The primary energy source has long been the geothermal heat is used. This seems to be an ecologically and economically sound solution. To obtain the most geothermal boreholes are used. Even in an object designed by us, we wanted to resort to such a heat source. Accordingly, we have several preliminary inquiries with the relevant authorities took. It turned out that our parcel is located in a water protection zone, as our land is near the shore of Lake Zurich. So there is a possibility that we will encounter groundwater. If this is the case, the hole will be broken, and we must find an alternative to the boreholes. So what are the alternatives? Our first thought was to switch to natural gas as our land is already developed accordingly. The client wanted to achieve but the Minergy standard and find an ecological solution.
This was the starting point for finding a real alternative. Accordingly, I was looking for another option, the geothermal energy use, and I came across the geothermal baskets. These are relatively new and not widespread in Switzerland. I, too, these baskets are new. So I try in the following sections to learn how they work? What is the difference to the geothermal probes? And if this is a real alternative in our specific case.
function of Erdwärmkörbe
Each basket consists of a geothermal heat about 50 m long, spiral-wound polyethylene pipe, which is UV resistant and frost resistant. This tube is applied to a basket-shaped scaffold. In the pipe circulates a heat transfer fluid and absorbs the heat of the surrounding earth. The cold heat transfer fluid flows in the outer spiral tube of the basket down to the ground to escape the maximum amount of heat, and then rises in the inner tube in the middle of the basket back up, to prevent cooling. Using a heat exchanger is the heat transfer fluid transfers its heat energy to the working medium of the heat pump, which in turn supplies the heating system with hot water.
The top of the geothermal basket comes to lie at a depth of 1.5 m, so that the heat is in the basket of frost-free zone of the soil. The geothermal baskets are therefore introduced at a depth of 1.5 to 3 m into the ground and are thus unaffected by the daily temperature fluctuations. In addition, do not run the seasonal variations in temperature at this depth in sync with the surface temperature. In this zone, the temperature of the earth in November, the highest (about 13 ° C), ie at the beginning of the heating season, and is deepest at the beginning of the summer (about 7 ° C) when the heater no longer needed or the system may be used for cooling. Because geothermal heat escape
basket plants the soil heat energy, lowers its temperature during the heating season. In the summer months must be adjusted so a new thermal equilibrium. Due to the shallow geothermal baskets regeneration of the soil mainly by solar radiation and the seepage of rain water is possible.
a distance of 4 m between the geothermal baskets is maintained to ensure optimal function the system be guaranteed.
For the installation of geothermal baskets with a shovel dug a trench of 60 cm width and a depth of less than 1 meter. Thereafter, a first hole is dug to a depth of 3.5 m and it installed a geothermal basket, lie about 1.5 m below the upper edge of the earth's surface is. The hole is then filled with excavated material which is yielded by the excavation, or sand, where the quality of the excavated material is insufficient. At a distance of 4 m another hole is dug, into which the next geothermal cage is installed. Experience has shown that optimal geothermal, three baskets are connected in series with each other and the individual groups should be aligned in parallel. If the geothermal baskets are inserted in the ground, they are interconnected and connected to the heat pump (distribution = cold side and the collector = hot side).
comparison geothermal baskets and boreholes
geothermal baskets
This was the starting point for finding a real alternative. Accordingly, I was looking for another option, the geothermal energy use, and I came across the geothermal baskets. These are relatively new and not widespread in Switzerland. I, too, these baskets are new. So I try in the following sections to learn how they work? What is the difference to the geothermal probes? And if this is a real alternative in our specific case.
function of Erdwärmkörbe
Each basket consists of a geothermal heat about 50 m long, spiral-wound polyethylene pipe, which is UV resistant and frost resistant. This tube is applied to a basket-shaped scaffold. In the pipe circulates a heat transfer fluid and absorbs the heat of the surrounding earth. The cold heat transfer fluid flows in the outer spiral tube of the basket down to the ground to escape the maximum amount of heat, and then rises in the inner tube in the middle of the basket back up, to prevent cooling. Using a heat exchanger is the heat transfer fluid transfers its heat energy to the working medium of the heat pump, which in turn supplies the heating system with hot water. The top of the geothermal basket comes to lie at a depth of 1.5 m, so that the heat is in the basket of frost-free zone of the soil. The geothermal baskets are therefore introduced at a depth of 1.5 to 3 m into the ground and are thus unaffected by the daily temperature fluctuations. In addition, do not run the seasonal variations in temperature at this depth in sync with the surface temperature. In this zone, the temperature of the earth in November, the highest (about 13 ° C), ie at the beginning of the heating season, and is deepest at the beginning of the summer (about 7 ° C) when the heater no longer needed or the system may be used for cooling. Because geothermal heat escape
basket plants the soil heat energy, lowers its temperature during the heating season. In the summer months must be adjusted so a new thermal equilibrium. Due to the shallow geothermal baskets regeneration of the soil mainly by solar radiation and the seepage of rain water is possible.
a distance of 4 m between the geothermal baskets is maintained to ensure optimal function the system be guaranteed.
For the installation of geothermal baskets with a shovel dug a trench of 60 cm width and a depth of less than 1 meter. Thereafter, a first hole is dug to a depth of 3.5 m and it installed a geothermal basket, lie about 1.5 m below the upper edge of the earth's surface is. The hole is then filled with excavated material which is yielded by the excavation, or sand, where the quality of the excavated material is insufficient. At a distance of 4 m another hole is dug, into which the next geothermal cage is installed. Experience has shown that optimal geothermal, three baskets are connected in series with each other and the individual groups should be aligned in parallel. If the geothermal baskets are inserted in the ground, they are interconnected and connected to the heat pump (distribution = cold side and the collector = hot side).
comparison geothermal baskets and boreholes
geothermal baskets
+ have a low installation height and are OK about 1.5m below ground
= behavior for a single family home to geothermal probes cost neutral
- Needs more space in terms of area. Compared with horizontal ground collectors is the gain in area but about 40%
- must be the basis of the geothermal baskets at least 2m above the highest water tables are
- There are in Switzerland, no approval process for such plants.
- In Switzerland, hardly used. It lacks experience
+ Can also be installed in the water protection zone
+ relative konstanteTemperatur throughout the year
Erdwärmesonden
- drilling to a depth of 150m - 400m. Depending on power demand
= behavior for a single family home to geothermal probes cost neutral
+ Does area the little room
- If encountered during drilling on groundwater that is, the bore will be canceled.
+ authorization procedures are in place
Resume
based on our project, the geothermal baskets a real alternative. The primary advantage is the low installation depth. In our case this is not helping to push into ground water, or more than 2m are to be above the highest water table. This has been the investigations of geologists shown and are included in his report. Thus, the installation also possible in the groundwater protection zone. From the functional principle, the geothermal loop geothermal heat and the fact hardly different baskets. The need area for the installation of geothermal baskets we have in our property. The only problem is the license for this type of geothermal energy. In our District, as already mentioned, no such authorization procedures are in place. But we are met with the competent authorities in contact and discuss the problem and hope to be allowed to use the geothermal baskets. For our client so we could cost-neutral and environmentally friendly alternative to offer the boreholes.
sources
www.geothermie.ch
www.effiziente-waermepumpe.ch/wiki
www.wikipedia.org
www.empa-ren.ch/Geothermie
geothermal project manual racks / author and co-authors Simone Bassetti, Ernst Rohner
on behalf of the Federal Office of Energy
HSZ-T I A06A I House Technology I Rico Bänziger
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