Production plant to turn coal into ethanol

China is set to start production of the world's largest coal-to-ethanol plant in September, which will be capable of producing over half a million metric tons of the key industrial ingredient each year, according to the Chinese Academy of Sciences.

Experts said the feat will cement China as a global front-runner in converting coal into pure ethanol, and it holds great significance in safeguarding China's food and energy security since it can turn low-quality coal into highly versatile chemical products without using grain or sugar cane.

The process used at the plant, which is located in Yulin, Shaanxi province, has been jointly developed by the academy's Dalian Institute of Chemical Physics and Shaanxi Yanchang Petroleum Group. Once in full operation, the plant will be able to convert over 1.5 million tons of coal into ethanol and other chemical products each year, potentially saving 1.5 million tons of grain if it were used to make ethanol.

"Ethanol is a chemical product with major strategic importance given its wide use in industries such as energy and health, as well as in our daily life," said Liu Zhongmin, director of the Dalian Institute of Chemical Physics.

For example, around 66 percent of all the ethanol produced in the world is mixed with gasoline and turned into biofuel that can improve fuel efficiency and reduce the carbon footprint of transportation.

In 2019, the world produced around 86.7 million tons of biofuel, with the United States and Brazil the two biggest manufacturers. Industries typically make ethanol via fermentation using food crops such as corn and sugar cane as feedstocks.

For China, it needs biofuel to improve its energy efficiency and reduce its reliance on imported oil. However, it is impractical for China to use food to create ethanol and biofuel since the country has a massive population to feed and is also reliant on imported grains, Liu said.

"What we do have in abundance is coal. Hence finding effective ways to convert coal into ethanol can safeguard our energy and food securities, as well as help us achieve our carbon goals," Liu said.

China's two carbon goals refer to achieving carbon dioxide peak emission by 2030 and carbon neutrality by 2060.

Scientists around the world have tried numerous methods to create ethanol with fossil fuel instead of crops, but these approaches are either too complex, too expensive or too hazardous for industrial-scale production.

In 2017, China launched the world's first plant capable of producing 100,000 tons of ethanol per year using coal, which was also developed by Liu and his team. The latest plant is essentially a supersized version using a similar production technique.

Liu's route uses cheap catalysts to convert syngas, a mixture of hydrogen and carbon monoxide, into dimethyl ether, which is further processed into methyl acetate. Then engineers add hydrogen to convert methyl acetate into methanol and ethanol.

Liu said this route has several advantages, namely it doesn't need expensive metal catalysts; the end product of ethanol is easy to extract; the process is safer compared to other routes because it doesn't create acid byproducts; and the ingredients involved in the reaction, such as methyl acetate, are also useful chemical products.

Several companies are building new plants across China, and by 2025, these plants' combined production capacity will reach around 4 million tons of ethanol each year, with an industrial value of around 25 billion yuan, Liu said.

"This route is also good for the environment because we can recycle emissions from steel plants, which contain the hydrogen and carbon monoxide that we need for our production," he said.

"It will be a win-win for the steel, energy and environmental protection sectors."

Zhu Wenliang, a researcher from the Dalian Institute of Chemical Physics, said that in the foreseeable future, coal will still be a mainstay in China's energy structure.

Therefore, using coal to create chemical products will allow China to substitute oil when making these key industrial chemicals, lowering its dependency on imported oil.

"This will have strategic significance in safeguarding our country's energy security," he said.