Calculadora de Tempo de Retorno Energético
Calcule quando um sistema energético devolve a energia usada para produzi-lo.
Energy Payback Time
1.7 years
Energy Payback Time vs Embodied Energy (Manufacturing)
Formula
How to Calculate Energy Payback Time
Energy payback time (EPBT) measures how long a system must operate to produce the energy used in its manufacture.
Formula
EPBT = Embodied Energy / Annual Production
EROI = Lifetime Production / Embodied Energy
Typical Values
Exemplo Resolvido
A solar system with 20 MWh embodied energy producing 12 MWh/year over a 25-year lifespan.
- 01Energy payback: 20 / 12 = 1.7 years
- 02Lifetime production: 12 * 25 = 300 MWh
- 03Net energy: 300 - 20 = 280 MWh
- 04EROI: 300 / 20 = 15x
Perguntas Frequentes
What is energy payback time?
Energy payback time (EPBT) is the time a system must operate to generate the energy consumed during its manufacture, transport, and installation. Lower is better.
Do solar panels produce more energy than they use?
Yes, by a large margin. Modern solar panels pay back their embodied energy in 1-3 years and then produce clean energy for 22-27 more years. Their EROI is 10-20x.
What is EROI?
Energy Return on Investment is the ratio of energy produced over a lifetime to energy invested in manufacturing. An EROI above 5x is considered good for energy sources.