What does geothermal means?
The geotherm, geothermia words derive from , geo’ and ,therme’ words with greek origin which both together have the meaning: geothermal. More precisely, the heat coming from the Earth’s core called this way which originates from the slow decomposition of those elements that the core is formed as well as the radioactive elements. In the earth’s crust, 10 kilometres beneath the surface, the amount of heat energy is more than 5000 times higher thanof the natural gas and crude oil resources.
Since the geothermal adjective could be translated as land heat working, land heat utilising, the geothermal is linked to the use of the land heat until the comprehensive science including knowledge, solution and technologies.
The geothermal energy has one of the biggest potential and it can be exploited the most efficiently, renewable energy source due to the natural conditions of Hungary. The Hungarian geothermal gradient nearly one and a half times higher than the world average so it holds a bunch of possibilites in the field of the future energy developments.
The essence of geothermal:
The main parts of the inside of the Earth: inner core, exterior core, lower mantle, upper mantle and the Earth’s crust. The approximately 1200 km radius of the core is formed by iron and nickel, the outer core is formed by molten rock. It is surrounded consisting upper and lower mantle piece and then eventually the crust.
The Earth’s crust is really thin compared to the other layer, its thickness with the top part of the upper crust changes among 50-100 km and it forms the bottom of oceans and continents. It consists of not related but different sized plates, the magma is often closer to the surface while it is moving so the geothermal energy becomes more accessible, which can be used in several ways like smaller, simplier geothermal systems to complex thermal power stations.
Utilization area of geothermal energy:
- to utilize shallow warm water sources and reservoirs in direct or district heating systems
- to utilize the high-temperature water of rezervoirs which can be found a few km beneath the surface for generating electricity in power station points
- using the water or soil temperature near to the surface for regulating the inside temperature of buildings
The geothermal ground source system offers the most effective and currently, the most well-known system. The most important part of the efficiency is the stable temperature of the soil which provides a temperature level between 0-10 C in winter and 15-20 in summer. The heating index between 4-7 called COP and the cooling index between 4-8 called EER could be achieved due to the exact calibration and the selection of product/material. It means that one unit of electrical consumption produces much more heating and cooling energy, so it operates more effective than any other exothermic. We would like to present a saving comparison which belongs to a 200kW heating/cooling system.
The planning of a geothermal heat pump system is a complex task. It has partly geological and building engineering aspects. The soil probe fields are calculated according to the regulations of a german standard called VDI4640. When it comes to installing a soil probe , the normative parameter is the thermal conductivity of the soil. The sizing of a soil probe being attached to the heat pump systems is determined by the accurate knowledge of the thermal conductivity of the soil. These values are defined with the help of either a probe test result or an ever-expanding database.
Geothermal Response Test
We make the probe tests with the collaboration of Geort Kft. and a testing machine that is a German development. Based on the made probe test, we model the function of the given probe field with EED software for 25 years. With the help of these results, we are able to define the size of an optimal soil probe system.
The hydraulics sizing is the other significant part of the planning. We need to provide: the turbulent flow in the soil probe, the lowest resistance with pipe dimensions, frost protection with small amount of antifreeze, adequate flow in the heat pump. For this task, we usually use a software developed by our company which takes into consideration these statements.
The soil probe systems are needed to be licensed at the Mining Authority in Hungary. The Mining Authority involves other special authorities to the proceedings if necessary. Our company has direct contact with all regional authorities due to the numerous licences and also can provide fast and effective proceedings to the business partners.
The soil probes are drilled with either water or air flushing technology. We apply water flushing technology in the case of the soil layers which can be drilled more easily. Through this process, the drill liquid is flowing downward inside the drilling rod, then it reaches the surface by moving forward next to the drilling rod. This drilling liquid brings sludge, which was drilled before, to the surface. The circulation is performed by a drilling-mud pump. The drilling bite may be diverse according to the drilling difficulty. We distinguish 3 categories according to the difficulty level in the case of flush drilling. There are significant time and tool-use difference among the drilling categories so their price can be variant as well. We apply air-flushing technology on stony-rocky areas, in this case the flushing is provided by the air pressure inside the drilling rod. The needed air-pressure is prepared by a compressor. In addition, the breakdown of the layers of stones is performed by impact drilling. This technology is more expensive because of additional equipments, excess energy and its much longer time-consuming process.
Filling the borehole (Grouting)
The VDI4640 standard describes the proper grouting process . The strictest regulation of the standard is the professional filling, which provides a long-term, calculable function beside an environment protection viewpoint and last but not least it guarantees a better performance due to the using of premium filling materials. Every soil probe installed by our company is filled from below upwards through a filling pipe to ensure the tightness of the hole. In addition to drilling and filling, we ascribe a great importance to the professional binding of the soil probes.Plastic weldings are performed with electrical connections. The welding machine called Frank GET Control and FGF prepare reports about every welding. These reports can be saved later. The antifreeze filling of the system is carried out by an industrial filling device.
Placing manifold, connecting
We usually apply two types of soil circle manifold during the installation of geothermal systems. The manifold shaft which is placed outside the building is used in the case of a higher number of probes while the preassembled manifold which is placed inside the building is used in the case of a less number of probes.
For achiving adequate, safe and economical operation, every unit are installed with temperature and pressure gauge, shut-off fittings, flow measurements and ball vaves which are needed to the adjustment. Using the rotameter the flow rate can be adjustable between 5-42l / min.
The header pipe leaving from the manifold mediates the collected heat towards the heating centre. These pipes are made from the PE100 material with electrofitting, welded bandages. It is necessary to place a defender pipe for the professional wall extension through the installation process. The impermeability between defender pipe and utility pipe is provided by a gaiter or pre-tension rubberseal seals. The filling elements up to 63 diameter used by us requires a defender pipe.
The system’s antifreeze filling is carried out by an industrial filling equipment with long circulation time thus we provide the fewest microbubbles in the antifreeze mixture. The freezing point of the mixture depends on the heating primer temperature in the calculations as well as the manufacturer’S instruction of the currently recommended heat pump. Our quotation contains in detail the type of antifreeze mixture and the freezing point.
We use only and exclusively products qualified according to a VDI4640 standard. Based on our several years experience, we attach great importance to the substance quality manufactured with high technology. We constantly pay attention and follow the technical innovations and technological innovation. We are working with products of several significance european importer who provides us unique conditions.