A serious threat to human population in near future is the energy crises. What could be the plausible solution?

Renewable energy production in the short term. But in the medium term, nuclear fusion will be more important by far.
I know this is not a popular opinion, but time will prove it right.

There are many solutions to the expected energy crisis. The most plausible one might be the collection of solar energy by the suborbital solar stations outside the Earth, and transmitting the energy back to the ground stations via visible light lasers, or other forms of electromagnetic radiation. Solar panels installed on International Space Station generate enough electricity to serve about 50 full scale houses. Putting 1000 of such panels in space will serve a town of 50,000 homes, or, about 200,000 inhabitants.

The energy crisis is, at least in European Union and certainly in the Czech Republic where I live, is driven by three factors: 
the brutal war of Russia against Ukraine (increasing prices of gas for EU) 
the Green Deal (aiming at decreasing the greenhouse gas emissions), putting a serious threat within the next few years of shutting down the coal-produced energy
the unreasonable German Energiewende shutdown of all nuclear power plants.

Unfortunately, only solar and wind power plants are strongly supported and growing in EU all the 21st century. However, during very common windless cloudy winter days and nights, they are useless, thus calling for more and more natural gas import. If you don't believe, model your prefered energy mix in our https://app.energy-mix.cz/ based on real data (not political opinions). This strongly unreasonable european energy policy is the main cause for the EU electricity high prices and insecurity, destroying the EU industry and so economy (especially in Germany which used to be the EU richest country). 

My proposed solution is to massively invest into nuclear power plants which supply clean energy 24/365. EU has already too many solar and wind power plants and importing 97% of its gas, which puts EU into serious geopolitical threat (currently from Russia). 

Using renewable energy sources, being socially responsible, adopting sustainable and energy-efficient solutions, recycling to an extent, etc. may be plausible solutions for energy crises. 

Waste generation and subsequent accumulation is also a concern. Hence measures can be taken to generate energy from waste (waste to wealth). This can mitigate waste, generate energy and contribute to economy.