This is because oil can be only bought in US dollars at the only two oil exchanges in the world- The New York Mercantile exchange and the London exchange. This is due to secret agreement between OPEC led by Saudi Arabia and the United States after 1970s. So the US can keep printing billions of dollars and pump into the world system but the world countries have to keep buying the dollar inorder to buy Oil. This is why the Saudi governments lending rate exactly match the US lending rates. Saddam Hussein tried to throw a spanner in the works by saying he was going to sell oil in euro and he was taken out. Iran has gone one step furhter and set that they are going to set a oil exchange in Kish Island in Iran where Oil will be sold in Euros or the local currency. That move if that happens will shake the world and importantly US thats why all the war rhetoric against Iran. If Iran gets the nuclear bomb I think they will put their plan in place, thats why the US and Saudi Arabia is pulling all stops to prevent that. Till the day three or four major oil producing countries can say we will sel Oil in another currency all the countries in the world have to keep a good chunk of dollar reserves and the US will keep printing dollars and spending lavishly. This might be a reason why the US hasnt really pushed on Alternative sources of energy other than Oil because that will be a big blow.
