Waste of time if you ask me. Plop plain ordinary PV panels on top of every gov't building and you'll have all the power you'd ever need ... and the gov't would make enough selling that power to cut your taxes in the process.
Way too expensive to build anyway. Plus, there is a secret to the interstate. What is asphalt made of? Oil. What were to happen if the US somehow runs out of oil? Rip up the interstate and use that oil. Ike was a genius.