In an increasingly complex world framed by a rising global population, finite natural resources and climate change, the term ‘eroi’ refers to the ‘energy return on investment’. EROI is a measure of the amount of energy that can be extracted from a resource in relation to the energy used to access and harvest the resource. A good EROI is reflective of an energy source that is economical to access and long term sustainable. This concept is important in considering renewable energy sources and provides an understanding of how efficiently energy is used which is critical in an effort to reduce our global footprint.​

See also: exponential growth, ecological footprint, renewable energy, nuclear power, fossil fuel