Lignite, often referred to as brown coal, is a soft brown combustible sedimentary rock formed from naturally compressed peat. It is considered the lowest rank of coal due to its relatively low heat content. It has a carbon content of around 25-35%. It is mined in China, Bulgaria, Greece, Germany, Kosovo, Poland, Serbia, Russia, Turkey, the United States, Canada, India, Australia and many other parts of Europe and it is used almost exclusively as a fuel for steam-electric power generation, but is also mined for its germanium content in China. 26.3% of Germany’s electricity comes from lignite power plants, while in Greece lignite provides about 50% of its power needs.

Lignite is mined with big machines: Bucket-wheel excavators (BWEs). These are heavy machines used in surface mining. The primary function of BWEs is to act as a continuous digging machine in large-scale open pit mining operations. What sets BWEs apart from other large-scale mining equipment, such as bucket chain excavators, is their use of a large wheel consisting of a continuous pattern of buckets used to scoop material as the wheel turns. They are among the largest vehicles ever constructed, and the biggest bucket-wheel excavator ever built, Bagger 293, is the largest terrestrial (land) vehicle in human history according to the Guinness Book of World Records (copied from Wikipedia).