A battery electric multiple unit (also known as a BEEMU) is a type of train that runs on electricity. Instead of burning fuel like a regular train, it gets its power from batteries. The batteries are charged up with electricity from the power grid and the train uses that electricity to power its motors. BEEMUs are cleaner and more efficient than regular trains, and they don't produce any air pollution. They are also quieter and more cost-effective to run.