/ 24 May 2016

We’ve captured the power of the sun and the wind, but where on earth will we keep it?

The installation of solar panels.
The installation of solar panels.

We are in the middle of the renewable energy revolution. Prices of solar and wind plants have plummeted in the past five years.

Entire countries are running for extended periods without using their coal-fired power stations. But the basic mechanics of nature are tricky: wind strength varies throughout the day and a sometimes shy sun enjoys hiding behind clouds.

Nuclear and coal power stations have an edge because they can provide baseload energy. But rapid advances in renewable energy storage are curtailing this rearguard action.

This process technically kicked off in the mid-1800s, when a French scientist invented the rechargeable lead-acid battery.

Humanity’s relationship with energy changed: instead of having to use it immediately, energy could be stored and used at a more convenient time.

This meant cars could carry around batteries, and people could use torches to see at night. That technology stayed pretty constant for the next 150 years. But it is inefficient and bad for the environment.

Now massive renewable energy plants – generating up to 3 000 megawatts of electrical capacity – are forcing the industry to evolve.

This evolution is the final frontier for energy. The objective is simple: create a battery that can store energy for long enough so that renewables can provide predictable energy all year long. Do that and the argument for other baseload energy types vanishes. But getting there is difficult.

The greatest challenge is the structure of global energy. Most of this is produced by big utilities. They build big power stations, and send their energy to where it is needed. In South Africa, this means coal-fired power stations in Mpumalanga keep the lights on in East London homes.

The growth of renewables hasn’t changed this. Solar farms in the Northern Cape still have to get their energy to Johannesburg. Moving that electricity around means a quarter is lost along the way.

It’s also expensive to build that transmission network – Eskom has had to take out a R6-billion loan so it can upgrade its transmission networks. This will allow power from renewables to get to where it is needed.

But small-scale energy will do away with the reliance on these large transmission networks; it will move energy from large utilities to individual households.

In even more localised forms, researchers for the United States Army are creating a system that harvests energy from each step taken by soldiers, which powers their equipment.

In Formula One racing, energy harvested from braking is being stored and then used to aid overtaking.

Going off the grid, once an idea reserved for ardent greenies, is now becoming part of local building regulation.

Efficiency measures are cutting out the waste in these smaller systems, and clever computers and smart grids are ensuring energy use is optimal.

That world is here, and the technology is making it mainstream.

Read about the storage technology making small-scale energy possible in tomorrow’s M&G Daily Edition

This is part of a series on renewable energy