It's unfortunate that the issue of batteries vs. natural gas is made to be as controversial as it is. Both the advantages and limitations of the two are straightforward and well understood -- at least by those who are able to look at the issues objectively, free of a partisan "good guys / bad guys" mindset. 

The issues largely come down to cost of electricity vs. cost of carbon emissions as a function of scale. It's all about strategies for coping with the intermittency of wind and solar resources as the contribution of wind and solar resources to overall energy supply rises. 

If anyone were to assert that there's no need for battery storage systems in the power grid -- that modern CCGT power plants with flexible response capability are adequate to balance variable supply from wind and solar resources with varying load -- they might of might not be technically correct. They would certainly be wrong from a practical and economic point of view.  To start with, high efficiency CCGTs with the required flexibility are rare and expensive. For providing short term ancillary services of voltage and frequency support to the grid, large battery storage systems are superior to even the most modern gas turbine systems. 

At the same time, anyone who asserts that large battery storage systems are all we need to support 100% renewables is mistaken. Our best chemical battery technologies are still orders of magnitude too expensive for economical delivery of the amount of electricity that would have to come from storage in a grid of 100% renewables. Even if we were content to settle for 90% renewables, battery storage would still be too expensive. Nor would addition of massive additions of off-river pumped hydroelectric energy storage be an attractive solution.

The problem with energy storage as a solution for intermittency is that energy storage facilities are consumers, not generator of power. All of the electricity delivered from storage must necessarily have been generated previously from other resources, along with enough extra to allow for conversion losses. So in terms of system costs, you're looking at the cost of the additional renewable energy resources needed and the cost of the energy storage and conversion facilities, for the same end service that renewable plus backing generation could have supplied. There's zero added capital cost for use of backing generation. It's already in place. It's just a matter of using it more of the time, and sitting idle less. The operational cost is a bit higher, because of the fuel burned. And of course the cost in carbon emissions is higher. Unless one chooses to implement CCS.

What it boils down to, in a nutshell, is marginally higher cost of electricity vs. marginally higher carbon emissions. Regardless of how one weights the two costs, there will be an optimum balance that is neither 100% storage nor 100% backing generation. There's room, and need, for both.

Yes batteries are getting better and lower cost all the time. New sodium lron batterues showvthey are 1/4th the cost of great lithium cells.

    Tesla has also just shown the Socal GRID that virtual batteries are here and ready. They software enabled thousands of home solar Power Walls to provide just 2 ton8 kWh and saved GRID brownouts . They are signing up Texas home for this summer.