So you want green power? Read this...

I’m doing a bit of light reading this afternoon. (Well, it’s actually a hefty volume that weighs about 4 kilograms.) HVDC Power Transmission Lines Book is an Eskom publication from November 2021 and a copy has landed on my desk, courtesy of one of the principal authors.

If you’re wondering why on earth I would be interested in High Voltage Direct Current transmission; and — more importantly —why you should care, let me give you some bullet points.

1. The most important science throughout human history is logistics. Steve Jobs was a visionary who designed great products, but Apple only became a multi-trillion dollar company thanks to the genius of Tim Cook. See, Apple’s true business is the ability to produce a billion iPhones in China and deliver them to 517 Apple Store locations around the world for a simultaneous product launch on a single day in less than a month.
2. Electricity is all about logistics. Producing electricity is the easy part; put a hamster in a treadmill with a magnetized axle surrounded by a coil of wire and you can charge your phone. Generating gigawatts of power across multiple locations and automatically rerouting that power to where and when it is needed? That’s logistics.
3. There are essentially four pieces that make up the business of electricity, Power stations generate electricity. Substations step voltage up or down to match the grid (because every single contributor to the grid has to be generating the same 3 phase alternating current voltage synced to the same frequency). Power lines carry the electricity across long distances. Distributors take the bulk power and deliver this to customers via a network of substations.
4. The key to solving energy and weaning us off fossil fuels is the ability to generate massive amounts of electricity and deliver that to where it is needed. The further the distance to be traversed, the greater the capacity of cables needed and the greater the loss of power. To deliver power directly from Koeberg near Cape Town to the Gautrain depot near Johannesburg would require 3262 tons of cabling at a cost of roughly US $250 000 per kilometer. Also, there is roughly a one percent loss of power per every 160km.
5. Now consider the logistics of creating massive offshore windfarms on the Atlantic seaboard, coordinating the cabling the output of those farms together, syncing that power to the grid, and then delivering it to where the country needs it in the Highveld.
6. The beauty of High Voltage Direct Current transmission is that one requires only one cable for every three High Voltage Alternating Current (HVAC) cables currently in use. One-third the cabling => one-third the cost.

As I said, light reading.