I have observed that if you build Distributed Energy, it behaves like Chain Gangs, a one turn improvement that is available to build again the turn after it completes.  However, if you build Microwave Pipes, you may not build Distributed Energy (it dissappears from the available structures you can build).  If you place them in the queue together, then buy both out, if Distributed Energy is before Microwave Pipes then both disappear, if Microwave Pipes is before Distributed Energy, then Distributed Energy will be in the queue next turn, blocking it, and must be removed manually.  I just figured Distributed Energy was a one turn improvement despite using the same icon as Microwave Pipes and that Microwave Pipes eliminated the ability to use Distributed Energy.