Client: Danville Sanitary District

Clark Dietz provided mechanical and electrical design and construction phase services to implement a backup power solution at the wastewater treatment plant. This solution included multiple power sources: one generator powered by diesel fuel and another powered by methane biogas produced by the plant’s anaerobic digesters.

Biogas-Fueled Generator:

A new Combined Heat and Power (CHP) system was installed, utilizing a biomass-fueled generator powered by biomethane produced in the plant’s anaerobic digesters. Clark Dietz designed and provided a complete CHP packaged system, which included the following components:

  • Container, engine-generator, control panel, radiator, exhaust gas heat exchanger, silencer, recirculation pumps, heat recovery heat exchanger, low-voltage switchgear, and all necessary appurtenances.

The system used conditioned biogas, delivered via an existing biogas conditioning system, to fuel the CHP generator. The fuel system was designed with controls to mix biogas and natural gas in varying amounts, depending on the biogas production levels at the plant. This allowed the generator to operate on:

  • Biogas only

  • Natural gas only

  • A combination of both biogas and natural gas

The generator was set up to operate in parallel with the utility electrical supply, reducing the plant’s need to consume electricity from the utility.

Additional Boiler Installation:

Two new 1.9 million BTUH natural gas-fired boilers were installed to supplement the biogas supply and replace the plant’s aging boilers.

Diesel Fuel Generator:

A full backup generator system powered by diesel fuel was also installed. This system included:

  • A generator with a diesel fuel storage tank

  • Fuel pumps

  • A cooler

  • Associated fuel lines

Additionally, the project involved replacing the 4000-amp, 480-volt main electrical switchgear, which was outdated. The construction process was carefully planned with the utility to ensure the new equipment could be installed without causing significant plant downtime.

Key Highlights:

  • 200 kW CHP generator powered by biogas or natural gas.

  • A new heat recovery system to capture waste heat from the engine.

  • New full backup generator system (1,250 kW, 480V) with remote starting capabilities.

  • New automatic transfer switch for seamless power switching.

  • New 4000-amp, 480-volt main electrical switchgear.

  • Two new 1.9 million BTUH natural gas boilers.