During the coldest of cold days last week, Bobbie Cruz asked her supervisors at the Toledo Area Regional Transit Authority to turn down the thermostat in the maintenance building where she washes buses.
The waste-oil burner the transit authority bought and installed last fall to heat the 8,400-square-foot building was doing its job too well.
Maintenance Superintendent Dave Burnham "came out to check out the heater once, and I had shut it down because it was too hot," said Ms. Cruz, who has been a TARTA employee for three months.
But she heartily endorsed the squat black box with gauges and pipes sprouting from its roof: "You might as well use the oil for something."
That's exactly what James Gee, transit authority general manager, had in mind when he bought the burner from Hoffman & Harpst Co. for $7,300 in September.
Instead of giving away used engine oil to a recycler who would just resell it, why not put it back to work for TARTA?
"It saves us money on the heating bill, and it's good for the environment," Mr. Gee said.
In November, the most recent month for which complete utility bills have been received, the transit authority used 672,000 cubic feet of natural gas to heat its headquarters and garage. That was 59,000 cubic feet less than it used in November, 2007, even though the more recent November was nearly a degree cooler on average.
Mr. Gee said the gas bill is $775 lower than the year before's. Nine more months like that, and the waste-oil burner will pay for itself.
Mr. Burnham said he's already had visitors from the Toledo and Oregon school districts who want to see the little furnace at work.
The transit authority changes oil on four vehicles each workday, with minibuses requiring nine quarts and full-size buses taking 27 quarts. The used oil drained from them is more than enough to keep the burner running all day, the maintenance superintendent said.
"It's really efficient," he said. "We'll pour a 55-gallon drum in there and it'll run the whole weekend."
The burner has a filter to keep out metal shavings and other contaminants common in waste oil, the maintenance superintendent said.
The only contaminant Mr. Burnham fears is anti-freeze, which the filter can't catch and which, in any significant quantity, would shut the burner down. So only oil from routine-maintenance changes is fed into it.
Waste oil from the transit garage's repair bays still goes to the commercial recycler, he said.
Most of the work in the daily-maintenance bay occurs at night, when the outdoor temperature is the lowest.
While most of Toledo sleeps, each bus is cycled through the garage for refueling, fluid checks, washing, and inspection.
With all that activity, Mr. Burnham said, the building's doors are open a lot, but the waste-oil burner keeps it warm. If the burner runs out of oil, he said, the natural-gas heater kicks on automatically.
"It's supplemental, but it has greatly replaced regular heat" in that building, Mr. Gee said.
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