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What is cogeneration? Efficient energy production for buildings and district heating networks

What is cogeneration? Efficient energy production for buildings and district heating networks

With this modern solution, which can be used to generate electricity and heat at the same time, energy is generated in a highly efficient and environmentally friendly manner, thereby reducing the costs of building heating and electricity.

  • Blog
  • End customer / Investor
There is huge environmental awareness in society, which influences the attitude of companies to energy consumption. In addition, rising energy costs are forcing companies to focus much more on their cost structure. These two factors mean that alternative energies such as sun, wind, water and biomass are becoming increasingly popular.

As a result, energy generation by means of combined heat and power plants is rapidly gaining in importance, as this form of energy generation brings both economic and ecological advantages.

How does cogeneration work?

With combined heat and power generation, electricity and heat are generated simultaneously with just one device. For this reason, so-called combined heat and power plants (CHP) are used. The main element of a combined heat and power plant is a highly efficient gas engine that drives a generator and thus generates electricity. The waste heat from the engine and the exhaust gases are recovered via heat exchangers and used for heating. The heat can be distributed to different customers via a network and used for heating or hot water.

A heating system with CHP can supply part of the required thermal energy of a building and at the same time generate electricity. By generating electricity and heat together, energy losses are minimized and the primary energy of the fuel is largely utilized. Therefore, efficiencies of almost 90% are possible.
Functional principle of CHP.

Advantages of cogeneration – energy efficiency and cost-effectiveness

The combined generation of heat and electricity allows a better use of primary energy than separate generation while reducing fuel consumption. The more efficient use of fuel reduces carbon dioxide emissions. The integration of a CHP plant into an existing heating system also reduces electrical operating costs. Less electricity has to be purchased, grid fees and other charges are waived and the price risk decreases. In addition, a CHP plant can be used as an emergency power generator, which significantly increases reliability.

PowerBloc CHP units

The reliability and low energy costs of combined generation make combined heat and power units increasingly popular. In addition, pollutant emissions are significantly lower than with decentralised heat generation. In the future, such units will therefore be among the most important technologies for the economic generation of electricity and heat for small and medium-sized facilities, but also for local electricity and heat suppliers.
PowerBloc combined heat and power plants consist of a combustion engine, a generator, a heat exchanger and a remote control system. They generate electricity and heat close to the consumer. This is the only way to achieve very high primary energy efficiencies of up to 90%. In comparison, conventional large-scale power plants only achieve primary energy efficiencies of between 30 and 50%. The rest is lost as waste heat. PowerBloc CHP units use the waste heat, for example, for hot water preparation or as process heat for industrial plants. The generated electrical energy is consumed directly in the building or can often be fed into the public grid against payment.

Thanks to their high efficiency, PowerBloc CHP units save energy and significantly reduce carbon dioxide emissions through resource-saving use. For example, a CHP unit powered by natural gas emits almost 60% less carbon dioxide. Hoval CHP units can also be operated with biogas.

PowerBloc CHP units for operation with natural gas or biogas vary in their electrical power range between 43 and 532 kW and in thermal outputs between 65 and 687 kW. Depending on requirements, they can be used for multi-family houses as well as for entire residential complexes or industrial companies.


Due to the modular configuration of cogeneration systems, the availability of the plants, the extensive application possibilities, the simple fuel supply and the relatively high efficiency, gas-fired CHP units are the most efficient plants for converting the primary energy contained in the fuels into electricity and heat. They enable savings of up to 30% of primary energy compared to separate generation of heat and electricity.

CHP units are often used, especially in industry, for individual devices with relatively low power requirements. There, they replace the heat generated in the boiler room or obtained from the grid and the electricity purchased. CHP units can therefore contribute a significant proportion of steam, hot water and hot air in the processing industry for technological purposes, heating and cooling and cover a large part of the electricity demand.

The economic viability of a CHP unit depends on the correct adaptation to the building. In order to use a maximum of the energy generated, the heat output of the CHP units must be correctly determined in relation to the heat demand of the building.

Hoval analyses various scenarios and creates detailed profitability calculations based on current framework conditions. For potential investors, this is a particularly important aspect. When cogeneration plants are well planned, they reduce energy costs and contribute to lower emissions, especially carbon dioxide.