Since publishing "Twilight in the Desert: the Coming Saudi Oil Shock and the World Economy" this past summer, and touching off one of the great debates of the early 21st century, energy banker Simmons has been squarely in the spotlight. Simmons argues that Saudi oil fields, contrary to reports, have been in decline for some time, and he views skeptically Saudi claims that it can adequately boost supply to meet accelerating demand. Simmons, who has headed the Houston-based energy investment banking firm Simmons & Co. International for 30 years, is no stranger to bold calls and controversy.