What is the National Grid? A Complete Guide

It’s the network that literally keeps the country running, and it works so well that we seldom even give it any consideration. The National Grid is like a circulatory system for the nation’s well-being, but what is it, what is its history, and what might its future look like when we need to drastically change our energy use habits?

What is the National Grid?

The National Grid is a 20th-century marvel, ensuring not only a constant supply of electricity to almost 70m people and the businesses that keep them at work but also that electricity generated anywhere on the grid can be used to satisfy demand elsewhere. Nationalised by the Electricity Act 1947, it has been administered by a private company, National Grid PLC, since 1990.

The History and Development of The National Grid

It’s been less than a century since the delivery of electricity in the UK was chaotic to the extent that it required government intervention to sort it all out. Electricity had been available in the UK since before World War I, but supply was inconsistent and expensive. A melange of small private companies and local councils could supply, but voltages could differ from street to street, while the cost of keeping five light bulbs illuminated is the equivalent of an average week's wages. By 1925, only 6% of UK households had electricity, with the rest remaining dependent on coal and gas for heating.

The Electricity (Supply) Act of 1926 changed all that. Proposed by Prime Minister Stanley Baldwin, it established a new body, the Central Electricity Board, which would oversee the standardisation of electricity supply across the country and set up what was originally called a ‘national gridiron’ to deliver a nationwide system of power stations, power lines, transformers, and electricity users to cover the whole of the country. By this time, the industry consisted of more than 600 different suppliers, so it was necessary. It was the single biggest peacetime construction project that Britain had ever seen at that time; the National Grid – 4,000 miles of transmission cable connecting 122 of the most efficient power stations in the country. It would take 100,000 men five years to complete, but when it went live in 1933 it was both ahead of schedule and under budget.

How Does the National Grid Work?

The National Grid is considerably more complex than the National Grid isn't just about supply. It is also important to make sure that electricity production keeps up with demand. The amount of electricity being used across the country changes throughout the course of each day, as people wake up, go to work, come home, and relax into the evening before going to bed. The operators of the national grid can predict when large amounts of electricity are going to be required, and adjust the amount of electricity being produced and transported accordingly.

Most of the time, power plants are running at below their maximum operating capacity, and can therefore generate a lot more electricity when the national grid demands it. Several smaller power stations are kept in a standby state that can be spun up relatively quickly if the demand is even higher than the standard power plants can supply.

The supply of electricity is dependent on transmission and distribution. These refer to the different stages of carrying electricity over poles and wires from generators to homes or businesses. The primary distinction between the two is the voltage level at which electricity moves in each stage. After electricity has been generated, a system of electrical wires carries the electricity from the source of generation to our homes and businesses. These lines can be found overhead or sometimes in the ground.

Transmission is effectively the motorway of electricity delivery, moving bulk electricity from the generation sites over long distances to substations closer to areas of demand for electricity. You’ll know transmission lines from the large pylons which support these wires over long distances, often–controversially–across the countryside. Transmission lines move large amounts of power at a high voltage level; a level far too high to be delivered directly into a home or business. Transmission lines, transformers and substations have voltages of 100kV (100,000 volts) and above.

The power moving through the transmission system must, therefore, be reduced to lower voltage levels by electricity distributors before it can be delivered to a home or business. Power, specifically the voltage level, sent through transmission lines is reduced, or ”stepped down,” via transformers and sent through distribution lines, which are then connected to homes and businesses. If transmission is akin to a motorway network, then distribution lines are the crisscross of roads in your town, with the transformers acting as junctions. Transmission and distribution are managed separately in the UK, with three companies responsible for transmission and ten, called Distribution Network Operators or DNOs, responsible for distribution.

The Importance of the National Grid

One of the key, defining features of the National Grid is its stability. It runs at a stable 50hz, and only a small variation from this could disrupt power supplies nationwide. If you want an understanding of how important this stability is, you only need to look at what happens when it’s not there. Perhaps the most striking manifestation of this came with the imposition of the “three-day week” at the end of 1973.

At the time, coal provided the majority of the country's fuel, and when the miners went on strike in the summer of that year, a highly controversial decision had to be made by Prime Minister Ted Heath to conserve coal stocks. From the 1st January 1974, commercial users of electricity were limited to three specified consecutive days' consumption each week and prohibited from working longer hours on those days. By this time, there had already been regular and widespread power cuts across the country.

Services deemed essential, such as hospitals, supermarkets and newspaper printing presses, were given exemptions, but television companies were required to cease broadcasting at 10.30 at night in order to conserve electricity, although this restriction was dropped after a general election was called over the issue, with the government emphasising the pay dispute with the miners with the election slogan "Who governs Britain?". The phrase became conspicuous by its failure. The public gave their answer, and after a change of government, the restrictions were lifted on the 7th March 1974.

