Ask HN: What is the best use for wasteland with little water in tropics?

I am planning to buy a wasteland measuring 5-10 acres in India without a lot of water. I plan to save water using rainwater harvesting and hoping that I run into some groundwater. This land has no irrigation facility.

What would be the most efficient use of something like this ? I am planning to start a small library/ school for impoverished tribals but I was wondering if there is any way a land like this can be made self sustaining using new technological or other solutions that I may not be aware of.

I always ask myself questions like:

What is the best way to convert sunlight & water to biomass ?

How to utilize solar energy locally ?

How much water can I reuse ?

The idea is to show that something sustainable can be done with right approach and hopefully support at least 4-5 poor people and more others (via education).