Nod, unlike GDI, continued the use of advanced power plants. Although they were much more expensive than the standard power plants, they provided more energy, becoming a viable choice for Nod commanders willing to build an elaborate energy-consuming fort. It also gave Nod the ability to build laser fences, a more efficient (but power-consuming) defense than ordinary walls.
They were high priority targets for enemy commanders if they wanted to bring Nod defenses down. Nod advanced power plants have a penalty of consuming more room, but enables them to nurture power better than regular power plants to power hungry structures like the stealth generator.