A new coal gasification technology called SES was improved based on existing methods for turning coal into gas using a fluidized bed and a U-gas circulation system. The researchers evaluated 9 different foreign coal gasification technologies being used in China. They focused on the U-gas method, explaining its benefits like efficient gasification of common Chinese coal types and by-products like gangue from coal washing. They described an example where the SES technology was used for cleaner energy production and to help small fertilizer businesses in China by improving their raw material processes. The technology was found to be effective at gasifying lignite, a type of coal widely found in China, as well as coal by-products like gangue.