What percentage of energy, available at the producer level is transferred at successive trophic levels in a food chain? 

Lindermann (1942) stated the 10% law of energy transfer in an ecosystem. According to this law, only 10% of energy is transfer from one trophic level of the food chain to the next, rest 90% of it is lost as heat into the environment  and some of it is used in digestion or respiration and for doing other work like growth, repair etc. Plants absorb 1% sun energy for primary production and can store only 10% of the utilized energy as net production available for the herbivores. When the plants are consumed by animal, about 10% of the energy in the food is fixed into animal flesh which is available for next trophic level (carnivores). When a carnivore consumes that animal, only about 10% of energy is fixed in its flesh for the higher level.