PTG Water & Energy’s award-winning technology features custom-engineered Combined Heat & Power systems.
The benefits include:

  • Saves up to 50% of total facility energy costs
  • Saves up to 75% on wastewater disinfection costs
  • Sustainable, chemical free/non toxic solution
  • Green technology/lowers carbon footprint

How CHP / Cogeneration Works

Combined Heat and Power (CHP), also known as cogeneration, is the simultaneous production of electricity and heat from a single fuel source (such as natural gas or biogas) in a unified system.

In this era of rising energy prices, businesses of all sizes are increasingly turning to CHP in order to cut their increasing power costs. Recent innovations in CHP technology have expanded the possible range of customer applications and sizes.


In the example of a traditional CHP system shown above, hot exhaust gases that come from the engine or turbine that generates electricity are used to heat water and/or create steam. The heated water and/or steam is then used to heat or cool a building or facility.

PTG applies these CHP concepts in several novel ways to address BOTH energy and water needs. Our systems beneficially use exhaust heat to create hot water that is used as an ingredient or input in our customers’ production processes. For example, hot water that a craft brewer would use to make beer, or that a food producer would use to create or mix food ingredients. In this case, our custom-designed CHP systems produce hot water at no additional cost by using hot exhaust gases created from onsite electric generation. This results in significant economic savings which rapidly pay for the investment in PTG’s systems.

We add significant value for our customers because we know how to BALANCE their water and energy needs in a single, EFFICIENT system so that our projects quickly recover their capital cost investment.

In another novel application, we use these same CHP principals to heat wastewater in order to disinfect the water before it is either discharged into a natural resource such as nearby river, or to support its reuse or reclamation. PTG’s patented wastewater applications are illustrated in more detailed below.


How PTG’s Integrated, Patented Wastewater Disinfection System Works

Cogeneration principals are applied to the problem of disinfecting wastewater using a process that is safe, toxic free, and has a low carbon footprint in a unified, integrated system.

Low-cost electricity is generated to save energy costs consumed throughout the wastewater treatment facility, while at the same time exhaust heat that is generated as a system by-product is used to disinfect wastewater at no additional cost, saving O&M costs traditionally incurred for disinfection, such as chemical purchases, power consumption, labor and consumables. The combined plant energy offsets and disinfection cost savings generate a positive cash flow stream that rapidly pays for the investment in PTG’s system.

PTG's Wastewater Disinfection System

In the diagram of PTG’s patented CHP-based disinfection system shown above, exhaust gases coming from the gas turbine that generates electricity onsite are diverted into a “waste heat recover unit” where the thermal energy is used to increase the temperature of incoming, pre-heated wastewater from 177⁰F to 180⁰F. At this point and temperature level, the wastewater in this example is completely disinfected. In addition, the 180⁰F wastewater is also full of thermal energy. In order to tap this embedded thermal energy–and also just as importantly to efficiently cool the hot, disinfected wastewater so it can be safely discharged into the environment–we pump the 180⁰F disinfected water into a separate custom-designed “preheater unit” where its thermal energy is transferred to the incoming wastewater, raising the temperature of the next batch of water up to 177⁰F. In this heat-exchange process, the temperature of the disinfected water has been lowered to 73⁰F, making it safe to discharge or to reuse.

This patented process is what makes our wastewater disinfection system so EFFICIENT because it leaves a mere 3⁰F temperature increase requirement for the gas turbine to handle. Basically, we RECYCLE thermal energy embedded in disinfected wastewater over and over in our uber-efficient CHP-based, patented process.

Our systems, as shown above, use either onsite renewable biogas or low cost natural gas to produce electricity for the entire wastewater treatment facility at a cost which is much lower than electric-utility produced power. This energy savings pays for the capital investment in PTG’s system within several years, and in a fraction of the systems expected 20-year useful life.

All of our systems and each of their major components can be controlled and monitored remotely by smart phone, personal computer or other electronic, real-time interfacing device.

Finally, as further illustrated above, the resulting disinfected wastewater, cooled to ambient temperature, fully qualifies under requirement of California Title 22 regulations either for safe discharge into natural resources or for non-potable water reuse, including landscape watering, facility equipment cleaning, and agricultural irrigation.