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A look at used cogeneration plants and how they can maximise sustainability

Used cogeneration plants offer a cost-effective solution for sustainable energy. (Image source: Surplex)

Düsseldorf-based Surplex GmbH is an industrial auction house specialising in trading in second-hand machinery. They explain how cogeneration plants can be made more efficient. Read on: 

Cogeneration plants are suited for a variety of environments, including commercial and residential buildings, as they concurrently produce heat and electricity. Their use of renewable energy sources and highly efficient combined heat and power (CHP) cycles contribute to their sustainability.

As a result, both the purchase of cogeneration facilities and the addition of produced electricity to the grid are supported by public funds. Buying second hand plants can encourage the sustainable usage of second-hand plants and expedite return on investment (ROI).

They are versatile, modular energy production systems that can generate heat as well as electricity. They can be used in a range of settings, including small and medium-sized businesses and residential buildings. 

They achieve excellent energy efficiency by minimising heat transportation losses with their close-to-consumer design.

Sustainability through cogeneration

Nearly all of the energy input can be used thanks to cogeneration facilities' combined heat and power (CHP) technology. Heat produced during the generation of electricity is specifically utilised for hot water preparation or heating.

A combustion engine is often the central component of a CHP. A generator transforms its mechanical energy into electrical power. 

Furthermore, the waste heat from combustion in the exhaust gas is used in CHPs in a heat exchanger to heat water, in contrast to other plants. 

As an alternative, process heat can be generated and utilised for thermal oil, steam, or hot air, among other things. Absorption heat pumps, which use the waste heat for cooling, can also be used to use waste heat for air conditioning.

Based on calorific value, cogeneration plants are capable of achieving an overall efficiency of up to 90%.

Sustainability achieved using renewable energy

Various fuels can be used for CHP operation, based on the installed engine type. Both renewable energy sources and fossil fuels like natural gas and heating oil are included in the spectrum. 

The latter comprises biodiesel, which is mostly used in diesel engines, and vegetable oils, particularly palm and rapeseed oil. Bio-, sewage-, and landfill gas provide greener substitutes for petrol engines. Steam power plants and engines with specific designs can be powered by renewable resources like wood chips and pellets. 

It is also possible to run CHPs with Stirling or diesel engines using light heating oil.

Cost efficiency of used plants

In addition to direct investment and running costs like depreciation, fuel prices, and maintenance charges, a thorough examination of the cost-effectiveness of cogeneration facilities also takes into account the profits from the sale of heat and electricity as well as the associated cost reductions. Programmes for public subsidies offer more incentives for investment.

An adequate number of working hours in the high load range per year is essential to the cost-effectiveness of cogeneration plants because it greatly expands the quantity of power that can be sent into the public grid above and beyond self-consumption. 

The quantity of power fed in is frequently compensated at higher, subsidised prices for cogeneration facilities that run on renewable energy sources. 

Larger plants may also be able to sell the heat they produce to the public network at a profit.

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