For facilities with high energy demands, balancing electricity production with reliable thermal output is a constant challenge. That’s where combined heat and power (CHP) – otherwise known as cogeneration (cogen plant) – delivers exceptional value. Instead of discharging waste heat as traditional power plants do, cogeneration systems produce both electricity and useful thermal energy from a single fuel source, achieving fuel efficiencies of up to 90%.

At EAI Water, we specialize in water and energy solutions that improve efficiency, reduce emissions, and optimize performance. With over 30 years of experience serving the Western U.S., we help industrial and commercial facilities implement smarter systems—including cogeneration setups tailored to unique load profiles. In this article, we explore how cogeneration plants work, what fuels they use, and why they offer such a compelling advantage in power and heat production compared to conventional systems.

What Is a Cogen Plant?

A cogeneration plant—also known as a combined heat and power plant—is designed to produce both electricity and usable heat from a single fuel or primary energy source together. Unlike conventional power plants that discard waste heat, cogen plants capture and repurpose thermal energy, making them far more efficient.

The defining feature of cogeneration is its dual-output capability. By generating electricity and capturing the heat that would otherwise be wasted, a cogeneration system can achieve overall energy efficiencies of 70–90%. This efficiency leads to reduced fuel consumption, lower greenhouse gas emissions, and cost savings for industrial, commercial, and institutional facilities.

Fuels Used in Cogeneration Plants

Cogeneration systems are flexible in their fuel use. The most common fuel is natural gas, especially in gas turbine and engine-based systems. These systems burn gas to produce electricity, and the high-temperature exhaust gases are then captured to generate steam or hot water.

Biomass—including wood chips, agricultural waste, and sugarcane bagasse—is also widely used in cogen plants, especially in the paper, sugar, and food processing industries. Biomass fuels provide a renewable alternative with a lower, carbon dioxide emissions footprint.

Other cogeneration systems can use waste gases from industrial processes, such as in refineries or chemical plants. This transforms a liability into a productive energy source, boosting sustainability and efficiency.

How Cogeneration Plants Produce Electricity and Heat

The hallmark of cogeneration is its ability to generate electricity and useful heat simultaneously. Here’s how that dual-function process works:

• Electricity Generation: Fuel is burned in a gas turbine, steam turbine, or reciprocating engine. This mechanical process drives a generator to produce electricity for use on-site or export to the grid.
• Heat Recovery: Instead of releasing the hot exhaust gases into the atmosphere, cogen plants use them to heat water or produce steam via a Heat Recovery Steam Generator (HRSG) or heat exchanger.
• Thermal Energy Use: The captured heat is distributed for space heating, water heating, industrial processes, or even absorption cooling (in trigeneration systems).

This synergy of power and heat production makes cogeneration uniquely efficient—getting maximum energy value out of every unit of fuel.

Types of Cogeneration Systems

Gas Turbine Systems

These systems combust natural gas to drive a turbine connected to a generator, producing electricity. The high-temperature exhaust gases are then captured and directed into a heat recovery steam generator (HRSG), where they produce steam for heating or additional power generation. Their ability to continuously deliver both power and thermal energy makes them ideal for large industrial facilities and utility-scale operations.

Steam Turbine Systems

Steam turbine cogeneration systems use high-pressure steam—often generated in a boiler fueled by coal, biomass, or waste heat—to spin a turbine and produce electricity. After passing through the turbine, the lower-pressure steam is recovered and used for process heating or space heating. This approach is especially common in energy-intensive sectors like pulp and paper, petrochemicals, and food processing.

Reciprocating Engine Systems

These systems use internal combustion engines—similar to those in vehicles—to generate electricity. Heat from the engine’s exhaust and cooling system is recovered and used for thermal applications such as domestic hot water, space heating, or low-pressure steam. Due to their modularity and relatively compact size, reciprocating engine systems are popular in hospitals, schools, hotels, and other commercial settings with consistent heat and power needs.

Biofuel Engine Systems

These cogeneration units operate on renewable fuels like biodiesel, biogas, or landfill gas, making them an environmentally friendly alternative to fossil fuel-based systems. In addition to generating electricity, they recover heat from the engine block and exhaust stream for use in thermal processes. Their ability to reduce greenhouse gas emissions and utilize locally sourced fuel and recycled energy makes them particularly appealing in agricultural, municipal, and waste-to-energy applications.

