Geothermal heat main installation begins

Work has started on the installation of the new heat main that will supply Eden Project’s Biomes, greenhouses and other buildings with geothermal heat.

The heat main consists of two 150mm (6”) steel pipes – a flow and return – each encapsulated in a thick layer of insulation to a total diameter of 280mm. They will be run in parallel below ground on the Eden Project estate for a distance of around 1.4km, linking the deep geothermal system at the Eden Geothermal well site with the Eden energy centre.

The complete heat network will operate as a series of 3 closed loops.

  • In the first loop, hot water from deep underground will be brought to the surface of the geothermal system and heat will be extracted from it using a heat exchanger. The newly-cooled water will then be returned underground to be reheated, in a continuous circulation system.
  • The new heat main will form the second closed loop, collecting heat from the heat exchanger at the Eden Geothermal well site and transporting it to the Eden energy centre on the main Eden Project site.
  • At the Eden energy centre, a further heat exchanger will extract heat from the heat main and transfer it to the third loop of the system: the heating circuit supplying Eden’s Biomes and buildings, where the heat will be used. After the heat has been transferred to this final loop, the cooled water in the heat main will be returned to Eden Geothermal for reheating.

Installation of the heat main will take two teams around 6 months to complete, and will involve welding together individual 12m and 16m lengths of pipe. Each weld will be X-rayed to check its quality, and a sophisticated real-time leak detection system, capable of pinpointing the exact location of any issue, will be installed.