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.

What steps can individuals, businesses or world leaders take to address the most pressing and often interrelated water and energy challenges?

To answer this question it is necessary to look at the sources which we walk on. From the volume perspective, only 1 % of the Earth is colder than 1000°C and 0.1 % is colder than 100°C. This amount of energy is available continuously 24/7 without any carbon dioxide or other pollution and practically not exhaustible. Heat under the Earth’s surface is still permanently produced in the Earth’s volume by decay of uranium, thorium, etc. For effective geothermal electricity production, there is a need to drill between 8-10 km in hard rock, where the temperatures almost anywhere in the world exceed 300°C, optimal for steam turbines and high enthalpy heat production. 

Research and development in emerging drilling technologies is aimed on effective deep drilling in hard rocks with the price linear with the depth, which is significant advancement in drilling technology. This enables to exploit geothermal energy practically anywhere in the world independent of the local geological situation. The most promising solutions are drilling systems based on thermal treatment on rocks. These systems provide cost effective and high speed drilling optimized for the hard rock environment. The technologies are oriented towards creation of power generation units ranging between 20 MW to 30 MW per unit, where drilling costs are expected to be less than $1M per drilled km. The main aim of the technology is to bring the position of the geothermal energy  in the world energy mix to its real potential as base load energy and real alternative to coal, oil & gas and nuclear, by RADICAL change through cost effective deep drilling.

Change of the strategy and paradigm of energy production: 

• Substantial contribution of geothermal energy to climate change mitigations. Energy distributed production to geographic localities where energy is needed and not where resources are available. It provides minimum transport losses in contrast to present day grids, high security against the collapse of energy systems and security against terrorist attacks.
• Affordability for developing nations, because the source of the energy the “fuel” is available anywhere. 
• Small footprint of geothermal energy production sites not harming the country environment in contrast to wind farms and photovoltaic large area fields.
• Safety of the processes compared to nuclear energy.

 
The emerging drilling systems are enabling technologies for future development of strategically important application areas as follows:

• Accessing new reservoirs of oil and gas - In recent decades new deep underground reservoirs that require significant advance in drilling technologies were discovered. One of the main innovations of emerging drilling systems based on thermal approach is the ability to produce continuous casing while drilling. Casing is created synchronously with the drilling process immediately in the drilling bit zone ensuring sealing and mechanical stability of the well all the time also in difficult conditions. This is a key factor in onshore, but even more considerable in offshore drilling with game-changing cost reduction. Moreover it reduces need for Shale Gas extraction and other methods with negative environmental impact. 
• Deep hidden water reservoirs and possible desalination on continents - Water wells in regions with limited access to drinking water but with rich sources of deep water reservoirs. Another utilization are geothermal wells for power generation aimed at desalination. Main targets areas are Africa, West and central Asia and Australia.
• Centers of prosperity - Geothermal heat cascade exploitation economy around each geothermal power generation complex, creation of new jobs and local autonomous economies. The cascade consists of hydrogen production, electricity production, lumber drying, direct building heating and cooling, biotechnology reactors, greenhouses, aquaculture, fisheries, wellness, geothermal heat pumps, etc. For development of such prosperity centers, the franchising concept could be applied. 

We believe that to address water and energy challenges it is necessary “to support development of emerging drilling technologies which will provide sustainable and safe energy for the future.”