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.
However, there is a limit. You cannot use this rule for very slow shutter speeds unless you use a tripod. For example, if you are photographing a landscape scene at 20mm then I can promise that setting your shutter speed to 1/20 of a second will not advance your clarity.