Hydrothermal Ocean Ridge Formation

1. Saline Hydrothermal Energy and its Potential For Hydrogen and Metals/Minerals - A Method for Bringing The Fluids To The Surface Dan Fraser, Dept. of Mechanical and Industrial Engineering, University of Manitoba fraserdw@cc.umanitoba.ca The whole concept of a hydrogen economy, to counter climate change, is predicated on finding large sources of hydrogen or the energy to create hydrogen. The need for a significant source of sustainable energy and metals/minerals is also crucial. A large amount of geothermal energy, methane, hydrogen and metals/minerals exists in hydrothermal fluids that originate from high temperature reaction zones. These zones exist where there are near surface magmatic chambers. The fluids could initially be harnessed from land-based systems in many locations around the world where ocean ridge spreading centers pass through, or close to land. Iceland is a prime example of a spreading center that passes through a land mass. However, many other similar regions exist worldwide (e.g. Azores, African rift valley, Middle East, Central America etc.). This global resource necessitates a range of research, from understanding the underlying characteristics of the hydrothermal systems, to applied research, which could lead to significant and sustainable sources of metals/minerals, hydrogen and thermal energy (for the production of electricity or perhaps additional hydrogen). Harnessing these hydrothermal resources presents several technological challenges. Discussed will be a patented method of bringing hydrothermal fluids laden with a high metal/mineral/gas content to the surface. Supercritical reactions that can lead to hydrogen production such as Supercritical Water Partial Oxidation (SWPO) will also be briefly addressed.

2. Hydrothermal Ocean Ridge Formation • Mid-Ocean Ridges are places where the Earth's tectonic plates are gradually moving apart • magma rises up to fill the gap • magma provides an enormous heat source that creates many seafloor hotsprings (black smokers etc.) along these ridges undersea. • thermal capacity is orders of magnitude greater than conventional land based systems • transports heat and chemicals into the ocean

3. Mid-Atlantic Ridge - Iceland • Plates are moving apart at a rate of only 2 cm/year • Mid-Atlantic Ridge occurs on the island Sub Continental Spreading Region Active Volcanoes Glacier

4. Chemistry of Seafloor Hydrothermal Systems  100 km Ocean P=gh  4000C # NOTE SCALE #

5. Black Smoker • Laden with metal sulfides that precipitate into suspended particulates on contact with the cold seawater

7. BLACK SMOKERS ON TOP OF MOTHRA Vent Chimneys can grow up to 10 cm/day with a deposition rate of only 1-5 % of the particulate flux. Hence, the estimated yield from similar fluids should be high!

8. Papua New GuineaBack Arc Spreading Centre Steve Scott (U of T) Most Advanced Mining Strategies VENT CHIMNEY/SUFIDE DEPOSIT COMPOSITION 11 wt% Cu, 27% Zn, 230 ppm Ag and 200 ppm Au

9. METALS AND MINERALS SOURCES LAND BASED VERSUS OCEAN/SALINE BASED Meteoric Water(Land Based Plants) Water on land that has percolated down through fractures to higher T regions. Fluids contain silicon, aluminum salts, potassium and other trace minerals (salts mainly) Oceanic Water(Iceland Pilot Plant - First worldwide) Complex process - supercritical aqueous chloride fluids strips metals, minerals and create gases due to an interaction with magma in the high T reaction zone? As yet undetermined, juvenile fluids may contribute substantially to both metal/mineral and gases present in the hydrothermal fluids?

11. Typical Metal/Salt Solubility H2O + Metal + Cl Binary System H2O + Metal or Salt Solubility Concentration High pressure oxidation leaching type region for extractive metallurgy ~420°C ~420°C Temperature Temperature Trends shown are only qualitative. Actual temperature where property variation occurs will vary depending on composition of the mixture.

12. P=23.5 MPa 300 Tpc400 500 Variation of Water Properties SCW PROPERTIES • Accounts for solubility variation • May account for some self sealing mechanisms – may cause increased pressures below such a formation • Low density permits higher wellhead pressures (at 5000C the density is around 1/5 of seawater) Accounts for high enthalpies

13. Supercritical Properties • Pseudo-critical temperature varies with Pressure and composition. • Liquid like and Vapor like properties • Solubility is dramatically affected in supercritical aqueous chloride solutions Qualitative Phase Diagram Solubility H20 + METAL/MINERAL Solid Supercritical Region Pressure CP Liquid Solubility Gas Temperature

14. P-H Diagram Supercritical Fluid • P-H diagram for pure H2O with selected isotherms • Conditions under which steam and water co-exist are shown by the shaded area • Arrows show various different possible cooling paths as the fluid is brought to the surface.

15. Pseudo - critical temperature line,PCTL Supercritical Fluid Drive the thermodynamic properties of the solution along this path (blue). very high solubility region Regions where solubility can vary. Varying minerals/metals behave differently As long as the fluid state is within the very high solubility region it will transport the minerals and metals dissolved in solution and suspended/dissolved in the brine phase (some precipitation may occur - see later slide). Moving outside of this region will cause the metals/minerals to precipitate out of solution. The faster the fluid is brought out of this region the more rapid the precipitation (shock precipitation). This will occur most rapidly along the blue path - across the PCTL. Solubility can vary by orders of magnitude across the pseudo-critical line.

