15 Advantages and Disadvantages of Cogeneration Explained

Advantages and disadvantages of Cogeneration are; energy conservation, energy efficiency, fuel efficiency, cost reduction, reduced emissions, adaptability, versatility, stability, sustainability, energy security, air quality, reliability (advantages); low output, environmental impact, regulatory challenges (disadvantages).

Advantages of Cogeneration

1). Energy Conservation

One of the primary outcomes of cogeneration, is energy conservation.

Because cogeneration minimizes losses in the process of energy production and power-generation, it often conserves significant amounts of energy [1].

The typical mechanisms by which energy is conserved by cogeneration systems, are very similar to those by which energy is lost in conventional systems. These mechanisms all border around energy (heat) transfer.

In the case of conventional systems, heat transfer mechanisms include conduction, convection and radiation; all of which cause losses of energy to occur. Cogeneration systems conserve energy through heat transfer, in the form of absorption of waste heat by a suitable; conductive material (usually a fluid such as water).

By absorbing waste heat (unused energy), cogeneration systems can achieve energy conservation of up to 60 percent (of total waste heat).

2). Energy Efficiency

Energy conservation and energy efficiency are both important concepts within the  context of sustainable development and environmental/social/economic sustainability.

When energy which would otherwise have been lost, is conserved, it becomes possible for the system to have more work done with less total energy input. This tendency to do more work with less energy can be referred to as energy efficiency.

For conventional (fossil fuel-driven) power plants in the United States, energy efficiency is about 33 percent on average [4]. This means that up to 67 percent of the total energy input to the system can be lost.

Cogeneration minimizes such losses, ensuring that about 60-80 percent of total energy input is used productively for work. This amounts to an increase in energy efficiency of the system.

The efficiency of cogeneration systems may vary with the design of the system itself. The following table lists a number of prime mover designs for cogeneration systems, alongside their average energy efficiencies;

3). Fuel Efficiency

The concept of fuel efficiency is similar to that of energy efficiency. It refers to the degree, to which less fuel or energy resource can be used to do work in a system.

Cogeneration increased fuel efficiency in the same manner as it improves energy efficiency; by minimizing energy (and fuel) wastage, and thereby increasing the amount of work that can be carried out on a specified quantity of fuel.

4). Energy-Cost Reduction

One of the notable economic benefits of cogeneration technology, is the reduction of the cost of energy, by this method.

There are different ways by which cogeneration reduces the cost of energy.

One of such ways is through the direct impact of efficiency. Because cogeneration often leads to higher energy efficiency and fuel efficiency, it tends to reduce the cost of energy consumed for a particular amount of work to be done.

In the scenario described above, energy cost reduces because energy consumption itself reduces. This is the positive economic effect of improved energy/fuel efficiency in cogeneration systems.

Cogeneration reduces the expenditure on heat (as different from power) since it conserves the heat produced during the generation of this power/electricity.

This has significant impact especially in industrial scenarios where heat energy is used extensively. The on-site cost of energy becomes less in such cases, as heat is made available along with power, by the cogeneration system.

Another way by which energy cost is reduced in cogeneration systems is through Power Purchase Agreements (PPAs), which allow the operators of cogeneration facilities to sell excess electricity to the local utility grid.

An arrangement such as the PPAs, whereby excess power is produced and sold, may cover the entire capital cost of construction and installation of the cogeneration system itself.

Due to policies and measures that support the development of cogeneration technology, tax incentives can be accessed by some facilities which use cogeneration systems [5]. These serve as an economic benefit in such cases where, they apply.

Cogeneration may also act as a buffer against the economic instabilities that come along with electricity distribution from the grid. This is because facilities that use cogeneration systems, are often unaffected by energy price-hikes; weather-related disruptions, and other similar challenges that affect others which rely on the grid.

5). Reduced Emissions

Compared to conventional methods of energy and power production, cogeneration can be said to offer some environmental benefits.

Because of the improvement in energy and fuel efficiency (with which they are commonly associated), cogeneration systems generally consume less fuel than conventional technologies.

Fuel combustion itself is associated with greenhouse emission, poor air quality, and global warming, among other environmental problems [7]. Therefore, reducing the rate of consumption of fuel implies less prevalence of such problems for the environment.

The conservation heat energy in cogeneration also means that less emission of some greenhouse gases like water vapor (steam) into the atmosphere will occur.

