Geothermal Well Earthcache EarthCache
Geothermal Well Earthcache
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Upon arrival at the posted coordinates, you'll find a great display of the many efforts that Sheldon Lake State Park (14140 Garrett Rd. Houston, TX 77044) are using to implement green building and alternative energy. The hours of the park are from 8am-5pm every day.
A geothermal well? In Sheldon Lake State Park? I know what you’re thinking – that there must be geysers and bubbling pools of mud! Well, not exactly.
A geothermal well is a man made system usually placed in geologically active areas of the world to take advantage of the thermal gradients available near the Earth’s surface. Since geothermal power production generally involves using the heat of the Earth to produce electricity by boiling water, high temperatures are needed. High gradients require either hot magma rising close to the surface, or abundant cracks allowing groundwater to carry heat efficiently to the surface. Either one is sufficient for energy production, but having both is best.
The edge of tectonic plates tends to be the place where high temperatures due to magma are readily available, with Iceland being one of the main countries to take advantage of magma driven geothermal energy. The American West and East Africa's Great Rift Valley also sit over magma. Fractured ground in these regions allow for ready access.
If the ground isn't hot enough to produce steam, simply using the hot water for heating rather than electricity generation has less demanding temperature requirements, which expands the geological range where geothermal wells can be used. Even in areas where the ground is too cold to provide adequate heat, it is still warmer than winter air, or colder than summer air. Seasonal ground temperature variations disappear completely below about 30 feet. The area where you are standing takes advantage of this consistent Earth temperature to heat and cool the building. Geothermal wells like this can be used essentially anywhere!
The process occurring here is similar to a conventional air conditioner which extracts heat from a building and transfers that heat to the outside air through the condensing unit. A geothermal heat pump transfers the heat of the building to the earth by circulating water through several geothermal wells connected in a big loop. The heat pump can transfer heat very efficiently, making the geothermal heat pump up to 50% more efficient than a conventional unit. In the winter time the process reverses and the heat pump extracts heat from the ground into the building.
To log this Earthcache, check out the displays around the posted coordinates involving the geothermal wells and answer the following questions:
1. How deep does the geothermal well display show the loops go into the ground?
2. Does the picture indicate that the geothermal wells are operating on a summer or winter day? Check out the colored arrows.
3. What is the average underground temperature at this location?
4. The park streams temperature data for their entire renewable energy system to this link. The temperatures for the geothermal well are on the Temps tab. The Heat Pump Temp In (red line) is the temperature of the water after circulating through the geothermal well, and the Heat Pump Temp Out (blue line) is the temperature of the water coming from the building. Tell me how much did the Earth heat or cool the circulating water at the time you visited? If the Heat Pump data is missing for the day you visited, used the Graph tab to plot the last several months and pick a day where both parameters are available. If the site isn't working at all, use the average underground temperature and the temperature it currently is outside to tell me how many degrees the well could heat or cool the building.
5. You are welcome to log your find, but MUST ALSO send your answers to me within a week of your log. Don't post them here!
References
Sheldon Lake State Park
About Geothermal Energy
Wikipaedia: Geothermal Power
Geothermal Heat Pump Installer
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