Electricity to gas conversion has terrible efficiency. 30-40% for the electrolysis and Sabatier process, and then ~50% efficient for the gas combustion engine. Net efficiency is in the 20-25% range. Hydroelectric storage is geographically dependent. Most of the US is in flat terrain.
California said they would do solar and wind plus storage. Then they realized storage was not possible, and they used fossil fuels instead. Similarly, Germany closed down their nuclear plants, saying they'll build intermittent renewables plus storage. And then they ended up building fossil fuel plants when they realized storage could not fulfill the base load they lost from closing nuclear plants.
If most of the energy consumption is supplied directly, the storage part need not be overly efficient as long as it can cover the slack. 40% seems good enough. Even 20% is workable, if need be, just need to over-provision enough PV / wind and the over-provisioning itself significantly reduces needed storage.
If combined with capacious long-distance electrical grid (e.g. HV DC), load scheduling, high-uptime offshore wind, some PV in deserts, maybe thermo-electric solar, some batteries for rapid load following, etc, we really can supply enough power even with 0 coal, gas and nuclear power plants, and it wouldn't even bankrupt us. All we need is will. The technology is already sufficient and with improvements it won't be even that hard.
For example, one estimate is that for Germany to rely on solar and wind would require about 6,000 pumped storage plants which is 183 times their current capacity:
>...Based on German hourly feed-in and consumption data for electric power, this paper studies the storage and buffering needs resulting from the volatility of wind and solar energy. It shows that joint buffers for wind and solar energy require less storage capacity than would be necessary to buffer wind or solar energy alone. The storage requirement of over 6,000 pumped storage plants, which is 183 times Germany’s current capacity, would nevertheless be huge.
https://www.econstor.eu/bitstream/10419/144985/1/cesifo1_wp5...
The problem isn't "can't". Storing energy is trivial. The problem is cost. How much storage is required, and how much will it cost to build it, and how much will that make the total cost of a new energy system?
All this "can't" stuff is, frankly, reactionary bullshit by some very emotional people who are rather in love with the idea of nuclear energy. That's why you never see hard numbers attached to it.