Nuclear power is necessary. But what about in the meantime?

This source already exists. It is known as medium-to-high enthalpy geothermal energy.

When we talk about geothermal energy, our minds tend to turn to the geysers of Larderello in Tuscany or the fields of Iceland. That is high-enthalpy geothermal energy: spectacular, but geographically limited.

Medium-to-high-enthalpy geothermal energy is a different matter altogether. It exploits deep hydrothermal reservoirs – between 3,000 and 5,000 metres below ground level – where the fluid temperature ranges between 110°C and 250°C. The optimal operating window, which balances energy yield and drilling costs, is between 110°C and 140°C: sufficient to drive ORC cycles for electricity generation and, using the residual heat, to supply district heating networks. It is available across much of Italy – in the deep sedimentary basins of the Po Valley, the Adriatic coast and certain areas of Southern Italy – and accessible using standard drilling technologies, the same as those used in the oil & gas sector.

The principle is simple: geothermal fluid is extracted via a production well, circulated through an energy conversion plant, and reinjected into the ground. The geological reservoir is naturally recharged by heat conduction from the Earth’s crust. The source is inexhaustible; the power output is not dependent on the weather, the time of day or the season, and is, by definition, programmable.

Any power generation plant releases heat into the environment for thermodynamic reasons that cannot be circumvented by the laws of physics. In a conventional plant, this ‘waste’ heat – the thermal waste – is released into the atmosphere and is lost.

In a geothermal power plant, however, it becomes a resource capable of supplying district heating and cooling networks.

The result is a primary energy utilisation rate that can exceed 70–80%, compared with 35–45% for a conventional power plant. Electricity is generated for the grid and heat for the local area, eliminating the use of fossil fuels from both processes. The impact on decarbonisation is twice as great as a simple comparison of energy sources would suggest.

The underlying issue is not ‘geothermal versus nuclear’. It is the opposite.

The energy transition cannot be achieved with a single technology, but rather through an integrated system in which each source plays the role for which it is physically best suited: renewables for distributed generation wherever and whenever conditions allow, nuclear power for long-term base load, and medium-to-high enthalpy geothermal energy for programmable base load in the medium term – the decade that nuclear power does not yet cover.

The real cultural shift required is not merely technological but systemic. We need to stop thinking in terms of energy sources and start thinking in terms of functions – base load, peak load, heating, cooling, storage – optimising the mix using the best technology available today, not just what is promised for tomorrow.

(*) Chairman of DBA Group