Autotrophs, plants, are the 1st trophic level and they get 100% energy from the sun. They use 90% in metabolism and pass on 10% to the herbivore that eats them, the 2nd trophic level. The herbivore uses 90% of that energy consumed and passes on 10% to the next level: 1% of the original energy from the sun. When the herbivore animal is eaten by a carnivore (3rd trophic level), it passes on 10% of the energy it had consumed: 0.1% of the original energy from the sun. If that animal is eaten by another (4th trophic level), it will be consuming 0.01% of the energy that first came from the sun.