HOUSE HEATING WITH GEOTHERMAL ENERGY

Transcription

1 HOUSE HEATING WITH GEOTHERMAL ENERGY By Þorkell Erlingsson Þorleikur Jóhannesson Þrándur Ólafsson

2 Introduction Content of the presentation Geothermal energy as a clean and renewable energy Change house heating systems from coal boilers General guidelines on geothermal system design Metering methods Increased service using geothermal heat Conclusions

3 Geothermal energy clean energy Geothermal energy is a renewable clean energy and its utilization can improve the living standard of people in a sustainable way. Several tons of harmful chemical compounds that would otherwise be emitted to air will be spared, and with geothermal space heating system, the official heating season will not be used as such.

4 Transformation from polluting coal boilers to clean geothermal energy The reduction of air pollution due to geothermal energy for space heating and for heating of domestic hot water is one of the main advantages of a geothermal district heating system. One of the best examples in this field is the city of Reykjavík which used to be covered with clouds of smoke due to the burning of fossil fuels (1930). Today, the inhabitants of Reykjavík enjoy an environmentally friendly and competitive energy coming from the earth.

5 Annual polluting emissions from three different cases Resulting emissions for three situations of power source. The service area is m 2 of typical new houses in Xianyang. As can be seen, the CO 2 amount is reduced by almost 90%, and other pollutants nearly disappear.

6 An assumption regarding the current radiator systems

7 First step: Ease the work of radiators and heating equipment One can easily argue that the heating equipment is the most important item in every room. Each radiator s performance and capability to deliver heat to each room depends on the conditions around it. Without heating equipment, or when heating equipment performs poorly, the comfort of living reduces drastically. All radiators should be installed close to the floor. Preferably under windows in order to counter the cold draft coming from these elements.

8 Hindering of free air-flow from radiators to the room The built in radiator will have very hot air around it, which has the effect that it will be harder to cool the heating water down in the radiator. Window Room Heat that is blocked (not used) for room heating The purpose of built-in radiators is to prevent people from burning themselves, but with a geothermal heat source the hottest incoming water will only be C. Built-in radiators are unwelcome in geothermal district heating as they will perform poorer than otherwise. Radiator Heat that is used for room heating Limited accessibility to radiators

9 Free flow of heated air as it should be The best situation is to have free flow around each radiator. In that case air will circulate freely in each room. Window Room Heated air is not directed into walls and heating will be uniform. Thus: A recommended first step in modifying heating systems towards geothermal heating systems is to remove all unnecessary blocks from radiators. Radiator Heat that is used for room heating Smooth heat circulation of air

10 Piping networks in properly installed geothermal house heating systems Parallel pipeline house heating systems require both a supply and return pipe, so that each radiator is connected directly with the source. The sizing of the radiators is a simple function of the room size (heating area size), irrespective of the level of installation. Main pipes can either go horizontally or vertically to the apartments.

11 The geothermal district heating control equipment for a whole building A common hot tap water heater is via a heat exchanger that heats cold water for the whole building. Here, each radiator has one thermostat.

12 General guidelines in geothermal heating system design 1. Utilize the temperature as much as possible, or economically feasible, in one step. 2. Keep the systems simple. 3. These two lead to the rule: Get as high ΔT as possible in the first step. 4. When renewal of water occurs slowly in the reservoir: 100% re-injection is always the future goal.

13 Proper steps in modifying old house heating systems 1. Remove all unnecessary blocks from radiators. 2. Put intake and outtake valves on all buildings that do not have any. 3. Add adjustment valves between old radiator intakes. Tune these valves during a cold day in winter and remove the adjustment handle. 4. Put up a differential controlling valve and begin work of a proper metering station. As soon as all houses have differential pressure valves, all pumps on proper systems can be taken down. 5. Put up a parallel pipe and connect the radiators in parallel. Put up thermostatic valves and remove the adjustment valves and handles. 6. Increase the surface of radiators, beginning at the top floor. 7. Add hot tap water heaters and necessary flow meters, in line with the new metering system used.

14 Metering methods The metering methods considered for comparison here are the following: Method Variables used 1) Square meter m 2 heated space. 2) Flow meter Volume flow 3) Maximum flow None (flow restrictors built in line) 4) Energy meter Supply and return temperatures, mass flow 5) Energy meter with fixed or Volume flow, supply temperature. calculated return temperature.

15 Increase in service using geothermal heat When using geothermal resources, heating can be used whenever needed. This increases the heating services provided and lengthens the current heating period by 2 months, to 6 months total. Red is temperature in Beijing. Blue is temperature in Reykjavik.

16 Increase in service using geothermal heat When using geothermal resources, heating can be used whenever needed. This increases the heating services provided and lengthens the current heating period by 1 to 2 months, to 6 months total. Typical heat load curve for northern China (this Xianyang). Energy needs, including sources of supply, over a time span of one year.

17 Implementing geothermal house heating systems in old and new buildings The implementation of a geothermal district heating system must include a different way of thinking in house heating systems than previously has been used. Old house heating systems need to be modified and new heating systems need to include a few components and pipes that are not used in current coal house heating systems. Floor heating is very effective when using geothermal heating. Hot tap water heating for bathing and other uses all year around.

18 To be able to create a successful and modern heating system, house heating systems need to be modified to suit a geothermal heat source. Conclusions Utilizing geothermal energy will reduce local air pollution and provide healthy indoor conditions, according to each user s need. The development of geothermal district heating can thus increase the heating services and create better air for inhabitants. The use of 90 C/70 C systems in coal heating is far from being suitable for a geothermal resource Considered in its widest implications, the use of a geothermal energy systems in place of a traditional coal fired boilers will be highly positive at local and global level.

19 THANK YOU