High Temperature ORC Systems

Abstract ORC systems are well known as the best available technology for electricity production from low temperature heat sources -such as geothermal ones - and continuous technical development is done to optimize performances by means of finding new working fluids and improved design criteria and thermodynamic cycles. With regard to medium and high temperature heat sources exploitation for electric power production, ORC technology and Steam Rankine Cycle solutions are competing in terms of power production, capital expenditures and O&M costs to become the preferred choice on a case-by-case basis. Commercially available ORC technology is currently limited to a maximum working fluid operating temperature of about 300°C, leading to a strong limitation on performances achievable. Finding new working fluids that could operate at Higher Temperatures and developing the related technical solutions, will enable to improve ORC technology competiveness also in other niches that now are Steam Rankine Cycles territory. Very High Temperature ORC technology will lead to new solutions for both power only production and cogeneration, allowing ORC technology to enter market segments traditionally belonging to other technologies (e.g. Steam Rankine Cycles, Otto Cycles, Bryton Cycles, etc.). The paper will present the technical and industrial development on High Temperature ORC systems, potential market development and a technology comparison to other generation technologies.