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The War of the Currents: Will Edison have the last laugh?

A bitter battle was fought more than a century ago to decide how our homes and our lives will be powered. The alternating current (AC) power system won the battle. Today most of our appliances are DC powered. What could be the tipping point when DC power system replaces the legacy AC power system?

To those unfamiliar with the first standards war, the early 20th century witnessed an epic battle to decide which form of current will become the mainstream current i.e. Direct Current led by the eccentric genius Thomas Edison Vs Alternating Current led by the industrialist Westinghouse supported by Nikola Tesla’s inventions like the induction motor and the transformer. The battle was fought in the full public glare with animals being electrocuted and enough reputation and money at stake because like the Game of Thrones it meant either victory or death (figuratively of course).

Ultimately the technically superior current of the time i.e. Alternating Current won. This victory was on full display in the 1893 Chicago World Fair where Westinghouse’s lighting system was on full display to the world. The victory was possible because alternating current using Tesla’s transformer could be stepped up to a higher voltage and thus transmitted to longer distances. Thus huge central power generating stations could be setup with a transmission network to distribute power to the far reaches of human population. It also ensured monopoly profits for the companies which setup the huge power infrastructure giving them almost assured returns on their capital. With the invention of the induction motor, it also meant that the consumers could directly consume the alternating current to make their lives comfortable. In the age of the analog devices all our appliances were thus powered by the ubiquitous alternating current.

The Monopoly of the Grid

Edison though the genius he was, had relied on distributed power generating stations as that would minimize the transmission losses for the Direct Current over the short distances. But what it entailed was setting up multiple stations at different locations which at the time was expensive. The alternate was to setup large single alternating current generating system enabling huge economies of scale and setting up a transmission and distribution infrastructure to deliver the power to the remotest corners. Well the consumer was at the mercy of these huge power generating and distributing companies, but what alternative did she/he have?

The 21st century with its huge advancements in electronics and distributed power generation has opened new vistas previously unthought of. Further with the focus on climate change and the need for renewable energy and an energy efficient economy we might need to reimagine our complete power infrastructure and the appliances we use.

The Digital World runs on Direct Current

Let’s consider the appliances we use. Most of our electronic gadgets are using transistors implying they run on direct current. We have largely transitioned from the incandescent bulb to light emitting diodes (LEDs) which are again running on direct current. With the brushless direct current (BLDC) motors we can soon have our complete cooling systems running on entirely direct current. But with our current power infrastructure designed for alternating current that requires converting the AC to DC this means an inefficient system as current is wasted during conversion. Unless this legacy infrastructure is updated for direct current.

Decentralising the Grid

With solar generating systems cost reducing to conventional energy generation costs or grid parity levels this has become a real possibility. We are today in a world where solar generating systems can be setup by retail customers giving them partial independence from the grid. With further developments in battery technology the day might not be far where we can have complete decentralised power generating systems as originally envisioned by Edison. Advancements in power electronics has made high voltage DC possible allowing for even large central solar generating systems to directly transmit DC current over large distances.

There are thus two major alternatives shaping our power infrastructure. One is between mass scale adoption of DC power at the national grid level using large solar and wind farms. Alternative is setting up micro and mini grids making power much more decentralized. Once our dominant current is DC then the obvious logical implication will be mass scale adoption of DC appliances. So what would be the trigger or the driving factor for either alternative?

The Tipping Point

It was for a while thought that data centers consuming huge amounts of electricity would be at the forefront for the large scale adoption of DC power, since they incur significant conversion losses from AC to DC to AC for the UPS systems. Though significant efficiencies can be achieved grid level adoption hasn’t yet happened.

The tipping point could be when we replace the combustion engine with the electric engine. And the most efficient electric engine is the BLDC or the Permanent Magnet Synchronous Motor. The adoption of the e-vehicle running on the BLDC motor powered by the direct current stored in energy dense batteries would change the way we live our lives. DC power system would literally power how we live and where we live. There would need to be a massive charging infrastructure for these e-vehicles and to maximise efficiencies DC power transmission from source to sink would need to be envisaged.

Evolution by Technology

High Voltage DC and Ultrahigh Voltage DC have made DC power transmission over long distances a reality. China is already setting up these energy superhighways over thousands of kilometers. It is already feasible to setup mini and micro grids to ensure more reliable and cost effective power without the need to invest in massive transmission and distribution networks. Perhaps as storage systems become more cost effective, thus allowing us better peak demand management we will see a complete transformation of our power infrastructure.

Can we have a world running purely on direct current powered by solar and wind energy stored in batteries at the grid level and/or at the retail level? I believe it is very much achievable. It will mean a pure decentralization of power in the hands of the consumer. But perhaps as history has taught us to ask this question - will it be more economical? With the efficiency achieved in energy consumption and the reduction in costs of setting up and maintaining such huge centralised transmission and distribution infrastructure it might very much be possible. Edison may have lost the battle a hundred years ago but he might very well win this war ultimately!


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