Eaposys – Technology

Local, tailorable and fair

Baseload Electricity & District Heating

Geothermal tremendous untapped reserves

Our planet has a sun inside

+99% of Earth’s mass is at temperature above 1’000°C
Just a 3 km layer at surface is below 100°C

There is permanently enough energy right under our feet!

Advanced Geothermal Systems (AGS)

AGS are closed-loop deep geothermal installations that tap into the largest planetary energy source: the heat of the Earth, stored anywhere in deep rock layers, just below our feet.

Unlike conventional hydrothermal or Enhanced Geothermal Systems (EGS), AGS do not produce brines from a hydrothermal or engineered geothermal reservoir but instead circulate a working fluid through sealed boreholes to recover the heat from deep hot rock layers.

AGS are purely conductive systems: the power capacity of the installation depends directly on the length of the heat collection well(s) at depth.

Building upon recent development honed by the oil and gas drilling industry in directional drilling and magnetic ranging solutions for well intersection, it is possible today to build AGS radiator-like installations, circulating a working fluid in series of deep boreholes loops deployed between an injection and a production well.

Predictable, tailorable heat output: AGS are largely independent of geology and do not depend on difficult to manage reservoir permeability. AGS can be dimensioned to match local energy needs.

No pumping is required, thanks to naturally occurring THERMOSIPHON EFFECT. Once the installation is started, the working fluid circulates by itself in the loop with no additional power needed for operations.

No fracking or reservoir stimulation and associated risk of induced seismicity, better social acceptance and urban deployment possibility for short-travel higher-efficiency energy supply.

No corrosive brines, minimal water use and treatment, reliable, long-term energy infrastructures with lower maintenance requirements, using working fluids with well maintenance properties.

EAPOSYS Multiple-Leg AGS Patented Design

EAPOSYS AGS delivers long-term energy in the form of heating and baseload electricity at the community level (a few MW thermal per installation unit).

The unique feature of EAPOSYS AGS lies in our patented service well that enables an incremental, butterfly-shaped deployment of the installation across the targeted heat depth sections.

Once the injection well (blue, for cold fluid distribution) and production well (pink, for hot fluid collection) have been completed, the horizontal well sections are drilled from the service well (dashed black) and connected to the injection/production wells to create EAPOLAPs heat recovery conduits linking together the injection and production wells in a circular closed loop.

EAPOSYS Patented Service Well USP

Incremental deployment

Shorter time to revenue: the system can start operation as soon as a first EAPOLAP connecting the injection and production wells is completed
Reduced drilling risk: shorter lateral length with side-track possibilities
Easier maintenance: EAPOLAPs can be re-accessed individually from the service well
The full installation can be drilled with a single rig, minimizing expensive non-productive time of the second rig

Butterfly-shaped geometry

Many possible geometries for optimal deployment in various geological context
Horizontal deployment of the EAPOLAPs maximizing recovery of natural Earth heat flow
Lower sensitivity to connectivity issues

Minimal

Incremental

Optimized

EAPOSIM: E.AGS Simulation Software

EAPOSIM consists of an initial software kernel enabling rapid calculation of E.AGS installations energy output.

This initial analytical calculation module allows the treatment of multiple wellbore sections along any pre-defined polygonal line geometries and parameters in a vertically linear geothermal gradient field. The module is developed by Prof Pierre Perrochet at the Center of Hydrogeology and Geothermics (CHYN) of the University of Neuchâtel.

Energy output results over time as a function of applied flow rate and injection temperature are available at the click, allowing for the rapid development of various usage scenarios and their associated configurations.

EAPOSIM module is built on:

Physics based 3D modeling tools: A platform consisting of parallelized FORTRAN90 software in a computing environment with a set of parallel multiprocessor nodes. The model implements sets of polygonal lines with mutual thermal influences, along which a 3D source term approach is coupled to a 1D advective transport process in the conduit network. Hence, the effects of proximity between different wellbore sections, such as the effect of the distance between the two branches of a V-shaped loop on the outlet temperature, or the proximity of the injection (cold) and extraction (hot) can be taken into account.
Maple tool: Analytical resolution of 1D transport equations coupled to 2D-radial thermal exchanges, accounting for mutual influence of parallel conduits and loops.
Excel model: User friendly tool replicating (1) and (2) instantaneously, with an accuracy of a few tenths of degrees (for configurations with no thermal influences), compared with the Physics based 3D modelling approach mentioned above.

EAPOSIM SIMULATION: E.AGS.1V, 3.5 km depth, 1 EAPOLAP level cumulating 2×2.75 km leg, geothermal gradient 30°C/km, standard rock and fluid parameters.