BRGM-SGRF (FR1.3)

BRGM Shallow Geothermal Research Facility

The BRGM Shallow Geothermal Research Facility (SGRF) studies the energy performance of closed-loop shallow-ground geothermal heat exchangers and geothermal heat pumps. The facility works as a semi-virtual laboratory, with a 200 kW thermodynamic machinery simulating the load demand in heat and/or cold power of any building or energy system within this power rating. Up to six independent test campaigns can be performed simultaneously. A number of closed-loop underground heat exchangers (borehole, horizontal, spiral compact, etc) are already installed and connected to this machinery, and the facility is regularly updated with innovative control solutions and new underground heat exchangers. The facility accommodates a wide range of metrology to control the tests and characterize the heat transfer (distributed thermal sensing, meteorology, heat and moisture transfer in the vadose zone, etc).

The facility has already supported several master’s thesis, PhDs and Post-docs. Regular research projects are performed with geothermal heat exchanger or heat pump manufacturers, engineering offices, start-ups, etc. The BRGM geothermal energy test facility is a leading research facility, but also a showcase of the possibilities offered by shallow geothermal energy. It is open for visit to any group willing to, from researchers to industrial and public officials. Most of the research projects on the platform come directly from such visits.

A research engineer is permanently dedicated to the SGRF as scientific and technical supervisor and coordinator, to provide scientific and technical support to any project on the facility. One or more lines of the thermodynamic machinery can be used according to the nominal mass flows and power ratings of each line. A support can be provided to set each test protocol and duration.

Additional installations can be considered to accommodate the potential energy system to be tested. The SGRF has a list of local subcontractors from different professions capable to undertake such modifications under the supervision of the SGRF technical supervisor.

A DTS measurement unit is permanently on site and can perform up to eight simultaneous automatic underground temperature surveys, with acquisition frequency as low as five minutes. All test results are store locally and on the BRGM internal network. Open access to the data can be provided by the BRGM on demand.

As part of the SGRF, the BRGM can provide support for the modelling of underground heat transfer and energy systems including geothermal energy. The SGRF develops its own shallow geothermal heat exchangers and borefield dimensioning software and has expertise on numerical software such as TRNSYS, DYMOLA, COMSOL, MATLAB, etc.

The facility accommodates seven individual borehole heat exchangers with different characteristics, a borefield of thirteen boreholes, a 400 m² horizontal ground heat exchanger at one meter depth, and six compacts (spiral) heat exchangers between one and three meters depth.

The main advantages of the SGRF are:

-       The thermodynamic machinery controlling up to six independent simultaneous thermal loads on the six lines of the machinery, with a limit of 200 kW of heating or cooling load, which is quite unique for a public energy research facility in Europe. Each tests can have different mass flows between zero and 3 m³/h and inlet temperatures between -5 and +50°C.

-       The vertical and horizontal exchangers are equipped with optic cables for Distributed Thermal Sensing (DTS). Approximately 15 km of optic cables allow to measure vertical or horizontal (at three different depths) temperature distribution of the ground.

-       A complete meteorology station above ground assesses the heat and moisture transfer at the surface and its impact on the shallow ground heat and moisture transfer.

Tests aim at characterizing the heat transfer in the underground for innovative geothermal heat exchangers, or characterizing the actual performance of new and innovative geothermal heat pumps, linked with geothermal heat exchangers already implemented on the test facility, or simulated underground heat exchangers via the semi-virtual laboratory for parametric sweep.