Cogeneration and trigeneration – efficient ways to save energy

The production of electricity is a process that also involves the generation of heat. To harness this potential, cogeneration technology has been introduced. An even more advanced process is called trigeneration. The integration of electricity, heat, and cooling generation processes is a manifestation of the pursuit of the highest levels of energy efficiency.

The challenges of the modern world are closely linked to the energy sector. Global energy demand is increasing, while trends aimed at reducing the negative environmental impact of energy production are driving the search for new solutions that ensure greater efficiency. Energy transformation entails not only expanding the use of renewable energy sources, but also maximising the efficiency of managing all sources, such as natural gas and biogas. Cogeneration and trigeneration play a vital role in this context.

What is cogeneration?

Cogeneration is a technological process in which electricity and heat are generated simultaneously. This means that in this process, two “products” – electricity and thermal energy – are produced from the same source. Such a solution is more advantageous than producing electricity and heat separately through two distinct processes.

How do cogeneration systems function? In the process of electricity production, which takes place in a cogenerator (e.g., a gas engine), heat is generated during the combustion of gas used to drive the generator’s shaft. In such a system, this heat can be utilised, for example, for building or water heating. Consequently, the thermal energy that would otherwise be wasted in conventional solutions is instead used to optimise costs. The primary energy source (in this case, gas) is utilised more efficiently than if electricity and heat were produced separately.

What is trigeneration?

Current trends in energy efficiency promote another advanced technology known as trigeneration. In simple terms, trigeneration can be described as extended cogeneration. In this process, in addition to electricity, heat and cooling are also produced. This is a solution that combines three production processes into one.

How does such a system work? Trigeneration employs cogeneration systems for the simultaneous production of heat and electricity. Additionally, when combined with a chiller, it enables the generation of cooling using thermal energy. Cooling technologies that utilise heat to produce cooling are known as absorption cooling technologies. They function by leveraging the absorption and desorption of the refrigerant from a solution. Although absorption chillers have lower efficiency compared to compression-based cooling technologies, trigeneration systems offer higher overall efficiency when the heat used for cooling would otherwise be considered waste in conventional energy production.

An example of such a solution is trigeneration in buildings. The use of a source that allows for the production of electricity, heat, and cooling enables, for instance, the use of heat for heating when needed, as well as the conversion of thermal energy into cooling, which can be used in air conditioning systems. Such solutions can be applied not only in residential buildings but also in offices or production facilities.

Benefits of cogeneration and trigeneration

Cogeneration and trigeneration systems, by combining two or three production processes, respectively, offer the following benefits:

• increased energy efficiency
• reduced electricity consumption
• lower carbon dioxide emissions

The key benefit lies in energy efficiency. Since a single fuel source can simultaneously produce electricity, heat, and cooling, this approach is significantly more efficient than producing electricity alone. Additionally, reduced electricity consumption is possible because, for example, the heat generated in this process can be used for building heating or air conditioning, thereby reducing the energy consumption otherwise required for separate heating or cooling processes. From a local perspective, this increases energy reliability and independence while avoiding excessive grid expansion, such as additional utility poles or new power lines.

The aforementioned benefits related to increased energy efficiency also contribute to reduced greenhouse gas emissions, including carbon dioxide. As such, cogeneration and trigeneration support sustainable development goals, making the production of electricity, heat, and cooling more environmentally friendly.