After the collapse of the Bretton Woods gold standard in the early 1970s, the United States struck a deal with Saudi Arabia to standardize oil prices in dollar terms. Through this deal, the petrodollar system was born, along with a paradigm shift away from pegged exchanged rates and gold-backed currencies to non-backed, floating rate regimes.
The petrodollar system elevated the U.S. dollar to the world's reserve currency and, through this status, the United States enjoys persistent trade deficits and is a global economic hegemony. The petrodollar system also provides the United States’ financial markets with a source of liquidity and foreign capital inflows through petrodollar "recycling." However, an explanation of the effects of petrodollars on the U.S. dollar requires a brief synopsis of the history of the petrodollar. (For more, see: Global Trade And The Currency Market and US-Saudi Relations: A Complex Scenario.)
History of the Petrodollar
Faced with mounting inflation, debt from the Vietnam War, extravagant domestic spending habits and a persistent balance of payments deficit, the Nixon administration decided to suddenly (and shockingly) end the convertibility of U.S. dollars into gold. In the wake of this “Nixon Shock,” the world saw the end of the gold era and a free fall of the U.S. dollar amidst soaring inflation. According to, Dr. Bessma Moomani in the article, " GCC Oil Exporters and the Future of the Dollar," through a series of carefully crafted bilateral agreements with Saudi Arabia beginning in 1974, the U.S. was able to promote bilateral political and commercial relations, market imported U.S. goods and services, and help recycle Saudi petrodollars (more on this later).
Through this framework of economic cooperation and, more importantly, petrodollar recycling, the U.S. managed to influence Saudi Arabia to persuade the other members of Organization of the Petroleum Exporting Countries (OPEC) to standardize the sale of oil in dollars. In return for invoicing oil in dollar denominations, Saudi Arabia and other Arab states secured U.S. influence in the Israeli-Palestinian conflict along with U.S. military assistance during an increasingly worrisome political climate that saw the Soviet invasion of Afghanistan, the fall of the Iranian Shah and the Iran-Iraq War. Out of this mutually beneficial agreement, the petrodollar system was born.
Benefits of the Petrodollar System
Since the most sought-after commodity in the world - oil - is priced in U.S. dollars, the petrodollar helped elevated the greenback as the world's dominant currency. In fact, according to the Bank for International Settlements (BIS) triennial survey, 88% of all foreign exchanges deals initiated in April 2016, involved the USD on one side . With this status, the U.S. dollar enjoys what some have asserted to be an "exorbitant privilege" of perpetually financing its current account deficit by issuing dollar denominated assets at very low rates of interest as well as becoming a global economic hegemony.
For instance, countries like China, who hold vast quantities of U.S. debt have voiced their concerns in the past about the possible dilutive effects to their asset holdings should the dollar depreciate. However, the privileges associated with being able to run persistent current account deficits come at a price. As the reserve currency, the United States is obligated to run these deficits to fulfill reserve requirements in an ever-expanding global economy. If the United States were to stop running these deficits, the resulting shortage of liquidity could pull the world into an economic contraction. However, if the persistent deficits continue ad infinitum, eventually, foreign countries will begin to doubt the valuation of the dollar, and the greenback may lose its role as the reserve currency. This is known as the Triffin Dilemma. (For more, see: How The Triffin Dilemma Affects Currencies.)
The petrodollar system also creates surpluses of U.S. dollar reserves for oil-producing countries, which need to be "recycled." These surplus dollars are spent on domestic consumption, lent abroad to meet the balance of payments of developing nations or invested in U.S. dollar-denominated assets. This last point is the most beneficial for the U.S. dollar because petrodollars make their way back to the United States. These recycled dollars are used to purchase U.S. securities (such as Treasury bills), which creates liquidity in the financial markets, keeps interest rates low, and promotes non-inflationary growth. Moreover, the OPEC states can avoid currency risks of conversion and invest in secure U.S investments.
(For more, see: A Primer On Reserve Currencies.)
Recently there have been concerns of a shift away from petrodollars to other currencies, such as the Chinese Yuan. These worries are not entirely without merit. The changing landscape of the global energy market points to a de-facto end of the U.S.-Saudi petrodollar agreement. According to Nick Chow of MarketSlant, the U.S. is becoming a major exporter of energy for the first time since the 1960s. This along with a strong domestic energy sector that focuses on exports is likely to cause a smooth transition away from the petrodollar as "energy exports replace the capital inflows from Saudi treasury purchases and uphold the global demand for the USD, rooted in energy needs. "  An added advantage for the United States is that it will ensure domestic energy security, which was the main reason for the 1973 petrodollar agreement in the first place.
While, it will not happen overnight, a drying up of recycled petrodollars would drain the liquidity of American capital markets, which will increase the borrowing costs for governments, companies and consumers as sources of money become scarce.
The Bottom Line
After the 1970s, the world switched from a gold standard and petrodollars emerged. These extra-circulated dollars have helped elevate the U.S. dollar to the world reserve currency. The petrodollar system also facilitates petrodollar recycling, which creates liquidity and demand for assets in the financial markets.
 https://www.bis.org/press/p160901a.htm (see para. 3)
 https://www.mironline.ca/petrodollar-regime-crumbling-will-u-s-economy-r... (see half way down the first para.)