Geothermal power plants – energy from 3000 metres below us !?
Renewable sources of energy use natural forces in order to generate electricity with them. Now one of the most powerful natural forces is our planet itself or its core to be precise because down at the middle of the earth there are temperature of up to 15000 degrees Celsius and since we know that the most common way of generating electricity is using heat to power a turbine, this looks like a really promising solution.
Luckily though, we do not need to go as deep as right to the middle of the planet, since we will already find temperatures high enough for our purposes at approximately 1200 to 3000 metres in the first layer of our earth’s crust, according to where we want to make use the planet’s heat. Bringing us straight to the first downside of Geo-Thermal power plants, because as with most renewable energy plants you can not build them just where you want to. Thus finding a location with a so called geo-thermal abnormality in the meaning of a very high temperature of the ground at very low depth to minimize the costs and increase the power output.
Therefore one of the countries that have already moven into Geo-Thermal electricity is Iceland, since there you have enormously high temperatures at enormously low depths which are the perfect conditions for a geo thermal power plant.
Luckily though, we do not need to go as deep as right to the middle of the planet, since we will already find temperatures high enough for our purposes at approximately 1200 to 3000 metres in the first layer of our earth’s crust, according to where we want to make use the planet’s heat. Bringing us straight to the first downside of Geo-Thermal power plants, because as with most renewable energy plants you can not build them just where you want to. Thus finding a location with a so called geo-thermal abnormality in the meaning of a very high temperature of the ground at very low depth to minimize the costs and increase the power output.
Therefore one of the countries that have already moven into Geo-Thermal electricity is Iceland, since there you have enormously high temperatures at enormously low depths which are the perfect conditions for a geo thermal power plant.
How can I gain electricity from our planet’s heat ?
Well as we mentioned earlier you will need a place with a very easy access to warm regions of the planet’s crust and after that it will require the following. At first you will need to drill two long pipes into the groung in order to pump water down to the hot layers. Down there the water will than evaporate and become steam. And plainly explained this steam has the urgent need to go up again because it is lighter than the surrounding material and since the first pipe is constantly pumping new water into the ground the only fast way for the steam is the second pipe.
However when the water evaporates there are also parts of the stones and minerals that are evaporated and therefore come up together with the steam which is why the rising steam needs to be filtered before it is actually sent through the turbines, in order not to damage them.
In addition to the generating of electricity there is a second application of the steam, because after it went through the turbines it is sent through yet another clever machine, a condenser to be precise. And the reason for this is that even after the turbines and the condenser the water is still between about 83 and 90 degrees Celsius hot which makes it usable for heating private households or hot water supply. In fact this so called ‘Electricity and Heat linking’ is held to be the most efficient way of using energy among all of the renewable sources.
However when the water evaporates there are also parts of the stones and minerals that are evaporated and therefore come up together with the steam which is why the rising steam needs to be filtered before it is actually sent through the turbines, in order not to damage them.
In addition to the generating of electricity there is a second application of the steam, because after it went through the turbines it is sent through yet another clever machine, a condenser to be precise. And the reason for this is that even after the turbines and the condenser the water is still between about 83 and 90 degrees Celsius hot which makes it usable for heating private households or hot water supply. In fact this so called ‘Electricity and Heat linking’ is held to be the most efficient way of using energy among all of the renewable sources.
Where do I find one of these ?
As Iceland is one of the very few places on earth where geo thermal heat is accessible only a couple of hundred metres below the surface it is the country with the longest geothermal tradition if you want to say so. As a matter of fact their experience goes back to 1947 when the first test drills and experiments took place aimed to evaluate the potential of this new tribe in technology. Between 1964 and 1986 specific test drills took place this time focused on finding the most suitable and profitable spot for the construction of geo thermal power plants.
One of the biggest plants on Iceland is the so called Nesjavellir plant which was finished in 2005 when the last of four 30 megawatt turbines set to work, resulting in an overall power of 120 megawatts which is enough to supply 150,000 households, which might not sound like that much but if you take into account that Iceland’s population is just under 400,000 people it is actually a lot.
Better still the Nesjavellir plant is actually one of the ‘energy heat linking’ plants which we explained to you earlier. And that means that it is capable of providing 1,100 litres of hot water per second, supplying the South West of the island with renewably heated households and hot water.
One of the biggest plants on Iceland is the so called Nesjavellir plant which was finished in 2005 when the last of four 30 megawatt turbines set to work, resulting in an overall power of 120 megawatts which is enough to supply 150,000 households, which might not sound like that much but if you take into account that Iceland’s population is just under 400,000 people it is actually a lot.
Better still the Nesjavellir plant is actually one of the ‘energy heat linking’ plants which we explained to you earlier. And that means that it is capable of providing 1,100 litres of hot water per second, supplying the South West of the island with renewably heated households and hot water.
Do they harm the environment?
So far we have established that geo thermal power plants are an efficient and powerful alternative to fossil fuels and that even among other renewable sources of energy they are considered to be one of the most efficient since you are capable of using the heat to generate electricity as well as providing hot water and thus a possible way of heating private houses. But are they really environmental friendly?
