Reinjection of carbon dioxide by steepslope9876



      From the geothermal power plants of
       Reykjavík Energy in the Hengill area
Hellisheidi geothermal power plant

                      Pilot plant
                      Location of equipments for
                      SF5CF3+N2 tracer.

                                                        CO2 pipeline from Pilot plant.
                                                        Pipeline will be above the surface.

                        Location of major equpments
                        for reinjection, data logger      HN-02 reinjection well
                        as well as other sensors and      of dissolved CO2 in water.
                                                          HN-04 sampling well.

                         HK-34 sampling well.

                                                       HN-01 Ground Water well.

                      Location of container
                      containing 14C tracer and
                      amidorhodamine G.
Reinjection of CARBON DIOXIDE
Geothermal energy is a renewable energy source that gives off low           Methodology:
emissions compared to conventional fossil fuel plants. Even though         Reykjavik Energy intends to move CO2 gas under pressure from its gas
emissions are low the steam used at the Hellisheidi geothermal power       purification plant at the Hellisheidi Power Plant to an injection well a
plant contains geothermal gases including carbon dioxide (CO2).            few kilometers from the plant. There the CO2 will be dissolved in water
CO2 is a greenhouse gas and is believed to play a key role in climate      and injected into the well at an approximate depth of 540 meters.
change. By capturing the CO2 and injecting it into selected geological     Prior to the mixing and injection, two types of tracers will be added to
sites where it will react with the basaltic rock and get stored as solid   the liquid stream and one to the gas stream. These tracers will be used
calcium carbonate, the adverse effects of the power plant can be            to monitor the sequestration process.
further reduced.                                                           Mannvit Engineering proposed several designs for the process and
                                                                           in collaboration with participants from the University of Iceland,
Objectives:                                                                the Earth Institute of Columbia University, CNSR and Reykjavik
 • Inject water with high enough dissolved CO2 concentration so            Energy came up with the final design. The final design combines cost
   that favorable reaction with the basaltic rock will occur.              efficiency, reliability and low maintenance.
 • Mix tracers with the fluids continuously so the CO2 sequestration
   can be monitored.

The design developed for the project is as follows:                              Conclusions:
 • The CO2 gas is lead in a plastic pipeline at a high pressure to               Down hole mixing of CO2 in water was selected as the
   the wellhead.                                                                 optimal solution for the re-injection of CO2 captured
 • A gas tracer is dosed into the CO2 stream from a high pressure                from the geothermal steam used at the Hellisheidi
   storage tank.                                                                 power plant. The solution combines cost efficiency,
 • The water is pumped up from a well a few hundred meters                       reliability in operation and low maintenance.
   from the injection well.
 • The two tracers are dosed into the water stream with high
   accuracy dosing pumps.
 • The water containing the tracers flows into the injection pipe.
 • The gas pipe continues down the well inside the injection pipe
   down to a water depth where the pressure in the gas pipe is
   only slightly higher than the hydraulic pressure in the injection
   pipe. This ensures that the driving force of the CO2 dissolution
   is high and the gas volume is kept relatively low.
 • The gas is injected into the outer pipe trough a metallic
   sparger in order to maximize the interfacial area between the
   gas and liquid phase to ensure a rapid CO2 dissolution.
 • A static mixer is placed lower in the injection pipe in order
   to get a uniform mixing of the liquid and help dissolv any
   remaining gas bubbles.
 • The injection pipe leads the water containing the dissolved CO2
   and tracers down to the desired depth.
This method is preferred since no additional compression of the
CO2 is required and gravity provides the required water pressure.
This method also makes it possible to decrease costs by making
most of the pipes out of plastic instead of using steel.

      Additional information:
      Teitur Gunnarsson:
              Mannvit Engineering
              Mannvit Engineering of Iceland was founded in 1963 and now employs
              a staff of approximately 400. The company provides a broad range of
              engineering and technical research services. Since the early seventies,
              Mannvit has been active in the area of renewable energy and has been
              involved in the development of most power plants in Iceland, both
              hydroelectric and geothermal. Services for these projects range from
              research and other preparatory work to complete design and construction

              The Mannvit website
              Mannvit’s corporate web site, contains further
              information and project examples for hydroelectric and geothermal power
              plants as well as contact information.


Mannvit hf.        Grensásvegi 1          @:          t: +354 422 3000
                   108 Reykjavík          w:             f: +354 422 3001

To top