6). Versatility and Adaptability

Two beneficial attributes of cogeneration include its relative versatility and adaptability.

Unlike many energy production technologies, cogeneration provides avenues for the use of different energy resources or fuels. These include non-renewable and renewable energy resources.

Fuels like coal, LPG, diesel, natural gas and biomass can be used in cogeneration [8], as well as renewable energy resources like solar.

What this implies is that cogeneration can be adapted to work with different fuels, more conveniently than conventional technologies.

Another area of versatility for cogeneration is the area of energy-production. Cogeneration produces more than one form of energy, unlike conventional technologies which may produce only heat or power. This makes it possible for cogeneration systems to serve multiple purposes simultaneously.

7). Stability and Sustainability

Cogeneration represents a step toward the goal of achieving sustainability in the energy sector.

There are various reasons for this. One of them is the fact that cogeneration conserves energy.

The conservation of energy by cogeneration technologies provides an opportunity to maximize energy resources and minimize environmental impacts. This makes cogeneration more sustainable on a long-term basis, than conventional energy-production technologies.

Another reason behind the sustainability of cogeneration, is the fact that it is versatile.

Versatility makes it possible to use different fuels in cogeneration plants. This reduces the risk of rapid depletion of any particular energy resource.  Cogeneration also makes use of renewable fuels like plant biomass, biodiesel, and biogas [2].

8). Energy Security

The concept of energy security is mostly concerned with the availability of energy itself, which depends on the level of demand, and the magnitude of available energy resources.

Cogeneration offers more energy security, mainly because it tends to reduce the overall energy demand.

Another way in which cogeneration improves energy security, is by enabling operators to have a vast range of options of energy resources. These resources range from non-renewable fossil fuels to renewable alternatives.

Considering the fact that many energy resources occur in limited volume on Earth; an approach like cogeneration which reduces the reliance on a singular energy resource, by diversifying the applicable options, can help to improve energy security.

Cogeneration also improves energy security by being resilient. This refers to the fact that cogeneration systems are generally not affected by many of the problems that can disrupt power supply from conventional energy systems, such as weather conditions and energy-resource shortages.

9). Air Quality Improvement

Extensive burning of fossil fuels to produce energy, usually has negative consequences on air quality. This is because fossil fuel combustion is associated with the release of large quantities of toxic air pollutants and greenhouse gases like sulfur dioxide, methane, and nitrogen dioxide.

Cogeneration improves air quality simply by reducing the rate and scale of fossil fuel combustion.

In buildings, cogeneration systems may be equipped with a dehumidifier [6], which absorbs and removes water vapor (moisture) from the air, thereby improving indoor air quality. Cogeneration-based dehumidification may also reduce the rate of energy consumption by air conditioning systems.

10). Reliability

Reliability within the context of energy and power, refers to reducing the risk of changes (mostly the unfavorable changes) in the trend of energy production, power generation and supply.

Cogeneration offers more reliability than conventional energy technologies in general, because of its conservative and resilient characteristics.

The risk of power outages for businesses and facilities that rely on cogeneration, is much less than that which is faced by their counterparts who rely on the utility grid [9].

By reducing the demand for power from the grid, as well as the cost of energy, cogeneration also makes power supply to be more reliable for the entire society.

Disadvantages of Cogeneration

1). Narrow Range of Suitability

In spite of the numerous advantages of cogeneration, it is not applicable to all scenarios where power or heat is needed.

Cogeneration is most suitable for industrial, large-scale settings, which require large amounts of both heat and power, on a consistent basis. It may also be suitable for centralized district and regional energy supply, where heat and power can be supplied to residential and business facilities continuously.

In scenarios where either heat or power is not always required, prolonged and repeated downtimes can cause inefficiency on the part of the cogeneration system.

2). Initial Cost

Capital cost is one of the deterrents for potential users of cogeneration technology.

For small-scale cogeneration systems in buildings, installation could cost more than $10,000 (as at 2022). The cost may however be much lower, at about $4,000.

For relatively-small energy consumers, the installation cost of cogeneration systems acts as a barrier to widespread adoption of this technology, in spite of the long-term economic benefits.

Aside the cost of installation, cogeneration systems may also incur huge expenses for maintenance and emissions control [3], especially when used for large-scale operations.

