Question 6 - CHP (CO-GENERATION) Flashcards
Q6A) What is CHP and what are the different Types
A heat or thermal engine can be defined as a system that performs the conversion of heat or thermal energy into mechanical work (and consequently electrical energy)
This is achieved by bringing a working fluid from a higher state of temperature to a lower state of temperature with proper thermodynamic transformations
As stated by the Carnot theorem, not all the input heat can be converted to mechanical work but a part of it is discharged to a cold “sink”
If the temperature of the cold sink is still suitable for industrial or civil applications, it is possible to exploit its thermal energy content
This allows for double explitation of the primary energy, allowing for one system to produce both electricity and useful thermal energy
Different types
GAS Turbine CHP: This system uses a gas turbine to generate electricity and captures the waste heat for heating or other purposes. Gas turbines are known for their high efficiency and quick start-up capabilities.
VAPOUR / STEAM Turbine CHP: In this setup, a steam turbine is used to generate electricity, and the waste heat from the turbine is recovered for various heating applications. This type is common in industrial processes that require both electricity and steam.
RECIPROCATING: Engine CHP: Reciprocating engines, such as internal combustion engines, are used to generate electricity, and the waste heat is harnessed for heating. These systems are versatile and can run on various fuels like natural gas, diesel, or biogas.
Q6B) What challenges does CHP face with decarbonisation ? i.e using natural gas/ future alternative
Most CHP rely on fossil fuels to operate, decarbonisation will transition and phase out fossil fuels.
Fuel Dependence
Technology and Infrastructure
Energy storage
Grid Integration
This is a big issue on the existing CHP infrastructure
-Adaptation and retrofitting of systems to accommodate new fuels or technologies may be required, and this transition can involve significant costs and technical considerations.
-Decarbonising involves the integration of renewable energy sources like solar and wind. However, these sources are intermittent and may not align with the demand for electricity and heat. CHP systems may required to need to adapt to the variable nature of renewable energy to ensure reliable power generation. E.g. introducing energy storage to the design of the system.
Q6C) CHP Plant Calculation
500 kW of electricity
500kW = 40% electricity produced
Gas Price
Electricity Price
Availability = 90% of the time
Maintenance = 2p/per kWh
Calculate the Annual Savings
Calculate the Operating Costs
Calculate the payback period
Savings Evaluation
40/40/20 = 40-Engine/Electricity 40-Waste Heat 20-Losses
-Establish Operating time in hr
-Annual Energy Input Calculation
Electricity Output (kWelectricity x hrs run) = 500kW x hr
Boiler fuel displaced (kWheat x hrs/0.75) = (500 x hr)/75
Gas Input (kW x hrs run) = 1250 x hr
-Savings
Displaced electricity savings = Elect output x elect price
Displaced boiler fuel savings = Boiler Fuel displaced x gas price
Total Savings = combine each
-Operating Costs
CHP Fuel = Gas Input x gas price
Maintenance Costs = elect output x 2p/kWh
Total Costs = Combine
-Simple Payback
Net return per year = Savings - Operating Costs
Capital cost
Payback = Combine
