CHP Plant
What does CHP mean? CHP is an acronym which stands for "combined heat and power". This type of technology has gained a significant amount of popularity in recent times due to the need to leverage more efficient methods of energy production. The number of CHP plants is therefore on the rise.
Sometimes referred to as "cogen power plants", it is rather wise to take a closer look at the fundamentals associated with this type of energy production. How does a typical CHP plant function? What are the core components of a CHP plant? How do CHP plants ensure higher levels of efficiency when compared to standard fossil fuels? What is the economic cost of running a CHP plant?
These and similar questions will be outlined below in order to provide a clearer picture of what the future may have in store.
What is the Main Purpose of a CHP Plant?
A standard CHP unit functions with a seemingly simple principle in mind. It is designed to use heat to generate a reliable source of power. At first glance, this may appear similar to traditional methodologies such as burning fossil fuels in order to turn a steam-driven turbine. However, a CHP plant will utilise any excess heat that is produced; dramatically increasing its overall rate of efficiency. CHP plants are therefore referred to as "reciprocal engines" on occasion.[1]
How Does a Basic CHP Plant Work?
Although some of the technical nuances associated with a combined heat and power plant are somewhat confounding to the uninitiated, every CHP generator produces energy in a handful of steps[2]:
- A CHP plant employs a source of heat (such as coal or natural gas).
- CHP plants use the produced heat to drive a steam- or gas-powered turbine.
- CHP plants recover excess heat (thermal energy) which can then be used within other commercial, industrial or residential applications.
The recovery process is particularly critical, as it is estimated that as much as two-thirds of thermal energy is lost when dealing with traditional forms of energy production. In other words, a CHP combined heat and power station is able to dramatically reduce ancillary effects on the environment while still providing a viable source of energy to its customers.[2]
What are the Two Most Common CHP Plant Configurations?
A CHP power plant will generally utilise one of two systems to generate energy[3]:
- A combustion turbine
- A steam turbine
As the first term suggests, this CHP system utilises a combustion turbine that will first burn some type of fuel. Common examples include oil, natural gas or biofuel. The heat generated is then used to mechanically turn a turbine; resulting in the production of electricity. Heat recovery devices thereafter capture excess thermal energy in the form of steam or hot water.
Steam turbines rely upon a separately heated boiler that transforms water into steam. Once again, this steam will thereafter cause an electrical turbine to rotate. Any remaining steam will be captured and stored as an additional form of thermal energy.
Note that the United States Environmental Protection Agency can provide further details in regard to both of these configurations.[3]
How can a CHP Plant Increase its Overall Efficiency?
A growing number of companies are producing what are known as "micro" CHP plants. These CHP engines are designed within a manufacturing facility and pre-packaged so that they can be quickly installed. The main advantage of this type of CHP power is that it is more affordable when compared to large-scale production facilities. Thus, such CHP energy could represent a viable option for home use. Note that similar advances have been made in regard to fuel cell efficiency, enabling extra heat to be stored and saved for future purposes.
The efficiency of CHP heating is also determined by the type of fuel source employed. For example, fossil fuels such as natural gas are more efficient (in terms of mean energy production) than biomass. While biomass is an environmentally friendly material, CHP plants powered by this substance might actually be less efficient. These variables will need to be taken into account when determining the intended CHP efficiency of an upcoming project.[4]
Are There Any Disadvantages to a CHP Plant?
While a CHP plant can generate heat and power with much less thermal waste, there are nonetheless some possible drawbacks to mention. These include[5]:
- Most CHP plants will require an appreciable amount of space.
- More insulating materials are needed to ensure minimal heat loss.
- Heat may still be lost to the ground via thermal conduction.
The installation cost of a CHP plant must also be addressed, as some larger units may be priced as high as €9,000 euros [6]. This naturally depends on other factors such as the size, the location, and the intended use (in terms of kilowatts per hour of energy generation).
We can see that there are several advantages associated with CHP gas and heating. In the same respect, a handful of possible pitfalls should be considered. The good news is that other technologies such as the use of hydrogen fuel cells may further increase the efficiency of CHP plants and therefore, their ultimate return on investment (ROI).[7]
