Strategic use of the underground in an energy mix plan: Synergies among CO2, CH4 geological storage and geothermal energy. Latium Region case study (Central Italy)

Abstract

In recent decades, the worldwide demand for energy has been increasing, with an associated rise in CO2 emissions being observed. In such conditions, the development of ‘‘low carbon energy technologies’’ and strategic energy-mix plans is necessary, and an evaluation of the underground energy potential may be a useful step in developing these plans. This evaluation involves the synergic development of such technologies as: coal combustion in combination with CO2 geological storage (CCS), natural gas geological storage (CH4-GS) and geothermal energy (GE), especially in densely populated countries, such as Italy. Currently, 13.7% of Italian energy demand is met by foreign providers. Most of the Italian regions have energy deficits, and the Latium Region (in Central Italy) represents one of those in the worst conditions. This work proposes a methodology to develop energy-mix scenarios, starting in Latium, to identify areas that are potentially suitable for CCS, CH4-GS and GE. Six geothermal systems and one CO2/CH4 storage potential area were identified. Three main scenarios are proposed: (A) a combination of CH4-GS with methane as cushion gas and GE; (B) a combination of CH4-GS with CO2 as cushion gas and GE; (C) a combination of CCS and GE. Scenario A results in a reduction of the regional energy deficit that ranges from 21.8% to 45.6%. In Scenario B, the regional energy deficit reduction ranges from 30.8% to 80.7% and the CO2 emissions reduction ranges from 1.4% to 5.6%, supposing an injection of 20 years. Scenario C shows a decrease in the regional energy deficit that ranges from 15.9% to 22.1%, while the CO2 emissions reduction ranges from 7.1% to 31.3%, over the same time period. The proposed scenarios may be useful not only for the scientific community but also for policymakers as they identify the most reliable energetic strategies. Thus, this case study could be extended to the entire Italian territory with the ultimate goal of reaching energy autonomy in each region.