Gainesville Regional Utilities (GRU) announced Thursday that it would again raise its fuel adjustment cost by 5 mills in February, following a mirror increase for January. The administration showed a steep increase in natural gas prices that started as the winter weather approached. The fuel adjustment on bills is a straight pass-through cost, with the utility earning no revenue from that portion. The Jacksonville Energy Authority changes its fuel adjustment cost on a monthly basis as natural gas fluctuates. Bierlarsk said GRU’s adjustment cost hasn’t kept pace with the natural gas prices.