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.
Castle of Leiria. Castle of Arraiolos. Portugal has well-defined geographic boundaries, with the Atlantic Ocean to the south and the west, and rivers and mountains to the east and north. It occupies the westernmost portion of the Iberian Peninsula, and is about the size of the American state of Indiana.