Once you're past the distance where transmitting electrical power is feasible, you would probably have to store the energy chemically. In principle you could charge gigantic banks of lithium batteries and then ship the batteries, but that would require infeasible (probably ludicrous) amounts of lithium, and lithium batteries are a pretty inefficient way to chemically store energy.
Alternatively, it probably isn't cost-effective with current technology, but on a fundamental level, you could use a nuclear reactor to power a system that chemically recombined atmospheric CO2 and water back into hydrocarbon fuels. Unlike fossil-derived hydrocarbons, these hydrocarbons would be carbon-neutral since you'd be sourcing all the carbon from the same atmosphere that it would eventually be dumped back into. This is probably going to make sense for things like vehicles, aircraft, rockets, etc. long before it makes sense for power generation, but there are definite benefits. We already have all the necessary technology to burn hydrocarbons, meaning that any improvements in synthesizing hydrocarbon fuels can potentially eliminate the need to switch these things over to batteries or whatnot. Which may be extremely helpful if we run into serious resource constraints over lithium, or if we grow increasingly concerned with the environmental byproducts of lithium battery production.
