Ideally, a hydrogen fuel-cell vehicle has no environmental impact. Energy is produced by combining hydrogen with oxygen pulled from the atmosphere, and the tailpipe emission is water. The hydrogen fuel could come from a number of sources (Iceland recently started pulling it out of the ground).
A fast shutter speed such as 1/400th of a second will produce a series of crisp frames that have a choppy look when played back. A slow shutter speed such as 1/30th of a second, on the other hand, will produce a series of slightly blurred frames that have a smoother look when played back.
In your camera's viewfinder, a shutter speed of 1/4 is displayed just as 4. A shutter speed of 4 seconds is displayed as 4  (with a double quotes afterward to indicate whole seconds). Shutter speed is the amount of time that the camera is permitting light from the lens to hit the film or digital sensor.