Electric Well Completion equipmentI wasn't aware of this technology when it was mentioned in a post. So I looked it up and indeed it has been in development since 2014 and is commericially available. US Well Services and Evolution Well Services are the main manufacturers of the equipment in the US. They cite advantages of more precise control, lower noise levels, lower equipment costs. The main cost reduction of course is using natgas as fuel which also lowers emissions to a fraction of diesel emissions.
In TCWs case the company has been on life support since about 2015 and they couldn't even think of upgrading their fleet until revenues are substancially higher than now. TCW announced a deal with Cummins where they will be upgrading the fleet with natgas engines rather than diesel. This will reduce fuel costs and emissions but doesn't address the other advantages claimed by electric driven frack pumps. There could also be some disadvantages to electrics.
US Well Service and Evolution both have informative web sites