Let's see what that means. There are ~2000 lbs/ton, so 500 tons/second. Search returns "On average, a ton of coal produces 21 to 22 gigajoules of energy." That'd imply about 1 TW worth of coal.

https://www.carbonbrief.org/mapped-worlds-coal-power-plants/ says it's 2 TW currently generated, which is (barely) within a factor of two of this.

There are ~3e7 seconds in a year, so 1.5e10 tons/year. If a ton is a bit under a cubic meter, this'd be very roughly a cube of >2km on a side.

Yeah, let's think about that.

In this video[0] of an open-pit mine, Sempertrans claims their conveyors move 6 meters per second,and elsewhere[1] they claim to move 18,000 tons an hour, ie 5 tons per second—just under 1 ton per meter of belt? It must be pretty dense, something like ~800kg/m^2? That checks out for cubes of lignite.

So only 198,000 such conveyors are needed in world.

0. https://youtu.be/b0JqGy-rs2I

1. https://easyengineering.eu/interview-with-sempertrans/