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.
print this map. Hundreds of rivers and their tributaries cross the European continent. Here we highlight those over 600 miles in length, and a few others of note. DANUBE: Beginning in the Black Forest region of Germany, it flows across central Europe and the countries of Austria, Hungary, Croatia and Yugoslavia. It then forms the border between Romania and Bulgaria, turning north across Romania to eventually end in the Black Sea. It is (1,771 miles) (2,850 km) in length, and one of the most significant commercial waterways on the continent.