Mind the gap - Development of a Directional Drilling Method for Shallow Geothermal Energy

The project develops a miniaturised directional drilling method enabling geothermal boreholes to be installed beneath existing buildings, addressing a major gap in densely built urban areas. By drilling from accessible edge zones and keeping all probes on private land, permitting procedures are simplified and public-space interventions minimized. The study assesses technical, regulatory and economic feasibility and forms the basis for subsequent prototype development.

Short Description

Starting point / motivation

Decarbonising the existing building stock is a key element of Austria's climate strategy. While geothermal systems are well established in new construction, densely built-up urban areas lack a suitable technical solution.

Modernisation efforts often fail due to limited free space, conflicts with existing infrastructure, or complex permitting procedures in public areas. As a result, significant geothermal potential beneath existing buildings remains untapped, as no appropriate drilling method currently exists.

Contents and goals

The goal of the project is to develop an innovative directional drilling method that enables boreholes to be installed from accessible edge areas, such as sidewalks or driveways, beneath existing buildings. The geothermal probes remain entirely on private property, minimising interventions in public space and simplifying permitting procedures.

Technologically, the approach is based on the miniaturisation and adaptation of established directional drilling technologies from HDD and the oil & gas sector. These systems are optimised for horizontal applications or large depths; their transfer to small-scale, predominantly vertical boreholes up to approx. 300 m has not yet been investigated.

The feasibility study addresses three key questions:

Technical feasibility: suitable borehole geometries, steering mechanisms and measurement systems in urban unconsolidated sediments
Regulatory feasibility: building and water law requirements and the applicability of existing standards (e.g., VDI 4640, Water Rights Act, building codes)
Economic viability: cost structure, scalability, deployment scenarios, and potential business and funding models

Methods

The analysis includes:

a technical assessment of existing directional drilling and measurement systems and their potential for adaptation
spatial and legal evaluation of regulatory pathways and normative requirements
an economic market and cost analysis, including an estimate of the addressable building stock
a sustainability and social-impact assessment focusing on CO₂ reduction, minimised construction impacts, and gender-sensitive implementation

The results serve as a decision basis for a subsequent R&D project aimed at prototype development

Expected results

The study will deliver:

defined technical requirements and risk factors for a miniaturised directional drilling system
recommendations for regulatory-compliant execution of subsurface drilling beneath buildings
an economic assessment of a potential market of approximately 240,000 buildings (EUR 2.4-3.6 billion), including initial business model and scaling scenarios
an ecological and social impact evaluation (15-20 t CO₂ savings per building per year, reduced disturbances, improved accessibility for households with limited budgets)

Overall, the project establishes the foundation for a technological step change enabling geothermal energy utilisation even in densely built-up urban areas.

Project Partners

Project management

Terra Umwelttechnik GmbH

Project or cooperation partners

Int. CSR Dialogforum - Kompetenzzentrum für integrierte Nachhaltigkeit in Wirtschaft und Gesellschaft e.V.
SGE - Sustainable Geo GmbH

Contact Address

DI Robert Philipp
Großmarktstrasse 7c
A-1230 Vienna
Tel.: +43 641 824 375
E-mail: Robert.philipp@terra.cc
Web: www.terra.cc