3). No Net Energy is Produced

Another way to describe this is by stating that cogeneration is not an intrinsic source of energy.

Cogeneration serves as a mechanism by which energy resources can be maximized. What this means is that cogeneration systems play the role of energy conservation, and while the fraction of useful total energy may increase with this method, no net energy is actually gained by the use of this method.

4). Environmental Implications

It is well-known that cogeneration can reduce the environmental impacts of power generation, by reducing the amount of fossil fuel that is burnt to produce energy.

However, most cogeneration systems still carry out fossil fuel combustion, meaning that greenhouse gases and other waste materials are released from cogeneration systems as well.

5). Regulatory Challenges

Regulations exist in several countries of the world, to guide the use of cogeneration technology. In some cases, these regulations may however act as a barrier to the adoption of the technology, for many individuals and corporations.

Conclusion

As a method of energy production, cogeneration has both advantages and drawbacks.

The advantages of cogeneration, basically hover around the fact that it is a method by which energy in a system can be conserved, by minimizing total energy losses.

Energy conservation, energy efficiency, fuel efficiency, and cost reduction are among the benefits of cogeneration.

The drawbacks of cogeneration include its capital cost, which is high compared to many other energy technologies. It is also not entirely sustainable as it may have some negative impacts on the environment.

Other drawbacks include the fact that cogeneration does not produce any energy on its own, but conserves the energy produced from other sources.

Regulatory challenges may also serve as a barrier to the full-scale and widespread adoption of cogeneration technology.

References

1). Balli, O.; Aras, H. (2007). “Energetic Analyses of the Combined Heat and Power(CHP) System”. Energy Exploration and Exploitation, Volume 25, 2007 pp. 39–62 39. Available at: https://journals.sagepub.com/doi/pdf/10.1260/014459807781036412. (Accessed 26 February 2022).

2). Beschkov, V. (2017). “(2017). “Biogas, Biodiesel and Bioethanol as Multifunctional Renewable Fuels and Raw Materials.” In E. Jacob-Lopes, & L. Q. Zepka (Eds.), Frontiers in Bioenergy and Biofuels. Available at: https://doi.org/10.5772/65734. (Accessed 26 February 2022).

3). De Rosa, J. and Salvadori, M. (2007). “Advantages and challenges of cogeneration.” Available at: https://www.waterworld.com/water-utility-management/energy-management/article/16222161/advantages-and-challenges-of-cogeneration. (Accessed 25 February 2022).

4). EPA (2021). “CHP Benefits.” Available at: https://www.epa.gov/chp/chp-benefits. (Accessed 26 February 2022).

5). Hugenberger. J. (2019). “The Question: To Claim (or not to claim) the CHP federal tax credit?” Available at: https://www.power-eng.com/coal/boilers/the-question-to-claim-or-not-to-claim-the-chp-federal-tax-credit/#gref. (Accessed 26 February 2022).

6). Kim, J.H.; Ahn, J. (2021). “Performance Analysis of Hybrid Desiccant Cooling System with Enhanced Dehumidification Capability Using TRNSYS.” Appl. Sci. 2021, 11, 3236. https://doi.org/10.3390/app11073236. (Accessed 26 February 2022).

7). Lelieveld, J.; Klingmuller, K.; Pozzer, A.; Burnett, R. T.; Haines, A.; Ramanathann, V. (2019). “Effects of fossil fuel and total anthropogenic emission removal on public health and climate.” PNAS April 9, 2019 116 (15) 7192-7197; Available at: https://doi.org/10.1073/pnas.1819989116. (Accessed 26 February 2022).

8). Liang, F.; Ryvak, M.; Sayeed, S.; Zhao, N. (2012). “The role of natural gas as a primary fuel in the near future, including comparisons of acquisition, transmission and waste handling costs of as with competitive alternatives.” Chemistry Central Journal 6 Suppl 1(Suppl 1):S4. Available at: https://doi.org/10.1186/1752-153X-6-S1-S4. (Accessed 26 February 2022).

9). Seltzer, A. M.; Povilaitis. J. F. (2019). “CHPs a smart solution to combat increasing blackout risks facing healthcare facilities.” Available at: https://www.healthcarefacilitiestoday.com/posts/CHPs-a-smart-solution-to-combat-increasing-blackout-risks-facing-healthcare-facilities–22304. (Accessed 26 February 2022).