The City of Sacramento moved toward compressed natural gas (CNG) vehicles with the purchase of its first heavy-duty CNG vehicles — two Elgin Broom Bear four-wheel mechanical broom sweepers. Its other natural gas vehicles include some light-duty CNG cars and trucks, a liquefied natural gas (LNG) refuse fleet.

"We ran the numbers and found a few areas where compressed natural gas just makes dollars and cents," said Christopher Kerhulas, shop foreman. He added that diversifying away from LNG means the city isn’t only relying on LNG transports from Boron, Calif., for its natural gas transportation needs.

The sweepers replace dual-engine diesel sweepers, and Kerhulas says by using CNG, the city could potentially save $6,650 per year, per sweeper in fuel costs. The fleet expects 10 years of service life from the vehicles. The cost difference between a diesel and CNG Broom Bear is about $35,000.

The fleet also expects that maintenance and operations costs will be lower. With the new single engine, the costs of maintaining a second engine are completely eliminated. With CNG, fleet staff will no longer have to worry about diesel particulate filter (DPF) and selective catalytic reduction (SCR) maintenance and can eliminate diesel exhaust fluid (DEF) costs.

The CNG sweeper is mounted on a Freightliner conventional chassis with fully dualized controls and a CNG engine that also powers the sweeper's hydraulic broom system. It also features a large 4.5 cubic yard hopper and 360-gallon water tank, which the fleet expects will extend productive sweeping time, according to Kerhulas.

The city will purchase renewable natural gas (RNG) from the Clean World BioDigester, which converts food waste into CNG. An alternative fueling station for CNG is at Sacramento Regional Transit.

The fleet is purchasing two more broom sweepers; one is expected to be put in service in April while the other is on order.