As a result of the 1973 oil crisis, SAAB started a project in 1974[36] codenamed ULF (short for utan luftföroreningar, Swedish for Without Air Pollution))[37] headed by Dr. Ove Platell[38] which made a prototype steam-powered car.[citation needed] The engine used an electronically controlled 28-pound multi-parallel-circuit steam generator with 1-millimeter-bore tubing and 16 gallons per hour firing rate which was intended to produce 160 hp (119 kW) of continuous power,[39] and was about the same size as a standard car battery. Lengthy start-up times were avoided by using air compressed and stored when the car was running to power the car upon starting until adequate steam pressure was built up. The engine used a conical rotary valve made from pure boron nitride.