Useful wasteland
Solar energy from the desert
Have you ever wondered how much energy the sun sends to our planet every year? The amount is unimaginably large: 1.5 x 10¹⁸ kWh. That is written out 1 500 000 000 000 000 000 kWh.
The consumption by mankind is currently at about 21 000 000 000 000 kWh per year. This means that the sun is sending about 7000 times more energy to the earth than we humans need.
If that doesn’t make you feel positive about the future of our energy supply, what does? Now, the pessimist might object that much of the earth is covered by water, and therefore we can’t use much of the sun’s energy at all. That’s right. However, the surface of the Sahara alone is 9 million km², compared to the Earth’s surface of 510 million m². This means that the surface of the Sahara corresponds to about 1.76 % of the Earth’s surface, which in turn corresponds to 2.64 x 10¹⁶ kWh of solar energy falling only on the Sahara. That is still 1257 times the amount of what humanity currently consumes per year. I think I have made my point. The amount of solar energy falling on the Sahara alone would be enough to easily meet the world’s current energy needs.
How far have we come technologically?
Of course, we still have many hurdles to overcome. For one thing, our current photovoltaic technology does not have an efficiency of 100 %, which I have assumed in the model calculation above. (This would mean that we could obtain 100 % of the solar energy for ourselves). Nor will this ever be completely possible. It could be that the photovoltaic cell converts 100 % of the solar energy into electricity, but due to line losses, losses in the inverter, etc., the efficiency of a system will never reach 100 %. However, I am optimistic that future developments can/will take us to a very high level. The current commercially available photovoltaic cells have an efficiency of about 20–22 %. The latest records from the laboratories of scientists reach an efficiency of 47.1 % under special conditions, such as concentrated light irradiation. In the case of thin-film photovoltaic cells, an even higher record was set under monochromatic light: 68.9 %.
We must stand together as planet
I am optimistic about the future of photovoltaic cells and the future of energy supply. The potential is immense, not only that it will allow us to generate electricity in an almost CO2-neutral way, provided that the production of the cells does not involve environmentally harmful resources and materials, but that the price of energy will also drop enormously.
But let’s come back to the amount of solar energy that hits the surface of the Sahara. Compared to our current consumption, it is so enormous that even with an efficiency of 20 % there would still be enough energy. So, the discussion about efficiency is not purposeful in assessing whether photovoltaics is useful or not. It already makes sense and with further development of the technology it will only become more obvious. Even if the photovoltaic systems are located far away, with this amount of energy, transmission losses are irrelevant. There is enough energy available.
How about a “moon project” like Apollo 11, only with photovoltaics and on Earth?
Technologically, the example shows that this is the least of the problems. The far bigger problem is that the nations of the world would have to unite. What I mean by this is that while there are deserts on almost every continent on earth that could be used for such a project, not every country has them. Therefore, countries would have to support each other and share. In this I see the much bigger problem, that again individual nations are not exploited and taken advantage of. This must be a joint effort that could bring us closer together in the future.
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