With specific subsidies, the area where they are less expensive is even larger.
Of course, fossil fuels receive considerable direct and indirect subsidies, further complicating answering the question "what's least cost?"
This is the received wisdom of the clean energy movement, but every report I’ve read says otherwise. Oil and gas receive little if no operational subsidies in most countries and in fact are heavily taxed at every stage of exploitation. Even government investments in oil and gas typically return far better than the risk-free rate, which is remarkable for government.
Of course there are some terrible externalities that we don’t price in...
Like securing our energy interests in "difficult" parts of the world using an intelligence service so pricey that it's illegal for us to ask how pricey it is. (Along with a pricey military to go along with that intelligence service now that I think about it.)
It’s already priced in.
There's a lot of tax credits and subsidies. "Clean coal" for instance, or 3.4 billion for carbon sequestration (did that get past the lab yet?)
https://www.taxpayer.net/energy-natural-resources/coal-a-lon...
So subsidies for coal are incredibly small.
I think it's past the point we started considering unpriced externalities as subsidies.
I'm not an expert on energy production but a study I recently read on this topic for the German "Energiewende" over here did not sound so great [1]. In Germany the renewables we can scale are mostly Wind + PV. However according to the study their seasonal patterns combined with the demand curve seem to make it pretty much impossible to actually expand them meaningfully. Over the year you'll get peak production far outstripping demand (we've already seen negative prices in our markets with current installed capacity) and in the troughs you will need huge production from other energy sources (mostly old coal plants at this point). As these are seasonal patterns this means you would need to store TWh over many months to average that out and make new installed renewable capacity actually useful. The study did some back on the envelope calculations for various options for that but none seemed to come close to achieving that.
If that is true, system wide such nice looking renewable price calculations are preconditioned on a backup structure of conventional plants being on standby to fill in the throughs. As this is highly uneconomical for them the cost for that will still have to be paid by the system. At the same time due to the extreme variability prices will drop to zero during peak times (well...unless you have feed-in tarifs) making cheap production prices still be a loss.
I imagine the calculations might look much more favorable in other locales where demand is better correlated with renewable production but I would be surprised if Germany is the total exception here.
[1] http://www.hanswernersinn.de/dcs/2017%20Buffering%20Volatili...
Here's a calculation for Solar from (sunny) India: A 5KW Solar Rooftop costs in the ballpark of Rs 300,000 (~4000 USD), which takes care of a bill of less than Rs 5000 per /month (~60, 70 USD). That'll take 5 years (at least) to recover the cost of install. Then there would be the added cost of maintaining the setup.
Now, USD 4000 might not sound like much to invest in a healthy future, but it's still a LOT of money for the majority of Indian households, and the idea is quite difficult to sell.
So the only help can come from the government subsidies. Unfortunately, while the govt has set huge public targets, the subsidy doesn't reach common people. The current Energy lobby is showing it's ugly face here, and the government is warming up to the idea of taxing solar products.
There's also the troubling fact that large corporations are setting up these huge RE powerplants (with backing from govts), when by the very nature, Solar energy should be rather distributed.
I just hope we talk about the hinderance by governments and large corporations in the RE space a lot more and not let them collude or slow down this natural progression.
Last I heard, nuclear was the only non-fossil fuel way of doing that. Is that still the case?
But yeah, obviously dams and deep wells with pumps are orders of magnitude less expensive than nuclear reactors. So that's likely where the money will go.
But it's ALL gonna be pricey. Only thing that isn't quite as pricey are the fossil fuels. Very little stomach for future development on those however.