Organic Rankine cycle application to recover waste heat in gas compressor stations

The aim of my work is to understand which are the most suitable market area for the implementation of the ORC application to produce electricity with the heat recovery from open cycle gas turbines. Furthermore, I analyze also the chance to develop a new ORC application in gas compressor stations that is no longer the electricty generation but the mechanical power supply coupling a centrifugal gas compressor directly to the ORC turbine shaft. The research of the potential market areas for Turboden passed through the identification of a preliminary list of countries potentially suitable for the implementation of ORC projects in compressor stations, then through the estimation of the heat recovery potential country by country and finally through the economical analysis of this ORC application. From the initial analysis five macro geographical regions came up: South Europe, North Africa, Middle East, Central Asia and South East Asia. By means of an integrated model studied ad hoc for this thesis, a technical and economical analysis has been carried out, addressing heat recovery potential in these areas and the economic feasibility of such kind of projects. The countries studied among these areas showed different ORC potential capacity, passing from Qatar, the best one with 1619 MWel, to Greece with 8 MWel. Unfortunately, the economical study revealed that in most of the selected countries the ORC solution for the electricity production is not feasible at actual conditions, assuming that payback period of more than 5 years is not accepted by investors. This is due primarily to low electricity tariffs determined by government subsidies for households and industry. This trend improves or even reverses if the Oil&Gas company, who invests monetary resources, receives an extra gain, in the form of annual revenues, for the quantity of fossil fuels, saved thanks to the heat recovery with ORC technology, that can be eventually exported. The ORC application dedicated to the production of electricity is not always possible for several reasons. For these cases, the ORC mechanical drive solution would be suitable. The application of this solution to a compressor station has never been implemented so an early stage feasibility analysis is conducted starting from real compressor stations. In particular, I analyze the existance of an optimization point between ORC and gas turbines performances. Moreover, for the same case studies I conduct an economical comparison between the two ORC solutions, electricity generation and mechanical drive, in order to assess which is the best or under which conditions is preferable one at the expense of the other.