Energy system in Åtvidaberg

Energy system Polyamp has expanded the factory in Åtvidaberg with about 35% more surface. However the main investments have been made to refurbish the rest of the plant and change our indoor climate. We use now Geothermal Heating and Cooling in combination with recovering the exhaust air ventilation energy. In Åtvidaberg the yearly average outdoor temperature is around +6.5°C well below 22°C, which is a comfortable working environmental temperature. Geothermal Heating In order to heat up we use the granite bedrock which keeps the water temperature above +4°C. We have five 230m deep drilled water filled holes containing plastic pipes filled with water and anti-freeze alcohol. The heat pump sucks out the energy by lowering the water temperature 3 to 4°C and pumps it back into the hole, which is warmed up again by the bedrock. As the Granite bedrock is practically homogeneous it has an "endless" mass, together with good thermal conductivity, it forms enormous energy storage. Even the temperature difference do not seem to be large the heat pump deliver +60°C water that is used to heat up the ventilation air. During cool days/nights the warm water is also distributed to radiators under the windows. Geothermal Cooling Even the average temperature is low in Sweden we have warm periods and we actually had problem with a too high working temperature in the offices. In this case we pump up the cool water from the holes, use a mechanical heat exchange to increase the temperature above the dew point, that is then distributed to the ventilation system. This method is very cost effective and was the main reason we chose the geothermal method. However it can only decrease the temperature by about 5°C. A side effect is that we pump energy back to the Granite bedrock that can be used cool days. Have we gained something? In energy cost terms we have not measured the difference yet. Our old heating system was based on an oil burner, with addition of so called direct electric heating under the windows. Still the main heating method was via the ventilation, but we had an old type of heat exchange that reutilised some of the ventilation air. Today 100% of the air is ventilated outside after use and 100% new air comes in. The heat exchange has around 97% efficiency; therefore very little energy is lost. In the beginning of 2010 we have experienced -10 to -20°C during a longer period and it works very well. We hope we can also test when we have warm weather ;-) In CO2 terms we have made a big saving as the Swedish electric grid has very low CO2 content. We are however completely dependent on electric energy for the heat pump, circulation pumps and ventilation. A heat pump supplies 4 to 5 times more of thermal energy than the electricity it uses. How about our production of DC/DC converter, it uses also electricity? We have calculated that we do not use very much electrical energy in the production to motivate special arrangements with loads etc. The electrical energy produces heat that is reutilised in the heat exchange. It means less energy is added to the "new air". We have although prepared water cooling pipes that are in connection with our Geothermal system in order to cool larger system loads. The CVN system needed up to 60kW cooling energy, which is not possible to recover even with an advanced load. We can now pump cooling water into our heating system or down to the Granite bedrock instead of using city water and heat up the sewer water.... {FacileForms:ContactWeb_Code_en,1,0}

Last Updated on Saturday, 09 January 2010 05:53