The energy sources for man are drying up. The era of fossil fuels is going to end very soon. Scientists are now working on to find new renewable sources of energy. Along with renewable energy sources like light and wind comes gravity.
Gravity is a phenomenon that existed from the very beginning of the universe but only discovered by Sir Isaac Newton not more than 400 years ago. Recently scientists started generating energy from gravity.
The basic concept of a gravity power generating mechanism is simple. When a body goes down from a higher altitude to a lower one its potential energy is converted into kinetic energy via linear motion. This motion is converted circular motion and is then converted to electricity using a dynamo.
One challenge in this mechanism is about getting continuous supply of energy. A body cannot go downward infinitely, but for continuous power generation this practically impossible scenario is necessary.
An interesting solution for this problem was invented by Mr. Rajesh Mulchandani and he has applied for patent. He uses gravity and buoyancy of water to generate a continuous up and down motion. The mechanism consists of a water filled tank with 50-60meters high with 2 balanced masses capable of moving using both buoyancy and gravity.
You can see the full mechanism here http://powerfromgravity.com/invention.aspx.
As a final year mechanical engineering project this may be too expensive. But there may be more simple ideas to generate motion continuously. Another example of such a mechanism can be found here. http://www.freepatentsonline.com/20090115195.pdf
Wish you all the best.