A common complaint from those opposed to renewable energy is that the technology is intermittent, thereby requiring the use of conventional fossil fuel plants as backup. However, energy storage technology can now address these issues thereby enabling renewable energy development to advance efficiently and at reduced cost. In the forefront of this technology is the vanadium flow battery.
A vanadium flow battery is a battery that uses a vanadium solution, consisting of vanadium mixed with another element such as sulphuric acid or bromide, as an electrolyte. Vanadium is a metal commonly used in the steel industry and is also widely found on waste tips of old mine workings, fly ash tips and so forth. The Canadian tar oil sands in Alberta produces masses of the stuff and that means there is a readily available supply of it.
One apparent drawback of vanadium batteries is that they are fairly bulky, although they are based on a simple design which makes them robust and cost effective. However, they can also be charged and recharged very quickly, thousands of times per year without any impact on their lifespan. They only need one electrolyte, rather than the two needed in conventional batteries and they also have almost unlimited capacity due to the design being based on a liquid storage tank rather than a cell. This means they are ideal for deployment with large renewable energy plants such as wind farms and solar farms.
“Flow batteries allow you to separate the power and the energy, so if you want more power, you just add more stacks” explains Tim Hennessy, President and Chief Operating Officer of Imergy Power Systems, a company based in California, USA. “If you want more energy, you just add more liquid into the tank, a bit like adding petrol to a fuel tank in a car in a sense.”
Vanadium flow batteries can also respond extremely quickly to load changes. The University of New South Wales found they can respond to a 100 percent load change in under half a millisecond, meaning that they are ideal for frequency regulation. The batteries can average out the generation of variable electricity enabling them to cope with large surges in demand. They can level out supply and demand in regions where energy is constrained, particularly in developing countries such as India and some of the African nations. Imergy will have about 200 systems installed in India by the end of this year with a similar number in Africa.
Most of those Imergy systems will be deployed in hot rural areas. While lithium ion can fail or even explode in hot temperatures, vanadium flow batteries can operate in areas where conventional lead acid or lithium ion batteries can’t.
The big advantage of using vanadium flow batteries in countries such as the UK, where the energy mix includes a wide variety of different renewable and conventional technologies, is that they give 5 to 10 hours of storage, can last store or provide energy through the night or cover for wind in areas where the wind speed falls and provide cover for possible outages. The levelling effect also eliminates the requirement for centralised generation while its efficiency and low cost will also have a positive effect on the overall levelised cost of electricity (LCOE).
Vanadium flow batteries are already being installed in countries all around the world, from Japan to Scotland. As their potential is increasingly recognised and exploited by developers, we can only expect this level of growth to increase even further.
I am an experienced freelance journalist with a wide and varied portfolio to my credit including web content, magazine articles, reporting, features, interviews, reviews and blogs. My special interests include environmental issues, particularly climate change, renewable energy, transport, green building and sustainable infrastructure. I have numerous secondary interests ranging from politics and current affairs to social justice, science, technology and innovation, historical topics and lifestyle subjects such as literature, psychology, contemporary spirituality and culture.