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I proposed the use of gravitational batteries: a mass rises mechanically, storing energy. When descending a mechanical system converts the vertical movement into rotation, which drives the generator. The stored energy is proportional to the mass and height, using simple mechanical elements. In addition, a vertical axis wind turbine will recharge our battery, using surface winds, weak and erratic, but useful due to the high atmospheric density. The final design is a 4000 kg lander, the majority corresponding to the weight of the batteries, with autonomy of 3 hours without winds and a power of 10 W, ideal for continuous meteorological and geological observation.

LINK TO PROJECT DEMO

Previous missions have shown that venus surface winds are erratic and weak, but a windmill would be able to generate power under these conditions thanks to the high atmospheric density of 67 kg/m3, which is 55 times 1, 2 kg/m 3 of the earth’s atmosphere. Vertical axis windmills are most efficient with low wind speeds, regardless of the direction from which it comes or the speed with which it varies. In fact, a wind of only 1.5 m/s is equivalent in terms of energy to a wind of 6 m/s on earth.

Venus has a thick, toxic atmosphere filled with carbon dioxide and it’s perpetually shrouded in thick, yellowish clouds of sulfuric acid that trap heat, causing a runaway greenhouse effect. It’s the hottest planet in our solar system, even though Mercury is closer to the Sun. Surface temperatures on Venus are about 900 degrees Fahrenheit (475 degrees Celsius) – hot enough to melt lead. [1]

We chose to design a fully mechanical system due to the high temperatures and corrosive atmosphere. Analyzing the following table, we propose to use the titanium material for its melting point.

The main structure of the lander consists of a 4 m wide hexagon with 2 m sides, where the wind turbine, the platform with instruments and the gravitational battery system are located. This hexagon is supported by a tripod-shaped landing system, with telescopic legs that allow it to adapt to irregular terrain and also reduce the space needed during the interplanetary travel stage. The total height of the lander on the surface of Venus will be 6.4 m, of which 4 m correspond to the useful length of the gravitational battery system.

A gravitational battery, essentially a mass that can move vertically along with a support or guide structure. [2] A mechanical system that links the mass and the generator through a vertical axis, transforming vertical displacements into rotation. A generator, which takes advantage of the descent of the mass to generate electricity, but also capable of inverting its operation to raise the mass using the wind turbine.

When the mass is at the top of the structure, the stored gravitational potential energy is maximum: E= mgh. When it is necessary to use this energy, the mass is slowly allowed to fall by the action of its own weight through the guides of the structure. The mechanical system transmits this movement to a vertical axis that drives the generator converting gravitational potential energy into useful electricity. If the mass reaches the base of the structure, the stored energy has been completely consumed. At this point, the excess energy generated by the wind turbine when the winds blow should be used to lift the mass again, transforming and storing electricity in the form of gravitational potential energy.

To improve the phase adjustment that must be meshed between the input and output rings in a planetary gear set, we propose to use Gear Bearings (GSC-TOPS-12) [3]

In addition, we opted for a planetary roller screw given the adverse conditions of the planet with a guide for the load and considering the experience prior to its positive operation on Mars. [4]

At its maximum capacity, using a mass of 4000 kg raised at 4 m, the system is capable of storing 141.9 KJ of energy on Venus, without loss while the system is not being used. By varying the rate at which mass falls we can alter the rate at which the stored energy is used.

For reference, since it is necessary to accurately determine the losses associated with friction, the system is capable of providing:

39.5W over 1hr 13.4 W over 3 hours 6.7 W over 6 hours The system to have 3 gravitational batteries with its generator, is redundant in case of failures

[1] NASA Science, Solar System Exploration https://solarsystem.nasa.gov/planets/venus/overview/#:~:text=Surface%20temperatures%20on%20Venus%20are,and%20thousands%20of%20large%20volcanoes

[2] Energy Vault, EVRC Energy Vault Resiliency Center https://www.energyvault.com/gravity

[3] NASA, Mechanical And Fluid Systems Gear Bearings (GSC-TOPS-12) https://technology.nasa.gov/patent/GSC-TOPS-12

[4] Matthew Redmond NASA Jet Propulsion Laboratory, Thermal Testing of a Planetary Roller Screw for the Mars 2020 Rover Sample Caching System, California Institute of Technology, 03/28/2017

#NASA #Energy #Venus #GravitationalBatteries #EnergyStorage