High-Level Project Summary
With our research, we thought up an energy system which produces energy by making use of Venus’s earthquakes. Our system is designed to be able to last for long periods of time under critical conditions. We planned to achieve this by using piezoelectric materials to generate energy while protecting the energy generators and batteries with titanium and aerogel. Titanium protects the system from high atmospheric pressures and aerogel provides heat insulation to preserve the batteries. There is also microgap cooling technologies installed inside the protective layers to keep the batteries’ capacity to a maximum.
Link to Final Project
Link to Project "Demo"
Detailed Project Description
Our main goal is keeping the spacecraft on Venus for at least 60 days. To do this, we had to design an energy storage system that was efficient and durable enough to keep the vehicle running for 60 days and could provide uninterrupted energy. So we thought it would make sense to use the constant earthquakes that we can take advantage of in the natural environment of Venus to ensure that the energy is uninterrupted and as efficient as possible.
While doing this, we used piezoelectricity, which can produce very high energies even with low pressure fluctations. The working system of piezoelectricity:
A quartz slab is a flexible solid with a f0 mechanical vibration frequency (expansion and compression). The value of this frequency is: f0= V/2e".
where V is the velocity of the vibration in quartz (3500 m/sec) and e is half the vibrational wave. For 1 mm thickness: f0 = 3500 / 2 x 0.001=1750000 hertz.
When a quartz plate vibrates at f0 frequency, this plate is placed on it accordingly.
A voltage varying at the same frequency f is obtained between two placed electrodes.
Therefore, the quartz plate can be compared to an oscillating electrical circuit. We have installed a plate system on the generator to ensure that the pressure is transferred to the piezoelectric. Since there is no pressure in space, this system would normally have to collapse outward. So when the spacecraft lands on the surface of Venus, the plate will deactivate itself.
To ensure that the system is consistently vibrating and generating energy, we placed a metal plate which can vibrate when exposed to pressure fluctations. But since there is no pressure in space, this system would normally have to collapse outward. So when the spacecraft lands on the surface of Venus, the plate will deactivate itself.
To make the plating itself vibrate, we can make use of the geography of Venus. Venus is a planet which has hundreds of active volcanoes on it. Thanks to this, there are constant earthquakes and storms happening on it’s surface. If our system is placed event remotely close to any of these areas, it can continuously make the plate vibrate and produce energy.
If there’s any excess energy generated in this process, it can be stored for the rover to use it whenever it’s needed. For this reason, we chose lithium-ion batteries which are widely used in spacecrafts. Lithium-ion batteries are batteries that can be recharged. Therefore, they are the most suitable option for our system.
The system above needs to be protected from the high pressures and temperatures of Venus and we came up with three protections.
Firstly, to protect the system from atmospheric pressure, we chose to cover the whole system in a layer of titanium (excluding the metal plating which needs to have the ability to move ). Titanium is extremely resistant against high pressures and corrosion which may be caused by acidic rains on the surface and has a low expansion coefficient. It is also not as dense as it’s alternatives and therefore will not have too much mass.
Next, there is a layer of silica-aerogel under titanium to provide heat insulation. Silica-aerogel is an extremely good heat insulator which can withstand even the most extreme temperatures. Despite it’s name, it’s solid and has lots of empty pores in it which reduces heat conduction.
Lastly, we need a cooling system in order to prevent the heat energy generated as a result of the operation of the system from disrupting the system. For this, we preferred microgap cooling technologies. The reason for this is that this system can work comfortably in cramped environments. It is also resistant to gravity.
The benefits of our system is that it turns the disadvantages of the conditions in venus into benefits by making use of them. While a normal spacecraft may not benefit and even work less efficient because of this, we aimed to make it our system’s one strong point.
We hope to make unexplorable areas in space explorable and our first goal is Venus.
Space Agency Data
From the European Space Agency, we learnt that the inventors of the lithium-ion battery won the chemistry nobel prizes. We decided to use lithium-ion batteries because they have completely exceeded other battery types in space missions and its rechargeability.
From NASA's article about microgap-cooling technology,we thought it was better than any type of cooling system in space because of its immunity to different gravity effects and its ability to work on cramped electrical circuits.
In this article about aerogel, it is said that aerogels can insulate against extreme temperatures and it is otherworldly to just hold one. So we've taken an interest to aerogels. After further research, it proved to be the ultimate insulation material because it is durable to high pressure levels too.
Hackathon Journey
We got to experience a competitive atmosphere thanks to Space Apps. Within these two days, we saw how important it is to coordinate our team and work in harmony. We also think that our ability to research and discern valid information has improved. Our resolve to make a contribution for a better future is what inspired us to choose this topic. The topic also aligned with our interest in space. Whenever we encountered a challenge in our work, we divided and distributed our workload and quickly overcame them. We'd like to thanks our mentors for providing support throughout the challenge and the METU Young Entrepreneurs Society for making this opportunity possible.
References
https://en.wikipedia.org/wiki/Piezoelectricity#:~:text=Piezoelectricity%20(%2F%CB%8Cpi%CB%90z,response%20to%20applied%20mechanical%20stress
https://www.youtube.com/watch?v=BBPESSFVe4Q
https://www.superradiatorcoils.com/blog/4-main-refrigeration-cycle-components
https://www.americanelements.com/silica-aerogel-7631-86-9
https://www.universetoday.com/143933/nasa-has-a-new-method-for-cooling-down-electronics-crammed-together-in-a-spacecraft/
https://en.wikipedia.org/wiki/Lithium-ion_battery
https://www.ulbrich.com/blog/titanium-facts-characteristics-manufacturers-guide/
https://spinoff.nasa.gov/Spinoff2010/cg_2.html#:~:text=While%20NASA%20uses%20Aspen%20Aerogels,and%20construction%2C%20appliances%20and%20refrigeration
https://www.elektrikrehberiniz.com/elektrik/piezoelektrik-nedir-10218/#:~:text=Piezoelektrik%2C%20belirli%20kristallerin%20do%C4%9Frudan%20piezo,g%C3%B6stererek%20kon
Tags
#Venus, #Piezoelectricity, #Energy storage