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.
Aperture vs. Shutter Speed. In photography, aperture (also called f-number) refers to the diameter of the aperture stop (the stop that determines the brightness in a photo at an image point). Shutter speed on the other hand, is the total amount of time the shutter of the camera is open.