has a rich cultural history much of it steeped in storytelling. Many people know the Christmas story of Santa and what happens if you misbehave during the year - a lump of coal is placed inside your stocking. A positive tradition practiced in Scotland and North England is giving someone a piece of coal on New Year’s Day as a sign of good luck and a wish for warmth in the year to follow.
Coal has long been known as a fossil fuel, a source of energy in the production of electricity. It is also commonly known and purchased as briquettes used in BBQ’s, open fire places and braai’s (a South African term for an outdoor fire-lit BBQ). Coal can also be converted into a liquid fuel like diesel or gasoline through several different processes.
What Is Liquid Coal?
Liquid coal is the result of coal liquefaction – the process of converting Coal to Liquid fuel (CTL). According to the World Coal Association
, two different conversion processes exist:
1. Direct liquefaction - works by dissolving the coal in a solvent at high temperature and pressure. This process is highly efficient, but the liquid products require further refining to achieve high grade fuel characteristics.
Beyond Fossil Fuel
2. Indirect liquefaction - gasifies the coal to form a ‘syngas’ (a mixture of hydrogen and carbon monoxide). The syngas is then condensed over a catalyst – the ‘Fischer-Tropsch’ process – to produce high quality, ultra-clean products.”
describes further how the liquefaction process is used at Sasol, one of the pioneers of Liquid Coal.
“The Sasol plant in South Africa uses an advanced form of the Fischer Tropsch process developed in Germany in World War II where steam and oxygen are passed over coke at high temperatures and pressure producing hydrogen and carbon monoxide are then liquefied. During the process sulphur, ash and carbon dioxide are removed. The sulphur is sold as a by product and the carbon dioxide can be injected underground.”
The concern of using coal liquefaction is the disposal of carbon dioxide, a by-product of the process. If carbon capture and storage facilities are not employed, the CO2 emissions greatly affect the carbon footprint of greenhouse gases causing more environmental damage. However, if proper equipment, storage facilities and plant designs are incorporated the process becomes a lot cleaner. Because the coal is gasified - and not burned like in conventional coal plants - the impurities will be removed from the synthesis gas and embedded in the ash by-product, making it a cleaner process.
What Is Liquid Coal Used For?
Liquid coal can become a petroleum substitute and be used in the transportation industry. It is used as alternative liquid fuels like methanol and dimethyl ether (DME), it is also used in lubricants, synthetic waxes and chemical feed stocks.
Where Is Liquid Coal Produced?
The Sasol plant in South Africa has been producing liquid coal since 1955. More plants are being opened across the world and China is notably creating the two biggest liquid coal plants in the world. Large coal reserves are found in the United States, China, India, Russia, Ukraine, Germany, Poland, South Africa and Australia, with most countries starting new Coal to Liquid projects.
Due to the concerns of the CO2 emissions organisations are researching new technological advancements in the liquid coal process. Below is a YouTube video of PhD students at the University of the Witwatersrand in South Africa who are working jointly with China in testing and creating these new processes.
Liquid coal is achieved through a process of liquefaction where coal is converted into a liquid fuel like gasoline or diesel. Concerns about carbon dioxide emissions have held back large productions of this process. South Africa has the only commercial Coal to Liquids industry in operation today but new projects and plants are beginning across the world. The goals for most companies are to diversifying the liquid fuel supplies and avoid reliance upon crude oil.
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