Last year, the Environmental Protection Agency finalized standards within the Clean Air Act to protect people and the environment from toxins released from boilers and incinerators. The new standards aimed to reduce air pollution from mercury, hydrogen chloride, particulate matter, and more. The main targets are pollutants that cause smog, acid rain, and measurable health problems. This is achieved by capping emissions from burning fuel such as coal, oil, natural gas, and biomass.
Under these standards, boilers are broken down into two main categories, major source boilers and area source boilers. Major source boilers are those that produce large quantities of polluted emissions, such as major industrial facilities. Area Source Boilers are those that cover a smaller, more targeted scope, including public buildings and universities.
Area source boilers have fewer restrictions than major source boilers. For biomass area sources, the only pollutant that must be limited is particulate matter.
A feature in Biomass Magazine provides specific details for new area source boilers: “Biomass boilers with a heat input between 10 MMBtu/hr and 30 MMBtu/hr are required to keep filterable particulate emissions below 0.07 lb/MMBtu, while boilers rated 30 MMBtu/hr and greater are limited to 0.03 lb/MMBtu.” For existing biomass area source boilers, however, there are no new limitations. They simply have to undergo regular maintenance and tune-ups.
For major source boilers, the regulations are stricter. These boilers must limit either filterable particulate matter or total selected metals, though the choice is theirs to make. In addition, they must limit carbon monoxide emissions.
Another hurdle for biomass boilers is the limitation of mercury. If mercury is in the fuel source, it will be expelled as waste in one of three ways, and each of those ways must be dealt with separately. Particulate mercury can be filtered out, while divalent mercury must be absorbed by activated carbon. To control mercury in its elemental form it must first be ionized, then absorbed by activated carbon before finally being captured by a particulate control device.
Boiler MACT is estimated to impact about 200,000 boilers around the country. For this reason, it’s imperative to stay in-the-know and ensure that all facilities are meeting necessary standards.