What is embedded generation and transmission connected generation?

What is embedded generation?

Embedded generation (also known as distributed generation or distributed energy resources) refers to electricity generation or storage plants connected to a distribution network rather than the transmission network. Embedded generation adds to the overall system inertia which is an important tool for maintaining the system frequency within the statutory limits.  

Small power plants that come on to meet peak demand, for example diesel generators and gas reciprocating engines, are also a type of embedded generation. These small plants can send any extra electricity they don’t need back into the main power grid for other use. 

NESO does not have real time visibility of most of the embedded generation, which accounts for 23% (Future Energy Scenarios, 2024) of generation capacity on the electricity network. The accuracy of our assumptions on embedded generation is crucial for effective demand forecasting and how we manage frequency. 

What is transmission connected generation?

Transmission connected generation is the large-scale power plants (such as gas, nuclear, and big wind/solar farms). It can help to think of it like road networks. The transmission network is like a motorway network which moves high voltage electricity around Great Britain.  

NESO has visibility of all transmission connected generation, however, because we don’t have sight of embedded generation, if a small embedded solar farm started producing electricity, we would not see an increase in supply, but rather a reduction in demand because it connected onto the network at a local level.   

In order to balance generation and demand, NESO conducts close to real-time demand forecasting to predict the minute-by-minute demand change.  

We expect to see more types of embedded generation in the future as renewable generation becomes more common. This helps us towards a carbon free future.