While you can of course use the space tether as a power generation device, generating small amounts of electrical power in space is easier done by solar panels.

While you can of course use the space tether as a power generation device, generating small amounts of electrical power in space is easier done by solar panels. The space tether is usually envisaged to be operated the other way around, to convert electrical power from a solar panel into propulsive force. In any case, you aren't really taking power "from the core", it comes from your own kinetic energy.