Cogeneration has emerged in recent years as a high-performance energy solution for simultaneously producing heat and electricity from a single energy source. By utilizing heat that is usually wasted, it significantly improves efficiency, reduces operating costs, and limits CO₂ emissions.
But is cogeneration suitable for all buildings and all businesses? What are its real benefits, its constraints and its conditions for profitability? And above all, how does it fit into an overall energy efficiency strategy ?
In this article, Powesco deciphers the operation of cogeneration, its use cases, its economic and environmental advantages, while showing how to go further through a comprehensive and controlled approach to energy performance.
What is cogeneration?
Cogeneration is an efficient energy system that allows, from a single primary energy source , the simultaneous production of thermal energy and mechanical energy , which is then transformed into electricity.
A cogeneration plant typically consists of:
- of a cogeneration module (engine + generator),
- by a heating system (often a condensing gas boiler),
- of an electrical connection of the cogeneration module to the grid.
Both the thermal and electrical outputs of a cogeneration unit can be utilized :
- Heat, used for space heating, industrial processes and/or domestic hot water (DHW) production,
- Electricity, consumed directly on site (self-consumption) or injected into the public electricity network.
In practice, the internal combustion engine heats the water in the primary circuit. Excess heat from the engine (primarily from the radiator and exhaust gases) is recovered via a heat exchanger. This energy then supplies the building's heating system and/or domestic hot water.
In parallel, the generator coupled to the motor produces electricity, which will be self-consumed in the building or sold back according to the chosen operating scheme.
The cogeneration module is installed in a conventional boiler room and is most often combined with a condensing gas boiler in a so-called base/supplementary logic , guaranteeing continuity of service and energy performance .
For which types of businesses is cogeneration suitable?
Cogeneration is a particularly suitable solution for cultural, sports and leisure facilities. These buildings have significant and relatively constant heating needs throughout the year: heating, but also domestic hot water production for multi-sports halls, swimming pools, water parks or other community facilities.
Cogeneration is also particularly relevant for healthcare facilities. These facilities require:
- a heating temperature above 19°C,
- high service continuity,
- a very strict level of comfort during the winter period.
These constraints fully justify the use of micro or mini cogeneration solutions , operating in a constant and secure manner .
Read also: Why is energy-efficient renovation in hospitals a priority?
Finally, cogeneration is also relevant to the following sectors: Offices, Hospitality / catering.
Why get involved in cogeneration?
Heat recovery
Cogeneration is based on a simple principle: to produce and use electricity and heat simultaneously from the same primary energy source and within a single installation.
When electricity is generated using a heat engine or turbine, a large amount of heat is produced. In conventional systems, most of this heat is lost. Cogeneration allows this thermal energy to be utilized, achieving an overall energy efficiency of up to 85%.
Reduce losses
A conventional electricity production installation has an efficiency of around 35%, with the remainder (nearly 65%) being dissipated as unused heat.
In a cogeneration system:
- 30 to 35% of the primary energy is converted into electricity via an alternator.
- 65 % is found in the form of heat,
- of which 50 to 55% is recovered to heat a water circuit using a heat exchanger.
Cogeneration thus optimizes the use of the initial fuel. However, to be fully efficient, it must be located as close as possible to the points of consumption, as heat is difficult to transport over long distances.
Self-consumption
The heat produced is used directly on-site. It can power:
- residential or commercial buildings,
- collective buildings,
- district heating networks,
- agricultural greenhouses,
- industrial sites (chemicals, paper, automotive, food processing, etc.).
The electricity produced can also be self-consumed, further reducing dependence on the grid.
Additional income
Electricity not self-consumed can be injected into the public grid, generating additional revenue for the operator, according to the contractual and regulatory mechanisms in force.
Cost reduction
Thanks to the simultaneous production of heat and electricity, cogeneration consumes 15 to 30% less primary energy than the best solutions producing these two energies separately (condensing gas boiler + combined cycle gas power plant).
