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.
Panning at slow shutter speeds. Although the shutter speeds and apertures are interchangeable as far as exposure is concerned, double the time the shutter is open and halve the size of the lens aperture to get the same exposure, they each have their own unique effect on the picture.