Will it replace chemical lights?

Tell you what. Let's put you in a darkened room full of an explosive gas-oxygen mix and have you pull out a light and read a newspaper. You can either pull out a chemical light or a Life Gear Glow Stick. Knowing that any spark will mean a violent and painful death should make your choice for you.

You might also consider what you want to carry if your using the light on the ocean and will need it after it has been in saltwater spray for a few months.

Chemical lights are not perfect. They have weaknesses. They deteriorate in performance as they age, particularly if the foil wrapper is breached. The light is not all that bright, they only run for about 12 hours and once activated they can't be turned off to extend their useful life, and once expended they are useless.

On the other hand they are safe around explosive atmospheres. They are immune to most corrosive agents and solvents. They are non-toxic, cheap, reliable as long as they are rotated, and they are both light and compact.