Endesa, S.A. is the largest electric

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

 utility

Public utility

A public utility is an organization that maintains the infrastructure for a public service . Public utilities are subject to forms of public control and regulation ranging from local community-based groups to state-wide government monopolies...

 company in Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

. The firm, a majority-owned subsidiary of the Italian

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 utility company Enel

Enel

Enel may refer to:*Enel SpA, an Italian electricity company*Enel , a fictional villain in the One Piece manga and anime series*Enel, meaning third in the fiction of J. R. R. Tolkien, cf. Awakening of the Elves...

, has 10 million customers in Spain, with domestic annual generation of over 97,600 GWh from nuclear

Nuclear power

Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, fossil-fueled

Fossil fuel

Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

, hydroelectric

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

, and renewable resource

Renewable energy

Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

 power plants. Internationally, it serves another 10 million customers and provides over 80,100 GWh annually. Total customers numbered 22.2 million as of December 31, 2004.