Regular power cuts, thankfully, now seem to be a thing of the past, but if anything we are now even more dependent on a regular and dependable electricity supply than we ever have been before. Industry is completely dependent on this, as are vital public services such as hospitals and street lighting, and this dependence has only been further heightened by our increasing reliance on the internet to keep our services running.

The Key Components of the National Grid Infrastructure

The National Grid infrastructure consists of approximately 4,500 miles of overhead power lines, over 900 miles of underground cable and over 300 substations. In addition to this, it also has gas pipelines, interconnectors and storage facilities to ensure that energy supplies are regular and reliable.

The Environmental Considerations of The National Grid

The environmental considerations of the National Grid have always been many and various. In its early days, there was considerable resistance to covering parts of the countryside. In 1955, future poet laureate John Betjeman wrote the poem Inexpensive Progress, which began with the haunting lines;

Encase your legs in nylons

Bestride your hills with pylons

O age without a soul

The construction of pylons was unavoidable. There was–and there remains–no other way of guaranteeing an electricity supply that is remotely feasible. But while we have largely accepted huge electricity pylons as an inevitable consequence of progress, other environmental considerations have arisen for the National Grid in recent years which have changed the way in which it works.

The Climate Change Act 2008 has been the key driver behind this change, imposing a legal duty on the Secretary of State to ensure that the net UK carbon account is at least 100 per cent lower than the 1990 baseline by 2050 or, as it’s more commonly known, ‘Net Zero’. This means that, by 2050, all UK GHG emissions must be balanced by schemes to offset an equivalent amount, such as planting trees and using technologies like carbon capture and storage (CCS). In other words, the UK must complete its transition to a net-zero GHG emissions economy by 2050.

Sustainability and renewable energy integration are at the heart of these changes. These include subsea electricity interconnectors, wind and solar power projects, competitive electricity transmission, liquefied natural gas, and battery storage. Investment has also been made into emerging technologies such as hydrogen, which it is hoped will play a key role in decarbonisation, as well as batteries and other energy storage systems that can store unused energy and save it for later use. This policy has already borne fruit. In 1990, the proportion of our electricity to come from low-carbon sources was 22%. By 2022, this proportion had risen to 41% and was set to overtake fossil fuels; it’s a third higher than China and almost double that of the USA.

Challenges Faced by The National Grid

The future challenges faced by the National Grid are a combination of the always-present pressures of delivering a completely reliable system, mixed with the further moves towards a more sustainable future and the threats posed by those who would seek to disrupt or destroy it.

It is important to continue to invest in the renewal of the Grid. While the operating lifetime of power lines is not eternal and the renovation or building of new power lines is costly, there is a constant need to increase its capacity. Maintenance and ensuring that demand can continue to be met is costly and critically important.

The digitalisation of the energy sector has its side effects as well. In 2014 James Arbuthnot, the chair of the government's defence select committee, told a conference in London that, “Our National Grid is coming under cyber-attack not just day-by-day but minute-by-minute.” A science and technology select committee report published the following year called “The Resilience of the Electricity System” stated bluntly, “While we note that the Government is taking action in this area, we are concerned about the threat in the medium term as the electricity system becomes increasingly reliant on fast communication, on data, and dependent on automation.”

It isn’t just cyber-terrorism that the National Grid needs to contend with, either. Although an attack on food sources or other vital supplies can cause major issues and panic in society, with today's transport options the situation can be solved relatively quickly. On the other hand, damage caused to power lines can take much longer to repair, meaning that those charged with the responsibility of keeping it running have to be both proactive and reactive in their approach.

The Future of The National Grid

The Grid’s future cannot be separated from sustainable energy. Central to this is ‘the great grid upgrade’. Described as “the largest overhaul of the electricity grid in generations”, this upgrade will enable the electricity grid to carry more clean energy to communities in every part of England and Wales, with the aim of reaching net zero more quickly than is currently forecast. It is intended to better connect clean energy that’s already being produced in the UK, increasing the self-sufficiency of energy supplies.

A close eye also needs to be kept on changing trends in the way in which we use electricity too, in order to maintain that supply. Electric vehicles, for example, have increased hugely in popularity, but more widespread use would substantially increase the pressure on the grid. After the eye-watering price increases of the last couple of years, the importance of maintaining its overall efficiency has never been greater.

Maintaining the National Grid is a balancing act, ensuring electricity supply meets demand second by second, hour by hour, day by day. And while we may not even notice it, it can be said with absolutely certainly would if it wasn’t there any more. There will be difficult decisions to be made about the future of our energy use in the years to come, but the National Grid, one of this country’s great infrastructural achievements of the 20th century, should be as well-prepared to deal with these challenges as any other in the world.