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HMC Technology Applications

Novel technology in the geothermal field is difficult to find. Like gas and oil production, geothermal development has largely been based on locating sites which feature geologically unique characteristics suitable for geothermal activities. For the production of commercially feasible electricity, that has meant finding locations which have adequate water supplies and sufficient heat to generate electricity. For most of the United States and much of the world, finding sufficient heat often means drilling to depths of 15,000 to 30,000 feet. The goal of the U.S. Department of Energy's Geothermal Subgroup is to develop the technology to drill to and operate at depths of 30,000 feet and temperatures of 300 °C or higher. While temperatures in excess of 300 °C are common at depths of 30,000 feet almost everywhere on Earth, the technology to operate at those temperatures does not currently exist. Even if possible, operating at those depths and temperatures would be extremely costly and would not be economically feasible for the foreseeable future.

Carbon dioxide (CO2) storage in deep saline aquifers and exhausted oil and natural gas fields has been widely considered as a means for reducing CO2 emissions to the atmosphere as a counter-measure to global warming. However, rather than treating CO2 merely as a waste fluid in need of permanent disposal, our technology utilizes CO2 as a working fluid in geothermal energy capture, as its thermodynamic and fluid mechanical properties suggest it transfers geothermal heat more efficiently than water. Energy production and sales in conjunction with storage would improve the economic viability of CCS, a critical challenge for large-scale implementation of CCS.

However, a challenge for large-scale implementation of sequestration is its cost. CCS could add 50% or more to the cost of fossil-fuel-based electricity generation. Therefore the most viable initial opportunities for CPG will likely be at those sites where companies are already engaged in CCS, or are planning to participate in CCS activities. These opportunities include CCS utilized in enhanced oil recovery (EOR) and CCS activities at coal fired power plants. Multiple examples of opportunities exist for CPG projects in the United States and Canada, especially in Alberta and Saskatchewan.

HMC is developing applications of its CPG technology for three areas of energy production

  • Large scale commercial electrical production at CCS sites

  • Moderate scale electrical production at EOR sites, and

  • Small to moderate storage of electrical power at wind farms 


Large scale commercial electrical production at CCS sites

Large scale carbon capture and storage (CCS) has failed to gain favor due largely to the extra cost it adds to industrial processes such as the production of electricity at coal and natural gas fired power plants, oil and gas refineries, cement plants, steel plants and ethanol plants. HMC’s patented CPG technology is capable of changing the calculation by turning CCS from a cost center into a revenue source.

Storage of large volumes of carbon dioxide (CO2) in deep, saline aquifers provides potentially significant levels of geothermal energy. Recycling the CO2 through a completely closed loop power system can both produce carbon neutral electricity as well as reduce the size of the pressure field of the stored CO2. Acting like a giant pressure cooker, the CPG power system vents off pressure to produce power and thereby minimizes the risk of leakage of stored CO2 out of the deep aquifers. Utilizing heat and pressure drawn from the stored CO2 reduces the pressure on aquifer and allows for effective risk management of the CO2 plume in the aquifer.

To use CPG technology to produce commercial amounts of carbon neutral electricity at costs competitive with fossil fuel power systems – and at a fraction of the cost of electricity produced by wind or solar systems – the minimum conditions are:

• a capped saline aquifer at least 2.5 km deep;

• a minimum aquifer temperature of 75 °C; and

• a minimum of one million tonnes of stored CO2.

© Saar & Randolph
Using Enhanced CPG technology, it is possible to produce commercial amounts of carbon neutral electricity at costs competitive with fossil fuel power systems with the following somewhat reduced minimum conditions:

• a capped saline aquifer at least 2.5 km deep;

• a minimum aquifer temperature of 50 °C; and

• a minimum of one million tonnes of stored CO2.

Larger amounts of stored CO2, greater depths and higher aquifer temperatures all will contribute to the production of more carbon neutral electricity and help to reduce the cost of production even further.

To learn more about CCS/CPG projects or to participate in a web presentation of HMC’s CPG and Enhanced CPG technology, please contact Kenneth Carpenter at

Moderate scale electrical production at EOR sites

HMC’s patent pending Enhanced CPG technology is a game-changer for EOR operators. The technology makes it possible to significantly improve the profitability of EOR operations. Using a combination of heat and pressure from any reservoir undergoing EOR operations plus the addition of waste heat produced at the site, it is possible to produce 10 MW or more of power at each EOR site. Best of all, HMC absorbs all costs of the installation and operation of the Enhanced CPG power system.


  To view the EOR process at the HECA - Elk Hills Project click here: Enhanced Oil Recovery Video 

• Under a cost savings and revenue sharing agreement with HMC and with a power purchase agreement from the servicing utility, an oil operator can receive revenues that can provide protection against oil price volatility and make the operation of marginal fields more viable. Even after the oil reservoir is no longer economically viable with EOR, the HMC Enhanced CPG system can continue to produce revenue from electricity sales for many more years.

• For more information or to discuss having an HMC Enhanced CPG power system installed at your EOR site, contact Kenneth Carpenter at


Small to moderate storage of electrical power at wind farms

CO2 Source – A relatively small amount of CO2 may be required. Best case scenario is that CO2 is already in the ground or otherwise near a CO2 source.
Geology – Low aquifer temperature and poor permeability allows potential application over a wide range of geological conditions.


 • Temperature - Greater than 10 °C higher temperature in aquifer is necessary to achieve 100 percent or greater return of stored energy. Aquifer temperatures greater than 25 °C higher than surface temperatures produce significantly greater energy than the amount stored.
• Depth - .5 km to 2 km in constrained aquifer below lowest potable aquifer.
• Permeability - Functional permeability in the range of .5 mD and above.


Heat Mining Company has exclusive, worldwide rights to the patent-pending CPG technology, which was developed at the University of Minnesota Geofluids group by a team led Drs. Martin Saar and Jimmy Randolph. In addition HMC utilizes proprietary computer modeling software for site evaluation, plume management and risk assessment combined with highly efficient, CO2 turbine technology. The total HMC CPG power systems are the only complete electrical generation systems which can utilize supercritical and near supercritical CO2 stored in aquifers.

The HMC Technology – Combining geothermal energy extraction with CCS to produce clean, renewable, carbon-neutral electricity 

The HMC technology utilizes CO2 captured from an emitter source such as a coal fired power plant or the CO2 plume in deep, depleted oil reservoirs resulting from EOR activities to generate clean, renewable electricity. Captured CO2 is compressed into a supercritical (liquid) state and is injected into deep sedimentary formations, either saline aquifers or depleted oil reservoirs, ideally at depths of 1.5 to 3.5 km. The saline aquifers are not potable and cannot be used by humans or for agricultural purposes. The aquifers are isolated from the surface and other aquifers by multiple layers of impermeable seals and caprock. Constrained sedimentary formations have trapped hydrocarbons such as natural gas and oil and naturally occurring CO2 for millions of years without their release into higher aquifers or the atmosphere. Read More...

To read more about the technology on which this patent was made, click here: 

To view a our patent click here: HMC Licensed Patent  

For a series of published papers by Drs. Martin Saar and Jimmy Randolph on CPG visit: http://www.geo.umn.edu/orgs/geofluids/publications_CPG.html