One borehole, in balance with the rock.
The NotusPiD system circulates water through a single deep borehole. It is a semi-open system: the water column stands in pressure equilibrium with the formation, so there is no exchange between the formation water and the water in the well. Nothing is produced and nothing is injected. Heat reaches the well by conduction and by convection — which is why it needs no aquifer, no second well and no reinjection.
How it works
Four steps, and none of them depend on finding a producible aquifer.
One well
A single large-diameter borehole is drilled to the depth the demand requires. Because the crust is saturated with water, the hole fills itself to the level where formation pressure balances atmospheric pressure. That water is the circulation medium — nothing has to be found or brought in.
Down the annulus, up the centre
An insulated production string hangs in the borehole, open only over a filtered section at the bottom. Cooled water travels down the annulus around it; warmed water returns up through the centre. The annulus is in contact with the formation through the gravel pack: semi-open, not a sealed loop.
Conduction and convection
The returned water is colder than its surroundings. That difference sets a heat flow going in the formation: heat travels to the borehole by conduction through the rock and by convection in the pore water around it. The effect grows with depth, in a pear-shaped zone — so energy is harvested over the full vertical length of the well, not over a short horizontal section.
Delivery
At surface the heat goes through a heat exchanger into the building, the district network or the process. A heat pump lifts the temperature further where the application asks for it.
Why one well instead of two
It is not a detail of the design. It decides where geothermal energy can be built at all.
A conventional doublet
Two wells. Hot water is produced from a permeable layer and pumped back into the ground through the second well. It needs an aquifer with proven flow, it stands or falls with reinjection, and it only becomes viable above a certain project size.
A NotusPiD single well
One well. Circulation inside a single borehole, in pressure equilibrium with the formation: no production, no reinjection, and essentially the same water going round. It works in any formation that is warm enough — hydrothermal or petrothermal — the subsurface risk is limited to temperature rather than flow, and it scales from a single building upward.
What sets the yield
The output of a single well is engineered, not discovered. Four variables decide it, and three of them are ours to choose.
Curious what one well would deliver at your site? Send us the location and the load: info@notuspid.nl
Depth and rock temperature
Every extra hundred metres adds temperature. The depth is chosen from the supply temperature the application needs — not the other way round.
Thermal properties of the rock
How fast the formation hands its heat to the well, by conduction through the rock and by convection in the pore water. Both are measurable and can be modelled before the design is fixed.
Flow rate and return temperature
Two variables you control at surface. Together with depth they set the power and the annual yield of the well.
Recovery
Because nothing is produced, the rock around the well recharges itself — by conduction and convection, out of a far larger volume than the borehole. Where the site also needs cooling, summer and winter can be balanced against each other by design.