During the Industrial Revolution, the improvement of steam engines greatly improved the utilization efficiency of coal. The coal required for the new steam engine is only 1/10 of that of the old model. Therefore, many people believe that the demand for coal will drop significantly. However, three years later, it was found that due to the reduction in costs, steam engines were not only widely used in locomotives, but also gradually introduced into factory production, textile machines and other equipment, which eventually led to a significant increase in coal demand. AI seems to be the same today