Estimating the sustained demand and determining the deficient when the wind does not blow by examining actual data over a three month period, it is determined that lead acid batteries with a value of 40 Wh/kg for 300 GWh of storage requires 7,500,000 tonnes of lead acid batteries. Lithium-Ion batteries were also considered, but lead acid are currently most cost effective.
So the battery storage is some $60 to $90 billion to store the surplus energy from 4,000 MW of new wind farms with substantial running costs due to battery lifetime and erratic discharges .
Thus it appears we are a long ways from being 100% renewable energy for electricity. Inclusion of solar power may help some, but, massive amounts of storage capacity will still be required for a state like Texas.
For Georgetown to assert that it uses 100% green energy is certainly not true as there are no direct transmission lines between the wind turbines and Georgetown and there are no electrical storage devices to provide electricity when the wind doesn't blow! Georgetown needs to be honest with their citizens and visitors.