By 2017, power generated from coal had fallen 700 billion kWh to 1.2 trillion kWh. Natural gas generation increased since then by 700 billion kWh to 1.3 trillion kWh, while wind and solar power grew by 300 billion kWh. (Including hydropower and biomass, renewables contributed a total of to 687 billion kWh in 2017).
So, natural gas has more than doubled the contribution of wind and solar power to the power mix since 2017, but the growth rates for wind and solar have been far greater.
So, let’s extrapolate. The BP Statistical Review shows that in the U.S., the output of wind and solar power over the past five years roughly doubled. Although growth rates have slowed in recent years, let’s make a generous assumption and project that they continue to double every five years.
At that rate, it would take two more doublings of wind and solar output to equal the 2017 contribution of coal to the power mix. One more doubling beyond that would then also equal the 2017 contribution of natural gas to the power mix.
So I think that makes a strong case the even with aggressive assumptions, coal will remain an important part of the power mix for at least another decade. (Although I believe it will be in the power mix far longer than this). Natural gas will continue to be an important bridge fuel during that time, and in the best case won’t be phased out for at least 15 years.
In reality, recent U.S. government policy decisions are likely to continue to slow the growth of wind and solar, even as they continue to become cheaper and cheaper. The speed of development of battery technology may also be a limiting factor. Thus, the U.S. is probably looking at natural gas as an important bridge fuel for at least two more decades. Globally, natural gas will probably continue to grow in importance through at least 2050.