This paper documents the origin and conceptual ambiguity of the terms Sustainable, Ecological and Agroecological Intensification. It defines the concept of Ecological Intensification from an agroecological perspective, and examines in energy terms whether it may be sustainable. To illustrate the theory, we apply Land Cost of Sustainable Agriculture (LACAS) methodology to Spanish agriculture, which is representative of Mediterranean agroclimatic conditions. As a result, we demonstrate the impossibility of generalizing an extensive Organic Farming (OF) scenario under the techniques currently used by organic farmers. This is due to the fact that it would bring about a reduction of 13% in agricultural production. Which necessarily means that OF has to be intensified under agroecological criteria. This option is also explored in two scenarios. As a result, we show that it is possible to compensate the yield gap between OF and conventional agriculture by implementing low-entropy internal loop strategies which reduce the land cost of generating the necessary nitrogen flows. However, these cannot exceed the limits established by the structure of Spanish territory. That is, agroecological intensification cannot be prolonged indefinitely over time since it is limited by the land available.