Now obviously there are some impacts exerted by these power plants since it is basically a disturbance of an ecosystem to constantly pump water into the ground of the earth so the question is what are the symptoms of that and how serious are they? Now as we said together with the steam there are some gases carried to the surface as well and in most cases they are methane and hydrogen sulfide so they have to be filtered out and retrieved safely.
Another issue that needs to be considered is that due to the ‘water injection’ the pressure in the zone that is influenced differs from the normal figures which can result in seismological activity. However the earthquakes that these differences could cause are only of any danger, if the geo thermal power plant is build on a very geologically labile region.
And the last thing that could turn out to be a problem is the fact that due to the different pressures experts have examined that the region where the geo thermal plant is build could sink into the ground. However luckily though these changes are so minimalistic that they could not have an impact on buildings, roads etc.
Now obviously there are some impacts exerted by these power plants since it is basically a disturbance of an ecosystem to constantly pump water into the ground of the earth so the question is what are the symptoms of that and how serious are they? Now as we said together with the steam there are some gases carried to the surface as well and in most cases they are methane and hydrogen sulfide so they have to be filtered out and retrieved safely.
Another issue that needs to be considered is that due to the ‘water injection’ the pressure in the zone that is influenced differs from the normal figures which can result in seismological activity. However the earthquakes that these differences could cause are only of any danger, if the geo thermal power plant is build on a very geologically labile region.
And the last thing that could turn out to be a problem is the fact that due to the different pressures experts have examined that the region where the geo thermal plant is build could sink into the ground. However luckily though these changes are so minimalistic that they could not have an impact on buildings, roads etc.
Conclusion are geo thermal power plants a suitable alternative to fossil fuels or even other renewable sources of energy ?
To our understandings they absolutely are because unlike most other way of generating electricity due to the fact that one can reuse the steam so easily they are relatively efficient plus unlike most other renewable sources of energy they are really reliable, because the earth is constantly warm and so you can gain a constant supply of energy.
As we have further established they are not an unproven playground. In fact there are geo thermal power plants running on Iceland since 1990, which means that we have relatively much experience with them.
Above all it is a safe technology that would in comparison to all other sources of energy extremely few harm to the environment, because unlike for instance photovoltaic cells there are hardly any precious and hazardous raw materials needed to build them. In addition to that on a long-term serice they will hardly do any damage either as the only consequences they do cause are so small that most people consider them irrelevant.
But after all there are a couple of downsides. One is that they are not really cheap to build since unless you build them in places with geothermal abnormalities you will need to drill very deep holes which are a very costly operation. And talking of which we have immediately named the second problem because they can only be build at very few places on earth of you want to run them with financial efficiency and output figures in mind.
However to sum this us one needs to acknowledge that geo thermal power plants are actually a very promising and efficient device and although they can not be operated anywhere, they would work brilliantly as part of an international energy grid, such as for instance the EUMENA project which we explained to you in the Desertec article.
As we have further established they are not an unproven playground. In fact there are geo thermal power plants running on Iceland since 1990, which means that we have relatively much experience with them.
Above all it is a safe technology that would in comparison to all other sources of energy extremely few harm to the environment, because unlike for instance photovoltaic cells there are hardly any precious and hazardous raw materials needed to build them. In addition to that on a long-term serice they will hardly do any damage either as the only consequences they do cause are so small that most people consider them irrelevant.
But after all there are a couple of downsides. One is that they are not really cheap to build since unless you build them in places with geothermal abnormalities you will need to drill very deep holes which are a very costly operation. And talking of which we have immediately named the second problem because they can only be build at very few places on earth of you want to run them with financial efficiency and output figures in mind.
However to sum this us one needs to acknowledge that geo thermal power plants are actually a very promising and efficient device and although they can not be operated anywhere, they would work brilliantly as part of an international energy grid, such as for instance the EUMENA project which we explained to you in the Desertec article.
Sources:
1.http://www.or.is/English/Projects/NesjavellirGeothermalPlant/
2.http://en.wikipedia.org/wiki/Nesjavellir_Geothermal_Power_Station
3.http://www.mannvit.com/GeothermalEnergy/GeothermalPowerPlants/GeothermalProjectNesjavellir/
4.http://www.green-economy.de/erneuerbare-energien/geothermie/glossar/umweltauswirkungen-der-geothermie.xhtml
5.http://www.welt.de/wirtschaft/energie/specials/geothermie-erdwaerme/article8796827/Das-sind-die-Nachteile-und-Vorteile-von-Geothermie.html
1.http://www.or.is/English/Projects/NesjavellirGeothermalPlant/
2.http://en.wikipedia.org/wiki/Nesjavellir_Geothermal_Power_Station
3.http://www.mannvit.com/GeothermalEnergy/GeothermalPowerPlants/GeothermalProjectNesjavellir/
4.http://www.green-economy.de/erneuerbare-energien/geothermie/glossar/umweltauswirkungen-der-geothermie.xhtml
5.http://www.welt.de/wirtschaft/energie/specials/geothermie-erdwaerme/article8796827/Das-sind-die-Nachteile-und-Vorteile-von-Geothermie.html