We 💚 Heat Pumps
Posted on Wednesday, August 25th, 2021
Posted on Wednesday, August 25th, 2021
To be candid, it was love at first sight, or rather first understanding, realising the sheer elegance of the heat pump technology that takes heat from the surrounding environment – we call it “locally sourced” – and boosts that heat to the target or “sink” using electrically driven pumps or compressors. We really like how a heat pump efficiently converts electrical work into both transferring the heat from the source to the sink, but also can increase the temperature of the heat at the same time.
Domestic heat pumps will be familiar to many people, but more so if you live in European country like Sweden; they are remarkably less common (so far) in other countries of similar climates such as Ireland and the UK. Domestic heat pumps extract heat out of the air outside the home or from the ground under the building by evaporating a “refrigerant” in the pump (see the picture below). That refrigerant is then squeezed in the pump with the compressor driven by electricity, from the grid, or from a local renewable source like solar PV. The compression adds energy to the fluid which is then released in the “condenser”, transferred to warm spaces or make hot water.
Our heat pump sweethearts are very efficient. The efficiency of the reversed Carnot Cycle is described as a Coefficient of Performance (“COP”). The COP is the provided heat power divided by the work done by the pump. For example, a domestic heat pump of 10 KiloWatts (KW) output with a COP of 2.5 uses an input electrical capacity of 4 KW and is drawing 6 KW from the ambient environment. Domestic heat pumps, providing a few KW of heat to a home typically have COPs of 2 to 5, depending on both the pump itself and the amount of heat being drawn from the surrounding environment. Ground-sourced heat pumps tend to be more efficient than air-sourced, but carry higher installation challenges and therefore costs. However, heat pumps are inexpensive life partners in the long run, because very low running costs and efficient use of electricity to amplify “free” heat outweighs the installation costs.
Industrial heat pumps are similar to domestic ones, but much bigger. They can amplify temperatures by as much as 70 ºC and up to 160 ºC with current technology and still maintain COPs greater than 2. They are typically deployed to recycle waste heat from a process that is powered by fossil fuel boiler combustion. The recycling by heat pumps dramatically reduces the amount of energy wasted and, depending on the carbon intensity of the electricity, reduce the overall cost of the process heat.
Causeway Energies’s technological approach also uses industrial heat pumps of MegaWatt (MW) scale. However, the basic source of heat for the pump is not waste heat from fossil fuel boilers, but instead is deeper geothermal heat harvested in geothermal wells. We call the system an Earth-Sourced Heat Pump™: similar to ground-sourced heat pump, but bigger – power ratings of MW rather than KW, and hotter – temperatures more than 120 ºC rather than less than 60 ºC.
The most attractive thing about both domestic and industrial heat pumps is the amazing heat decarbonisation that happens when the electricity used is largely from renewable energy sources (RES) such as wind and solar PV. Causeway Energies has calculated that using Irish or British grid electricity, both having high penetration of RES, allows for industrial heat to be delivered to customers from clean geothermal heat at 10% of the GHG emissions of a fossil fuel boiler equivalent.
Ground-sourced shallow geothermal heat pumps for homes and smaller commercial buildings, larger industrial-scale Earth-Sourced Heat Pumps™ for industrial processes and large commercial facilities. Cheap, clean and reliable heat in a variety of settings and scales, addressing energy decarbonisation challenges of global scale.
What’s not to love?