On December 5, 1993, at 1000 hours central standard time, a Balloon Work Firefly 715, N9079M, piloted by the commercial pilot on a cross country pleasure flight, sustained substantial damage when it struck power lines during a descent to land in the vicinity of Pratt, Kansas. The commercial pilot, the sole occupant, reported no injuries. Visual meteorological conditions prevailed for the flight, no flight plan was filed. The flight operated under 14 CFR Part 91, and originated from Elizabeth, Colorado,at 0422 Mountain Standard Time. The pilot stated the flight was intended as a record breaking (distance) flight. She indicated the weather forecast was ideal, with strong winds aloft, and surface winds expected to calm near sunset. The pilot reported she expected to remain airborne approximately 8 hours, touching down near sunset. The basket was loaded with nine(9) ten(10) gallon propane tanks prior to departure. The pilot stated the propane was consumed almost twice as fast as was calculated. The balloon was at 17,000 feet MSL when the pilot switched to the ninth and final tank, and initiated a descent for a precautionary landing. The pilot stated she maintained a 500 foot per minute (FPM) descent until 4000 feet MSL, where she slowed her descent to 200 feet per minute. She reported she attempted to level off about 1000 feet, but it felt like the balloon was being "...forced down... ." When the balloon touched down in a flat, open field, the pilot vented the top of the envelope and shut off the pilot light to the fuel source. The envelope was still partially inflated, and the balloon was blown across the field and contacted some power lines. The basket continued to drag until the envelope deflated. The pilot estimated the surface winds were out of 350 degrees at 30 knots.