**Acknowledgements**

electrical power. One of these innovative emerging technologies includes renewable lowtemperature (low-enthalpy) geothermal energy source for clean electrical power generation. This promising technology offers potential applications in generation of electric power which can be produced using the vast renewable low-temperature geothermal energy re‐ sources available worldwide.In this chapter, the concept of ORC binary technologyfor pow‐ er generation using low-temperature geothermal heat source was introduced and its potential applications and limitations for small-scale geothermal power generation and its relevant environmental and economic considerations were presented and discussed. Also, recent developments of ORC-based low-temperature geothermal power generation with their significant and relevant applications were presented and discussed. A number of suc‐ cessful ORC binary plants were installed in different locations (e.g. remote and rural sites) worldwide which demonstrated the ability of this promising alternative and green technolo‐ gy to utilize renewable low-temperature geothermal energy sources for generating electrici‐ ty. Also, several patents were reported on the application of this innovative technology. Geothermal ORC power generation plants are normally constructed and installed in small modular power generation units. These units can then be linked up to create power plants with larger power production rates. Their cost depends on a number of factors, but mainly on the temperature of the geothermal fluid produced, which influences the size of the ORC turbine, heat exchangers and cooling system. Currently, ORC power cycles exhibit great flexibility, high safety (installations are perfectly tight), and low maintenance when coupled with low-enthalpy geothermal heat sources. The future use of low-temperature geothermal energy resources for generating electricity would very much depend on further overcoming technical barriers both in utilization and production, and its economic viability compared to other conventional and renewable energy sources used for power production. Another emerging "dual-benefit" technology is EGS using CO2 as the working fluid for combined clean power generation and geologic CO2 sequestration. CO2 is of interest as a geothermal working fluid mainly because it transfers geothermal heat more efficiently than water. While power can be produced more efficiently using this technology, there is an additional benefit CCS for reducing GHG emissions. The second part of the chapter presented the mer‐ its and fundamental aspects of CO2-based EGS technology.In 2000, Brown, D. (Pruess, 2006) proposed a novel EGS concept that would utilize supercritical CO2 instead of water as a more efficient heat exchange (carrier) fluid (due to its favorable properties over water), and would simultaneously achieve CO2 geologic sequestration as an additional benefit.It was found that CO2 is superior to water in its ability to exchange heat from EGS hot fractured rock and reduce hydraulic power consumption for fluid injection and circulation in the EGS reservoir. It was concluded that an EGS system running on CO2 has sufficiently attractive features to warrant furtherinvestigation.It was also concluded that EGS for power genera‐ tion is still relatively a novel technology and remains to be proved on a large scale and that further research is needed for additional exploration oftechnological and economic aspects regarding the opportunities and challenges for CO2–based EGS technology for combined

324 New Developments in Renewable Energy

carbon sequestration and power generation.

The author of this chapter would like to acknowledge the funding contribution by Goldcorp Canada Ltd.-Musselwhite Gold Mine that mainly supported the collaborative geothermal energy & heat pump (GHP) technology research project (author was the PI of the project) at their site in Northern Ontario; a contracted research project with Lakehead University (2007-09). Acknowledgement also goes to Natural Sciences and Engineering Research Coun‐ cil of Canada (NSERC) for the Discovery Grant (Individual) funding that was provided to the author's research in the area of clean energy technologies related to CO2 membrane gas separation from industrial flue gases for GHG emissions reduction.
