在19世纪以前,世界的科学技术水平还很落后,人们使用的燃料是固体燃料,如木材和煤炭,这样的时代叫固体燃料时代。人类进入20世纪后,科学技术突飞猛进,使得对石油的开采愈来愈厉害,石油的产量愈来愈高,人类进入液体燃料时代。可是,在地下经历了亿万年积累的煤和石油,终将有消耗尽的时候,而且这样的时候已经为时不远了。所以,科学家提出,21世纪将是燃气时代。21世纪前半期,人类将以天然气为主要能源。一方面,天然气的资源暂 Before the 19th century, the science and technology level of the world was still lagging behind. People used fuels such as wood and coal as solid fuels. This era is called the age of solid fuels. After mankind entered the 20th century, science and technology advanced by leaps and bounds, making the exploitation of oil more and more powerful. The output of petroleum became higher and higher, and mankind entered the era of liquid fuel. However, coal and oil that have accumulated over the past billions of years will eventually be exhausted, and this time is not far away. Therefore, scientists propose that the 21st century will be the era of gas. In the first half of the 21st century, humans will use natural gas as the main energy source. On the one hand, natural gas resources are temporarily