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What is a Ground Source Heat Pump? How does it Work?

What is a Ground Source Heat Pump?

What is a Ground Source Heat Pump (GSHP)?

“A ground source heat pump (GSHP) extracts heat from the ground using pipes buried underground. This can then be used to heat water in radiators, underfloor heating as well as providing hot water.” (Energy Saving Trust, 2007).

What is a Ground Source Heat Pump? A GSHP extracts the heat or thermal energy gained by the earth through solar radiation. As the interior of the earth has constant temperature after a certain depth, the outside temperature changes frequently with atmospheric conditions changing. GSHP does its job by circulating a fluid through a closed loop of underground pipes. This fluid absorbs the heat from the earth and is transported to the heat pump attached to the building to heat the premises. In summers, the circulating fluid, transfers the heat from the building and transfers it to the earth through the same already laid underground water pipes. It is one of the most efficient technologies in extraction and transportation of heat. As ground is the main source of energy, this fact makes this technology more self-sufficient, cheap and thus viable. (Cui, Man, & Fang, 2015)

Geological Considerations before installing Ground Source Heat Pump

Pipe being laid for a Ground Source Heat Pump in Hayatabad, Peshawar

How does Ground Source Heat Pumps work?

In winter, water is pumped from inside the building which circulates in the pipe loop buried in the ground. The inside of the ground having higher temperature than the outside, heats the water. The warm water is then circulated in pipes through the building where the heat is spent by warming the surrounding, the water becomes cold and returns back to the ground for getting warmed by the heat stored inside the earth. A single geothermal heat pump can transfer heat stored in the earth into a building during the winter, and transfer heat out of the building during the summer. GSHPs also do not need any specific geological conditions like hot springs etc. for its successful operation. Along with high efficiency, GSHP systems provides appealing benefits as opposed to traditional modes like environmentally friendly, low maintenance costs, building aesthetics and payback of the invested amount. The concept of using the GSHP was found in a Swiss patent as old as 1912. (Cui, Man, & Fang, 2015)

Significance and Applications of GSHP

GSHPs have high efficiency and is one of their greatest benefit. It is due to the same reason – efficiency – that financially GSHP system is more viable. If a GSHP system is insulated well it can provide 3 - 4.5 times the amount of electrical energy it expends for heating homes. A high co-efficient of performance (COP) of up to 4.5 is only possible because GSHPs only relocate heat from one place to another, rather than burning fuel or generate energy. For instance, the best oil-fueled furnaces can only be 100% efficient in terms of energy spent to heat energy provided while a COP of 4.5 means efficiency of 450%.

The study is significant in the field of renewable and alternative energy sources as it will increase the awareness regarding the cost of installation and the price of the GSHP. It will also enable the readers to know the price range of this system and hence, better prepare them to take more informed decisions in the use of energy conservation and the quest for alternative/renewable energy means.

Ground source heat pumps (GSHPs) offer a more efficient and environmentally responsible alternative to traditional heating and cooling systems. Using the earth’s constant subsurface ground temperatures to generate heating and cooling, GSHPs allow for a decrease in fossil fuel dependence, reduced greenhouse gas emissions and economically more viable for heating and cooling purpose. Another advantage of GSHPs is that they can effectively be switched into reverse, so that they can operate in both ways, heat the building as well as cool it. Standard AC units are air-to-air heat pumps which operate in-efficiently on hotter days because they have to work hard to reject heat to a heat sink, which is already at a higher temperature. For GSHPs, a heat pump would operate considerably more efficiently as it rejects heat to a relatively colder reservoir (ground). (Banks, 2008) The same rejected heat can be utilized in cold weather to heat the building too.

Cost of Ground Source Heat Pumps

The cost of a ground-source heat pump system is greater than that of a conventional system (Imal, Yılmaz, & Pınarbaşı, 2015) but GSHPs have better Coefficient of Performance (COPH) than traditional air-conditioning units. Most GSHPs have a COPH of at least 3, and can even reach 4 under good operational conditions. Ground source heat pumps are among the most efficient, and therefore least polluting, heating, cooling, and water-heating systems available. (Colorado Renewable Energy Society, 2019) So, the GSHPs can payback the entire cost of its investment by incorporating the monthly savings done in the form of reduction in electricity/gas bills. If one applies the same payback concept to a standard/traditional HVAC system, there never truly is payback because there are no savings. Fuel/electricity costs are paid on a frequent basis. The use of geothermal energy for heating and cooling is valuable due to the environmental, economic, and social impacts that it has on the area of its use. (Snelling, Harris, & Wilson, 2017).

With increased interest in using renewable/alternate energy sources there is a need to determine the experimental, performance as well as economic feasibility of these systems for our locality. This will result in analysis of energy efficiency of different heating/cooling mechanisms, energy conservation, cost savings, pollution reduction etc.

BIBLIOGRAPHY

  • Cui, P., Man, Y., & Fang, Z. (2015). Handbook of Clean Energy Systems, Online. Jinan, China: John Wiley & Sons, Ltd.
  • Energy Sage. (2020, February 16). Costs and benefits of geothermal heat pumps. Retrieved from Energy Sage: https://www.energysage.com/green-heating-and-cooling/geothermal-heat-pumps/costs-benefits-geothermal-heat-pumps/
  • Energy Saving Trust. (2007). Domestic Ground Source Heat Pumps: Design and installation of closed-loop systems. London.
  • Imal, M., Yılmaz, K., & Pınarbaşı, A. (2015). Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System. Sustainability, 2.
  • Banks, D. (2008). An Introduction to Thermogeology: Ground Source Heating and Cooling. Singapore: Blackwell Publishing.
  • Colorado Renewable Energy Society. (2019, February 27). Geothermal Energy. Retrieved from Colorado Renewable Energy Society: https://web.archive.org/web/20110716140006/http://www.cres-energy.org/techbasics/geothermal_div1.html
  • Imal, M., Yılmaz, K., & Pınarbaşı, A. (2015). Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System. Sustainability, 2.
  • Snelling, Z., Harris, C., & Wilson, C. (2017). A Proposal For Geothermal Heating & Cooling at the University of Richmond. Richmond.
Let us know in the comments what you think about the concepts in this article!

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