The intention was not to provide an alternative to your current lighting methods and reduce the drain on the National Grid, but to provide something that can provide a quaint decorative eco-friendly light source.

If you like big words then try photoluminescence, it has something to do with how the Glow brick works.

Recharges from energy in natural light during the day.
Glows at night. Made with a real light bulb trapped in a solid acrylic brick.

• Simply charge the glow brick up in sunlight or via a lightbulb, take it into a dark room and leave it glowing in darkness - it'll work for up to about 3 hours.
• Made from phosphor luminescent material and encased in acrylic.
• Size 110 x 80 x 80mm.