A technical, economical and market review of organic Rankine cycles for the conversion of low-grade heat for power generation

This paper presents an overview of the technical and economic aspects, as well as the market evolution of the Organic Rankine Cycle (ORC). This is an unconventional but very promising technology for the conversion of thermal energy, at low and medium temperatures, into electrical and/or mechanical energy on a small scale. As it makes a greater and/or more intensive use of its energy source, this technology could facilitate an electricity supply to unconnected areas, the self-production of energy, the desalination of seawater for human consumption, or even to increase the energy efficiency in the industrial sector respecting the environment. A look at the scientific publications on this topic shows an open research line, namely the selection of a suitable working fluid for these systems, since there is as yet none that provides all aspects that must be taken into account in ORCs. Furthermore, a description and an analysis of the applications of the proposed technology is carried out, specifying the main providers, which at the present time is limited mainly to the range 0.2–2 MWe with a cost of around 1 and 4 × 103 €/kWe. Lower powers are in pre-commercial status.