Kilowatt-Hour per Unit of Fuel. The energy value of a unit of fuel depends on its mass, carbon and hydrogen content, and the ratio of carbon to hydrogen. In general, hydrogen generates approximately 62,000 BTU per pound and carbon generates around 14,500 BTUs per pound.
Quick Answer. The three largest rivers in Portugal are the Tagus River, the Douro River and the Guadiana River. All three rivers also flow through Spain. The largest river in Portugal is the Tagus River; it is 645 miles long. Continue Reading.
Of the five main rivers in Spain, the Tajo, Duero, Guadiana and Guadalquivir all flow southwards and westwards out into the Atlantic ocean, whereas the Ebro has its outlet in Tarragona in the Mediterranean Sea. The River Tajo, also known as the Tagus, is the longest river of the Iberian Peninsula. It starts from the mountains east of Madrid and passes Teruel and Toledo in central Spain, before crossing the Spanish-Portuguese border and flowing out into the sea at Lisbon.