What is DE?

WADE defines ‘Decentralized Energy’ (DE) as:

"Electricity production at or near the point of use, irrespective of size, technology or fuel used - both off-grid and on-grid."

It includes:

The term 'DE' may be relatively new, but the concept is as old as commercial electricity. The very first power plant in the world, in New York City in 1882, provided both electricity and useful heat to the neighbouring buildings.

Pearl Street CHP station

Pearl Street Station was the first DE plant, providing both useful heat and electricity.

 


What determines whether electricity generation is DE is not so much how electricity is generated rather where power is generated. DE technologies generate electricity where it is needed. Central generation on the other hand generates electricity in large remote plants and power must then be transported over long distances at high voltage before it can be put to use. It does not matter what technology one employs, whether it is used in connection with an existing grid or in a remote village, or whether the power comes from a clean renewable source or from burning fossil fuel: if the generator is ‘on-site’ it is DE. This means that, strictly speaking, DE could imply technologies that are not necessarily cleaner for the environment such as diesel generators without heat recovery. More often that not, however, DE is synonymous with cleaner electricity- indeed that is one of DE’s main benefits.

There are many different terms used in the context of DE and it can get confusing. Below is a table that lists many of the terms, defines them and explains how they are related to DE:


Term

Acronym

Notes

Decentralized Energy

DE

Electricity production at or near the point of use, irrespective of size, technology or fuel used - both off-grid and on-grid. DE includes high efficiency cogeneration (CHP), on-site renewable energy and industrial energy recycling and on-site power.

Renewables/ Renewable Energy

RE

Energy sources that are naturally replensihed in the short term, including non-carbon technologies such as solar energy, hydropower and wind as well as carbon-neutral technologies such as biomass. There is considerable overlap between renewables and DE. When renewables are used to generate power where it is required renewables can be said to fall within the DE definition. On the other hand large wind farms, that are built remotely from where the electricity is used, do not fall under the DE definition.

Distributed Generation

DG

Often used interchangeably with DE although sometimes DG refers to power only whereas DE includes thermal energy and electrical power.

Microgeneration


Very small scale applications of DE- usually at the scale of an individual home.

District Energy (District Heating/Cooling)

DE/DH/DC

Production of steam, hot water or chilled water, or a combination of the three, at a single central plant for distribution to other buildings through a network of pipes. The term is closely related to DE. It often, but not always, overlaps with DE. When district energy systems employ waste heat from electricity generation to supply heating/cooling networks they can be considered DE. In some cases, however, district energy plants are used in heat only applications in which case they are not considered DE.

Combined Heat and Power

CHP

The simultaneous production of both electricity and useful heat. CHP can be on any scale from very large applications in refineries to tiny machines in individual homes. CHP is one type of DE.

Cogeneration


Term used interchangeable with 'combined heat and power'. Cogeneration is the simultaneous production of both electricity and useful heat. Cogeneration can be on any scale from very large applications in refineries to tiny machines in individual homes.

Combined Cooling Heating and Power/Cooling Heating and Power

CCHP/
CHP

CCHP is the simultaneous production of electricity and useful heat and cooling (usually by a heat powered chiller). CCHP is one type of DE.

Trigeneration


Term used interchangeably with CCHP. Trigeneration is the simultaneous production of electricity and useful heat and cooling.

Uninterupted Power Supply

UPS

Term often used to describe on-site power, especially in the context of emergenecy power for computers. The term is usually associated with fossil-fired generators and implies power only applications, however it can also refer to applications where waste heat is recovered in which case greater environmental benefits would be realized.

Backup Generator


Usually associated with fossil-fired generators and implies power only applications, however it can also refer to applications where waste heat is recovered in which case greater environmental benefits would be realized. Renewable technologoiges are also increasingly being employed to provide backup power.

Captive Power


Term closely related to DE often used to describe on-site power. The term can imply either power only or cogeneration applications.

Embedded Generation


Closely related term often used to describe on-site power. The term can imply either power only or cogeneration applications.

Micro grid


A collection of DE technologies grouped together in a specific area and often connected at a single point to the larger grid.

Distributed Resource

DR

Often used interchangeably with 'Decentralized Energy' or 'Distributed Generation' but because a resource can also be either supply or demand side DR also includes conservation measures at the point of consumption.

 

 

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