Concrete pavers with embedded phosphorescent crystals can emit light every night for about 10 hours without added electricity, making them an eco-friendly source of light. Developed by German-based manufacturers Kann and NightTec, the NightTec Leuchsteine are charged with sunlight by day and reduce the need for artificial light. They can be used as a surface finish in both interior and exterior spaces, including stairways, emergency paths and to mark door handles. The technology has a potential to save 212 million megawatt-hours annually in Germany.

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