Fuel options at a Sioux Falls, South Dakota, gas station on Aug. 22, 2025. The nationwide average price of a gallon of gas was $4.55 May 22, 2026, up from $3.20 a year ago. The steep increase has turned some lawmakers' attention alternative fuels like ethanol. (Photo by John Hult/South Dakota Searchlight)Proponents of ethanol, including lawmakers from corn-growing states, say year-round sales of a gasoline blend containing 15% of the biofuel wou…