The federal stimulus package has spurred city leaders to seriously begin exploring ditching the city’s aging fleet of diesel transit buses and replacing them with alternative fuel vehicles.

Commissioners at their meeting tonight will be updated on the latest efforts to replace the fleet of 12 buses with new buses that run either on compressed natural gas or a renewable fuel source such as biodiesel.

“These additional funds from the federal government have given us additional possibilities, and that definitely includes alternative-fuel vehicles,” said Casey Toomay, the city’s interim director of public transit.

The city appears likely to receive $1.9 million in transit funding as part of the recently approved stimulus package. Toomay said it likely will be staff’s recommendation that all the money be used to partially replace the city’s fleet of buses, which are nearly nine years old.

The use of the federal stimulus funds, though, will mean that the city will have to make a decision on whether to buy alternative-fuel buses relatively soon. The stimulus guidelines call for at least half of the $1.9 million to be spent in 180 days.

Cost concerns will be part of the decision. Toomay said the city is estimating that traditional diesel buses will cost about $320,000 per vehicle. Alternative-fuel vehicles likely will be closer to $480,000 per vehicle, she said.

Compressed natural gas buses — which are used at the Kansas City International Airport — and buses that run on biodiesel fuel appear to be the most feasible alternatives currently, Toomay said.

In the past, the city has had concerns about the feasibility of compressed natural gas because it would require a new, specialized fueling station that would be expensive to build. But Toomay said the city believes there may be a private fuel-retailer that is interested in building a compressed natural gas station in the city. That would allow the city to simply buy the natural gas rather than investing in its own fueling station.

Mayor Mike Dever said he’s particularly interested in the compressed natural gas option. He said as the Environmental Protection Agency continues to look at whether Lawrence’s air quality standards meet new federal standards, options like cleaner burning natural gas vehicles could be important.

“This could be a real opportunity for the city to help bring a whole other energy source for the community to use,” Dever said.

Dever also thinks making the switch would make the city’s buses more cost-efficient from a miles per gallon standpoint. Supporters of natural gas vehicles have estimated that fuel costs average about 30 percent less than diesel.

Commissioners tonight are expected to give staff members approval to pursue other funding for buses as well. Commissioners are being asked to approve a list of projects to be considered for congressional earmark money. That list includes $1.6 million for transit buses.

The city in the past has been successful in receiving earmark money for buses. The city currently has $1.9 million in earmark money — in addition to the stimulus money — for buses. The city received that earmark money in past years, but had not spent it because until last November’s sales tax election there was uncertainty whether the bus system would continue.

If the city were to get the $1.6 million in new earmarks, there should be enough money to replace all 12 buses.

Other projects for which the city will be seeking earmark money include:

• $7.5 million to extend 31st Street from Haskell Avenue to O’Connell Road.

• $6 million to rebuild Kasold Drive from 31st Street to Clinton Parkway.

• $2 million to improve stormwater flow near 23rd Street and Ousdahl Road.

• $5.5 million to build a new North Lawrence stormwater pump station at North Fifth and Maple streets. The city also is holding out hope to receive stimulus money from the U.S. Army Corps of Engineers for the project.

Commissioners will meet at 6:35 p.m. today at City Hall, Sixth and Massachusetts streets.