**2. Fundamental concept of a binary fluid ORC system using LTGE resources**

**Figure 1** depicts a schematic representation of an ORC binary fluid system utilized for electric power generation using LTGE resource.

The initial (main) fluid collected from the LTGE resource *via* the production well is the geo-fluid. The geo-fluid transports heat from the liquid-dominated LTGE resource (being the heat carrier) and effectively transfers this heat to the lowboiling point organic-based working fluid (the secondary fluid) through an efficient heat exchanger. Typical ORC organic fluids may include pure hydrocarbons (e.g., pentane, butane, propane), refrigerants (e.g., R134a, R218, R123, R113, R125), or organic mixtures. More details about the selection criteria of these ORC organic fluids for optimal performance can be found in Refs. [1–4]. The ORC is a thermodynamic Rankine cycle that uses the organic working fluid instead of steam (water). In this binary fluid ORC LTGE system, the low-boiling point organic liquid absorbs the heat which is transferred by the geo-fluid and boils at a relatively much lower temperature (compared to water) and as a result develops significant vapor pressure sufficient to drive the axial-flow or radial-inflow turbine. The turbine is coupled to an electric generator, which converts the turbine mechanical shaft power into electrical power. The organic working fluid expands across the turbine and then is cooled and condensed in the condenser before it is pumped back as a saturated liquid to the heat exchanger using a condensate pump to be re-evaporated, and the power cycle repeats itself.

#### **Figure 1.**

*A schematic showing the fundamental concept of an ORC binary fluid technology utilizing LTGE resource for power generation.*

*Introductory Chapter: ORC Power Generation Technology Using Low-Temperature Geothermal… DOI: http://dx.doi.org/10.5772/intechopen.101577*
