Submissions are welcome for the new Special Issue at Energies MDPI where I am guest editor.
Deadline: April, 27th 2022. https://www.mdpi.com/…/Building_Sustainable_District
Our latest paper introduces a tabulated tool that aids in the early design of geothermal systems, by providing estimates of the system’s efficiency according to the chosen energy piles field configuration and heat pump sizing.
Direct link: https://doi.org/10.1016/j.enbuild.2020.110178
The paper can be downloaded FOR FREE for 50 days at this link:
Geothermal systems are often employed for both the heating and cooling of sustainable constructions. Energy piles (U-shaped heat exchangers inserted into the foundation piles) are widely included in these installations, whose performance is usually estimated by means of complex, time-consuming simulations already at an early design stage.
Here we propose a simple methodology, where a hand calculation tool provides the condenser yield per pile meter, ground area yield and demand covered by the heat pump by specifying only building heat load and geometric characteristics of the energy piles field. Our tool is tested by assuming 20 years of operation in a hall-type commercial building in a cold climate. A validated IDA-ICE parametric study couples the heat pump evaporator operation with heat transfer processes between energy piles and soil. Various system configurations are considered and thermal storage in the soil is included.
We find that the expected yield is not directly proportional to pile separation, while a smaller extraction power is favoured. Thermal storage in the soil is also confirmed to be critical. Besides our specific quantitative results, our practical guideline is qualitatively general and can be extended to any given building type and climate.
Sector coupling is a concept referring to the electrification of end-use sectors (e.g. heating and transport); it aims at increasing the share of renewable energy (solar, hydro, geothermal, wind, bioenergy, waste heat…) in these sectors.
In practice, this is a strategy “to provide greater flexibility to the energy system so that decarbonisation can be achieved in a more cost-effective way”.
The EU has committed under the Paris Agreement to make an effort to keep the global temperature rise below 2ºC, and the decarbonisation of the energy system can be crucial to this purpose. Sector coupling then becomes a key player for the EU “policy objective of shifting from our current highly centralised and mainly fossil fuel-based energy system to a more decentralised, energy efficient and renewable energy-based energy system”.
The quoted paragraphs are taken from an official European Parliament document on Sector Coupling, which you can find at the link below. I strongly encourage everybody interested in energy systems to read it (especially those who are critical towards the usage of wind and solar energy…yes, they still do exist!).
A short and coincise presentation I gave in Trondheim (Norway) on 7.11.19, which summarizes the parametric study reported in the conference paper (see the link below).
Here you can download the pdf (open access):
I will give the talk next week at the 1st Nordic nZEB+ conference in Trondheim, Norway!
Geothermal energy constitutes an important renewable resource that will become increasingly prominent in future constructions. A common method of extraction and usage consists of installing, inside the foundation piles of buildings, U-shaped heat exchangers called ”energy piles”.
In this paper such installations are addressed by means of a full parametric study, performed for a hall-type commercial building in a cold climate. By computing the transient heat transfer between energy piles and ground for a period of 20 years, guidelines for a preliminary sizing of the geothermal system as a whole are provided. These are valid for this specific building and climate, for a clay-type soil and without assuming thermal storage.
A highly nonlinear behaviour of the expected yield in relation to pile separation and evaporator extraction power is observed. Furthermore, 15m-long piles are found to be more efficient than those with double length, a smaller extraction power seems to be more favourable and differences in the pile diameter have little impact for heat transfer. A geothermal system sizing guide, which is useful for a preliminary quantitative test prior to any installation, is introduced. Even though our specific results are valid only for a commercial hall-type building in Finland, our procedure is qualitatively general and can be utilized for any given building type and climate zone.