For decades, coal has been known as one of the world's most important energy sources. It powers thermal power plants, supports heavy industries, and has played a major role in economic development. However, advances in chemical engineering have revealed another surprising use for coal—it can help produce the plastic used in modern polymer banknotes. At first glance, the idea sounds unbelievable. After all, how can a black rock buried deep underground be connected to the colorful currency notes people carry every day? The answer lies in chemistry. Coal is not converted directly into money, but it can be transformed into valuable chemicals that eventually become the raw material for high-performance plastics. As more countries adopt polymer currency, this little-known connection between coal and cash is gaining attention. A Different Kind of Currency Traditional banknotes are usually made from cotton-based paper rather than ordinary paper. Although these notes are durable, they event...