Last week, I advised that, at the Data Center Dynamics conference, in San Francisco, in the US, the following was reported: “At this year’s Data Center Dynamics conference, in San Francisco, speaker after speaker took to the stage to lament how utility companies refuse to provide even the largest corporations with the renewable energy they want.”

I explained in last week’s column that, unless there is a direct connection from the renewable-energy generator to the data centre, the renewable energy is generated into a power grid and the grid supplies the data centre. And, since the grid has many generators of nonrenewable energy connected to it, the grid power has only a fraction of renewable power in it. Further, since the solar renewables do not work at night and the wind power renewables do not work in still conditions, then, for an unbroken supply, nonrenewable power has to be accepted on occasion.

I asked the question: Is it possible, with an unlimited budget, to create a renewable-energy transmission system that will allow renewable energy to be fed into the grid at one end and to be supplied to a consumer at the other, without building a dedicated grid for renewable energy alone?

The answer is ‘yes’. How to do it? Well, some education: A harmonic is a waveform that is a multiple of another waveform. Harmonics can be odd or even multiples of another waveform. As an example, the third harmonic of a 50 Hz power frequency wave is a 150 Hz power frequency wave.

In South Africa, owing to the very many mines, there is considerable use of very large motors and electronic power system drives – for example, mine winders that hoist mining cages and ore skips up and down shafts, crushers, ball mills, et cetera. These generate third (and other) harmonics.

Now let us consider the average solar or wind farm. The average wind farm capacity is about 130 MW, normally made up from about 60 turbines, each rated at about 2 MW. The way to connect and transmit renewable power and nonrenewable power on the same power line is this: at each turbine, change the turbine output from 50 Hz to 150 Hz. Then inject this power (say “renewable power”) into the existing power system. The result will be a waveform that is a 50 Hz waveform, modified by a 150 Hz waveform. This is then connected to the grid. Then those users who want to use renewable power only can connect to the grid through a third harmonic pass filter, which effectively filters out the 50 Hz component (generated by nonrenewable generators) and leaves the 150 Hz components. This will then have to pass through a 150 Hz to 50 Hz converter, thus resulting in 50 Hz renewable power.

Cost: this system will be very expensive. A 2 000 kW frequency converter will cost about $200 000, a little over 10% of the cost of a wind turbine. At the supply end, the filter and converter will be about $150 000 for, say, a 1 000 kW supply.

Will it work? Yes. How do you connect the 150 Hz power to the grid? Ahhh . . . that is the question. While I deeply want to be of benefit to humankind, this does not extend to explaining to the world in general how one connects a 150 Hz source to a 50 Hz grid. If there is, out there, a company which is so dedicated to the planet that it wants to have a system such as I have described, then I am more than willing to assist but I would expect a fee to build a ‘proof-of-concept’ system and provide a design.

The crux of the matter is that it is possible to create a renewable-energy transmission system that will allow renewable energy to be fed into the grid at one end and to be supplied to a consumer at the other without building a dedicated grid for renewable energy alone. Very expensive. But possible.