With the smokestack of Maryland’s largest trash-burning incinerator in the background, dozens of protesters held a rally on Friday in south Baltimore’s Carroll Park to demand either a shutdown or stronger pollution controls on the BRESCO waste-to-energy plant.The activists gave speeches and waved signs beneath a banner that read, “Burning Trash is Not Clean Energy.” That’s a reference to a 2011 state law that gives the 33-year-old incinerator, operated by the New Hampshire-based Wheelabrator company on contract for the city, millions of dollars in tax breaks as a source of allegedly “green” energy, like solar or wind.