Thursday, October 9, 2014
Research of supercritical water may bring geothermal revolution
In recent years, a large effort has been done to utilize a heat from the earth. Geothermal companies all over the world try to make another step to this goal. They get started an intensive research of supercritical fluids, mainly supercritical water (SCW).
SCW is a specific state of water which is very hot and under so much pressure that it exists somewhere between water and steam. The boundary of this state are conditions with temperature higher than 374°C (705°F) and pressures over 22.1 MPa. SCW has several interesting features; its main disadvantage is the fact that it is very corrosive. On the other hand, advantages can be utilized in several industry segments.
Nowadays the most famous attempt to utilize the supercritical water as an energy source is the Iceland Deep Drilling Project (IDDP). The approach in this case is simple; developers are trying to drill a well two miles deep into the active Volcano crater, Krafla and that way to reach 400-600°C hot supercritical hydrous fluid at a rifted plate margin. When this fluid hits the surface, it will have much more energy than fluid in conventional thermal cycles. The result is radical increase of power output from one geothermal well. It is necessary to mention that geothermal conditions in Iceland are extraordinary and there are just a few other locations in the world with similar opportunities. More detailed information you can find on IDDP.
Therefore, for the utilization of this phenomenon is required an improvement of current drilling methods for accessing the geothermal reservoirs with supercritical conditions. On the other hand, SCW could be an effective support during the process of drilling. Its aggressive and corrosive nature can are suitable for increase of the disintegration process. Naturally, the drilling tool with high corrosion resistance is required. This process is mainly suitable for drilling techniques based on thermal approach, such as plasma, which offer high heat flow required for supercritical conditions.
SCW could be utilized not only in geothermal segment, but according to recent research, using it in the process of material or waste disintegration is very promising. We hope that research of the SCW in all mentioned segments will continue and bring sufficient results.