YANKTON, S.D.(WNAX)- For those that heat with natural gas, prices have risen substantially this winter.

Geoff Greenwood with Mid-American Energy says the gas supply is adequate.

Greenwood says they have tracked the costs from last year to this year.

Greenwood says despite the supply, demand for natural gas is up worldwide.

Mid-American serves about one hundred four thousand gas customers, mostly in southeast South Dakota.