SAGE Geosystems is a Texan enhanced geothermal systems (EGS) startup based in San Antonio. It is led by Cindy Taff, a former drilling boss at Shell.
The firm has a deal to supply power to Meta's data centres. At a site in Christine, Texas, it has built a geothermal energy-storage system it calls a "lung". The company drills about 3km deep and fractures the rock to create an underground reservoir. Water is pumped from a surface pool and stored under high pressure underground. When power is required the well is opened and the pressurised water—forced up by the rock's natural inclination to close the fracture—rises to the surface and turns a turbine to make electricity.
The project has demonstrated the ability to store and release 3MW of power to the Texas grid. The system can store power for much longer than lithium batteries and, because its main hardware costs are fixed, the cost per unit of stored energy goes down the longer it is designed to run.
He walks as if balancing the family tree on his nose.