16. Blue Path.Drive the thermodynamic properties of the solution along this path. This is identical to what occurs at or near the exit section of black smokers. Shock precipitation occurs while crossing the pseudo-critical temperature line. very high solubility region Red Path. Path the fluid follows in a normal well. Note that decreasing solubility is not well demarcated (occurs over a wider variation of properties). Hence, precipitation will occur over a longer length of pipeline. This was seen in Reykjanes well #9 although the starting point is below supercritical. Solubility variation within the superheated region, as one drops below the critical pressure, is very poorly understood.

17. Notes WRT Previous Slide • The temperatures and pressures over which the solubility varies are only shown qualitatively. The two-phase system shown was for pure H2O. • Actual T and P may vary considerably (e.g. the critical T increases with increasing salt/metal/mineral concentration etc.). • Solubility variation when crossing the pseudo critical T line is very poorly understood yet exhibits the trends shown in the following slides. It happens extremely rapidly such as that which occurs at the exit of a black smoker vent. • Solubility variation in the superheated region is even less understood!! As the fluid passes through this region precipitation will occur slowly. This is what occurs in a normal well and hence plugs a considerable length of pipe (around 1 km at Reynkjanes well #9). For a large metal (sulfide) concentration, at SC conditions, this will plug a well quickly. • Fluid is like a two-phase mixture of a more pure water phase and a highly saline brine phase in the highly soluble regions. • The brine phase is mostly responsible for the transport of the metals/minerals and salts.

18. NOTES ON GEOCHEMISTRY • Even in the highly soluble region the flow is like a two-phase type (purer water and a brine). • The brine can precipitate as sticky salts even within the highly soluble region. These salts may become anhydrous and form a solid coating. Since the brine will carry the metals etc. some of these will likely precipitate along with it. • It can be hypothesized that as the fluid passes outside of the highly soluble region across the PCTL, salts become re-dissolved in the water and hence can no longer carry the metals as dissolved ion complexes (e.g. ferrous chloride, gold chloride etc.). Precipitation occurs much faster here. • Up until just recently most geochemical research was limited to data obtained under sub-critical conditions (mainly T < 3800C). However, under supercritical conditions with the addition of chlorides (supercritical aqueous chloride solutions) dramatic changes in solubilities (orders of magnitude) have been noted. Most of this stems from research on hydrothermal vent fluid chemistry at locations such as the Juan De Fuca Ridge (e.g. NEPTUNE project) • In general, solubility is a function of both pressure and temperature in all regions. As P increases solubility increases; as T increase solubility increases (in SC high solubility region).

19. To plant Reykjanes Drill Site Cold Water Injection or Hot with Chemical Buffers Not to scale For more detailed information on the design of the down-hole system contact the author. Highly fractured basalt magma

20. Other Methods • Suspension of particles to help nucleate sulfides and/or continuously scrub lower pipe entrance (plenum) • Additives that reduce Ph and/or Cl concentration may permit precipitation at high T and hence conserve buoyancy. Some data ( on vent fluid chemistry) supports this. Scale inhibitors such as those used at the Salton Sea system will likely be ineffective as additives due to the high degree of supersaturation of the solution as it passes outside of the SC high solubility region. • Process flow modeling using state of the art CFD codes is underway.

21. Where Do We Go From Here • Need to assess the mineral yield within these fluids. This may be accomplished partially by; • Obtaining fluid samples from a clean flowing well. This requires the development of high T samplers. Both Randy Norman (Sandia Labs) and the University of Manitoba are planning to collaborate on this. • A study performed on fluid inclusions (from drill cuttings) may provide an easier assessment for now. • A proof of concept experiment on the patented downhole application should be performed. The U of M is applying for funding. • Due to the large energy available, the potential for various other Supercritical Water Processes (such as Supercritical Water Partial Oxidation) to produce H2 (from hydrocarbons, biomass etc.) are being assessed. A binary system could be used to transfer the thermal energy to a secondary process loop. • International collaboration with the USA and Canada Neptune project should be actively pursued. This will put the worlds experts on geochemistry and high T and P sensor/fluid samplers together. • Samples at varying depth (coring) should be obtained while cleaning the currently plugged Reykanes #9 well. This should provide valuable insight into the mineral paragenisis and subsequent modelling of the system.

22. INTERNATIONAL COLLABORATION • Neptune - full scale sub-sea instrumentation on the Juan-De-Fuca Ridge off the west coast. Geochemistry research and the need to develop new sensors/ fluid samplers is crucial to both the Neptune and the IDDP project. Additional affiliates to Neptune are shown on the following slide.

23. NEPTUNE -USA And Partners

24. CONCLUSIONS • The Icelandic Pilot Plant will provide an unprecedented opportunity to access ocean based geothermal/hydrothermal systems and extract valuable metals/minerals, gases and enormous energy potential. • Proven technology could later be exported world-wide to other accessible regions • Methods of producing H2 such as the separation of H2 from H2S should be studied (See other presentation for Pradeep Agarwal) • Using efficient SCW processes could help speed up the Hydrogen Economy. Electrolysis using cheap electrical energy will also be very competitive.