Batteries are expensive and use toxic chemicals to make them.

A really encouraging technology to replace them called Vanadium flow batteries hasn’t fulfilled its early promise. I’ve been following this technology for about a decade. Some tiny changes to the acid used – adding 7 parts HCL to 2.5 parts sulphuric acid – seems to revolutionise the performance. Both in terms of adding 70% more power density and increasing the operating temperature range from previous 10 to 40 C to -5 to 50 degrees C.

This should make this battery type hugely more cost effective as they’ll no longer need a built in cooling system slashing the price to build them. This should mean smoothing out electricity production from renewables sources such as wind and PV cells becomes much more economic.

http://www.eurekalert.org/pub_releases/2011-03/dnnl-utv031711.php