The UK
Electricity System

The UK electricity system is one of the most sophisticated in the world – a complex machine with many moving parts. Previously, large coal, gas and nuclear power plants were the main source of electricity, dominating the UK electricity generation market. These plants were relatively easily controllable and could be turned up or down in response to national demand.

As new forms of generation are progressively replacing traditional plants, 1000’s of decentralized generators are changing the pattern of electricity flows. As the flow of electricity is getting more complex, the National Grid ESO works hand in hand with the energy industry, continually finding ways to innovate, invest and adapt the electricity system to keep electricity flowing reliably to consumers across the UK.

Mast Energy Developments

National Grid Electricity System Operator

Generated electricity is transported through the UK’s nationwide transmission network. The it is moved to where it is needed, balancing supply and demand second by second, 24/7. The National Grid ESO operate the system but is not responsible for the infrastructure.


Aggregators are businesses that work with industrial and commercial energy consumers, who are able to flex their energy use to reduce or increase their demand in response to price signals.

Distribution Network Operator

Distribution Network Operators (DNO) move electricity from the grid through their own network to homes and businesses, converting high voltage electricity that’s in the network to the lower voltage electricity that homes and businesses use.

Energy Suppliers

Suppliers buy electricity from generators and then sell it on to customers, competing to supply homes and businesses who are free to choose any supplier they like.

What is Reserve Power ?

Reserve power (RP) is the process of timing energy supply so it can be used during periods of peak demand

Smaller grids can only manage smaller power plants, requiring peaking plants to be installed in areas of need

Plants comprise multiple small reciprocating engine gensets (1.5-4MW) housed in containers that include noise abatement
and control systems

Plants are unmanned with remote dispatch of gensets through data connection

RP plants are distinct from other types due to specific characteristics:

Small gas-fired power plants less than 50MW in size (diesel also possible but produces high emissions)

Dispatchable (can be turned on and off quickly to generate power on demand)

Essential for when system needs additional power quickly due to loss of generation or due to increase in demand

Able to supply power rapidly (reaction time of under 10 minutes)

Able to run for long periods continuously

Operate for limited number of hours per year (approximately 1000)


Offtake and EPC agreements secured, Development and monetisation already locked-in
MED has partnered with highly successful, international leaders and Blue Chip service providers such as Statkraft (offtake), AB Group and Clarke Energy (EPC and O&M)


Reserve Power Plants are small, flexible, and can produce electricity immediately when there is a shortage in supply


High variety of revenue streams, including a contracted 15 year revenue stream from the Capacity Market, contracts from National Grid to help balance the UK network, specific benefit due to plants being located in the distribution part of UK grid system and merchant power revenues


To acquire assets of varying capacity (typically 5-10MW) that have been developed with planning permission already in place and binging grid and gas connectivity quotations provided. MED will develop the targeted sites to fully commercially operating units. Each site is contracted with MED via a master service agreement.