Cogen, Cogeneration, and Combined Heat and Power (CHP) all refer to a system defined by generating electricity right near where it will be used, and then recycling the thermal energy for heating or cooling.  

It's very efficient and already supplies 10% of our nation's energy! A CHP system provides electricity and heat at a combined efficiency approaching 90%. This is a significant improvement over the 33% efficient electric utility.

For single small buildings, a micro-CHP system will be the most appropriate. For larger buildings or complexes, a CHP system that utilizes solar, natural gas, or biomass can be designed. District CHP systems are the largest size, suitable for larger complexes, campuses, or business districts. The excess heat in a cogen system can be captured using a heat exchanger.

CHP Microsystems
Micro-CHP (Combined Heat and Power) is a hybrid technology that combines an internal–combustion engine generator or fuel cell with a space and/or water heating device. The unit produces heat and electricity at the same time. This allows the small municipal building to self–generate a portion of its electricity. By capturing the waste heat from the electric generation and using it for space heating, less fuel energy is used when compared with traditional technologies.

Micro-CHP systems are most cost–effective in regions with colder climates and high electricity prices. Although initially more expensive than traditional solutions, micro CHP systems save you money by offsetting your electricity costs throughout the winter months.

Cogen Flexibility for a Single Building
CHP is a type of distributed generation, which, unlike central station generation, is located at or near the point of consumption. Instead of purchasing electricity from a local utility and then burning fuel in a furnace or boiler to produce thermal energy, consumers use CHP to provide these energy services in one energy-efficient step. As a result, CHP improves efficiency and reduces greenhouse gas (GHG) emissions. For optimal efficiency, CHP systems typically are designed and sized to meet the users' thermal baseload demand.

The design of the system is very flexible and can use a variety of energy sources - natural gas, biomass, anaerobic digestion, or solar. For example, biomass facilities with access to cleaner biomass can employ the latest generation of CHP technology. The timber industry has partnered with energy companies to burn forest by-products in a CHP system design to produce energy, and the excess heat is captured. The CHP plant design also prevents the hazardous emissions that would be produced if the waste were left to decompose in a landfill.

Manufacturers / Products / Links

Iberdrola Renewables has built power plants using renewable technologies, a recent one being a combined heat and power facility using latest-generation technology. They minimize environmental impacts through innovative techniques. At Lakeview, OR, the plant will burn forest by-products and will be entirely air-cooled – reducing water use by more than 80 percent as compared to conventional water cooling.

Cummins Power develops custom solutions to meet your energy needs, whether for combined heat and power, a waste-to-energy plant, continuous power generation or peaking applications. They work with you to develop power plants that combine our centralized "factory" knowledge with our distributors' local knowledge and proximity. Cummins power provides a variety of energy solutions for the gas-fired, mid-power, distributed generation market in the 2 MW to 20 MW range.

District Energy
District Energy is cogen on a large scale for an entire set of municipal buildings, or a university, office park, medical campus, mixed use sustainable development, or downtown.

Over 400 building networks in the U.S. already use district energy systems, and the number is on the rise. A preferred method of heating and cooling most major college and university campuses, they are most familiar through their network of steam heat.

District energy refers to generating any combination of electricity, steam, heating, or cooling at a central plant and then distributing that energy to a network of nearby buildings. As a result, individual buildings connected to the network avoid the need to install and maintain their own boilers, furnaces, chillers, or air conditioners, saving on capital and maintenance costs. Many district energy schemes use combined heat and power, recycling the thermal energy left over from electricity generation for heating or cooling. District energy is an efficient, reliable, and cost-effective option for any cluster or network of buildings.

Waste Heat Recovery in a Cogen System
Capturing the heat involves the use of heat exchangers. Two main types of heat exchangers exist, differing in using an intermediate storage or direct transfer of heat.

1. Regenerator:   heat from the primary medium is first stored in a thermal mass and later (next cycle) regenerated from that mass by the secondary medium. The thermal mass can be the wall material of the flow ducts or a porous medium, through which alternating the primary and the secondary flow is led.
2. Recuperator:  both media are separated by a wall through which heat is transferred directly. Generally, a recuperator is more efficient than a regenerator.

MLC can help you add waste heat recovery to your plant and make it more efficient!

Cogeneration / on-site utility energy offers a number of significant benefits:

• Immediate reduction in energy costs.
  On-site energy can cost 5% to 25% less than the rate charged by your current energy provider. Your municipality will also realize tremendous energy costs savings over the course of the lease!

• Positive impact on your balance sheet.
  With MLC lease financing for your energy project, you have no capital investment and you can get your project started now and reap all of the cost-savings benefits. This makes sense because you can make better use of your capital for other important needs.

• Cogeneration provides clean, cost-effective and environmentally friendly energy.
  Cogeneration units typically run on natural gas, which is the cleanest fossil fuel, helping to qualify this equipment as a Green Energy Solution. The quality of power generated at your site is cleaner and more consistent than from utility lines. Conventional municipal and commercial energy users can have spikes and low-voltage situations which can damage your electrical equipment.

• Cogeneration is much more efficient than energy from by regional suppliers.
  Onsite generation eliminates these loses and have proven energy efficiency exceeding 88%. Monitoring software and systems can even exceed this level of efficiency, making this an unbeatable alternative energy.

• Proven, reliable systems.
  Introduced in the early 1980s, the combined heat and power (CHP or cogeneration) and chiller systems we install have been deployed in thousands of installations nationwide. We select only the best on-site energy systems for your property.

• Reduced operating costs.
  Your boilers will operate less, extending their life and reducing your operating and maintenance costs.

• Cleaner, fuel efficient technology.
  The on-site energy systems approach 90% efficiency, while conventional, central power plants can only achieve 30% efficiency. You will save money while helping to conserve energy and improve the environment.  Your site consumes less carbon and your building may earn LEED credits.

• Zero risk.
  Your building remains connected to the electric grid, natural gas utility and your on-site boiler, so your existing infrastructure provides additional assurance that you are never without electricity, heat, hot water or cooling.

• MLC will fastrack your equipment lease to get your project up and running in no time.
  Our energy performance audit and contract partners can perform an assessment of your current systems against your usage needs. Then MLC secures the lease financing to fund your project quickly. The MLC team also provides the professional assistance you need to navigate regulations or restrictions, and help you make the most of local, state and federal incentives. Which means you get all of the benefits, and none of the hassles!