Development of New Biphasic Metal Organic Working Fluids for Subcritical Geothermal Systems Geothermal Lab Call Project

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Last modified on July 22, 2011.

Project Title Development of New Biphasic Metal Organic Working Fluids for Subcritical Geothermal Systems
Project Type / Topic 1 Laboratory Call for Submission of Applications for Research, Development and Analysis of Geothermal Technologies
Project Type / Topic 2 Working Fluids for Binary Power Plants

Project Description In binary-cycle plants the cycle efficiency improves as pumping energy is reduced and from maximizing the enthalpy gain of the working fluid for a given amount of heat extracted from the geothermal source brine. Enthalpy gain of the working fluid in the heat exchanger occurs principally from sensible heat gained while passing through the heat exchanger in the liquid state and from vaporization of the organic working fluid near the exit of the heat exchanger. Additional heat transfer is limited after the vapor phase transition due the low thermal conductivity and heat capacity of the vapor. Also, operating pressures and temperatures are constrained by the bulk phase behavior and thermodynamic properties of the working fluid (boiling point, latent heat of vaporization, density, heat capacity, etc.). The fundamental underlying goal of this project is to overcome the cycle efficiency limitations imposed by the bulk thermodynamic proper-ties of the working fluid by introducing a metal-organic heat carrier (MOHC) into the system.
State Washington
Objectives Develop a new type of biphasic working fluid for subcritical geothermal systems that utilizes microporous metal-organic solids as the primary heat carrier and heat transfer medium to support an organic Rankine cycle.
Awardees (Company / Institution) Pacific Northwest National Laboratory

Funding Opportunity Announcement DE-PS36-09GO99017

DOE Funding Level (total award amount) $760,000.00

Total Project Cost $760,000.00

Principal Investigator(s) B. Peter McGrail
Other Principal Investigators Praveen K. Thallapally and Robert J. Robertus

Targets / Milestones - Explore several classes of materials for suitability as MOHCs.

- Measure thermophysical properties of the suitable MOHCs.
- Develop Simple Aspen Plus models to give baseline data on power generated and plant efficiencies without MOHCs and compare to MOHC-enhanced systems.
- Laboratory performance testing to identify performance problems in the key components and identify suitable operating parameters that would help minimize or eliminate problems.

Location of Project Richland, WA

Funding Source American Recovery and Reinvestment Act of 2009

References EERE Geothermal Technologies Programs[1]


  1. EERE Geothermal Technologies Programs