Development and Analysis of the Novel Hybridization of a Single-Flash Geothermal Power Plant with Biomass Driven sCO2-Steam Rankine Combined Cycle.

Balkan Mutlu,Feyza Kazanç,Derek Baker

doi:10.3390/e23060766

Abstract

This study investigates the hybridization scenario of a single-flash geothermal power plant with a biomass-driven sCO2-steam Rankine combined cycle, where a solid local biomass source, olive residue, is used as a fuel. The hybrid power plant is modeled using the simulation software EBSILON®Professional. A topping sCO2 cycle is chosen due to its potential for flexible electricity generation. A synergy between the topping sCO2 and bottoming steam Rankine cycles is achieved by a good temperature match between the coupling heat exchanger, where the waste heat from the topping cycle is utilized in the bottoming cycle. The high-temperature heat addition problem, common in sCO2 cycles, is also eliminated by utilizing the heat in the flue gas in the bottoming cycle. Combined cycle thermal efficiency and a biomass-to-electricity conversion efficiency of 24.9% and 22.4% are achieved, respectively. The corresponding fuel consumption of the hybridized plant is found to be 2.2 kg/s.

Highlights

The performance of geothermal power plants can degrade over the years, as the geothermal resource is exploited
The underlying reason for this result is the increase in the main compressor (MC) inlet temperature (State 1) of biomass topping cycle (BTC)
The increase in MC inlet temperature is directly proportional to BTC flow rate while being inversely proportional to BBC flow rate for a fixed effectiveness value of the BTC cooler, since the working fluid of BBC acts as a heat rejection medium for BTC

Summary

Introduction

The performance of geothermal power plants can degrade over the years, as the geothermal resource is exploited This degradation can be due to decreases in fluid temperature, flow rate, and pressure at the production wellhead over the lifetime of the geothermal resource. These decreases can reduce both the quantity (thermal energy) and quality (temperature) of the heat input, and lead to reductions in both the output and the thermal efficiency of the plant [1]. The hybridization of geothermal resources with other renewable thermal energy resources offers the potential to increase the performance of geothermal power plants while being economically feasible, since the need for land and grid infrastructure can be reduced or eliminated. In the context of this article, Kızıldere-1 (KZD-1), an existing single-flash Geothermal Electric Power Plant (GEPP), operating significantly below design capacity, is considered as a case study for hybridization with biomass energy

Objectives

Results

Conclusion