What is eroi?

EROI, or Energy Return on Investment, is a measure that evaluates the amount of energy gained from a particular energy source relative to the energy invested in extracting, processing, and delivering that energy. It is expressed as a ratio; for example, an EROI of 20:1 means that 20 units of energy are obtained for every unit expended. A higher EROI indicates a more efficient and sustainable energy source, while a lower EROI suggests greater energy input is required for lesser returns. Understanding EROI is crucial for assessing the viability and sustainability of different energy resources.