You may have heard of the “war of the currents”, a battle waged in the late 19th century between Thomas Edison and George Westinghouse over the dominant system for transmitting electricity. Nikola Tesla’s technology formed part of the fight. Stray animals were electrocuted. And the ground was laid for a feature film starring Benedict Cumberbatch as Edison.
It also laid the ground for the transmission systems in today’s electricity grids.
The history of electricity grids is littered with a range of other fascinating facts. For instance, early electricity generation was surprisingly green: In 1900, 40% of the world’s electricity came from hydropower compared with about 15% today. That meant that the valleys of the Swiss Alps were one of the early cradles of the electrical industry, because of their abundant hydropower resources. A long-term consequence of this is that Switzerland has long had the most electrified railway system in the world.
Early electrical power was also predominantly DC (direct current), which is the kind of electrical power you get from a battery. As the name suggests, the current flows in only one direction. Modern electrical grids, by contrast, use AC (alternating current), which flows first in one direction, then the other.
That’s because the voltage of AC power can easily be transformed up and down – which is needed as high voltages are a lot easier to transmit efficiently over long distances, while much lower voltages are needed for safe domestic use. Main transmission lines in the UK are 275,000 volts while domestic use is 240 volts. This is also why we have transformers and substations dotted around the country. You might have noticed that many electronic devices in your home such as computers and TVs use DC, which means they need built-in voltage rectifiers. But the ease with which AC can be transmitted over long distances makes all this worthwhile.
In the beginning, there was light
To see how we got here, we need to go back to the 19th century. The Victorian era was a time of breathtaking technological change. At the beginning of the 19th century, most people in Europe lived lives the Romans would more or less recognise. By the end of that century, the streets were traversed by electric trams, and people could make international phone calls, ride escalators, visit cinemas and drive cars.
The rapid development during the second half of the 19th century owed a great deal to electricity. At the Paris Exposition in 1878, electric arc lights powered several streets. Soon, dozens of cities had arc lighting. This was high voltage, used AC and produced very bright light – but it was too dangerous for domestic use. In 1879, Thomas Edison demonstrated his incandescent lightbulb (he did not, contrary to popular belief, invent it). This used DC but at a much lower voltage (110V), which was suitable for homes.
Edison threw his weight behind DC and domestic electric lightbulbs quickly became widespread in cities. But the problems with DC also became apparent. Because it was harder to transform the voltage, transmission distances were limited to a few miles and small generators needed to be located near end-users. Moreover, industry, which used higher voltages, required different generators to domestic users. This was extremely inefficient and many cities in the late 19th century were festooned with spider webs of electrical cables, all carrying different voltages to different end users.
AC v DC in the ‘war of the currents’
The earliest sizable AC systems were built in Italy, followed by the UK. But the real story took place in the US – as the so-called “war of the currents” commenced. Thomas Edison was Team DC and George Westinghouse and Tesla were Team AC. Westinghouse had licensed several of Tesla’s key AC patents. Dirty tricks abounded with Edison’s associates electrocuting stray animals with AC in public exhibitions to demonstrate how dangerous it was. But ultimately AC simply had too many advantages.
In 1893, Edison’s General Electric bid to electrify the 1893 World’s Fair using DC for $554,000, but Westinghouse countered that he could do it for $399,000 using AC and won. Later that year, Westinghouse won the contract to generate power for Buffalo, New York, using hydropower from Niagara Falls, 26 miles away. After this the die was cast. DC slowly withered.
Centralised grids take shape
As the 20th century progressed, power grids grew and were connected into larger grids, standardisation took place and transmission voltages rose, increasing efficiency. In 1935, the UK’s National Grid became the first integrated national grid in the world. It was built around coal-fired power stations in the UK’s industrial heartlands, transmitting power to the rest of the country. It was supplanted by a 275kV supergrid in 1953. Meanwhile, subsea cables connected the British and French grids in 1961.
While power for integrated national grids was largely generated by fossil fuels – in 1960, 90% of the UK’s electricity was derived from coal – there were other energy sources. The first nuclear power plant was connected to the USSR’s grid in 1954, and the UK’s first commercial nuclear power stations were commissioned in 1962.
The UK’s first windfarm was completed in Cornwall in 1991. Less than 30 years later, in 2019, more electricity was generated from zero carbon sources than fossil fuels. The following year was Britain’s greenest year, with 68 days of generating electricity without coal.
Renewables and a return to decentralised generation
In recent years, as the world has shifted to cleaner and more sustainable energy from renewable sources such as wind and solar, we have seen a shift back to more decentralised local power generation. For instance, solar panels on roofs can sell energy back to the grid, while the intermittency of solar and wind power has increased the need for stored sources of energy, such as batteries, for the grid to draw upon.
Solar panels produce DC electricity and so they need inverters before they can export power to the grid. The connection of these microgenerators makes for a modern grid that increasingly recalls the early days of DC generation.
Companies such as Iberdrola are supporting these increasingly decentralised electricity grids and using artificial intelligence and digital solutions to model new demand and generation scenarios, which promote flexibility.
While the grid of the future may look more like the early grids, albeit with efficient AC, not DC, the DC story has an interesting ending. Particularly in US cities that electrified early, it took a long time for DC to die out entirely. The US company Con Edison maintained a small DC power station in New York City until the 21st century. This served some of the last vestiges of New York’s original DC power system until 2007 when it was finally taken offline.
It goes to show that the story of the electricity grid is one of constant reinvention. As decentralised generation and renewable sources of energy take centre stage once again, this time AI will play an integral part – proving the evolution of the electricity grid is far from over.
