Main content | back to top
Coal gasification
Coal is the world’s most abundant fossil fuel, with estimated reserves of almost 1 trillion tonnes. Burning it releases greenhouse gases, toxic heavy metals, and sulphur which is a main cause of acid rain.
Major economies such as the United States, China and India are turning to coal gasification technology to unlock the value of their vast coal reserves more cleanly than conventional methods and to reduce their dependency on imported energy that is often more expensive.
Shell’s coal gasification technology turns coal and coke feedstocks into synthesis gas (syngas), a mixture of hydrogen and carbon monoxide that burns as cleanly as natural gas. Syngas can then be used to produce a wide range of high-value products such as electricity, fertilizers, transport fuels and chemicals.
Compared to conventional coal-fired power plants, those producing electricity using the coal gasification process emit less CO2 and pollutants. Moreover, the CO2 from gasification can be more easily captured than from smokestacks – potentially for storage underground.
To create the syngas, pulverized coal is mixed with oxygen and steam at 1,400-1,600°C (2,552-2,912°F). Shell’s technology uses compressed nitrogen to transport a dense stream of coal into the gasifier – a more efficient approach than the slurry of coal and water used by other techniques.
The process produces a number of by-products which is sold for use in other industries: Fly ash is used in the cement industry; sulphur is used to make fertilizer and for chemical applications; and slag is used in building materials and road fill.
Shell’s technology uses a protective layer of steam-filled pipes in the gasifier, which lasts the life of the plant and prevents molten slag from damaging the interior walls. In most rival processes, the brick gasifier walls are gradually eaten away by hot slag and must routinely be replaced, causing shutdowns that reduce efficiency. The technology can be designed to a wide range of coal qualities. Once designed, the composition of the coal fed to the gasifier needs to be of a consistent quality within the range the equipment is designed for.
Shell’s involvement in gasification began in the 1950’s. In the1970’s the technology was further developed and coal was added to the range of feedstocks. The first commercial-scale plant using Shell’s coal gasification technology started up in 1993 with a power plant in Buggenum, the Netherlands. Now the technology is licensed around the world, including to China, Vietnam, United Kingdom, Australia, the Netherlands, and South Korea. Most of the licences are in China which has the world’s second largest reserves of coal and relies on it for 70% of its energy.
Page Tools
Discover more
King Coal comes clean
Burning coal to generate power produces the noxious gases and heavy metals that cause acid rain. A cleaner and more energy-efficient way of using coal is to gasify it.