The field of energy storage is extremely active with a constant stream of innovations being deployed to address some major design challenges. At the heart of this activity is the commercial drive to increase energy density (energy stored per unit mass), extend battery life and improve overall charge/discharge efficiencies in order to reduce unit costs and enhance product reliability. While great progress has been made in the last decade, certain industries still have a long way to go.
Invinity to build 20MWh flow battery in UK
A surprising comment for someone who (I think you´ve said in the past) worked in the industry. National Grid have a variety of reserve service schemes...