This is a good idea, but I am sorry to say that it is probably beyond your ability to do in a middle school science lab. The organs that sea birds have that allow them to remove salt have evolved over millions of years, and being able to duplicate that for human purposes would require heavy-duty genetic engineering. They rely on specific proteins ("enzymes") that move salt molecules across cell membranes using (relatively) less energy. You would need to manufacture enzymes yourself. Finally, the way that the birds do it does take energy, but that energy can be eaten through food rather than some other source.

I am going to suggest something you can do instead: you live in a desert. That means that it's sunny most of the time. Have you considered distilling water using the energy from sunlight? It is not energy-efficient, but it is a kind of energy you have more of than you need.

What you might try to do is make a bottle of seawater, connect that via a plastic tube to another, empty, bottle, and stick black cloth into the seawater. The idea is that the black cloth will absorb the sunlight and heat the water, which will then evaporate move to the other bottle where it will become liquid again. The salt will be left behind in the bottle with the cloth.

Before you do this, understand this: I DO NOT KNOW IF THIS IS GOING TO WORK. I am just using an idea based on what I know about Physics. But then, this is science - you don't know whether it will work or not. If you did know, there would be no reason to experiment on it. So there is nothing wrong with trying it!