Carnot-cykeln Copy Copy


Literature references

  1. Degree project on EGS Hanna Kervall Lund University
http://lup.lub.lu.se/student-papers/record/8918423
  • Presentation from DOE
https://www.energy.gov/eere/geothermal/how-enhanced-geothermal-system-works
  • ST1 Presentation of deep geothermal plant in Espoo
https://www.st1.se/geotermisk-varme
http://altarockenergy.com/wp-content/uploads/2013/06/Swyer-et-al.-2016.pdf
  • Transitioning Coal to Geothermal. Petty, S. Forty-first Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 22-24, 2016. SGP-TR-209.
http://altarockenergy.com/wp-content/uploads/2013/06/Petty-2016.-Transitioning-Coal-to-Geothermal.pdf
http://altarockenergy.com/wp-content/uploads/2015/10/Cladouhos-et-al.-2015.pdf
http://altarockenergy.com/wp-content/uploads/2015/10/Cladouhos-et-al.-2015.pdf
  1. Results from Newberry Volcano EGS Demonstration, Cladouhos, T., Petty, S. Swyer, M., Uddenberg, M., Nordin, Y. 2015. PROCEEDINGS, Thirty-Ninth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 26-28, 2015. SGP-TR-204http://altarockenergy.com/wp-content/uploads/2013/06/Results-from-Newberry-Volcano-EGS-Demonstration.pdf
  1. Deep Stimulation at Newberry Volcano EGS Demonstration. Grasso, K., Cladouhos, T., Petty, S., Garrison, G., Uddenberg, M., Swyer, M., and Nordin, Y. 2014. American Geophysical Union Annual Meeting, December 15-19, 2014. Paper number H43A-0940.
http://altarockenergy.com/wp-content/uploads/2015/01/Newberry_AGU-2014.pdf
  1. Results from the Newberry Volcano EGS Demonstration Project- 2014, Cladouhos, T., Swyer, M., Petty, S., Moore, M., DeRocher, T., Nordin, Y., Uddenberg, M. 2014. Geological Society of America Annual Meeting, October 19-22, 2014 Abstract number 249196
http://altarockenergy.com/wp-content/uploads/2013/06/GSA-2014_ms.pdf
  1. 10. An Assessment of Enhanced Geothermal Systems for Water Management and Power Production. Garrison, G., Uddenberg, M., Cladouhos, T., Petty, S., and Coleman, T. Geothermal Resource Council Transactions. 2013.
http://pubs.geothermal-library.org/lib/grc/1030564.pdf
  1. 11. Groundwater Monitoring and EGS: The Newberry EGS Demonstration, Grasso, K., Cladouhos, T., and Garrison, G. 2013. American Geophysical Union Annual Meeting, December 9-13, 2013. Paper number H53B-1423.
http://altarockenergy.com/wp-content/uploads/2015/01/AGU-2013_kg.pdf
  1. Microseismic Monitoring of Newberry Volcano EGS Demonstration, Cladouhos, TT, Petty, S., Nordin, Y., Moore, M., Grasso, K, Uddenberg, M., Swyer, M., Julian, B., and Foulger, G., (2013), PROCEEDINGS , Thirty-Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 11-13, 2013 SGP-TR-198.
https://gdr.openei.org/files/271/cladouhos_newberry_meq_SGWS_2013.pdf
  1.  Multiple Zone Geothermal Stimulation Case Study: Fluid Diversion Using Thermo-Degradable Zonal Isolation Materials, Nordin, Y., Petty, S., Cladouhos, T., Swyer, M., and DeRocher, T. (2013), GRC Transactions, 37, 51-55.
http://pubs.geothermal-library.org/lib/grc/1030548.pdf
  1. Improving Geothermal Project Economics with Multi-zone Stimulation: Results from the Newberry Volcano EGS Demonstration, Petty, S. Nordin, Y., Glassely, W. and Cladouhos, T. (2013), PROCEEDINGS, Thirty-Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 11-13, 2013 SGP-TR- 198.
https://pdfs.semanticscholar.org/f969/1f13979b569e85422933eb66e732ed5821bc.pdf
  1. 15. Newberry Volcano EGS Demonstration — Phase I Results, Cladouhos, TT, Osborn, WL, and Petty, S., (2012), PROCEEDINGS, Thirty-Seven Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 30-February 1, 2012 SGP-TR-194.
https://people.wou.edu/~taylors/newberry/Cladouhos_etal_2012_Newberry_PhaseI_EGS_Results.pdf
  1. The Role of Stress Modeling in Stimulation Planning at the Newberry Volcano EGS Demonstration Project, Cladouhos, T., S. Petty, O. Callahan, W. Osborn, S. Hickman, and N. Davatzes (2011), PROCEEDINGS, Thirty-Sixth Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 31 - February 2, 2011.
https://www.researchgate.net/publication/229045186_The_Role_of_Stress_Modeling_in_Stimulation_Planning_at_the_Newberry_Volcano_EGS_Demonstration_Project/link/0a85e5372f8d8e0d18000000/download
  • Fluid Diversion in an Open-Hole Slotted Liner, Petty, S., Bour, D., Nordin, Y., and Nofziger, L. (2011), PROCEEDINGS, Thirty-Sixth Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 31 - February 2, 2011 .
https://www.researchgate.net/publication/236361964_Temporary_Bridging_Agents_for_use_in_Drilling_and_Completion_of_Enhanced_Geothermal_Systems/link/556ca8e008aeab777223193b/download
http://pubs.geothermal-library.org/lib/grc/1029284.pdf
http://pubs.geothermal-library.org/lib/grc/1029258.pdf
http://pubs.geothermal-library.org/lib/grc/1028814.pdf

The Carnot cycle consists of two isothermal processes and two adiabatic processes. It can be considered as the most efficient cycle for a heat engine that the laws of physics allow. When the second law of thermodynamics states that not all the heat supplied in a heat engine can be used to perform work, the Carnot efficiency sets the limit value on the part of the heat that can be used for work.

In order to be able to approach Carnot efficiency, the processes that are part of the heating engine cycles must be reversible and do not entail any changes in entropy. Thus, the Carnot cycle is an idealization, as no real motor processes are reversible and all real physical processes involve a certain increase in entropy.

A heat engine works by transferring energy from a hot area to a cool area and by converting some of that energy into mechanical work. If you take the example from Chena hot springs where the water holds about 70 ℃ and we expect that we could extract the energy in the water by lowering the temperature to 0 ℃, the highest theoretical effect would be around 20 %. This is, as I said, in an ideal location and in reality the efficiency is considerably lower, not least because the temperature does not allow to decrease so much.

In the plant where the picture above is taken you have a delta T around 65 ℃. With the temperatures present in the system, about 150 ℃ up and a return temperature of 67 ℃, the theoretical Carnot effect is 18.9 % while the actual effect is just over 10 %.

The carnot effect is calculated by using

((Thrs - Tc) / Thrs)*100

and is thus the highest theoretical power one can extract from a heat engine. Temperatures should be stated in Kelvin.