[evan_au]

With our present technologies, we prefer electrical sources with a consistently low electrical impedance. This lets us draw as much power as we like, without the source voltage changing much, and dissipating most of the power in our load, rather than in the source.

In a battery with a high source impedance/resistance, the output voltage collapses as soon as you try to draw any useful power. Lightning charges in thunderclouds store large amounts of energy, but initially the impedance is too high to draw any useful power. But when the air breaks down into a lightning bolt/plasma, the impedance drops to a very low value, and all of the energy is dissipated in just microseconds - too fast for us to collect it in a controlled manner.

There is a large amount of electrical energy in space, but it is spread out over an extremely large volume. To draw useful amounts of power in space, you need a very large collecting antenna, positioned where the plasma currents are highest. Local eddies in the current would need to be locally converted into useful energy.

It takes a lot of energy for a space rocket to approach the Sun, so perhaps magnetic braking could be used to spiral inwards towards the Sun, while collecting some electrical energy from the plasma?