> What's the real number the

First, we need to understand that the problem is power, not energy, generation and transport. The difference between the two is massive.

Second, we need to understand that we need power over and above the currently installed capacity. This should be self-evident; we consume the power we generate today. We don't have enough excess capacity. I live in California, we have blackouts and the government has asked our insignificant number of EV owners to alter their charging behavior during period of peak demand. We need more power.

Third, in the US, we need approximately 1200 GW in new power generation and transport capacity. Of course, this would be distributed non-uniformly according to regional requirements. The grid needs to be able to move this power as well. The current infrastructure cannot.

For context, the entire power generation system in the US is good for about 1200 GW today. In other words we, conceptually, need to create a full duplicate of the US power generation and transport system.

This isn't trivial. We can't even build a high speed train and now we are talking about doubling our power generation and transport capacity in just a few years. CA wants a major transition to EV's in eight years. This is demented. I don't even want to imagine the power problems and fires we are going to have to live through.

> What prevents us replacing the first 30% of fossil fuels in the areas 90% of people live

> What prevents another 30% being replaced with wind?

Let's start with this: Solar and wind are unreliable.

To illustrate, here's an example from about one month ago from my own 13 kW solar array:

https://i.imgur.com/A0u4I0R.png

First thing to notice is that the peak is nowhere near 13 kW. In other words, you don't get twelve hours of power at the peak power rating of the panels. The most I have seen is a 10 kW to 11 kW peak for a few minutes around April/May.

What are those horrendous dips?

Clouds.

Yup. Now imagine an entire city relying on this for power? Wind is similar.

Here's today so far. It's horrible. Again, clouds.

https://i.imgur.com/breTHQd.png

We actually went from a potential peak of 8 kW down to 0.792 kW around noon. Once again, imagine an entire town with this problem.

Batteries?

Sure.

So, you build one array to supply power during the day. And then a full duplicate of that array to charge the batteries you will need to provide power at night.

However, it isn't that simple. If you notice, the power generation output curve is an inverted parabola. The integral of that parabola over time is 2/3 the area of the enclosing constant power rectangle.

This means you have to build an array 1.5 times larger in order to fill the voids, store that energy and be able to provide constant power even when the sun is up.

If we continue to analyze and compensate for deficiencies and reliability problems, it is very easy to show that a solar system capable of replacing a fossil fuel or nuclear power source has to be built 7 to 15 times larger than the required steady-state output. This includes an absolutely massive amount of batteries, of course.

The only real solution I see is a large amount of new nuclear power generation and, yes, some solar and wind. I don't think there's another way to do it. Part of me think that manufacturing, transporting and installing that many panels and batteries is likely to create a far greater ecological disaster than most people imagine. Just a hunch, haven't done the numbers on that one.