Roy Dowd sniffed the air during a dairy tour he was leading last week on the edge of Bakersfield.

"That's the smell of money," joked the director of operations, maintenance and research at a Visalia company, California Bioenergy LLC, helping local dairies turn manure into a new revenue stream.

Don't hold your nose: Methane from cow manure at local dairies has taken on new value as both a clean-burning fuel and a greenhouse gas to be harnessed.

Growing numbers of dairies are earning a percentage of sales from the electricity generated by combusting "biogas" produced on their property. Soon, some of the gas will be refined on site and injected for sale into natural gas pipelines.

By John Cox, Bakersfield