As Atlantic Power seeks permission to burn a higher percentage of rail ties in its Williams Lake Power Plant, Tribune reporter Monica Lamb-Yorski (MLY) contacted a power plant in the U.S.
During a phone interview plant manager Mark Paitl and air control quality environmental analyst Tina Ball at Excel Energy’s French Island Generating Plant (FIGP) in La Crosse, Wisconsin, a waste fired electrical power station that has been using rail ties as fuel for 20 years, answered her questions.
MLY: How long have you been using rail ties for fuel in your plant and to what per cent?
FIGP: At least 20 years. We started out with a small per cent our air permit didn’t specify what percentage we could burn, we just had to record what percentage it was. As our sawmills closed or took their bark to other sources, such as landscape material, I needed another source to replace that such as wood waste or rail ties. We slowly increased our percentage of rail ties to where 50 to 60 per cent of our wood waste total is shredded rail ties.
MLY: Are you shredding the rail ties on site?
FIGP: No. There is a facility about a half mile away from our plant that the ties come in by truck or rail and are off-loaded. They have a grinder there where they grind them, remove all the metal and then put them in a shed that has a black top base and a cover over it. One of their stipulations is they can store the whole ties on the ground but once they grind them they have to be stored underneath the storage building.
MLY: How close is your plant to residential areas?
FIGP: We are actually right on the Black River in the back waters of the Mississippi River on the point of French Island. We have residences across the river about a block and a half away and then the residential area starts a block from where the grinder/shredder is located. There’s nothing between that facility and ours.
MLY: When you went to burning more rail ties is that something you had to get approval for from the regulators?
FIGP: We had to get approval to burn the rail ties and within that approval there was no limit because we’d proven by stack testing that there was no percentage if we wanted to go more or less on that.
MLY: What is the standard for emissions?
FIGP: The State of Wisconsin standard for burning wood waste only. But we also burn refuse derived fuel. We take our cross county garbage and turn it into waste and into a fuel. When we burn that fuel we have to follow federal standards.
MLY: Are you self-regulating the emissions?
FIGP: No we have an outside stack test firm come in and they do annual stack tests on our emissions and then the other pollutants we have are monitored through continuous emissions monitoring, where we have instruments that we have to have an outside firm come in every year to check that they are working. We submit to the agencies a quarterly, semi-annual and annual report of our emissions along with the annual stack test.
MLY: What is the volume of rail ties you are burning in a year?
FIGP: In the last couple of years we’ve been between 30,000 and 37,000 tons a year.
MLY: Do you have any pollution control equipment that is part of the operation?
FIGP: We have a bag house we installed in 2000 to catch particulate.
MLY: Have you ever had concerns from residents?
FIGP: We at the plant have not had concerns but I know they’ve had some over at the grinding facility about dust and odour. They are also regulated with their storm water, plants and also the State of Wisconsin visits them to make sure they are meeting their permits.
MLY: Did the increase of rail ties as fuel change the nature of the ash in anyway?
FIGP: We sample our ash quarterly and annually and with the increase in railway tie burn we did not see a change at all.
MLY: What are the measurements you use to test for emissions and the levels they have to be below.
FIGP: The main driver is the dioxins and furans so we need to be below 30 mg by standard per cubic metre of air.
MLY: Have you seen any change in emissions from burning rail ties to meet that standard?
FIGP: No and those limits are waste combustion limits not for burning rail ties but because we burn garbage at the plant as well.
MLY: How is garbage used as fuel?
FIGP: It’s processed into refuse-derived fuel (RDF) — a fluffy light burnable fuel. It’s comprised mostly of paper, cardboard, those kinds of things.
MLY: Where does the waste come from?
FIGP: Right from the curb side pickup to the plant where we process it and burn it. The county also has curb side recycling so they do recycle ahead of the material being brought to the plant. So what we do is remove the non burnables, we remove any metals, and aluminum still with the products. Then we make the RDF and blow that into our boilers with our wood waste.
MLY: How much of the volume does the RDF comprise?
FIGP: Typically 50 per cent of our fuel mix, is RDF and the remainder is wood waste and half of that is rail ties.
MLY: Is the ash from the plant used for anything and is it covered?
FIGP: We have a cell that our ash goes into and it is covered daily. Our other plant that burns wood waste with rail ties they have been reutilizing their ash for six or seven years. Because of the garbage component, the ash at this plant isn’t as homogeneous as the state would like for reuse so we don’t.
MLY: Is the creosote from the rail ties still in the shavings when they arrive at the plant?
FIGP: There is no way to take it off so it definitely comes in with the ties, but it’s so volatile that it burns up and is destroyed in the combustion process.
MLY: Have you had concerns about creosote from the public.
FIGP: Several years ago at our other plant when we first started burning rail ties, we had the same concerns about how different is it than wood waste. We did some stack testing back then comparing a wood tie mixture to a wood only mixture and there was no difference in emissions. In fact in the wood tie mixture we had saw better emissions in some things we were looking for just because they burn hotter. The ties are drier and with the creosote being so volatile, actually make a nicer fuel than straight wood waste.