The World's #1 Renewable Energy Network for News, Information, and Companies.

Geothermal Energy: Why It Is Different From Shale Gas

The possibility of producing shale gas in some European countries has triggered a very heated debate about the environmental and social impacts of the technique used to extract gas from shale rocks (today only in the US and Canada); this technique is widely known as hydraulic fracturing or fracking.

Recently, part of the gas industry has claimed 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.  Whilst there are similarities, it is important to understand the intricacies and differences between the two technologies.

An Enhanced Geothermal System (EGS) is an underground reservoir that has been created or improved artificially.  Traditionally, we only saw geothermal power plants in areas with highly permeable rocks and high underground temperatures, such as Tuscany and Iceland. EGS allow us to increase the permeability of rocks, which means we can use the geothermal resources right across Europe – even in areas with lower temperatures.

Drilling operation at Egoci project - EGS (France)

Both EGS and shale gas extraction technologies have a shared objective: to use stimulation techniques based on the high pressure injection of water in order to extract as much mass flow as possible. However, the target is different, either heat or gas. Shale gas is locked in rocks, typically with low permeability in sedimentary basins, in a dispersed form without fluid. Geothermal power production targets semi-permeable rocks, so the pressure of the required injection is lower.

There are also important differences in terms of the fluid used. With EGS, no specific additives are required; the fluid includes water, which may have minerals added so that the water’s composition matches that already existing in the subsurface. The advantage of EGS is that the permeability is permanently increased, the artificial reservoir is self-sustaining and does not require further stimulation. The stimulation fluid does not need to be pumped back up to the surface as it now forms an integral part of the newly created reservoir.

In the case of shale gas, there is always a need to create new fractures and in order to keep the fractures open, additives and sand are mixed with the water. As these fluids can reduce the production efficiency, they need to be pumped back to the surface. The absence of a natural fluid in the underground requires the supply of water from external sources. A large quantity (10.000–20.000 m3/well) is required and as a result significant level of chemicals.

There has been public concern about micro-seismic activity (less than 3.5 on the Richter scale) in relation to hydraulic stimulation. Monitoring protocols have been established by the industry, using the long experience of the oil and gas sector in this area. Geothermal drillers install seismometers and use special purpose software to map the faults and assess the local geology. This enables them to monitor what will happen during the stimulation, to create a risk management plan, and to control micro-seismicity.

Drilling site for an EGS project

The European Parliament’s resolution (2011/2309(INI) urges public authorities to introduce underground regional planning in order to optimise resource allocation between geothermal energy, shale gas, carbon capture and storage (CCS) and possible other possible underground uses, and thereby maximising the benefits of our underground resources for society.

As our use of the underground changes, we will need to prioritise the way we use it. Shale gas is an extension of classical hydrocarbon technology whereas geothermal energy is a sustainable and renewable energy resource.

Philippe Dumas is Secretary General, and Luca Angelino is Policy and Project Officer, at the European Geothermal Energy Council.

Images courtesy European Geothermal Energy Council

RELATED ARTICLES

US Capitol

Republicans and Democrats Back Bill to Level the Playing Field for Renewable Energy

Vince Font, Contributing Editor U.S. Senators Chris Coons and Jerry Moran are leading a bipartisan effort to reintroduce tax code legislation aimed at leveling the playing field for renewable energy investment. The Master Limited Partnerships Parity Act w...
Pope Francis

The Common Goals of the Pope and Clean Energy

Paul Stinson, EDF Pope Francis turned a keen eye toward the environment and the problem of climate change with his encyclical,“Laudato Si” (“Praised Be”). As a clean energy advocate, I’m heartened that Pope Francis recognizes the need t...
money pile

Deeper Capital Markets for Renewable Energy

Tomas Gardfors and Ann Vesely, Norton Rose Fulbright Following the global financial crisis, a more diversified funding market is developing in Europe. Institutional investors are helping to fill the funding gap left by the contraction in bank lending in the wake of the crisis...
Clean planet

Renewable Energy Responsible for First Ever Carbon Emissions Stabilization

Vince Font, Contributing Editor Carbon emissions in 2014 remained at the previous year’s levels of 32.3 billion metric tons — a milestone that points to the impact worldwide renewable energy investment is having in the face of a 1.5 percent annual increas...
Philippe Dumas, after a master in European Affairs in 1999, first worked in a European engineering company as representative in Brussels for EU affairs (2000-2007). Firstly involved in geothermal energy with EGEC, starting as project manager for ...

CURRENT MAGAZINE ISSUE

Volume 18, Issue 3
1505REW_C11

STAY CONNECTED

To register for our free
e-Newsletters, subscribe today:

SOCIAL ACTIVITY

Tweet the Editors! @megcichon @jennrunyon

FEATURED PARTNERS



EVENTS

SAP for Utilities

The SAP for Utilities conference is the most comprehensive SAP for Utili...

GRC Fieldtrip - McGinness Hills Geothermal Plant

The 13.4 MW Salt Wells Geothermal Plant is owned by Enel North America a...

GRC Fieldtrip - Steamboat Geothermal Plant Complex

Ormat’s Steamboat Geothermal Power Plant Complex located...

COMPANY BLOGS

Net Zero Energy Efficient Buildings and Geothermal Heat Pumps

As the U.S. market for green building design and construction evolves, ...

Geothermal Earth Day Visual: Shaping Environmental Solutions

Earth day 2015 is an important point in history for the environment. Mem...

Environmentally friendly solutions for projects

geoAMPS joins the celebration of the worldwide observance of Earth Day o...

NEWSLETTERS

Renewable Energy: Subscribe Now

Solar Energy: Subscribe Now

Wind Energy: Subscribe Now

Geothermal Energy: Subscribe Now

Bioenergy: Subscribe Now  

 

FEATURED PARTNERS