Energy Return on Energy Invested (EROEI)

Energy Return on Energy Invested (EROEI) measures how much usable energy is gained from an energy-producing process compared to the amount of energy required to make it happen. For example, if you spend 1 unit of energy to extract or generate a certain energy source and end up with 10 units of usable energy, the EROEI is 10. A higher EROEI indicates a more efficient process, meaning more energy output relative to input, which is crucial for understanding the sustainability and economic viability of different energy sources.