By Brittany Smith

Boston residents’ environment will change from “Beantown to Greentown,” said Mayor Thomas Menino of the city’s environmental efforts Friday at City Hall Plaza during the fifth annual AltWheels Festival.

AltWheels, the largest exposition of alternatively-fueled cars in New England, presents the newest innovations in environmentally friendly transportation each year. Sponsors like Ford, Chevrolet and Honda displayed gas and electric-powered hybrid vehicles, while some independent entrepreneurs showcased cars run only on vegetable oil.

On Friday and Saturday, attendants were encouraged to explore ways to reduce the consumption of fossil fuels. Besides boasting bicycles, the festival unveiled the proposal for a wind turbine on City Hall Plaza, which is normally a desolate, wind swept brick plain. The wind turbine will potentially be a 150-foot tall structure that could generate up to one-quarter of the electricity used at City Hall.

Free fluorescent light bulbs were given to each day’s first 150 patrons, and all attendants were treated to a plethora of displays on alternative transportation, alternative fuels and other green topics. Visitors who wanted to get a full scope of the newest green technologies could experience the “Energy Freedom Trail.” They could also receive free bike repairs, watch biodiesel being made or calculate their carbon footprint, which is a measure of carbon dioxide emitted into the atmosphere.

Representatives from the Husky Energy Action Team (HEAT) manned a table at the event.

Kevin Cunningham, HEAT’s media director, was thrilled that HEAT was asked to join the conference.

“Even though we don’t specialize in alternative fuel