Prediction 2

In my new (self defined :-) ) role as a futurologist, I thought I should add my next prediction / suggestion of a new technology.

With the growth in renewable, sustainable electricity generation, particularly wind and solar, comes the problem of matching generation to demand.

Storage is the answer. Not small scale storage like a battery bank, but large scale storage. This is already achieved to an extent by such projects as Dinorwig Power Station, where off peak electricity is stored as water pumped to a high reservoir, then released through turbines during peak demand periods.
There are only so many sites where this kind of geography exists, what is needed is a large scale storage solution that can be placed at any location, preferably near to the place where the electricity will be consumed to keep transmission losses low.
One solution that is being considered, is storage of energy as compressed (liquid) air which is then used to power a gas turbine as the air is allowed to expand during periods of demand. This does seem like a good solution, but has inherent dangers due to the storage of compressed gasses, and technical difficulties due to the generation of ice during decompression.

Another solution that has been investigated (in New Zealand) is the large scale Redox battery. This works in a similar way to traditional battery charging, where energy is stored chemically in an electrolyte. In the Redox battery, electrolyte is 'charged' and then stored in a tank. Only a small unit is needed for the relatively expensive battery electrodes, but a large amount of electrolyte can be stored in relatively cheap tanks. The New Zealand system uses Vanadium.

This is the kind of technology I am interested in.  In preference to vanadium, I am investigating iron  as my storage chemical using activated carbon electrodes. The benefits of this medium, is its low cost, relative abundance and low toxicity. During my experiments it has also come to my attention that the charged iron slurry that is produced during charging of the battery can be attracted by a magnet, and pumped around using a pump constructed like a linear motor. The basic chemistry is that iron oxide is converted to iron in an activated carbon slurry using electrolysis. This can be pumped and stored in tanks. When electricity is required, the slurry is oxygenated to oxidise back into iron oxide. This acts as an iron air battery, creating usable electricity.

I'll write more on this when I have progressed further. Family calls :-)