CHP vs traditional generators: Efficiency and payback

CHP recovers engine-driven generator waste heat to improve overall efficiency and reduce payback compared to standard power-only generators. CHP better utilises fuel consumption, which would otherwise be lost to the atmosphere, by more than doubling the efficiency of generators (approximately 30% to in excess of 80%) by capturing thermal energy and turning a generator into a combined heat and power plant.

 

CHP compared to conventional generators

The efficiency of traditional generators is usually lower; only approximately 30% of the energy from the fuel is converted into electricity, with the rest wasted as heat in the exhaust system and the engine cooling system. Around 50% of this fuel input is recovered as useful heat in CHP systems and the recaptured heat may be reused for district heating, hot water, space heating, process heating, further power generation, or absorption chiller cooling, making a single gen-set a multi-output energy source.

 

The sources of CHP efficiency

The largest single system is typically exhaust gas heat recovery, which captures approximately 55% of the engine’s waste heat and transfers it to a water system for practical use. The engine jacket water (approximately 24%), the intercooled charge air (approximately 12%), and the lubrication system (approximately 9%) can further be used to recover additional energy through heat exchangers specific to each flow. When these components are combined properly, total CHP efficiencies of more than 80% can be achieved, compared to the 30% electrical efficiency of a conventional generator.

 

Payback potential of CHP vs generators

Since the recovered heat requires no additional fuel, the CHP can easily be used to provide a low-cost heat source that can reduce site heating and process energy bills by a large margin throughout the life of the installation. In continuously operated or heat demand applications, like industrial plants, district heating networks, or large commercial sites, the value of this free heat reduces payback times and improves payback on investment. Vital shell and tube heat exchangers, specifically designed to operate in engine-driven gen-sets, help ensure long life and reliable operation, helping operators save over time.

 

CHP is especially useful in the following applications

Gen-sets equipped with CHP are especially appealing in cases where both electricity and hot water or space heating are required simultaneously, such as residential and commercial developments, off-grid facilities and most industrial processes. Other, more specialised applications of CHP heat recovery include research stations in inhospitable climates, grain drying plants, and recreational amenities, which have used it to reduce fuel consumption and enhance energy security. To upgrade an existing gen-set to a high-efficiency combined heat and power solution while leaving the engine alone, exhaust, jacket water, charge air, and oil coolers may be added to an existing power-only generator.

 

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CHP vs traditional generators: Efficiency and payback

CHP recovers engine-driven generator waste heat to improve overall efficiency and reduce payback compared to standard power-only generators. CHP better utilises fuel consumption, which would otherwise be lost to the atmosphere, by more than doubling the efficiency of generators (approximately 30% to in excess of 80%) by capturing thermal energy and turning a generator into a combined heat and power plant.

 

CHP compared to conventional generators

The efficiency of traditional generators is usually lower; only approximately 30% of the energy from the fuel is converted into electricity, with the rest wasted as heat in the exhaust system and the engine cooling system. Around 50% of this fuel input is recovered as useful heat in CHP systems and the recaptured heat may be reused for district heating, hot water, space heating, process heating, further power generation, or absorption chiller cooling, making a single gen-set a multi-output energy source.

 

The sources of CHP efficiency

The largest single system is typically exhaust gas heat recovery, which captures approximately 55% of the engine’s waste heat and transfers it to a water system for practical use. The engine jacket water (approximately 24%), the intercooled charge air (approximately 12%), and the lubrication system (approximately 9%) can further be used to recover additional energy through heat exchangers specific to each flow. When these components are combined properly, total CHP efficiencies of more than 80% can be achieved, compared to the 30% electrical efficiency of a conventional generator.

 

Payback potential of CHP vs generators

Since the recovered heat requires no additional fuel, the CHP can easily be used to provide a low-cost heat source that can reduce site heating and process energy bills by a large margin throughout the life of the installation. In continuously operated or heat demand applications, like industrial plants, district heating networks, or large commercial sites, the value of this free heat reduces payback times and improves payback on investment. Vital shell and tube heat exchangers, specifically designed to operate in engine-driven gen-sets, help ensure long life and reliable operation, helping operators save over time.

 

CHP is especially useful in the following applications

Gen-sets equipped with CHP are especially appealing in cases where both electricity and hot water or space heating are required simultaneously, such as residential and commercial developments, off-grid facilities and most industrial processes. Other, more specialised applications of CHP heat recovery include research stations in inhospitable climates, grain drying plants, and recreational amenities, which have used it to reduce fuel consumption and enhance energy security. To upgrade an existing gen-set to a high-efficiency combined heat and power solution while leaving the engine alone, exhaust, jacket water, charge air, and oil coolers may be added to an existing power-only generator.

 

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