There cogeneration is the combined generation of thermal and mechanical and/or electrical energy in a system using a single energy source, which often produces significant reductions in the rate of energy input compared to separate production.
Cogeneration is a highly efficient process By capturing and using heat that would otherwise be wasted, cogeneration reduces the overall fuel consumed in the process: it is one of the cleanest and most economical options available for energy production.
In other words, it is a system that simultaneously produces heat and electricity in a single plant, powered by a single primary energy source, thus ensuring better energy yield than that which could be obtained from two separate production sources.
The Most used cogeneration technologies involve the combustion of fuels such as natural gas, LPG, diesel, biogas, biomethane, vegetable oil or biomass.
How does cogeneration differ from “conventional” energy sources?
Large utility companies typically generate electricity in a centralized location and then transmit it over miles of wires (often called a “grid”).
The transmission process and waste heat loss in the centralized power plant result in high energy losses.
In contrast, a cogeneration system is typically located on-site and the system is designed to capture waste heat from electricity generation and utilize it (producing both electricity and heat through a single process).
How do cogeneration systems work?
The conventional power plants generate electricity with average electrical efficiencies between 50 and 55%.
Instead, a cogeneration plant captures and uses waste heat, for example, by piping hot water and supplying it to a consumer (be it a factory or a group of buildings).
This is one of the main advantages of cogeneration, as it leads to greater energy efficiency: up to 70-90% of the input energy is used, with only 10-30% of the input energy wasted.
What are the advantages of cogeneration?
A cogeneration system can offer significant benefits to commercial and industrial customers because it produces heat and electricity at the same time.
Using the same fuel to generate both heat and electricity therefore improves energy efficiency, achieves environmental benefits and ensures savings.
The European Union has incorporated cogeneration into its energy policy aimed at reducing greenhouse gases.
Cogeneration has represented the 12% of European electricity production and 14% for heat in 2019, according to Eurostat data, and COGEN Europe estimates that the number could increase to 20% for electricity and 25% for heat by 2030.
Cogeneration systems can:
- Improve overall power generation efficiency by combining heat and power generation in a single process
- Reduce energy costs
- Reduce emissions
- Reduce the risk of power outages due to network problems
- Take advantage of financial incentives related to energy efficiency projects
- Use renewable energy sources such as biomass
- Promote energy self-sufficiency and reduce energy imports
What are the different types of cogeneration?
There are different types of cogeneration, including:
- Gas turbine cycles: these systems use the waste heat present in the exhaust gases of gas turbines to generate thermal energy in the form of steam, hot water, thermal oil. Typically they use natural gas as a fuel source;
- Gas engine cycles: in this cogeneration process a reciprocating gas engine is used. These types of cogeneration plants are generally built as completely monobloc units that can be installed inside a dedicated plant room or in a dedicated outdoor space and are easy to connect to the site's electrical and heating or cooling infrastructure;
- Biofuel cycles: these systems are very similar to the previous ones, in that they use a reciprocating engine or turbine to use biofuel as a fuel source. The use of biofuels reduces the consumption of fossil fuels and leads to a reduction in carbon emissions. These systems are also usually supplied in assembled units that are easy to connect to the heating or cooling infrastructure of the site;
- Combined cycles: these systems add the use of a steam turbine for a further increase in cycle efficiency.
What is meant by high-efficiency cogeneration?
The concept of “high-efficiency cogeneration” was defined by the European Union with Directive 2012/27/EU, which replaced the previous Directive 2004/8 EC. According to the latest directive, “high-efficiency cogeneration” must meet the following criteria:
- Cogeneration production from cogeneration units guarantees a primary energy saving of at least 10% compared to the references for the separate production of heat and electricity
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