Solar Power

If we are looking for where we can find the 1 Terawatt of power we need for our mission, we probably need look no further than the big fusion reactor in the center of the Solar system. The Solar Constant, the power per unit area emitted by the Sun as measured at the Earth's radius is about 1.3 kilowatt per square meter. Equivalently we get better than a Gigawatt per square kilometer, so a fully efficient collector could be as small as a square 30 kilometers on a side.

Of course there's no reason why we need to build the collector at the Earth's orbit: the closer we get to the Sun the smaller we can make it. The linear size of our structure goes down directly with the distance from the Sun. If we go into about Mercury's radius we can only need about 100 square kilometers or a square 10 km on a side.

So we need only very modest structures to collect solar power and since it's already in the form of electromagnetic radiation we can build mirrors to concentrate and direct it where we want.