SCHEMATIC: Explaining Geothermal / CO2 recycling

Lehigh’s Energy Research Center and the University of Michoacan San Nicolas de Hidalgo are developing and testing methods of using carbon dioxide from oil- and coal-fired power plants to enhance the extraction of geothermal energy from underground aquifers and rock formations. The project will help reduce emissions of carbon dioxide (CO2), a greenhouse gas, while boosting the use of geothermal power. Geothermal plants generate electricity continuously, not just when the wind blows or the sun shines. And unlike fossil fuel plants, geothermal plants produce power cleanly. The process is explained here.

1. Carbon capture

CO₂ is captured from a fossil-fuel power plant.

2. Aquifer prep

Engineers drill an injection well and a production well into a deep saline aquifer (DSA) nearby.

3. CO₂ prep

CO₂ is piped from the fossil fuel to the geothermal power plant. It is heated and pressurized and injected into the aquifer via the injection well.

4. Warm regards

The supercritical CO₂ percolates through the DSA, then heats up and rises through the production well.

5. Power play

The CO₂ can turn the turbines of the geothermal plant to power the generator. Or it can be diverted to a heat exchanger working with an organic fluid or other medium. The heat would convert this fluid to steam to turn the turbines.

Illustration by Harry Campbell