The advantages of high-efficiency cogeneration systems
High-efficiency cogeneration systems enable the simultaneous generation of electricity and useful heat, with lower fuel consumption than would be required to generate them independently, resulting in benefits in terms of both the cost and environmental protection
Published on 9 March 2020
One of the basic principles of physics is that energy is neither created nor destroyed: it is simply transformed. What we can do is we can try to use these transformations in ways that are more efficient. When you generate electricity by burning fuel, a part of the energy that derives from the combustion process is transformed into electricity, whilst another part is converted into heat that is generally lost without being utilised.
Cogeneration systems – i.e. the combined generation of electricity and heat – recover this thermal energy and use it for heating purposes. Physics also tells us that it's impossible to utilise all the residual heat: the quantity increases or decreases depending on the amount of energy the system recovers.
The definition of high-efficiency is somewhat arbitrary, and can vary from country to country. For example in the EU, Directive 2004/8/EC of 11 February 2004 states that a cogeneration system is defined as high-efficiency if the energy saving obtained through the combined generation of heat and electricity, compared to their separate generation, is greater than 10% for systems over 1MW, whilst for smaller systems there simply needs to be any level of energy saving.
The primary advantage of a high-efficiency cogeneration system is the amount of money that's saved on the fuel (be that natural gas, diesel, biomass, biogas or biodiesel), which would otherwise be needed just to meet the heating requirements, given that the heat generated is essentially free because it's recovered from the production of electricity. This can result in savings of up to 30% on energy bills. In addition, reduced fuel consumption also means less greenhouse gas being emitted into the atmosphere, so there are also important benefits for the environment.
Furthermore, if the installation is carried out by a specialised company, the efficiency of the system can really be maximised. The market also offers financially advantageous packages that include the entire lifecycle of the system, from its design to its set up, right through to the supply of fuel and often also the maintenance of the system.
Further advantages are offered by an even more advanced version of the technology – trigeneration systems, which are particularly suitable for large facilities such as hotels, factories and shopping centres. This technology, in addition to generating electricity and thermal energy for heating purposes, harnesses part of the residual heat to power the cooling system.