Central steam plant emmissions

Solomon Rosenbaum

Does anyone know of a source where I can find data on central plant emmissions?

I am looking for data that would back up the claim that the emmissions from a central plant are lower than that of the collective emmissions of the boilers that would have to be used in its place.

Or perhaps the data will show that I am wrong in this claim.

Bob D._2

Central Plant Emissions

For really simple figures, use the EPA website and look up AP-42, which gives emission factors for a bunch of different combinations of sizes, fuels, and burners. AP-42 is pretty dated, but better than nothing. For a little more accuracy, use 40 CFR 60, EPA New Source Performance Standards (NSPS), Subpart Dc. [All this stuff is available on line from the gov'ment]. This is typically for units greater than 10 million BTU/hr input and less than 100 MMBtu/hr. These are the regulations that all states permit programs are based on, and set max. limits on various emissions (NOx, SOx, particulate, etc.). You can't turn the key until you have the permit. You can also look at specific burner manufacturers, and use their "advertising" figures.

Constantin

So many factors...

... generally speaking, you have a far better opportunity to scrub gases at a large plant than many small ones due to economies of scale. However, that presumes that the plant operatir wants to incur the expenses of doing so, which is pretty rare in a day and age where the clean air act got rolled back repeatedly.

Then you'd have account for the transmission losses from the central plant to the point of use. Every percentage lost along the way is more fuel that has to be burned, more emissions that have to be scrubbed.

Where things get interesting is plants where the fuel is free, i.e. garbage processors. Not only do you end up with much less landfill space being required (since paper makes up 60%+ of local waste streams), but you get free heat and power too. Getting the exhaust gases on an uncontrolled fuel to be happy though is a bear.

Lastly, it very much depends on the fuel source that is being used. Cleaning the fuel and using high efficiency burners/boilers may allow homeowners to exceed the theoretical efficiency and cleanliness of larger plants due to transmission losses.

Nevermind some fuels like coal that continue to douse the wider landscape with large amounts of mercury and radioactive ash. Scrubbing the mercury out is an option, the radioactive isotopes is a different matter.