The flow of the future

I had a day without electricity to think about power storage. True to my personal motto “every problem has its own solution” I don’t think Li-Ion-batteries are the fit for any energy storage topic.

Actually, since Lithium is a rare resource, I’m not really impressed by Teslas energy storage “farm” (e.g. in Australia). We already know that for all the batteries needed, it will be really challenging to get all the Lithium. At the moment Lithium batteries have a good energy storage to cost ratio and a high energy density. Especially the latter is an essential feature for batteries in cars or other vehicles.

For stationary/grid storage, however, energy density per weight is not so much of an issue. From my point of view, other factors become more important: Long life of the installation, low fire risks, available and non-hazardous substances are the three factors, which come to my mind first.

There are various storage ideas out there and I think, everyone should be investigated further. As you know, my motto is "every issue contains its own solution". If we focus too much on just one path, we may lose critical innovations into the future.

My favourite though, since the technology is pretty advanced, are Redox flow batteries. The main feature is, that you “load” one liquid chemically with the electrons from a second liquid. With unloading you just reverse this process. The more energy you want to store, you just have to scale the tank size.

The principle was developed in by the German scientist Walter Kangro in 1954 and then NASA tried in the 70ies to make this not only a scientific, but also real-world technology. But it took another scientist to really make it work. This scientist was Maria Skyllas-Kazacos.

While I normally summarize the life of the researchers, this time I want to take a different approach. I found a really inspiring interview with her online. It is a honest discussion about migration, how life “happens”, doubts about your own capability, being a woman in science, having a supporting and challenging superior, becoming famous overnight and much more. It is a little bit longer and we all havn't the patience for articles longer than 5 minutes any more. But I still encourage you to get a cup of coffee or tea and read this one yourselves:

Researchers as Maria are the ones which inspire us to be the best version of ourselves.

So, she found a new Anolyte/Catolyte-System based on Vanadium in the mid 80ies. It uses the fact, that Vanadium can exist in different oxidation states (as can seen in the picture on the right). Today the Vanadium redox flow batteries are the most advanced and common ones.

But there are new ideas to improve flow batteries out there, e.g. by using organic/polymer systems as electrolytes (as in the title picture by PNNL, one electrolyte containing methyl viologen and another with 4-HO-TEMPO, both inexpensive substances).

Of course, since polymers are my passion, I’m really interested, if this works out.

However, I strongly believe that the redox flow batteries will have their application in the future, where we need to store the green energy in smart ways to meet the goals of a sustainable (carbon zero) economy. In a future, where we still can enjoy the benefits of electricity without shortages.

PS: If you are interested in a “in depth” information about redox flow batteries, here is a nice academic presentation: