Ground source heat pumps vs geothermal

What is the difference between ground source heat pumps and geothermal heating?

The term geothermal heating is very often confused with ground source heat pumps, and mistakenly the two terms are used almost interchangeably.

For clarity, Kensa manufactures ground source heat pumps, not geothermal heating. Read on to find out more about ground source heat pumps compared to geothermal.

Ground Source vs Geothermal Heating

There is often much confusion when it comes to comparing ground source heat pumps vs geothermal heating. Some people use the terms interchangeably but there are some key differences.

The reason geothermal heating is often confused with ground source heating is that both ultimately harness heat energy from the ground to provide heating and hot water to buildings.

However the key difference is how geothermal energy is produced in terms of where the heat is coming from and the application the heat will be used for.

How is geothermal energy produced?

  • Geothermal heat comes from the earth’s core; ‘geothermal’ literally means ‘earth’s heat’. In the UK you have to go down 500m – 2500m before there is any appreciable input from the earth’s core. This form of heat tends to be used directly by very large-scale applications.

How does a ground source heat pump work?

  • Ground source heat pumps, like those manufactured by Kensa Heat Pumps, are heat pumps that absorb the sun’s energy stored in relatively shallow ground and upgrade this for use in domestic and commercial applications. Ground source heat pumps generally take heat from 1.2m – 200m depths. In this zone, there is a large amount of low grade energy available which needs a heat pump to upgrade this to more useful temperatures.

Why Does This Difference Matter?

The implication of the term geothermal energy is that the supply of energy is virtually infinite, while solar energy is very finite and very measurable. It means that the pipes buried in the ground for the ground source heat pump have to be accurately designed to ensure that the system is not taking more heat from the ground than that can be replenished via heat from the sun or rain. Ground source heat pump collector arrays are sized to meet the heat needs of the building; geology and the ground condition thermal conductivity are taken into account when sizing the ground collector.

What's In A Name?

Other less commonly used terms for ground source heat pumps:

  • Water-source heat pumps.
  • Geothermal Heat Pumps (GHPs) – A common term in the US.
  • Geothermal (Ground Source) Heat Pump (shallow neutral earth temps)
  • GeoExchange heat pumps.
  • Earth-coupled heat pumps.

Other less commonly used terms for geothermal heating:

  • Deep geothermal.
  • Enhanced Geothermal Systems.
  • Geothermal, Direct Use.
  • Hydrothermal.
  • Hot rocks.
  • Hot dry rocks.
  • Geothermal power.

What is geothermal heating and how does it work?

Geothermal heating uses heat direct from either drilling deep or sometimes shallow sources emanating from the earth’s core, such as hot springs, geysers and volcanic hot spots.

Geothermal systems operate at temperatures of 120°C – 300°C and therefore do not necessarily need a heat pump, or a ground loop system.

Borehole drilling for geothermal heating can often be drilled to depths many km below the ground.

Large-scale plants and communities tend to use geothermal energy over ground source heat pumps.

Geothermal typically needs to be deployed at large scales to make it financially viable.

Ground source heat pumps vs geothermal heating - A geothermal power plant

Ground Source Heat Pumps

Ground source heat pumps absorb heat energy from the sun and rain (solar gain) which is stored in the ground or water sources, typically at temperatures of 8°C – 12°C.

Water sources such as lakes, streams, and ponds are also extremely effective heat sources for ground source heat pumps.

Very little of the heat absorbed by the ground source heat pump system originates from the earth’s core (unlike geothermal).

Ground source heat pumps slinky trench

What Is A Heat Pump?

At depths of 2m and more the ground temperature does not deviate very much from the average summer/winter surface temperatures (around 8° to 12°C in the UK depending on location).

Ground source heat pumps absorb this heat energy stored in the ground at depths from just 1.2m (for slinky ground arrays) to around 250m (for borehole ground arrays).

Find out more about how ground source heat pumps work on our page ‘what is a heat pump‘.

Kensa’s ground source heat pumps absorb the heat energy stored in the ground or water via ground arrays or ‘collectors’.

The absorbed heat is then upgraded to provide 100% of the heating and hot water requirements of small one-bed flats up to large scale commercial premises.

Read more

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