What "one power source" do you think they're arguing against? The person you're replying to has noted that renewables are diverse and abundant, while refuting the notion that coal is important to the US because of its abundance because it's less abundant than many other sources of energy.
I think the counter argument is that renewables are never going to replace coal/oil/gas completely as there will always be the boogey man of “what if there is no wind/sun”. Having a small amount of fossil fuel based capacity in reserve would make a huge difference politically and of the options, coal is probably the best for that.
It is less environmentally damaging than maintaining fracking operations for oil/nat gas, extremely abundant in the U.S., and can be spun up or down on the order of hours so emissions can be kept minimal when plants are not needed.
What sort of earth has no sun or wind but bags of coal, which has to be dug up, transported and burned?
Sun and wind are different to coal and oil as power generation sources, however oil n that are finite and diminishing. OK so they probably won't run out in your or my lifetime but that is hardly "never".
Totally fair and I agree. But what about between now and eventually?
Eventually renewables will be all we use and eventually fossil fuels will no longer be needed. But between now and eventually, maintaining backup capacity is necessary and coal is probably the best option for that for the continental U.S. Nuclear only works as a base load, fracking/oil has even worse side effects, fusion isn’t ready, and we don’t have much untapped hydrothermal/geothermal
Coal is certainly not the best option for the continental US. That would be natural gas. Natural gas can be burned directly in combustion turbines with a fraction of the capital cost of a coal burning powerplant. They are also faster to turn on/off, being basically jet engines.
Most natural gas in the U.S. comes as a byproduct of fracking oil, which imo is worse than coal as reserve power because you have to maintain fracking sites and usually pump a fair amount of oil and briny water alongside the gas. Coal is easier to mine in small amounts afaik and has less local harms (e.g. water contamination, earthquake risk, etc.).
Fair enough, but bear in mind that "solar" effectively created coal and oil! We don't need a backup as such - but the renewables need a bit more time. We have burned oil for millennia. Solar is only about 50 years old.
I still drive a petrol (gas) powered car and even when I eventually get my eye wateringly expensive electric car, I might have range issues, despite living on a small island group off of Europe - the UK.
However, that new car (with loads of plastics etc etc) will run on unicorn farts ... electricity. What generates that 'leccy is another matter too.
You and I cannot change the world but we can at least point ourselves in the direction that we would like it to go. For me that would involve less fossil fuels.