What is a cogeneration plant?
Cogenerators are sophisticated Micro Generating Stations that make two useful forms of energy: Electricity AND Heat.
 
The fuel of choice is natural gas.
 
Cogenerators are compact, quiet and extremely clean.

Cogenerators feature sophisticated computerized controls that ensure optimal operation and energy savings.
 
In current form, cogeneration has been around since the 80's, and is widely used in Europe and Japan. As the price of energy is increasing and the need to conserve is becoming more acute, cogeneration is gaining acceptance in the US.
 
Cogeneration machines are available in varying sizes, and are made by GE, Caterpillar, Cummins, Tecogen, Aegis and others.

 
Is there a difference between Cogeneration and CHP?
There is no difference. Both terms refer to the same technology. CHP (Combined Heat and Power) is the one gaining acceptance, and is used by the EPA, Dept. of Defense etc.
 
In this Q&A section we used cogeneration consistently, but you'll find both terms used interchangeably in this site and elsewhere.


Why is cogeneration so efficient?
Whenever electricity is generated, heat is the by-product. This heat is discharged into the atmosphere as wasted energy. In the US the numbers are staggering- 65% the fuel used for electricity generation in this country is wasted. It is inefficiency on a colossal scale.
 
In contrast, cogeneration, as the name implies, captures the heat and channels it to useful uses in the building, such as space and water heating.
 
As a result, cogeneration raises the fuel utilization efficiency from 35% to 85%.
 
 
How does cogeneration save money?

By squeezing every bit of usable energy out of 1 fuel.
 
Currently the building purchases both Electrify for power + Oil (or gas) for heating.

 
Cogeneration uses 1 fuel (natural gas) to make electricity and heat. In other words- the process of making electricity it is displacing most of the oil that the building is buying.
 
Why is it environmentally beneficial?
Cogeneration is beneficial because we are doing more with less fuel, thereby discharging less Green House Gases (GHG). The cogeneration plant will displace GHG's that are now emitted when the building is burning oil. In addition, burning #6 oil is incredibly polluting. A gas-burning cogeneration plant is dramatically cleaner and eliminates NOx emissions on site. Statewide the plant reduces electric use, gas use and emissions.
 
The plant qualifies the building for 3 to 8 LEED points if the building were to pursue a LEED certification. Cogeneration is a green technology and officially recognized as such.
 
Where else is it done?
Cogeneration is prevalent in northern Europe where it is used for apartment-block heating as well as in factories and hospitals. In the US you'll find most cogeneration plants in the North East and in California, where the high price of electricity motivates people to find ways to reduce energy costs.
 
In NY City, cogeneration plants can be found in hospitals, factories and a few co-ops. The newest Fairway supermarket in Brooklyn has a cogeneration plant on the premises.

How much money will we save?
The savings associated with the introduction of cogeneration range from 30% to 40%. The savings depend on several factors, such as how inefficient was the boiler plant that is being replaced, and how much of the thermal output can be used in the summer.
 
How much money will a plant cost?
The cost of a plant is determined by many factors, but as a rule of thumb, we recommend that a project be green-lighted if the initial analysis indicates an ROI of 4 year payback or better. In the New York City area we find that because of high utility rates, 3 years payback is achievable.
 
Is there any government support for such an initiative?
Yes. NYSERDA (New York State Energy Research and Development Authority) is very keen on cogeneration and has several programs that promote and subsidize it.
 
On the federal level, cogeneration is eligible for several tax breaks. For the NY State grid operator, cogeneration plants are considered a Special Case Resource, and thus obtain monies from the NYISO. Cogeneration is a Green technology that can be monetize and sell "white tags" when carbon trading becomes a reality.
 
Are we going to get off the grid?
No. A cogen plant does not take the building off the grid. Even with a cogen plant on the premises, the local utility continues to supply electricity to the building, just much less of it.
 
Is there a risk to the building's electricity supply? Are we going to lose power if the cogeneration system is off?
No. If the cogen plant is off (for maintenance, for example), electricity from the utility keeps flowing and takes up the slack without any interruption. The process is wholly automated and seamless.
 
Will we be penalized by ConEd for taking away so much business?
No. For obvious reasons ConEd in not a big fan of cogeneration. As a result, they asked regulators to design an electric rate specifically for facilities that use cogeneration. This "Stand By" tariff is not great, but it is fair. For systems smaller than 1 MW, the building can choose under which tariff it wants to pay for the electricity it still buys from ConEd. More, the building can change its choice periodically to take advantage of the best rate.
 
How reliable are cogeneration plants?
Cogen plants are designed for long continuous service. At the heart of the generator set is an engine that's designed for marine applications. They are very robust and computerized units. Our plants commonly achieve 95% up time.
 
Like any machine, cogeneration plants require regular maintenance. The service takes a couple of hours, during which the plant is shut down. In case of a breakdown, all the manufacturers maintain parts depots in the NY area. The plant is under 24/7 remote supervision, and if any sensor indicates that there's a problem, technicians are dispatched to the plant.
 
Will the cogeneration plant provide Back-Up power?
The plant can be designed to keep working if there's a blackout. The plant will provide electricity only for the most important building functions such as elevators, pumps and emergency hallway lighting. In NY State, the ability to provide back-up power is now required for plants supported by NYSERDA.
 
Can the heating be interrupted?
No. The cogen plant's hot-water plumbing is integrated with the existing boiler. The boiler in the building is designed to keep operating at a minimal level at all times to keep its fuel flowing. If the cogen plant is off, the boiler simply picks up the slack.
 
What happens if the cost of gas goes up?
Cogeneration plant owners buy gas under long-term agreements to avoid volatility, and even more important, because the federal government wants to promote cogeneration, it requires suppliers, such as ConEd or Hess, to deliver gas at a reduced price, under a cogen-friendly commodity rate.
 
Since most electricity generation in the North East is with gas, gas price hikes affect the utilities as well, and in response they hike electricity rates to the consumer. Because cogeneration plants use gas so efficiently, they consistently maintain an advantageous "spark spread" (the cost difference between generating on site or buying electricity from a utility).
 
Where would it be located?
The cogeneration system is usually located in the boiler room, but obviously every building is different and other locations may be better suited for the plant.

Any smells?
There are no smells. Cogeneration exhaust meets very stringent EPA clean air requirements, and is much cleaner than the exhaust of oil boiler. In fact, one of the main reasons NYSERDA is promoting cogeneration is because it dramatically reduces emissions of NOx pollution from the existing boiler.
 
Is the system noisy?
The cogen machines are less noisy than the building's boiler. Since the plant is usually located in the boiler room, tenants are not going to hear it.

Who keeps an eye on the plant?
The plant has a very advanced electronic controls and system. The system is in constant communication with a response center. If there's any malfunction, technicians are summoned to take care of the problem. What's more, the system remotely monitors all aspects of the performance making sure that the plant stays at optimal output to ensure the savings.
 
Would we need to hire additional personnel to handle the plant?
No. Since the system is managed remotely, there's no need for intervention in its operation. We found however that in many cases the building personnel is very enthusiastic about cogeneration, and make it their business to learn about its workings. Even then, their involvement is kept to a minimum.
 
Can you point me to web sites where I can learn more?
Please click here for a list of relevant links.