Earth act like a SINK, it absorbed heat that cannot be used immediately or it can act as SOURCE to provide heat when it is needed. This thermal characteristic makes earth to be used as heat exchanger.
Geothermal Reservoir (GR) is an efficient heat exchanger which uses Sink/Source thermal characteristic of earth below 6 feet of grade level and can be used as:
Geothermal Reservoir (GR) TM uses high density polyethylene (HDPE) pipes connected in a closed loop reverse return fashion to form a continuous, sealed, buried heat exchanger through which heat transfer fluid which is a mixture of water and antifreeze solution passes to and returns from the building HVAC system.
Geothermal Reservoir (GR) TM has alternate descriptions but all have one purpose – to answer the need for on-site renewable energy without burning fossil fuels:
On building heating or cooling demand, the central building controller will energize the geothermal VFD pump which is a part of Hybrid geothermal skid to circulate the heat transfer fluid through series of buried HDPE pipes to either reject or collect the thermal energy from the earth.
Geothermal Reservoir can be an integral part of Hybrid Geothermal system so it can absorb or reject thermal energy when needed via Thermal Energy Absorber or Thermal Energy Rejector respectively.
Experience Counts…..Results define us……
Geothermal industry is growing in Canada & ABS leading eco-friendly group of companies are among the leaders in promoting this industry. Our efficient, reliable and cost effective Geothermal Reservoir design and Thermal modeling utilizes earth thermal inertia, undisturbed earth temperature and other building annual energy usage to size an efficient and economical Geothermal Reservoir.
Since establishment, ABS has developed, designed & engineered many notable and state of the art geothermal projects in Ontario. Some of our projects use no (Zero) fossil fuel system and the entire building heating demand is satisfied with geothermal system:
The earth energy is transferred daily to and from the earth’s surface by solar radiation, rainfall, wind, etc. Because of its own insulation the earth’s soil temperature is more moderate year round than outdoor air and are delayed four weeks compared to soil surface temperature. Only a small part (less than 2 to 3%) of the stored energy in the earth’s crust comes from its hot core.
Many studies suggested that the undisturbed earth temperature at a depth of 30 feet is constant year round and approaches the annual average air temperature. It is normally 50°F in cold climates such as Canada and very close to 85°F in hot climate such as Saudi Arabia. Subjected to earth geology and local climate conditions, the earth temperature will vary very little between summer and winter as heat only moves very slowly in the earth.
Thermal Inertia is a characteristic of earth which means thermal energy only moves very slowly through it – as slowly as couple of feet a month. Oil and Gas drilling logs show the normal increase in the earth’s temperature to be from one to three degrees Fahrenheit for each 100 feet in depth. This is due to lower thermal conductivity of earth which ranges from 0.4 to 2 Btu/(hr ft oF) and lower thermal diffusivity ranges from 0.01 to 0.05 ft2/hr.
A subsurface application of thermal energy storage using earth water and/or the earth for storage of supplied energy.
Where horizontal heat exchanger is not practical than a vertical energy storage system can be feasible such as energy Borehole Thermal Energy Storage system. A vertical BTES is created by drilling a borehole field, a set of boreholes drilled to depths of 183 meters or less. This is described as Borehole Thermal Energy Storage – BTES. In BTES, a closed loop high density polyethylene pipes are inserted after drilling, the borehole is then filled with a high conductivity grouting (K=1.0 Btu/(hr•ft•°F). ) to provide a good thermal contact with the surrounding soil. Borehole can be drilled at an angle. Angled boreholes, also called an inclined boreholes with or without directional angles, can be used if surface area is limited, thereby saving on investment costs.
Energy stored for use in a later season.