February 21, 2006
IEEE Delaware Bay Section meeting 

Tour: Delmarva Power's Thermal Plant in Wilmington, DE.

Thanks to John Zhang of our section and Tom Langley of Delmarva Power for arranging the tour, and to Bud Seward and Tim Wells, our tour guides. About 25 people attended.

So what is a thermal plant doing in the bottom of the County Building in downtown Wilmington? The state asked Delmarva Power to build a plant that would supply hot and chilled water for heat and air conditioning for as many government buildings and also private buildings as they could handle, with the promise that several of the county and state government buildings would subscribe. The plant started up in 2001 at a cost of $13 million. Presently, the County Building, and the New Castle County Courthouse are subscribers. The power unit has 6 - 1000 ton chillers, and the load on this system is presently only 2000 tons, so Delmarva Power is looking for additional subscribers for the 4000 tons of extra capacity. The heat and chill is moved to the customer using a closed loop water system. Flat plate heat exchangers are at each end, with the customer supplying his own circulating system for his building.

Other facts:

  • The controls and automation are state of the art AB Control Logix PLC, and using Rosemont sensor transmitters for critical functions. A fiber optic link is used for communications.
  • The system can be brought on line from shutdown to full operation in 1.5 hours.
  • Response to a severe change in load is 15 minutes.
  • There is a water treatment plant to keep the closed loop circulation system clean.
  • The premises are as clean as any of us have ever seen. This is due to maintenance, and a clean air system.
  • The load is balanced automatically to maintain customer hot and chilled water conditions.
  • Power in is via 12,500 volt electrical service from Delmarva Power. Batteries back up critical control and sensor functions.
  • There is a thermal plant similar to this one, but much larger, in Atlantic City, NJ.


Tour Guides: Bud Seward and Tim Wells stand in front of the main control cabinet. The controls were A/B Control Logix PLC and the PLC and sensors were networked to the control room.


Tom Langley, Delmarva contact, and John Zhang, Delaware Bay Section arranged tour. 

We had subs from Casapulla's North and sodas via Tom Langley prior to the tour.

Bud Seward shows us some BIG pipes.

Bud and Tim give us the data before the tour.

In the control room