Harnessing heat from the seabed to generate electricity. Interview with Diego Paltrinieri, co-founder of Athanor Geotech.
“Italy has enormous potential in terms of geothermal energy, perhaps second only to Iceland, the United States, and the Philippines. Unfortunately, however, we have fallen incredibly behind in this field.”
This statement comes from Diego Paltrinieri, marine geologist, entrepreneur, and co-founder of Athanor Geotech, who spoke to Atlas21.
The study of the Marsili volcano
Geothermal energy represents a sector rich in opportunities for Italy: producing electrical energy from the heat generated by underwater volcanic structures could cover a significant portion of the national energy needs.
Athanor Geotech is a startup founded in 2023 that has its roots in an idea born about 20 years ago, concerning marine geothermal energy in the southern Tyrrhenian Sea area, particularly on the Marsili system which, located between Palermo and Naples, is the largest underwater volcano in Europe.
In 2006, this scientific team coordinated by Paltrinieri organized a two-week expedition (privately funded) in the southern Tyrrhenian Sea in the Marsili area. The results gave the green light to the first research permit in the world to produce off-shore geothermal energy.
But Paltrinieri recounts:
“We probably started too early, at least for a country like ours.”
Several factors subsequently halted the project. However, the knowledge learned by the team during that period remained. “Having seen an opening and an awareness in the public debate” – explains Paltrinieri – “three years ago we reassembled the technical-scientific team, expanded it, and from there Athanor Geotech was born at the beginning of 2023.”
The Italian potential
According to UGI (Italian Geothermal Union) evaluations, the geothermal energy extractable in Italy within the first 5 km of depth is estimated, at minimum, between 5,800 and 6,000 thermal TWh. Another great production potential comes from off-shore exploitation, which could be of an order of magnitude equal to or greater than that of on-shore.
However, for the subset of geothermal applications for electricity generation, energetically more “valuable”, Paltrinieri emphasizes that it is not enough to have just a large heat flow, but there must be conditions for the presence of confined geothermal reservoirs, i.e., “water containers”, otherwise exploitation would become extremely difficult.
“For example, on Marsili, with the research permit, we ascertained the presence of a huge high-enthalpy and rechargeable geothermal fluid reservoir of about 100 km3, within fractured basaltic rocks.”
In terms of orders of magnitude, according to some data published in international journals, the amount of thermal energy generated by off-shore geothermal energy is approximately equal to half of the annual global energy demand, estimated at about 580,000,000 TJ.
The growing interest in the potential of geothermal energy in Italy seems to be starting to reach the public debate. In April, the Minister of Environment and Energy Security, Gilberto Pichetto Fratin, highlighted the country’s great potential in the sector and emphasized the need to pursue stronger policies from this point of view. Another aspect that gives hope is the European Parliament’s resolution on geothermal energy. “With this resolution, the Parliament commits the Commission and the European Council to encourage policies for geothermal energy both for production and management,” explained Paltrinieri.
The generation of electrical energy
The production of geothermal energy, in its most traditional form, is based on the extraction of high-temperature geothermal fluid which, through various processes, feeds the turbines to generate electricity. The residual geothermal fluid, if it contains specific chemical elements (such as metals, lithium, and rare earth elements), can be further exploited.
Our work, as Paltrinieri explains, “consists of precisely characterizing the geothermal field to be cultivated, ensuring that the identified system is capable of self-sustaining and remaining productive for decades.“
It’s important to highlight a fundamental difference between on-shore and off-shore. While medium-high temperature on-shore wells produce about 5-6 MW per well, in the off-shore part, where temperatures can exceed 400°C, the average production can reach even 50-60 MW per well. Therefore, despite a higher initial expense, there is a higher productive return compared to on-shore.
Projects under study
Today, Athanor Geotech is focused on the Aeolian Islands area, which presents a high heat flow (one of the highest in the Mediterranean and Europe) and many manifestations of geothermal fluids present between Salina, Panarea, Lipari, and the Island of Vulcano. The projects that the company is keeping an eye on are smaller in size compared to the Marsili project, which is more challenging both from an investment and production perspective. “It’s strategic to carry forward projects in the areas of Panarea or Lipari in the on-shore domain and then move almost naturally towards the off-shore,” stated Paltrinieri.
For example, in Panarea, moving just a hundred meters in depth, it’s possible to find hydrothermal manifestations with geothermal fluid outflows exceeding 120-150°C.
Regarding the Marsili project, Paltrinieri is aware that “it’s not something short-term, given its complexity.”
There are also other areas in the Mediterranean where geothermal projects can be activated, including in the off-shore domain, such as in Spain or Greece.
The pioneering countries
“The public sector should facilitate the conditions for the initial investment of the exploratory well, which is the most expensive and complex for investors, especially regarding the authorization and regulatory part,” stated Paltrinieri.
Countries such as Indonesia, Philippines, United States, Iceland, New Zealand, Turkey, and Kenya have defined national strategies that have allowed for the investment and development of several GW of geothermal energy.
“Iceland is very advanced in geothermal energy, especially in the on-shore part. Among the most important projects is the IDDP (Iceland Deep Drilling Project), a project carried out by the government together with the most important scientific institutions, which aims to drill up to 5 km deep to reach supercritical conditions of geothermal fluids, much hotter than those exploited so far.”
The role of Bitcoin mining
As explained by Paltrinieri, one of the possibilities being considered is the creation of off-shore platforms with multifunctional hubs. In addition to the production of electricity from geothermal sources, these centers could also integrate wind and solar generation, and mining activities.
Another very interesting option would be to include data centers for data processing and, why not, also for Bitcoin mining, which, as several studies have already shown, could act as a buyer of last resort for electrical current to absorb any excess energy production from a plant. Regarding geothermal energy, El Salvador cannot be overlooked, where the combination of exploiting this resource and mining is already a reality, at least in the on-shore domain. The off-shore potential could represent a chapter entirely to be explored and of considerable interest for future exploitation initiatives.
Some papers have also shown that mining can promote the adoption of renewable energies such as wind and solar, making such projects profitable. The same logic can therefore apply even more so to on-shore and off-shore geothermal plants, which are characterized by constant electricity production throughout their useful operating life.
“We believe that behind-the-meter Bitcoin mining (i.e., adjacent to production units) can improve energy efficiency and help from an economic point of view projects that exploit geothermal energy.”
