Development and assessment of a low-emissions gas turbine system for power utilities incorporating intercooling and solar preheating

Abstract

• 1. Two novel solar-hybrid gas turbines with high compression ratios are proposed. • 2. The novel cycles use PTCs to preheat the compressed air before their combustors. • 3. A high solar share of 24.3% and lower CO2 emissions of 28.14 can be achieved. • 4. The novel cycles have high efficiencies and low electricity costs. • 5. The novel cycles have low fuel consumption rates with short payback periods. Literature shows that using medium-temperature solar collectors, such as parabolic trough collectors (PTCs), to heat the gas turbine's compressed air before it enters the combustion chamber is unfeasible with high-pressure ratio gas turbines. This is because the compressor's outlet air temperature exceeds the solar field's maximum operating temperature. In this study, PTCs technology was integrated into intercooled gas turbine cycles to solve this problem. Intercooling a gas turbine improves its performance and allows for solar energy integration of PTCs. Two inventive solar preheated intercooled gas turbine power plants with a high-pressure ratio of 37 have been proposed and investigated: solar preheated single-intercooled gas turbines (SP-IcGT single ) and solar preheated double-intercooled gas turbines (SP-IcGT double) . Under design and off-design operation conditions, the plants' performance and optimal solar field area were evaluated. A comprehensive economic and environmental analysis of the novel cycles was also conducted and reported. The study shows that the solar integration of PTCs with intercooled gas turbines is a promising technique, providing a fuel-based efficiency of 54% for the SP-IcGT double and 51.3% for the SP-IcGT single . In addition, the analysis shows that the novel cycles have a high solar share, save more fuel, and are more environmentally friendly than solar-preheated conventional gas turbines. SP-IcGT double saves 28.2% and SP-IcGT single saves 19.3%. The SP-IcGT double and SP-IcGT single consume 6675 and 7017 kJ/kWh, respectively, compared to 9500 kJ/kWh for solar preheated conventional gas turbines in the previous literature. Furthermore, the economic analysis shows positive prospects for solar preheated intercooled gas turbine projects. The SP-IcGT double has a payback period of 6.409 years and the SP-IcGT single has 5.545 years. Overall, the solar integration of PTCs with intercooled gas turbines is an attractive technology in Sunbelt countries.