How to Choose CHP Technology for a Specific Investment

Choosing the right Combined Heat and Power (CHP) technology is crucial for the efficiency and profitability of an investment. Two main solutions dominate the market: gas gensets (gas engines), such as those offered by Caterpillar, and gas turbines, like Solar Turbines. Both solutions are proven and reliable, but they differ fundamentally in design, operation, and optimal application.

Differences in Operation and Construction

Gas Gensets (Gas Engines – e.g., Caterpillar): These operate on the principle of an internal combustion engine. Fuel burns in cylinders, causing pistons to move. The design is complex, with many moving parts.

Gas Turbines (e.g., Solar Turbines): These operate on the principle of continuous flow of compressed air, which mixes with fuel and combusts. Hot exhaust gases drive the turbine. They are characterized by simpler construction and fewer moving parts.

Key Factors for Choosing CHP Technology

The choice between a gas genset and a gas turbine depends on the specific conditions and requirements of a given investment. Neither technology is universally “better”—each has its optimal application niches.

Electrical and Heat Demand

Gas Gensets: Typically more suitable for smaller installations, with electrical power ranging from 100 kW to approximately 5-10 MW. They offer high electrical efficiency (up to 45%) and overall CHP efficiency (up to 85%). They are a good choice for facilities with more variable and cyclical electrical and heat loads.

Gas Turbines: Ideally suited for larger installations, from approximately 5 MW to 100 MW and more. Their biggest advantage in CHP applications is a high heat-to-power ratio and the production of a large amount of high-temperature exhaust gases (around 490°C, compared to about 400°C for gas engines). This makes them excellent for producing high-pressure steam for industrial processes, achieving overall system efficiency of up to 90% or more. They are preferred for high and relatively constant electrical loads.

Capital Expenditure (CAPEX) and Operational Expenditure (OPEX)

Gas Gensets (e.g., Caterpillar): Generally have lower initial costs per kW in smaller projects. They are economical to install and operate.

Gas Turbines (e.g., Solar Turbines): Although the unit cost may be higher, their long-term operating costs and high availability can offset the initial investment at larger scales.

Operational Flexibility and Tolerance to Conditions

Gas Gensets: Perform well in intermittent operation and with partial loads, as their electrical efficiency does not decrease as significantly. They are more sensitive to fuel quality.

Gas Turbines: Characterized by fast start-up and high reliability, often achieving 98% availability. They are less sensitive to fuel quality and can be powered by various types of fuels.

Emissions and Environmental Requirements

Both technologies are constantly improving their emission parameters. Gas turbines, thanks to technologies like Solar Turbines’ SoLoNOx, are known for low emissions. They do not require additional DeNOx systems like gas gensets.

Space and Dimensions

Gas Turbines: Often offer higher power density (more power in a smaller footprint), which is beneficial when space is limited.

Gas Engines: While effective, they take up significantly more space and are heavier than gas turbines of comparable power. Thus, a gas engine installation with the same power as a gas turbine requires approximately four times more space and is three times heavier.

Summary and Recommendations

There is no single “best” CHP technology. The decision should be made after a thorough analysis of many factors specific to a given investment:

• Load Profile Matching: Is the demand for electrical and heat energy constant or variable? Is high-pressure steam needed?
• Project Scale: What is the required electrical and thermal power?
• Investment Budget and Expected Return: Long-term CAPEX and OPEX analysis.
• Location Conditions: Available space, emission requirements, environmental conditions.

In many cases, especially in larger, complex projects, the optimal solution may even be a combination of both technologies in a hybrid system to maximize their advantages and meet diverse needs.

Before making a decision, a detailed technical and economic analysis is recommended, often with the involvement of experienced energy consultants. Therefore, we encourage you to listen to our series of thematic videos on using two complementary solutions within cogeneration. We also invite you to directly contact our energy solutions specialists, who will help analyze your needs and choose the most economically optimal solution.

Author: Eneria Expert Team

Jakub Bigoszewski and Adam Kiciński

email: marketing@eneria.pl