How energy reaches your home
Tomorrow's green energy system is made up of a whole lot more than wind farms and solar panels. Energy production is just one part of the equation: there's an equally important job in actually getting those green electrons to the homes and businesses that use them.
This is where the ‘grid’ comes in. The grid is not only central to keeping the lights on, but also to building a cheaper, greener system - so how exactly does the energy grid work?
The backbone of the grid
The UK’s electricity grid is the infrastructural system that delivers energy to consumers across the UK. The backbone of the national grid is the ‘transmission grid’ - a ‘motorway style’ series of heavier duty wires, pylons, and underground cables that take large amounts of energy from relatively powerful generators and transport it over long distances.
Britain technically has 3 Transmission Owners (TOs): National Grid plc, ScottishPower Transmission in the south of Scotland, and SSE in the north of Scotland, who own the infrastructure, and are responsible for transmission grid buildout, for example. As well as being a transmission owner, National Grid plc is the ‘Transmission System Operator’ for the entire transmission grid.
A spidery distribution network
From there, electricity is fed from the transmission grid into a series of 14 spidery distribution networks, run by 6 DNOs (distribution network operators). Here, electricity is ‘stepped down’ at substations, and then brought down to the street level. Because both the transmission grid and distribution grids are considered ‘natural monopolies’, they are regulated by the energy regulator OFGEM, who set financial incentives and disincentives aimed at getting these companies to meet certain targets.
Keeping the grid up to date
Britain’s regulatory systems for ensuring ‘security of supply’ have long been considered extraordinarily robust, but it has long proved difficult to adequately encourage preemptive investment - and infrastructure buildout more generally - via these mechanisms. This is of increasing importance as we need to transport increasing quantities of green energy to places where it is needed - and decarbonise the energy system more generally.
Balancing the grid
Crucially, the grid must always be ‘balanced’ at a frequency of 50HZ. If electricity supply drops below demand, this frequency will fall and there can be power cuts; if demand overwhelms supply, a rise in frequency can overload the system, damaging grid infrastructure. The Electricity System Operator (National Grid ESO, another subsidiary of the wider National Grid company) is responsible for balancing the grid in real time - matching supply with demand around the country. This generally means telling generators to turn on or off, or telling batteries to charge or discharge, for example. The Government is currently in the process of establishing a Future Systems Operator (FSO) - which looks set to be an independent public corporation, and will also be trusted with a greater role in system planning to achieve Net Zero.
Every electrical system clearly needs ‘wiggle room’ in order to adapt when either supply or demand changes unexpectedly - this is known as ‘flexibility’ in the industry. Traditionally, our grid has been a centralised, ‘one way’ system, with energy sent ‘downstream’ from large coal and gas power stations, through the transmission grid, down to the distribution grids, and into our homes.
Low carbon flexibility
‘Flexibility’ in this system has long come from ‘turning up’ or ‘turning down’ these fossil generators in line with consumer demand, and adjusting the amount of energy that flows downstream. These days, it’s worth noting that as more people begin to generate and store their own electricity, sending it back to the grid - this ‘one way’ model is being challenged.
More importantly, however, as energy generation becomes more decentralised and ‘intermittent’ (we can’t call on the sun or wind whenever we want), Britain can no longer afford to rely on turning dirty, expensive power stations on or off for flexibility, so flexibility across the grid is going to have to come from elsewhere.
Fortunately, clean flexible tech (from large grid-scale batteries, to smart tariffs and smart schemes that encourage customers to match their usage with the availability of clean energy) is well placed to make sure we can fit clean, cheap ‘intermittent’ generation to energy demand. As such, low carbon flexible tech must become a more visible, better integrated feature of Britain’s ever-smarter power grid over the next few decades.
Published on 14th June 2023 by:
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