Potential of Organic Rankine Cycle for waste heat recovery from piston engine-based power plants in isolated power systems

Abstract

Waste Heat Recovery with Organic Rankine Cycle (ORC) in piston engine-based power plants placed in isolated systems is addressed in this paper. The power plant subjected to study is located in La Palma, Canary Islands, considered a representative example of small-to-medium isolated power system where the diesel engine is the solely or the main conventional technology for generation. In those systems, the power plant load control to cover the grid demand results in a noticeable variability of the available heat. This challenge is addressed in this paper through a performance and economic evaluation of an intermediate thermal energy storage system. A techno-economic analysis of the proposed power plant is performed taking as input the annual exhaust thermal energy available. The ORC-Diesel unit interaction is studied by means of an in-house developed plant load management model. An annual power plant fuel economy gain and pollutant emission reduction between 5% and 7% is estimated. In addition, the extra power and spinning reserve provided by the ORC allows the power plant to reduce its operational cost through the reduction of the number of diesel units starts. • Waste heat recovery assessment from power plants in isolated power systems. • Efficiency increase and emission abatement due to the additional energy generated. • Additional power and spinning reserve allows diesel units disconnection. • Economically attractive solution, with payback times lower than 5 years.