Idling cargo ships use enough electricity to power cities

When a giant container ship docks, it doesn't simply turn off. To keep refrigeration units running and lights on, these vessels traditionally burn heavy diesel in their massive auxiliary engines, emitting as much pollution as thousands of idling cars. Engineers in ports like Rotterdam are solving this by treating ships like giant appliances. They use 11,000-volt cables to deliver 10 megawatts of power directly from the shore, a process known as cold ironing.