"If you were to have fruits and vegetables produced year round locally, significant amounts of energy would be required to heat green houses or other structures for these products to grow in winter (or vice versa in southern U.S. States in summer). Despite the options you have proposed for this, the cost and energy used to build and run such structures is significantly higher than shipping fresh product around the world. "

Good point, and this is why the push for eating locally also needs to start focusing on eating SEASONALLY. There is no reason to expect summer crops in the winter, other than because we have grown so accustomed in America to wanting what we want when we want it, and getting it.

It's the small steps that will get us to where we are going. If people insist on out of season or out of climate food, perhaps there could be a market for developing an energy efficient greenhouse or something to make that happen on a small scale.