A technical-economic analysis and optimization of a direct molten salts linear Fresnel plant

This study investigates the pseudo-transient behavior of a direct molten salt linear Fresnel solar plant, which thermally assists a steam Rankine cycle. The linear Fresnel system, which is thermally and hydrodynamically modeled using a 1-D, axially discrete formulation, is subjected to annual solar and meteorological TMY data with an hourly resolution. The analysis explores three aspects of the coupled system. First, it performs a parametric analysis quantifying the impact of several parameters on the system’s performance. Next, it performs a multivariable optimization aiming to determine the geometric and operational parameters that minimize the system’s LCOE. Finally, it performs a break-even analysis aiming to determine the cost reduction required for such systems to be economically competitive with CSP systems. The parametric analysis confirms that, as the temperature of the heat transfer fluid increases, the solar field efficiency drops while the power block’s increases. The LCOE has a minimal value of 104.9 US$/MWh considering a solar field with a solar multiple of 4.9 and an outlet temperature for the heat transfer fluid of 568 °C, a power cycle pressure of 171.7 bar producing 300 MW. Finally, the break-even analysis indicated that a solar field cost reduction of approximately 30% would lead to a LCOE around 95 US$/MWh and a plant initial investment of 4508.9 US$/kW, which is competitive with operating CSP plants.