Ideal location: a desert with high sunlight hours and strong winds…

The Gobi Desert, spanning southern Mongolia and northwestern China, has these characteristics, and the potential for choosing different heights for power generation plants. It is already being studied with the aim of developing natural-energy power plants. Sun here is abundant during the day; winds reach peak at around 4 pm, but they are still quite strong at night, hence bridging the period when photovoltaic panels are inactive.

How could a renewable fuel plant work?

> Photovoltaic (solar) panels produce peak power during the day; the night is bridged via wind power.
> Electricity is used immediately for generating hydrogen and concentrating CO2 from the air.
> Hydrogen and CO2 are (using the plant’s own clean energy) synthesized into a range of chemicals, e.g.
– Methanol and methane for fuel and synthesis of chemicals and materials
– E-fuels, e.g. synthetic… kerosene for jet airplanes, methanol/gasoline for cars, and methanol/DME for trucks
> Heat released in synthesis reactions is used to drive capture of CO2 from air.

The materials produced can be easily transported/piped with existing technology to where they are needed….

We must make sensible compromises: no animal, including humans, can exist on Earth without an impact. We must reduce ours to the minimum. We can do this in the energy sector by using deserts where nobody lives, there is no agriculture, and biodiversity is relatively very low.

The products of the chemical syntheses range from methanol, through methane, to liquid fuels similar to diesel, kerosene or gasoline. It avoids a completely new storage and distribution infrastructure for pure hydrogen (greyed out in the figure below), and employs very inexpensive pipes and storage vessels. It is very easily up-scalable, and can store very large amounts of energy for very long periods without appreciable losses:

If we use pure hydrogen as a form of storable and distributable energy, we need a very large, costly and maintenance-intensive system of high compression, cooling and high-pressure distribution, which also has a relatively short life cycle (needs replacing/repairing more frequently than conventional infrastructures. To make synthetic CO2-neutral carbon-based fuels we also need hydrogen, but at much lower pressure: it can go directly into the production pathway without needing to be stored at minus 253 oC or distributed in very long and highly-specialized pipelines; instead it is used immediately, together with CO2 (captured from air or flue gases), to make fuel that is easy to store and distribute. The analogy with green plants is very strong: plants do not store hydrogen, rather they convert it immediately into carbon-based energy carriers.

Choice of location: Exploring the feature in more detail…

There are many largely barren areas on Earth that are suitable for EITHER photovoltaic OR wind power, and these are also attractive sites for power plants. Bridging of energy troughs between photovoltaic and wind power could be done non-locally via power lines. Many of these already exist as part of the normal grid, and enlarging its carrying capacity is a moderate challenge. A few places on Earth — largely on, or near, oceans — have such high winds throughout the 24 hours of a day that wind power alone could form a constantly-running high-output and high-efficiency fuel synthesis facility. A pilot plant already exists near Punta Arenas in southern Chile. This type of approach uses hydrogen from splitting water with electricity, and CO2 filtered from the air, or from industrial flue gases.

Why are sunny and high deserts so attractive for such facilities? The higher in altitude one goes, the less biodiversity one has to be careful of; also, in high deserts one generally has more wind, which is particularly important at night. The synthesis plant needs, for maximum efficiency, to stay active day and night. On the scale of a few hours, even small batteries may be a good solution to bridging the troughs in solar energy. In biological cells, the strucures called „mitochondria“ store electrical energy for very short-term use; for longer term use, i.e. via storage, and for transportation of energy, biology uses carbon-based substances.

Extent of fossil fuel replacement: An example…

If we envisaged all three types of location in the image at the start of this page, we could probably generate enough electricity to replace all current gasoline consumption worldwide. To do that, we would use less than 1% of the area of all deserts and largely barren, constantly windy places on Earth. Even better would be to reduce gasoline consumption drastically at the same time!

Further reading:

> Choice of optimal sites for desert-situated photovoltaic plants
> Potential for wind energy and photoelectric energy generation in Saudi Arabian desert
> Choice of optimal sites for wind energy generation
> How much of current energy demand could be satisfied by renewable energy plants in low-impact areas of the Earth?

Copyright Andrew Moore 2024