Benefits of Cogeneration

1. High Energy Efficiency
By producing electricity and heat together, cogen plants can reach up to 90% efficiency—far surpassing the 30–40% range of traditional power generation.

2. Lower Operating Costs
Higher efficiency means lower fuel use and significant savings over time. Facilities can cut utility bills, generate energy, and reduce reliance on external energy sources.

3. Environmental Impact
Cogeneration reduces CO₂ and other emissions by using fuel more efficiently and avoiding separate heating systems.

4. Reliable Power Supply
On-site distributed generation also improves energy resilience and can help facilities operate independently from the grid, especially during outages.

Applications of Cogeneration

• Industrial Facilities: Industries with high thermal demands, such as chemical manufacturing, food processing, and pulp and paper, rely on cogeneration to supply both electricity and process heat. The ability to recover and reuse waste heat supports operations like drying, sterilization, and steam-based production processes, helping to cut energy costs and improve operational efficiency.
• Hospitals and Universities: These institutions require a reliable and uninterrupted supply of both electricity and heat for critical operations, including lighting, HVAC, sterilization, and hot water. Cogeneration systems are particularly well-suited to meet these needs efficiently while also supporting sustainability goals and reducing reliance on the utility grid.
• Airports and Commercial Buildings: Facilities with large and fluctuating energy demands, such as airports, hotels, and shopping centers, benefit from cogeneration by reducing peak electricity costs and improving overall energy efficiency. The heat recovered can be used for climate control, hot water, and backup power during outages, providing both economic and resilience advantages.
• District Heating: In urban and campus settings, cogeneration systems can supply centralized heating by distributing steam or hot water through a network of insulated pipes. This model reduces the need for individual boilers in each building, lowering emissions and improving energy management across large building clusters or city blocks.

Comparison with Conventional Power Plants

Traditional power plants convert fuel into electricity, then dump the waste heat—losing more than half the full energy produced. Cogeneration flips this model by capturing that waste heat and using it productively.

System Type	Energy Efficiency	Heat Reuse	Emissions
Conventional Power Plant	30–40%	None	Higher
Cogeneration Plant	70–90%	Yes	Lower

The result is not only greater efficiency but also fewer emissions, lower costs, primary energy savings and more sustainable energy use.

Challenges and Disadvantages

Despite its advantages, cogeneration faces some hurdles:

• High Upfront Costs: Installation and equipment can be expensive, though often offset by long-term savings.
• Maintenance Complexity: Systems require regular servicing and technical expertise.
• Regulatory Barriers: Permitting and compliance can vary by region and may delay projects.

These challenges can be mitigated with proper planning, support from experienced partners, and favorable energy policies.

Where Our Water Treatment Comes Into Play

While EAI doesn’t supply cogeneration (cogen) equipment directly, our role has been essential in keeping these systems running efficiently especially when steam is part of the equation. Our specialized water treatment services directly support the operational efficiency and longevity of critical cogeneration components, including boilers, turbines, and HRSGs, ensuring maximum energy recovery and system reliability. In systems using steam turbines or HRSGs (Heat Recovery Steam Generators), high-purity boiler feedwater is critical because even trace levels of dissolved solids, oxygen, or hardness minerals can lead to scaling, corrosion, and fouling, all of which reduce thermal efficiency and drive up costs.

EAI designs and manages custom water treatment programs for cogeneration plants that help protect critical assets, reduce downtime, and maximize energy output. Our solutions include:

• Boiler water treatment programs to minimize scale and corrosion
• Condensate polishing to preserve water quality throughout the steam cycle
• Pretreatment systems for makeup water, combining chemical and mechanical approaches such as reverse osmosis systems
• Monitoring and testing services to maintain tight water chemistry control

With over 35 years of experience supporting facilities across the western U.S., we understand the demands placed on cogen systems in hospitals, campuses, industrial plants, and commercial energy centers. Our job is to make sure water-side systems are clean, efficient, and built to support your energy-side goals — safely, sustainably, and with performance in mind.

Get Reliable Performance from Your Cogen Plant

If you’re managing a facility that relies on steam-based power or cogeneration systems, contact EAI today. Our team can assess your boiler water quality, provide precision treatment solutions, and help you ensure dependable power and heat output every day of the year.

Frequently Asked Questions