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).
4) Fast, Slow and Long Shutter Speeds. Fast shutter speed is typically whatever it takes to freeze action. For me, it is typically above 1/500th of a second for general photography and above 1/1000th of a second for bird photography. NIKON D700 @ 420mm, ISO 450, 1/2000, f/5.6.
Slowest Practical Shutter Speed for Handheld? I have never heard of the film speed rule but I have heard of the lens focal lengh rule. I use the focal lengh rule alot but I have had good results at 1/8 and 1/15 of a second. I do mostly portaits so I use a tripod 70% of the time.