March 15, 2022

The Basics of Combined Heat and Power

The Basics of Combined Heat and Power

 Not only is combined heat and power (CHP) one of the oldest energy strategies — it’s also one of the most efficient. Combined heat and power is the concurrent production of electricity and thermal energy from a single source of energy. With CHP, significantly less electricity is wasted and fewer greenhouse gasses are emitted into the environment. Having increased efficiency makes it possible for CHP systems to have reduced overall energy inputs and emissions, which is good for business and good for the planet.

Almost two-thirds of the energy used by conventional electricity generation is wasted, but CHP offers a brighter and healthier alternative. CHP can achieve efficiencies of over 80%, compared to 50% for typical technologies, according to the Environmental Protection Agency.

Rather than being a single technology, CHP is actually a system of individual components that work together to produce electricity and heat. The efficiency of a CHP system depends on the technology that’s used and the overall system design. Working with a firm that has experience with CHP systems is the best way to ensure a system is optimized to run as efficiently as possible.

Although CHP systems are usually located at facilities or buildings where there is a demand for both electricity and thermal energy, they don’t have to be. CHP can also be district energy or utility resource.

Because CHP systems are designed to operate every day, they are more reliable than emergency backup generators during power outages. This incredible resiliency makes CHP a valuable option for condominium developments and multi-family buildings, as well as critical care facilities, like nursing homes and hospitals.

What Are CHP Systems Used For?

Demand for CHP systems is on the rise, thanks to growing interest in energy efficiency, grid outage resiliency, and broader environmental awareness. The heat generated from CHP can be used for anything — not just commercial applications. That includes everything from household hot water and space heating, all the way to district heating and industrial process heating. Heat derived from CHP processes can also be used for cooling when it is used to drive absorption chillers.

How a CHP plant is designed depends on the nature of the electrical and thermal loads that are being served. While rare, CHP plants can be coupled with energy storage systems to overcome problems caused by fluctuating loads.

Common Applications

Currently, CHP is used in more than 4,400 facilities across the United States. The most common types of facilities to use CHP include:

  1. Commercial buildings
  2. Residential buildings
  3. Institutions (universities, schools)
  4. Municipal (city buildings)
  5. Manufacturers

Basic Components of CHP

What does it take to build a CHP system? CHP systems require a prime mover, a generator, heat recovery equipment, and (in most but not all instances) an electrical interconnection. The prime mover is what drives the combined heat and power system, so it’s usually seen as the most important part.

CHP systems are often identified by the type of prime mover or source of power.

Most Common CHP Power Sources

CHP power sources are also known as “prime movers”. The five most commonly installed power sources are:

  1. Steam turbine
  2. Reciprocating engine
  3. Combustion turbine
  4. Microturbine
  5. Fuel cell

According to data from the U.S. Environmental Protection Agency, CHP systems with steam turbines and fuel cells offer the greatest overall efficiency, followed by reciprocating engines, gas turbines, and microturbines.

Reciprocating engine systems are the most well-known. These systems burn either natural gas, oil, or biogas to turn generators and produce electricity. They rely on heat recovery devices to capture heat from turbines or engines. Heat is converted into thermal energy in the form of hot water or steam.

Environmental Benefits of CHP

CHP systems are an economically and environmentally attractive way to produce energy with higher efficiency and lower emissions than conventional systems. CHP is considered fuel neutral, which means that CHP processes can be applied to both fossil fuels and renewable energies.

Generally speaking, CHP systems burn less fuel to produce each unit of energy output, and in turn, that results in less emissions of greenhouse gasses, such as carbon dioxide (CO2), and air pollutants like nitrogen oxide (NOx) and sulfur dioxide (SO2).

Capturing heat that would otherwise be wasted means that CHP can use less fuel to produce the same amount of energy as a system that involves purchased electricity and thermal energy produced on-site.

Financial Benefits of CHP

Environmental benefits aren’t the only reason why companies and districts are switching to combined heat and power. Financially, making the switch can be very lucrative.

CHP’s high efficiency leads to lower energy bills. Systems regularly achieve total system efficiencies of 60% to 80%, compared to 50% for conventional technologies, like purchased utility electricity.

Beyond the efficiency aspect, CHP systems usually run on cheaper fuels, such as natural gas. Because natural gas is cheaper than purchased electricity, most companies find that running CHP is more financially lucrative than conventional systems. This is especially true for organizations that are currently working with older heating equipment that will need to be replaced in the near future. Opting for CHP avoids capital costs and provides less exposure to electricity rate increases.

KMB’s Leadership in Combined Heat and Power

Demand for CHP is growing across the U.S. and abroad as more communities search for low-cost energy and look for ways to lower their carbon dioxide emissions. However, the full benefits of CHP are only realized when a system is appropriately matched to a building’s use and size. Site-specific factors will determine if CHP is a good fit for your facility. Speaking with a member of the KMB team is the best way to quickly tell whether your facility is a candidate.

Let KMB’s team of combined heat and power specialists evaluate your facility and provide a custom recommendation. With thousands of projects nationwide, we have become an industry leader in combined heat and power. Read more about KMB’s combined heat and power services: https://www.kmbdg.com/services/combined-heat-power/