Geothermal heat pump or wood pellets

What exactly do you still need to know? The house will have a footprint of 90 sqm. The soil survey report is still pending. For the ground source heat pump, a surface collector is planned. I have already heard that over the years the ground can "wave." Is that true? For pellets, there would be an underground tank in the yard.

For surface collectors/heating systems, it is already important to roughly estimate the annual consumption and heating load, because the consumption, required area, etc. depend on that. With proper design, the earth does not wave, but it also depends on what kind of soil you have and how much area you can use. Pellets are usually not necessarily cheaper in terms of consumption price; there is a bit of work involved (procuring pellets and maintaining the feeding unit), and pellet prices are also rather rising.

I could recommend the pellet heating system to you. I myself heat with pellets and am completely satisfied because pellets are not expensive either. In addition, they are climate-neutral because the combustion of the pellets produces approximately as much CO2 as the trees from which the pellets are made have absorbed from the atmosphere. After a quick internet search, I found a website where you can get even better information about it.
Hope I could help.

Best regards
Sebastian

Brine water heat pump. Theses: Pellet+tank with auger is more expensive, smells, requires more maintenance, and needs active raw material purchase.

I would only make pellets as a forest owner ;-).