| Abstract |
In Portugal, the presence of high enthalpy geothermal resources is restricted to the volcanic islands of Azores Archipelago, located in the North Atlantic Ocean and which are associated with the triple junction of the North American, Eurasian and African (or Nubian) plates. Power production from geothermal resources in Azores meets about 23% of the total demand of the archipelago, even the geothermal projects being confined to the S. Miguel and Terceira islands. Present investment projects at the Ribeira Grande Geothermal Field (RGGF) on the island of S. Miguel, implemented by EDA RENOVÃVEIS S.A. (former SOGEO – Sociedade Geotérmica dos Açores S.A.), led the installed generation capacity to a total of 23 MW net, with the contribution of the Ribeira Grande plant (13 MW net), operating since March 1994, and the Pico Vermelho plant (10 MW net), which went into operation in November 2006. Today, power production from geothermal resources in S. Miguel is stabilized since 2013 and meets about 44% of the electrical consumption in the island. On Terceira Island, a 3.5 MW pilot power plant is in operation since November 2017 at the Pico Alto Geothermal Field (PAGF), with a power production that corresponds to about 10% of the electrical consumption of the island. Geothermal energy is expected to assume an even more impressive role for electric power self-sufficiency of this Autonomous Region of Portugal, particularly in S. Miguel and Terceira Islands. However, its development is now considered in conjunction with other energy sources (particularly wind energy and waste production), energy storage and daily needs/consumptions issues. Low-temperature geothermal resources in Mainland Portugal are exploited for direct uses in balneotherapy and small heating systems. In the Azores Archipelago low enthalpy resources are also traditionally used in balneotherapy, and pilot/demonstration projects are being developed to take advantage of this resource on DWH (e.g. hotel) and buildings air conditioning (cf. in the area of Caldeiras da Ribeira Grande/RGGF). In Portugal, ground source heat pump technology (GSHP) is gaining penetration in the heating and cooling of buildings market. At present, new regulations for shallow geothermal purposes are being prepared to regulate all new GSHP’s installations (including its registration), to avoid bad practices and get more realistic statistical data on the new installations. These regulations, financing programs now available, and new data to be incorporated in a Portuguese heat flow density map, will for sure enhance geothermal in Portugal Mainland. It has been noticed in recent times that several brands of AVAC equipment have placed new GSHP models on the Portuguese market, showing that there is an increasing interest in this solution. A large shallow geothermal installation is being built in the Algarve, south of Portugal, for heating, cooling and to produce DWH for a hotel, a club house on a golf course and several individual villas, with about a total pavement area of 14,000 m2. The total installed capacity is expected to be about 1200 kW for cooling and 2360 kW for heating. The total expected number of boreholes heat exchangers is 244, with a depth between 110 m and 150 m. This large installation will in future increase the visibility of this type of facilities in Portugal. At Madeira Archipelago, the LNEG - Portuguese National Laboratory for Energy and Geology carried out in 2013 a geothermal survey for the EEM- Empresa Eléctrica da Madeira, including geological, geochemical and geophysical investigations (e.g. magnetotellurics). The available results indicate the existence of geothermal potential within the island with conditions for the development of enhanced geothermal system (EGS). |