Single Flash Geothermal Power

App to calculate power output of single flash geothermal power plant

This app enables you to quickly estimate the electrical power generated by a single flash geothermal power plant. It uses steam tables for fluid properties and isentropic efficiency for turbine genset power output.

The single flash process has four steps:

1) Reservoir/well

2) Separation

3) Turbine inlet

4) Turbine outlet

Water as saturated liquid 1) at a certain temperature and pressure is reduced to the flash temperature 2). After pressure reduction (flashing) the water/steam mixture is separated in the separator where the saturated steam is directed to a turbine 3) -4) and the water/brine is redirected to the injection well. The steam propels a turbine which generates electricity.

Inputs are entered in two windows (see buttons on bottom), one for well inputs and one for flashing and turbine properties.

One recent development for the app is that one can choose whether to enter temperature or pressure, this is really helpful if your information is mixed, e.g. you know well temperature, flash pressure and turbine outlet pressure. You can now enter these values and the app will calculate accordingly and list the parameters in the main window.

1) Well: brine flow and temperature or pressure.

2) Turbine: turbine inlet temperature or pressure (separation values), genset (turbine + generator) efficiency and turbine outlet temperature or pressure.

The main output is the electrical power generated, additional outputs are pressure, temperature and mass flow values at the relevant process points, i.e. well, injection, turbine inlet and outlet.

The app is not intended to replace due diligence or proper plant design, it is a simple calculation tool which could be useful for a first step in e.g. a feasibility study or if you need quick calculations on the go.

If you are unsure which parameters to enter, try these test values:

Brine temp: 240°C

Brine flow: 200 kg/s

Genset efficiency: 90%

Flash Temperature: 180°C

Turbine outlet temp: 100°C

This gives you an output of 9537 kWe.

If you have a condensing turbine your outlet temperatures typically lie in the range of 50°C to 70°C. For a backpressure application your temperature will lie around 98°C to 105°C all dependent on altitude and pressure loss in stack and/or silencer.

I really hope you enjoy the app and wish you happy calculations