Maybe it's the benign-sounding name: biomass. Maybe it's because it applies to such familiar and seemingly harmless materials: discarded lumber, yard waste, old shipping pallets. Maybe its advocates have just hired good lobbyists.Whatever the reason, said Mary Booth, director of the Massachusetts-based environmental group Partnership for Policy Integrity, this source of power has a reputation as "clean, green and carbon neutral — none of which happens to be true."Yes, Booth said, the people promoting biomass incineration have done a first-class job of "green-washing," spinning an environmentally destructive practice to make it seem harmless or even beneficial — such a good job, in fact, that new plants like the one being built to replace a coal-fired furnace on Cemex property northwest of Brooksville can qualify for tens of millions of dollars in federal renewable energy tax breaks.And what would proponents of biomass say if they told the truth about this power source?Well, that in a lot of ways it's worse than coal.The American Lung Association has come out against biomass incineration. So has the Florida Medical Association. And, last week, so did the Hernando County Medical Society.The group's president, Spring Hill pain management doctor Deborah Tracy, sent a letter to the County Commission objecting to the project at the Central Power and Lime plant, saying the emissions represent a real danger to county residents, especially those with asthma or other lung ailments.Tracy is probably way too late. The state Department of Environmental Protection issued a permit for the project in January, and county planners long ago determined the company building the plant — Texas-based Florida Power Development LLC — didn't need a zoning change.Still, she's got a good point.Let's assume, as the power company states in its permit application, that the plant will burn clean material, such as lumber that has not been pressure treated.Even so, woody matter creates more of most kinds of waste than coal, per amount of energy produced, because it's less efficient. For example, the old coal plant could produce 150 megawatts of power, compared to between 70 and 80 megawatts at the new facility.Because the biomass plant is new, it will have better filters and other pollution controls than the old one. That's the main reason why, according to its DEP permit application, the plant will release far lower levels of nitrogen oxides, a major contributor to acid rain. So is sulfur dioxide, emissions of which will be lower in the new plant because coal is naturally high in sulfur and because of the new filters.But even with this improved pollution control, the plant will release more mercury and more particulate matter than the coal plant did between 2006 and 2010, when it was running at less than full capacity. It will also spew out more carbon, though here the comparison gets tricky.The federal government is working to develop standards on how to treat the carbon from biomass plants. The biggest factor in this decision: Biomass, presumably, would decompose and its carbon would be released regardless of whether it was incinerated.The carbon in coal, on the other hand, could stay locked up underground indefinitely.Okay, Booth and other critics of biomass burning say, but burning wood means putting a big load of carbon into the air right away rather than over the course of decades.That means it's far from carbon neutral.I agree, though I'd be willing to give biomass the faintest praise possible for an energy source: when it comes to carbon, long term, it seems somewhat preferable to coal.So, why would a company with a coal-fired plant that produces electricity from a relatively cheap fuel source spend millions of dollars to rebuild it as a biomass plant that produces half as much energy?We don't know for sure because no one connected with the project would grant an interview, and Tony Hopkins, the power development representative listed on all of the permits, sounded miffed I'd even asked."No comment. I'm out of the country," he said when I reached him on his cell phone.One probable reason: tax breaks that can come to $46 million for the lifetime of a 50-megawatt plant, Booth calculated in a recent report.There's also money in burning stuff that people will pay to get rid of, which means toxic stuff, such as the plastics, treated lumber and construction debris that the current permit forbids.Even with that permit, there's no guarantee bad stuff won't slip into the stream of material that is chipped and then burned in the incinerator. The gatekeeper, Booth said, "is usually somebody making $7 or $8 per hour picking out the lumber that looks like it's pressure treated."A bigger threat, in the long run, is the strong economic incentive for the company to apply for permission to burn more toxic material.We residents and our concerned doctors need to keep an eye out for this and try to stop it. Before the permits are issued.Follow Dan DeWitt at [email protected]. Also look for his Quick Hits column each Monday at tampabay.com/hernando.