**Title**: Energy in the North - Aaron Marohl
**Date**: May 6, 2026
**Participants**: Amanda Byrd, Aaron Marohl

00;00;00;13 - 00;00;10;24 [Aaron Marohl] Each harbor has a used oil receptacle, and then the harbor department will pump that out into a portable tank that they have and deliver it to the landfill.

00;00;10;24 - 00;00;32;13 [Amanda Byrd] This week on energy in the North, I speak with Aaron Marhol, public works director for Petersburg, Alaska. All communities across Alaska must contend with disposing of waste vehicle oil. In Petersburg, they found a novel approach to using that oil. And I began the conversation with Aaron by asking him, where does the waste oil come from?

00;00;32;13 - 00;03;21;04 [Aaron Marohl] The majority of our used oil comes from our boat harbors, down from our commercial fishing fleet and the harbor department has a portable trailer. Each harbor has a used oil receptacle, and then the harbor department will pump that out into a portable tank that they have and deliver it to the landfill. From there, we have five storage tanks in the tank farm area that we hold it. Typically, we get approximately 12,000 gallons a year of used oil. And what we do is we have several stages of filtering that oil and prepping for burning. We use it to heat our sanitation facility. We have two waste oil heaters. One is 500,000 BTUs, and the other one is 350,000 to use. And those we're purchased from, Fire Lake in Seattle. From the holding tank we pump, 750 gallons at a time into a cone tank, which is a large vertical tank which has a cone on the bottom and that oil. The longer it sits, the better. All of the impurities, the water and the impurities. The, settle down to the bottom of the cone tank when we're ready to use that oil. I've got an immersion heater in the tank, and I'll turn that on for at least 24 hours. And I believe that sets up a kind of a convection as the oil's heated and it transfers around the tank, and it allows more impurities to fall to the bottom, and then we drain off those impurities into a sludge barrel. And then we run the oil, through a dual centrifuge system. From there, it goes into an underground tank, which is where we hold it to be pumped into the building. We have a day tank, a 50 gallon tank inside the building that operates on a, float system, a float switch system. And so as the level of the day tank drops, it will turn on a pump, which will then fill that day tank. I have a second immersion heater inside that day tank. And what that helps do is separate more of the water as the oil comes into a warm building condensate. And that immersion heater inside the day tank, helps draw that condensation out. And so a couple times a week, we just drain off the bottom of the tank, get all the water out of there. And so with our oil as pure as we can get it, we make sure we have clean air supplied to the heaters because, what the heaters do is they atomized the oil, and then from there it's just like the boiler inside the house. The atomized oil is burned and heats our facility, 

00;03;21;04 - 00;03;28;16 [Amanda Byrd] but it's a great use for what would otherwise be a waste resource just sitting there.

00;03;28;16 - 00;03;57;17 [Aaron Marohl] You know, I mentioned earlier, the sludge that we drain off the bottom of the cone tank, but every two years, we send off a shipment of oil that we can't burn or our sludge to a company in Ketchikan called Full Cycle. And they actually, refine that product, and they turn it into, the mastic for, asphalt roads. So, you know, if we didn't use it, somebody else could. But the way we're using it, we don't have to pay to ship it off, which is very expensive.

00;03;57;17 - 00;04;09;26 [Amanda Byrd] Aaron Marhol is a public works director for Petersburg, Alaska, and I'm Amanda Byrd, chief storyteller for the Alaska Center for Energy and Power. Find this story and more at uaf.edu/acep