A renewable-energy company wants to invest more than $100 million in a biofuel plant in Kansas that it estimates would create 225 jobs and generate $3.5 million a year for area farmers. But some Sumner County farmers and others in the area are concerned about what the plant could mean for their water supply. The VNA Corp.’s proposed plant would turn water and baled crop residue — such as wheat straw and corn leaves, stalks and cobs— into natural gas. The plant would need 50 million gallons a year of water and more than 75,000 metric tons of straw and stover — a common name for corn leaves, stalks and cobs — for its first phase of operation. The plant would not produce ethanol, cellulosic ethanol or bio-diesel. It would create bio-methane — or renewable natural gas — through anaerobic digestion.