I saw an advertisement recently for the film ‘The Current War’ which set me off thinking about why we are still using alternating current or AC in our homes and businesses when actually what we need is direct current or DC power. While I recognise that this is a function of the century old ‘war’ between Thomas Edison (DC) and Nicola Tesla and George Westinghouse on the other side, it is my belief that Thomas Edison was right, and that DC will win the next War of the Currents.
Going forward, I see three drivers pushing us further towards DC:
1.Ongoing digitalisation of the world. The fact is that all digital devices, be they an iPhone or a Google server, require DC power. Currently, the AC power coming into homes and businesses needs to be converted into DC which is why electronic devices have small transformers either built into them or attached to the power chord. This trend to DC is already well underway in our homes and in fact I counted only two rooms in my house, the kitchen and the washroom, that have AC devices. Even our lightning today in the form of LEDs requires DC power. At the commercial level, it is even more apparent with companies like Amazon, who are among the biggest power users in the world. They are leading the way by moving directly to DC power, saving them both cost and energy, noting that some 5-10% of bought power is lost through converting grid power in the form of AC into DC.
2. Decreasing costs of decentralised solar and energy storage. In many parts of the world it is already cheaper to use solar power rather than buy it from the grid. However, the problem with this low-cost power is that it is DC which means an inverter is needed to convert it into the AC power our power system needs. The other issue is that solar power is intermittent which is where going forward, cheap electrical storage in the form of batteries and maybe even hydrogen (and related fuel cells) comes in. Given that they all use DC power, it may make economic sense to get rid of the complex and expensive power electronics and just go DC. This is particularly the case in places like Africa and Asia where they may take a big technical leap forward by doing so.
3. The electrification of transport. The final nail in the coffin for AC may well come from the electrification of the automobile. As it currently stands the battery can be charged with AC power, but it is generally slow as a heavy and expensive onboard charger is needed to convert that power into the DC power that the battery requires. The far more efficient and effective way is to fast charge with DC, which is exactly what Tesla does and is also the main reason why charging such cars takes such a short period of time.
The first “War of the Currents” took place over a century ago. Thomas Edison was the major advocate of DC but despite him running a smear PR campaign to discredit AC by linking it to the dangers of electrocution and death, AC prevailed as the global standard for transporting electricity. But that was in the 19th century and as we now power through the 21st century, I am sure that the next war of the currents will be won by DC!