Tuesday, January 14, 2014

Shale gas in Europe – Good as geothermal energy?

Shale gas is natural gas found in shale rock. It has been reported that according to the latest estimates North America has around 1,000 trillion cubic feet of recoverable shale gas which is enough to supply U.S. natural gas needs for almost 50 years. The shale gas has taken United States with the storm and it is no wonder that EU is also considering this option when weighing new options for more diversified energy portfolio.

The possibility of producing shale gas in some European countries has caused very heated debate among several different EU industries. There has been plenty of talk about the environmental and social impacts of the technique used to extract gas from shale rocks used in North America, and widely known as hydraulic fracturing or fracking.

The differences between shale gas and geothermal industry

There have been several different opinions on this matter with part of the gas industry claiming that fracking for shale gas is comparable to the hydraulic stimulation process used for geothermal exploration and that the granting of geothermal exploration permits whilst those for shale gas are rejected is creating a double standard.

Though there are certain well noticeable similarities between these two it is also important to understand the major differences between the two technologies that set these two aside.

First of all, an Enhanced Geothermal System (EGS) is an underground reservoir that has been created or improved artificially.  As many of you already know most of today’s geothermal power plants were constructed in areas with highly permeable rocks and high underground temperatures, with the most widely known example being Iceland. Enhanced Geothermal System, on the other hand, allow us to increase the permeability of rocks, which means we can harness the geothermal resources across much wider areas, even in areas where temperatures aren't as high.

Both EGS and shale gas extraction technologies use stimulation techniques based on the high pressure injection of water in order to extract as much mass flow as possible. The end product however, differs greatly, either heat for geothermal or gas for shale rock. Shale gas is locked in rocks, typically with low permeability in sedimentary basins, in a dispersed form without fluid while geothermal power extraction targets semi-permeable rocks, so the pressure of the required injection is lower.

There are also some notable differences in terms of the fluid used for extracting. EGS does not require any specific additives; the fluid includes water, which only may have certain minerals added so that the water’s composition matches that already existing in the subsurface. The advantage of this technology is therefore in the fact that the artificial reservoir is self-sustaining and does not require further stimulation and so the stimulation fluid does not have to be pumped back up to the surface since it eventually becomes an integral part of the newly created reservoir.

This however isn't the case with shale gas extraction as there is always a need to create new fractures. Not only that, in order to keep the fractures open, additives and sand need to be mixed with the water. Since the mix of these fluids can reduce the production efficiency, they need to be pumped back to the surface. What this means is that this absence of a natural fluid in the underground requires the supply of water from the surface. As a result of this, a large quantity (10.000–20.000 m3/well) is required, which doesn't make this process sustainable.

Public has also been concerned about micro-seismic in relation to hydraulic stimulation and because of this the monitoring protocols have been established by the industry, which means that the geothermal drillers install seismometers and use special purpose software to map the faults and assess the local geology. This protocol enables them to monitor what will happen during the stimulation, which is necessary to create a risk management plan, and to control micro-seismic activity.

The latest study by British scientists also studied the difference between geothermal energy and shale gas production. Fracking rock to get out shale gas is different from geothermal energy as it also has unintended effects that can be critically harmful to our environment.

It has been reported that when rocks are fractured to release natural gas so it can be extracted and used, the gas leaks up through the soil and around the pipes for years after the well has ceased production, and from the pipes during extraction. The problem is that natural gas is largely compounded of methane and the leakage of methane is very bad thing for our climate because methane is between 20 and 100 times more potent than carbon dioxide (CO2).

Carbon dioxide and methane are the main greenhouse gases causing global warming. There are various negative impacts connected with global warming and climate change such as sea level rise, floods, droughts, wildfires, ocean acidification.


Geothermal power is one of these safer, alternative energy industries while the same cannot be said for shale gas extraction, especially not in relation to climate change and global warming.

When natural gas is burned, it produces about half as much CO2 as burning coal and about 70% as much as burning diesel, which makes it somewhat positive from the environmental point of view However, one has to include potentially massive warming effect of leaks from the drilling process and also from old pipelines, which could in the end mean that the actual use of natural gas is no better for the climate than coal or oil. Current field studies show that there is leakage into the atmosphere of between 4% and 15% of the natural gas processed and sold.

In this sense, it is difficult to fully support the idea of increased shale gas extraction and development throughout the Europe. Geothermal energy still remains significantly better energy option, because it is both renewable and sustainable source of energy. Currently used shale gas extraction technologies have some major deficiencies that need to be fixed before shale gas can be put in the same sentence with geothermal energy.

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