn, the water is converted to steam that drives the turbines generating the plant’s electrical power.
Pearl’s treatment plant is able to handle 280,000 barrels of water a day – or over half a tonne of water every second.
Pearl GTL achieved full production towards the end of 2012. It has the capacity to produce 140,000 barrels of oil equivalent (boe) a day of liquid products such as cleaner-burning diesel and aviation fuel, and oils for advanced lubricants. Pearl also has the capacity to produce 120,000 boe a day of condensates, liquefied petroleum gas and ethane for industrial uses.