Utilization of Excess Steam from a Vent Valve in a Geothermal Power Plant

Abstract

A novel strategy is presented for the utilization of the excess steam released into the atmosphere from the vent valve of a geothermal power plant. In particular, three possible approaches are considered: dry-steam cycle, binary cycle, and Kalina cycle. Thermodynamic models of these different power cycles are defined accordingly. The simulations are carried out using Aspen HYSYS®, used to solve the corresponding mass and energy balance equations. The feasibility and advantages of the different approaches are discussed from different points of view, i.e., energy, net power, and overall efficiency. Moreover, exergy analysis is used to identify the location, magnitude, and origin of thermodynamic inefficiencies. Economic aspects are also considered in terms of electricity or levelized electricity generating cost (LEGC) for the three considered cycles. Performances are quantified in terms of Capacity Factor (CF), the ratio between the actual power produced by the generator in a given period and the maximum output power that can be achieved according to the design capacity. The environmental impact is also considered.

Keywords

• Dry-steam cycle
• Binary cycle
• Kalina cycle
• Excess steam
• LEGC
• Capacity factor