Energy returned on energy invested

Energy Returned on Energy Invested (EROEI) is a way to measure how much energy we get back from something compared to how much energy we put into it. It's like a savings account; if we put money in the bank and get more money back after a certain amount of time, it's a good thing. EROEI is the same concept but with energy instead of money. If we use energy to make energy or make something else, like electricity, we want to make sure we get more energy back than what we put in. That's what EROEI measures.