In 20 years the cost of PV installations has decreased a magnitude. Lithium battery energy density has increased a magnitude while prices have fallen a magnitude. Maybe it's time to shift expectations as to what solar can achieve when properly integrated into the existing energy grid.

> How many more decades before we can replace that with a renewable option?

Roughly one. According to Wikipedia, the US added 35 GW of each of PV and wind between 2016 and 2020, and has 95 GW of nuclear. Accounting for capacity factor, the quantity of renewables TWh produced roughly doubled, and is currently 14% vs. 20% for nuclear, but (worldwide at least) renewables are close to an exponential trend.

The main constraint the USA should have here is storage and/or long-distance transmission.

Such is exponential growth.

Though you’re right: needlessly closing nuclear reactors is bad for the environment as the most important problem right now is the CO2. Coal needs to go first, then oil, then natural gas.

I'm not sure which point you think you're refuting. Renewable options are here and are being used and grid storage is a solved problem, though with the current balkanised and underfunded state of the US grid it is unsurprising there are significant ongoing problems there caused by lack of long term investment in infrastructure.

IMO existing nuclear plants should be kept until they can be replaced easily, and the US may well take decades to do so as they are very slow on the uptake. Other countries are doing a lot better, some have reached 100% power from renewables already for short periods of time and are on track to do it for long periods in the coming decades.

Greenhouse emissions are not rising in the US, they are gradually falling as renewable options become cheaper and are built out and EVs spread:

https://en.wikipedia.org/wiki/Greenhouse_gas_emissions_by_th...

I'd expect them to keep falling given transport and electricity generation are the main sources.

Greenhouse gases have fallen in the United States because we have closed a lot of coal power plants and replaced them with natural gas.

Emissions are increasing globally because we are building a lot of coal plants.

The fact remains that we are at least 2 or 3 decades from renewables being able to replace fossil fuels for power generation

That’s half a century of waiting

Not even by your calculations is that half a century of waiting (30 years is not half a century!), but your 'fact' of a 2-3 decade wait are demonstrably wrong and unsupported by the evidence.

Why do you insist on attempting to set renewables and nuclear in opposition?

Scotland for example recently hit generation of 97% of demand from renewables in the year 2020. As part of a larger grid with appropriate balancing and storage, 100% renewables is absolutely doable, and as part of a grid with some base load generated from nuclear (as the US and UK for example already have and is not going away soon), it's definitely doable right now with sufficient will and resources:

https://www.bbc.co.uk/news/uk-scotland-56530424

The only reason the US is trailing so far behind other countries is a lack of will to transition off fossil fuels, a chronic lack of investment in infrastructure and a balkanised electricity grid run for profit, all of which is fixable.