The Benefits of Geothermal Energy
Renewability and Sustainability:
- Modern geothermal plants produce
zero CO2. - It is independent of climatic variation unlike other renewable resources such as wind and solar energy and can operate almost 100% of the time thereby combating security of supply.
- An abundant resource of naturally produced
renewable energy. - It is a proven technology unlike other emerging
renewable energy sources.
Environmental and Economic Advantages:
- Developing geothermal energy can assist Governments to achieve challenging renewable energy targets.
- Not only can geothermal energy reduce national expenditure on energy imports, but will support direct investment and
development back into the economy. - Used to generate electricity for connection
to a grid. - Minimum impact on the surrounding
environment.
How Geothermal Energy Works
Geothermal Energy
- Geothermal energy is a natural renewable heat generated at the earth’s core that radiates to the surface constantly.
- The earth’s core is in excess of 6,000 degrees Celsius and this heat is generated from the decay of natural material in the earth’s core.
- 4,000 times the earth’s energy demand can be met by geothermal energy.
Exploration
- Firstly a geological desktop study is carried out to assess the potential for the resource using geophysical geological & existing drilling data.
- An exploration programme using seismic acquisition and other geophysical techniques is used to develop a three dimensional model of the subsurface and target geothermal formations.
Drilling
- The next phase commences with the drilling of a production & reinjection well to a depth of up to 5km.
- The wells are drilled 2km apart in the reservoir to ensure that cold reinjected water does not come into contact with the hot water pumped from the production well.
Extraction
- Geothermal energy is harnessed using a ‘well doublet’ system. Hot water from the aquifer or geothermal reservoir is pumped to the surface using a production well.
- The heat is extracted through a heat exchanger system on the surface and the colder geothermal fluid is pumped back down into the reservoir to ensure long term life of the reservoir and so as not to cause any environmental impact.
- Depending on the temperature obtained from the reservoir, geothermal resources can be used to provide direct heat through and district heating networks or to generate electricity.
Heat Exchange
- A heat exchanger is used to transfer the heat from the geothermal fluid to a secondary liquid where it will be utilised to deliver heat or generate electricity.
- Heat exchanger technology is used to minimise surface and aquifer environmental impact as well as ensuring the long term operation of both the reservoir and surface plant equipment.
Distribution (Heat)
- Customers extract heat upon requirement of hot water or space heat from the network through individual heat exchangers.
- Cooled water from the building is returned to the district heating network where it is circulated back to the district heat exchanger unit.
- Heat from the geothermal fluid is transferred from the heat exchanger to a district heating network and fresh water is used to deliver this heat to the customers connected to the network.
Distribution (Electricity)
- Heat is transferred from the heat exchanger which changes a fluid with lower boiling point to a gas.
- A binary cycle plant uses this gas in a closed system to power the turbine.
- The electricity generated from the binary cycle plant is fed to the national electricity grid through a sub station.