I try to stay at least reasonably well-informed of developments in the space, and the bottom line is two-fold:

1) There is no magic bullet technology just around the corner that will solve all our problems for either energy generation or carbon sequestration. Fusion is decades away from practicality, renewables will take decades to slowly scale up and replace fossil fuels, carbon sequestration at scale is expensive without a real economic output, and climate change is a global problem rather a country-specific one, which leads to #2

2) We have all the technology we need today. What we lack is the political, social, and economic willpower to make climate change a priority globally. A true carbon tax with proceeds going to renewables development & sequestration would solve a huge portion of the problem, as would removing subsidies for high-pollution activities. The fact that these things aren't even taken seriously at the congressional level tells you all you need to know.

>If for example a cheap, simple new technology would be out by tomorrow, that provides allmost unlimited energy (let's say a wonderful simple approach to cold fusion◇) - then all the dirty stuff we do today, because it is cheap - could be done without the dirt of fossil fuels.

To paraphrase something that I remember reading once but now cannot find because Google cannot ever help you find anything useful (nor can the others but at least you aren't giving them all your privacy for nothing):

The person who creates a new and abundant source of energy without at the same time creating an equivalent heat sink for this planet would be history's greatest monster.

Interesting thought, but energy is not the same as heat. Energy is the potential to do things. Like moving heat away. Whether it will be practical to do so is another question ..

Maybe. The amount of energy used by humanity is miniscule compared to the amount of energy we receive from the sun every day.