Molten Salt as a Heat Transfer Fluid
Molten Salts have a history of reliable performance in the energy industry since the 1950s. Elements used in molten salts for thermal applications include but are not limited to:
sodium, calcium, potassium, fluoride, lithium, sodium, zinc, magnesium, and boron.
The most widely used varieties are nitrate-based mixtures. Depending on the specific use, the blends are formulated for optimal specific heat capacity, thermal conductivity, melting point, and density. AGP's patents are inclusive of all varieties of molten salts.
-Molten salt is an excellent Heat Transfer Fluid (HTF).
-It is environmentally benign, non-toxic, and non-flammable.
-It lasts over 30 years with little degradation.
- It is 2-4 times as thermally conductive as water.
-It has a low vapor pressure.
-It has a high specific heat capacity, and only loses 1% of its heat per day in a properly insulated tank.
-It is very stable above 400°C and, depending on the species of molten salt, has working temperatures from 65°C – 1000°C.
In case you're wondering, even common table salt (NaCl), when heated enough, becomes a molten salt. However, its very high melting point of around 800ºC precludes it from being an option for geothermal processes where temperatures of less than 400ºC are much more practical.
AGP Closed-Loop Molten Salt Geothermal Energy Collection System
Advanced Geothermal Energy Technologies By AGP
Our basic geothermal closed-loop system works by circulating molten salts through a heat zone and transferring the thermal energy to the molten salts. There is no exchange of fluids between the natural in situ geofluids and the heat transfer process fluids.
Our system can be used in two ways:
1. Circulate in situ geothermal fluids to the surface, then transfer the heat to molten salt which allows the storage of heat. This method is best for fluids from 160°C – 350°C.
2.Circulate molten salt down into the heat zone , extract the heat , then return the heated molten salt to the surface. This works best for temperatures from390°C – 1000°C (e.g., crustal magma or very hot rock.)
There is much discussion as to whether abandoned oil and gas wells have to be properly cleaned up and decommissioned to prevent methane leakage, or whether the valuable infrastructure can be reutilized for environmental advantage. In the latter, AGP`s geothermal closed loop system technology has vast superiority to reuse such wells for the recovery of high grade geothermal energy and simultaneously produce a profitable revenue stream. In some regions of extensive hydrocarbon explorations, the geothermal gradient is often quite high, providing numerous potential well candidates for conversion. This avoids the major upfront costs of drilling and significant risks of nonperforming geo reservoirs that remain major obstacles in the development of geothermal energy. Pilot projects and feasibility studies that have been performed worldwide confirm the viability of this concept, but at low efficiency. AGP`s closed loop geothermal system can turn many of these orphan well environmental hazards into safe, clean and green economic performers. Geothermal energy is endless so there is no limit, over time, as to how many terawatts of thermal energy that can be extracted from these types of wells.