One of the things I love so much about the MOON game is the ability to modify your production capacity to accommodate your energy output. It is not fixed like our traditional web2 war games. As we know, your resource production might be negatively impacted if your energy is negative, as those buildings consume energy to create resources.
If you find yourself with negative energy and can't easily upgrade your power plants to scale, simply click on resources on the left, where the menu is.
Then use the percentage modifiers to reduce the production of the resources you don't need much of at that moment.
Another advantage of this is that the production of other resources will increase.
Of course, the best method of accumulating resources is to pillage and plunder your enemies!! Destroy their planet and watch the world burn!!!