The Electricity Grid
Before electricity there was gas to provide heating and lighting. This was predominantly producer-gas, a mixture of carbon-monoxide and hydrogen, reticulated through pipes from a gasworks. And so, with the advent of the dynamo, early electricity grids were similarly represented, to the degree that people often turned-off switches to prevent the electricity leaking into their homes.
Now most people know that electricity is fundamentally different. Whereas gas is a fuel in itself, electricity is nothing but an energy transmission medium. In addition, it requires a completed 'circuit' to flow. Albeit, that this could incorporate you, as a component.
The Current Wars of the 1880's
In the United States, Thomas Edison, wanted to commercialise his electric light bulb as a competitor to gas lighting. So, initially, the Edison Electric Light Company used coal-fired steam engines to spin German dynamos, to provide low voltage (110V) DC electricity to supply his incandescent lighting customers. This required many small local power stations (deriving their energy from fossil fuels), as the low voltage and resulting high currents heated the distribution cables, losing energy, and limiting the practical range to a few tens of miles.
His local competitor, George Westinghouse, would acquire the US right to European (British/Italian) technology that overcame the distance problem, using AC at relatively high voltages (3,000 to 5,000VAC) limiting the current (see above) and extending the range. These voltages facilitated electric arc lighting, used in large public spaces, but which was unsuitable for domestic use.
In the, now familiar manner, transformers, also invented in Europe, were used to step-down the voltage and the step-up current near the consumer. These brought Westinghouse into direct competition with Edison. A brilliant engineer, employed by Westinghouse, would improve transformer design, such that (for small single-phase transformers) it has hardly changed ever since. Although, switch mode (electronic) power supplies have replaced many small transformers in the past four decades.
Edison claimed that this high voltage AC distribution was extremely dangerous and electrocuted a number of animals to demonstrate his point. It was indeed dangerous, as the high-voltage lines were mounted on the same poles as the telegraph. A telegraph lineman, John Freeks, was soon electrocuted, forcing the high voltage lines underground.
But unfortunately, Edison's design for an electric chair overestimated how instantaneously deadly Westinghouse's few thousand volts could be. It virtually burnt the man to death.
My father told the story of the notoriously bad-tempered man who collected the fares on a New York streetcar.
| One day, the ticket-collector lost his temper, yet again, he'd been warned several times, and angrily threw and old lady under the wheels of a passing horse-drawn cart. He was sentenced to the electric chair for murder. But after the third attempt to electrocute him, he remained unharmed. So, under the US Constitutional prohibition against 'cruel and unusual punishment', the Governor was obliged to grant him a pardon, conditional upon his attendance at an anger management seminar. An outraged reporter asked him if he had employed some trick, as he had requested specially imported red bananas for his last meal. "Was it those expensive bananas in your foul gut that saved you, you damn nanny-killer?" the reporter demanded to know. "No," came the man's calm reply (the seminar had worked), "I'm just a very bad conductor." |
But in the end, AC was here to stay. The Current Wars ended when Edison lost full control and his company, General Electric, became one of the world's great manufacturers of turbo-alternators and high voltage (AC) grid equipment. Seventy years later a subsidiary, Australian General Electric, would employ my father and put a roof over our heads.
In Europe a similar process was underway, advanced by the invention of arc lighting by Sir Humphrey Davy and the incandescent lamp by Swan (Edison's partner), first demonstrated in Newcastle in England; the modern transformer in Budapest; and the invention of three-phase long distance transmission grid in Germany.
I add these because many Americans and therefore Australians, seem to believe that electricity transmission and electric lighting were exclusively invented in North America. Yet it's true that the great American entrepreneurs certainly knew how to develop and commercialise an idea. See: The History of Alternating Current (an American perspective).
So, in Australia, we have a hybrid and our electrical engineers like to think it's the best of both worlds. For example, our very functional 240VAC domestic plug is actually an American design, well in advance of the various British equivalents, that has served us well for around a century.
During that time electricity became our predominant source of domestic; industrial; commercial; and increasingly, transport; energy and the electricity grid grew to become one of the largest in the world. Yet as a result of high levels of urbanisation, separated by vast distances, electricity distribution in Australia faces some unique challenges. See the Appendix: The National Electricity Market (NEM) for more details.
Like the managers of electricity grids worldwide, the Australian Energy Market Operator (AEMO), that manages the eastern Australian grid, has the task of matching supply to demand.
Electricity demand is extremely volatile. It varies greatly during a single day from hour to hour; it differs from day to day during a week; it differs from season to season; it's affected by the temperature and the weather; even by sporting matches other events; and what's on television. At one time most of this was quite predictable, so sufficient generators could be on standby or safely taken off-line for maintenance.
Yet a small but increasing number of solar and wind generators are unpredictable, at the whim of nature, so there needs to be a means of meeting demand peaks when it is dark and there is no wind and, conversely, when there is plenty of wind and the sunny skies are clear but little demand.
As a result of the NEM, when demand is low, and a lot of generators, particularly wind and solar are feeding the grid, the wholesale price of electricity can go negative.
On the other hand, when generation falls short of demand, the price per MWh can go very high indeed.
With a preponderance of wind energy, the spot price in South Australia often reached the $15,000 maximum this year, sometimes several times a day, while at other times the price went negative so that generators had to pay to dispose of excessive electricity.
These fluctuations provide a strong market incentive for storage providers, for example battery owners or pump-hydro facilities, to buy electricity at very low prices and sell it back at very high prices.
Therein the difficulty lies, storing electricity on a large scale, without significantly increasing its cost, is problematic.
