Hello, I am Horníček! Come underground with me: we will learn to recognise rocks, minerals and raw materials.
What do you want to do?
Level
Contest
Renewable sources are constantly replenished (the Sun, wind, water, wood, the Earth’s heat). Non-renewable sources (hard and brown coal, oil, natural gas) took millions of years to form, so one day they will run out. That is why it is important to save energy.
🖼️ Rock gallery · Photographs from Wikimedia Commons, the authors are listed in the gallery.