In addition to this:
- improved overall energy performance,
- the reduction of losses on electrical networks, which can reach up to 15% in low voltage and 6.5% in high voltage, thanks to the proximity of consumption points.
Low carbon strategy
While fulfilling the same function as a boiler for heating needs, cogeneration reduces primary fossil fuel consumption and CO₂ emissions . It therefore fits perfectly into a low-carbon and energy transition trajectory
Support the network
In a context of massive development of intermittent renewable energies, cogeneration constitutes a valuable tool for supporting the electricity grid.
As an example, the 1,800 MW of industrial cogeneration covered by the capacity contract between 2014 and 2016 showed an availability of more than 95% during peak consumption, contributing significantly to security of supply.
Going beyond cogeneration with Powesco
While cogeneration is an effective solution, it is only one lever among many for sustainably improving a site's energy performance. At Powesco , we don't directly install cogeneration systems, but we support our clients in a comprehensive energy efficiency approach , which is often more cost-effective and better suited to the actual uses of their buildings.
Insulation
Before producing better, it is essential to consume less. Improving thermal insulation drastically reduces heating needs and optimizes any existing or future energy solution.
Powesco offers relamping solutions , which involve replacing old light sources with high-performance LED luminaires . This modernization significantly reduces electricity consumption , improves lighting quality, and lowers maintenance costs thanks to the extended lifespan of the equipment. It's a quick and easy way to generate immediate energy savings while improving visual comfort on-site.
HVAC (Heating, Ventilation, Air Conditioning)
Outdated and inefficient heating and domestic hot water systems represent a major source of energy waste. Upgrading HVAC equipment is often a priority before considering complex solutions like cogeneration.
Read also: Building management systems (BMS) a major lever for the energy performance of buildings
Charging stations
In line with a global energy transition strategy, Powesco installs charging stations for electric vehicles adapted to the needs of businesses, communities and commercial sites.
The deployment of charging stations allows for:
- to support the electrification of professional fleets,
- to offer an additional service to employees, users or visitors,
- to promote the site and its environmental commitment,
- to anticipate regulatory changes (greening of car fleets) and new mobility uses.
Energy management
Finally, control is key. Thanks to the SEME by Nexstep platform , Powesco enables intelligent energy management , based on data, consumption monitoring and continuous performance optimization.
Energy purchase
Beyond technical solutions, Powesco also supports its clients in energy procurement, a key lever for sustainably controlling operating costs. Thanks to its expertise in the electricity and gas markets, Powesco helps businesses and local authorities secure supply contracts tailored to their needs, consumption patterns, and budgetary objectives.
This offer allows you to:
- to optimize the pricing conditions for purchasing electricity and gas,
- to reduce exposure to the volatility of energy markets,
- to align supply choices with a low-carbon strategy,
- to effectively complement the energy efficiency and conservation actions implemented on site.
Cogeneration is a powerful solution, but it is by integrating it into a comprehensive energy strategy that companies truly maximize their economic and environmental gains.
FAQ
What are the different cogeneration sectors?
There are several pathways:
- Biomass cogeneration : uses organic waste or biomass material to produce energy.
- Cogeneration by gas turbine : transformation of fuel energy into electricity and heat.
- Cogeneration by steam turbine : combined production of heat and high-pressure steam.
- Stirling engine cogeneration or fuel cell : innovative solutions for specific applications.
How is biomass used in cogeneration?
Biomass or biogas from methanization or the organic waste sorting process is burned or converted to produce steam or residual heat. This energy is then used for heating , steam production , or combined heat and power generation , reducing environmental impact and CO₂ emissions.
Sources:
https://cegibat.grdf.fr/produit/mini-et-micro-cogeneration
https://www.connaissancedesenergies.org/questions-et-reponses-energies/quest-ce-que-la-cogeneration
https://atee.fr/efficacite-energetique/club-cogeneration/la-cogeneration
