Dyson sphere

A Dyson Sphere is built around a star, not too close, of course. Just enough so that much of the star's energy can be captured/harnessed.

This is a Dyson sphere...

Or the theoretical model of one.

Some believe that the major Type 2 civilizations on the Kardashev scale they own one.

Thus obtaining all the energy they will ever need, from their star.

Some models of Dyson spheres are intended to almost completely enclose the star, so that every iota of its emitted energy could be obtained.

That, in theory, would give us something like 400 septillion watts of power. Per second, of course. Which is on the order of a trillion times more energy than our current global consumption.

But according to Stuart Armstrong of the University of Oxford, building a Dyson Sphere that completely encloses a star is not feasible. Because the tensile strength, necessary to prevent the sphere from breaking, completely exceeds that of any known material.

Estimates for a Dyson Sphere like the one I showed you in the picture put the resource materials needed somewhere around 1.82E + 26 Kg. That's 182 septillion tons of materials. The number may vary, of course, depending on the density of the materials used.

Some have even asked here on Quora, if we could currently build one. And the answer is, of course, no. We do not possess the proper propulsion technology, resource harvesting technology, or space survival technology necessary for such an undertaking.

With current technology, it would take something like 120 billion years to build a Dyson Sphere around our star.