Since the Industrial Revolution, the world has been dependent on power and energy. This reliance has led to a whole new field of study: how to make more energy in less time, while also keeping the environment healthy. While energy production may be the hot topic on everybody’s mind, I chose to look at a region of energy that could provide a better, more healthy, and more impactful outcome: storage. Too much energy goes to waste nowadays due to the Energy Bell Curve. For example, while solar panels are generating energy in bulk during the middle of the day, barely any of it is getting used because the weather is already nice and the lighting is already good. The energy that dissapates and goes to waste is actually needed during the darker hours (mornings or nights), when the lights are on and the heaters turned up. I could also solve the same yearly curve, in which excess solar energy is produced in the summer months, and the winter months don’t yield the needed amount. In this project, I discover solutions that could majorly impact how we view energy storage. I took action designing, 3D printing, and building a small scale Gravity Battery that is easily scalable and can be used any instance or time to store energy. I tested its ability to generate certain voltages, and also how long it could produce those voltages with varying weights. Given the size and drop height of my project, it could not store very much energy, however, with a scalable design like this, a couple large assemblies could be a probable solution to our energy needs.

The Solar Energy Bell Curve provides many problems for the usage of the energy produced every day from the sun. The daily bell curve entails that solar energy production peaks around midday when the sun is the highest and most direct in the sky, while less or no energy is produced at dusk or dawn. The annual curve is similar, where on average, more energy is produced per day in the summer than in the winter because the sunlight is both more direct and shines longer. However, energy usage throughout the day has an inverse curve and usage throughout the year stays close to consistent, so a large amount of solar energy goes to waste at the peak time of day or year. 

A solution to this problem would be a battery that is easy to charge and discharge at anytime. It can store all the wasted solar power that isn't used in the grid to save for when the production falls short or the usage picks up. One of the best solutions is a gravity battery.

I began my project by custom designing a Gravity Battery to use in my tests. I created sketches and extrusions in a 3D modeling tool called Onshape to design the gears and supports. It took a lot of trial and error to get the design right, but with a great tool like a 3D printer, I was able to print out small test gears and supports to make sure the design worked perfectly. However, not everything could be 3D printed, because that would introduce too much friction into the battery, decreasing its efficiency. So, I purchased 2, 6-inch-long threaded axles for both gears to mount on, then 18 appropriately sized hex nuts to ensure the gears would spin along with the axles and to keep everything else in its place. Finally, as bearings for where the axles meet the supports, I purchased 4 bushings, along with 8 large washers to keep the bushings in place. Later, I added a motor mount to the design to make it easier to keep the motor in place. This completed my Gravity Battery design.

The 150-gram weight dropped for around 15 seconds with an average of 1.245 volts produced. Its maximum voltage was 1.38 volts, while the minimum without outliers was 1.1 volts. The 140-gram weight produced and average of .646 volts for 28 seconds (max = .81 volts; min= .5 volts). Finally, the 125-gram weight produced .34 volts for 55 seconds on average (max= .6 volts; min= .13 volts). The variance of the voltage shown in the graph is most likely due to inconsistent measurements from the cheap voltmeter.

Overall, the lines of best fit show a very consistent production of voltage for each of the weights. This concludes that different weights can efficiently serve as different voltage batteries based on what is needed to power. Evidently, as the weight of the battery increases, the voltage of the battery also increases, however, the time that the battery can be used decreases, due to a faster velocity. This claim means that no matter how much weight you add to the battery, the amount of watt-hours (voltage (volts) x current (amps) x time (hours)) produced will be around the same due to the proportionality that as voltage increases, time decreases the same amount if the current is constant. The different voltages ensure efficient usage of the electricity being produced.