Loosely to this thread, but how close are renewables to being cheaper than coal IOTL?
It depends on the meaning of the word cheaper.
Right now, all new generating assets except for geothermal are more expensive than grid power. That means it is generally less expensive to use whatever generating assets already exist than to replace them with anything new. Geothermal hasn't really been coming online to replace existing facilities due to legal issues, and since new power costs more than old power capacity is only going to be added to meet new demand or renewable energy requirements.
If you want to build a new facility, geothermal is the cheapest option in terms of levelized costs (total life cycle costs divided by total power production), followed by natural gas and wind which are very close in price. New hydro is a middle space, and then coal and nuclear are a step up and cost about the same. Everything else is very expensive. It's like this:
Geothermal: $40 per MWh range
Wind/Natural Gas: $70 per MWh range
Coal/Nuclear: $90 per MWh range
Advanced Coal, CCS technology, biomass, solar, offshore systems: over $100 per MWh
The really accurate data can be seen
here, and I can get you facility construction costs if you're interested in that too.
Among existing facilities that have been depreciated, hydropower is still the cheapest form of energy, followed by nuclear and then coal. Non-hydro renewables don't really have a service life beyond depreciation, they are more fragile than the hydro and thermal power stations that have been traditionally used. After 20 years you really need to replace one.