I got to tour the Hennepin Energy Recovery Center (HERC) this week, and it was fascinating. The amount of trash was staggering, but I'm glad it wasn't going to a landfill and that it was generating energy to heat downtown buildings and put some electricity onto the grid.
Trucks are constantly coming and going, dumping their loads of trash.
The grapple (I call it The Claw) picks up the trash and tosses it like a salad as the operator works to get the right mix of wet and dry for a good burn. Are you seeing this massive amount of trash?!!
The grapple drops giant clawfuls of trash into two big hoppers on the upper right. Trash slowly drops down the chutes into the two burners, which run 24 hours a day 365 days a year (except a few times a year for maintenance).
Look at the size of it.
Sometimes a big hunk of metal like an appliance will get through, and when the operator spots it, he plucks it out of the trash pile.
The plant's processes are constantly monitored with sensors, and deep in the bowels of the facility, Covanta operators go through their paces, using all of their senses (except taste!) to gauge whether things are working right. They can also tell by how the flames look whether things are burning well or not. This was just after our big snow storm Saturday, and as one guy put it, "snow doesn't burn well."
I was mesmerized by the fire.
The control room operator works 12-hour shifts in front of a bank of computer screens, monitoring everything in the building and constantly tweaking the flow of air and steam, rate of combustion, the speed of the trash in the furnace. The HERC produces steam, which drives a turbine to produce electricity. To read more about the process, click here.