History of Solar Balloons
The innovation of solar balloons starts after the invention of hot air balloons. The first hot air balloons were sailed in August 1709 for The King John V of Portugal by a priest. On September 19, 1783, a scientist named “De Rozier” sailed the first air balloon with a passenger. For the balloon, the sheep, the duck, and the rooster were the first passenger. That was the first successful attempt & it floats for 16 minutes in the sky. After that, it falls.
In 1972, Dominic Michaelis, an architect, and Engineer belief that solar balloons will fly with solar energy. To do an experiment with this. he builds a balloon (1 cubic meter) with a double skin envelope. He got motivating results. Due to that, he built a size 10 meters balloon. His son was the first Human to be lifted by the solar balloons.
What is a Solar balloon & how does it works?
Solar balloons are the balloon in which the inside air gets heat and expands in the envelope (Use of fabric to contain the air). Then the air ( contained in an envelope) becomes lighter than the surrounding air. It causes the Balloons to float in the sky.
As the name suggests, a hot air balloon works on the principle of lift (buoyancy) caused due to the inner hot air present in the envelope. This air gets heat by solar energy. It is the same force acting on the object when they are in the water, as described by the Archimedes’ principle.
It can manufacture in size small or large as per the requirement and depending on the use. Air becomes thinner as the altitude increases. At high pressure, the hot air balloon can lift easily. As per some research, hot air balloons can lifts easily on snow rather than sea because the balloons receive more light due to more reflection.
At some specified altitudes, if the ambient air becomes cool the temperature difference is going to increase. Due to which the volumetric mass differential increases. It causes the aerostatic force to increases and, lift is also increased. In winter we get the best results.
Types of Solar balloons
There are different types of Solar balloons. The design is different from the requirement of films produces. The adhesive tape uses to construct the self-made solar balloons. It imposes some weight on the balloons. To avoid this, it uses welding techniques.
The solar worm is a type of solar balloon which is few meters long. It like a worm in design and, it can be 50m or long using standard garbage bags.
Constructional Material & requirements
Tetrahedral design is four smooth surfaces used to construct a solar balloon. Its constructed easily. Mostly use of Nylon in solar balloons is common. Nylon can sustain heat and tension better than other materials. So that panels are made of Nylons which are stitched by skilled Scheuer.
As the air traps in the envelope (balloon bag), it gets heated up above the normal air temperature by solar energy. It causes the balloon to get a lift in the air due to the positive buoyancy or lift. Compare to the hot and cool day, the cooler the surrounding air, the more lift is gained by the hot air balloon and less temperature is required to launch it.
As the air inside the envelope gets allow to cool, it will start to get down. Lifting a hot air balloon of 1 Kg weight require 3.91 m^3 of the envelope and heated to (99 °C,210 °F).
For Launching the solar balloons, there should be light wind and sunlight.
Below are some Consideration in Solar balloons
Heat radiation for the sun-
Isolation is solar radiation receiving on a given surface area in a given time. Many of the rays are absorbed and scattered in the atmosphere. So those are the losses. It reduces the earth isolations by approximately 1000 watt per square meter, which is perpendicular to sun rays at sea level on a sunny day. The average solar radiation is from 120 to 260 w/m^2 for the entire year considering day and night.
Reflected Solar Radiation-
Depending upon the type of soil and material, some of the radiation reflects. Albedo is the proportion of reflected solar radiation. For soil, it is 0.3 to 0.4, water-0.05 to 0.1, but for black polythene is zero. It absorbs all the solar radiation and reflects zero. Black is a good absorber and, it is the perfect material for Solar ballooning. Dark materials are using for hot air ballooning. Black plastic has an emissivity of .95 and, it will reflect 0.5. So maximum energy falling on the surface will get absorbed.
The heat exchange the occurs for the envelope to the outside air or inside air.
Inside heat convection-
The temperature difference that develops near the envelope surface causes the variation in the density of local air. It results in the circulation of air and equalizes temperature differences.
Outside heat convection-
The temperature difference that develops near the envelope surface causes the variation in the density of local air. It results in upward circulation movement.
Comparison of Hot air balloons Vs Solar Balloons-
Solar air balloons create less buoyancy as compared to hot air balloons as the used fuel. They can fly for a long time than hot air balloons in good weather. Solar balloons have material limitations as it uses typical black plastic film while hot air balloons use silk material which is thermal resistance. Hot balloons have windy weather as they can change the direction, while solar balloons are less sensitive to wind.
Solar balloons are not useful for transport people as weather clouded, they cannot lift and sail down.
Future of Solar Ballooning-
Jean-François Guillemoles solar researchers are proposing floating solar balloons, which can generate three times more energy. CNRS, a French researcher institution, working with an Idea given by a Japanese group. Solar balloons produce direct electricity and producing Hydrogen with it. So it will be working as energy storage for producing electricity in fuel cell after the sunset. The solar balloons deployed above the cloud (6km from the ground) will produce three times the electricity than a square foot basis.
There are some advancements in making solar balloons for commercial purposes. It has bright future at tourist places like some organizer has done more experiments with solar balloons. They used tetrahedral-shaped balloons for more than 30 years. A French solar ballooning group has been working on the Solar Balloons project. Some tour organizer is working for fly a tetrahedral shape balloon filled with helium Tt enter Mesosphere (Earth’s Atmospheric Layers from 50 to 85 km).
Cameron Balloons (Balloon designer and Manufacture) are Solar-powered balloons. These are certified Hybrid lighter balloons than air hybrid aerostat in the world. It is a hybrid aircraft balloon in size of 150000 cubic feet and, a combination of black and silver super lightweight fabric. It uses the energy of the sun and a partially conventional hot air propane burner. To get the best result, they Minimize the temperature difference between inside and outside air utilizing maximum solar heat while minimizing the heat loss. The black side will be exposed to the sun to gain maximum heat while the other shaded side was insulated. They used double fabric and maintained a gap in it to avoid heat lost by radiation.
NASA (National Aeronautics and Space Administration) is working for the future envelopment of solar balloons for exploring Mars and Jupiter and Moon Titan.
Advantages of Solar Balloons
- As Sun is a natural renewable energy source, we can produce natural and clean energy.
- Sun as an energy resource has a nonpolluting and continuous energy source.
- Produces energy at a cheap cost.
- As balloons are light in weight and can be deflected easily and can be bought easily into action.
- The maintenance cost will be less and safe and environment friendly.
Disadvantages of Solar Balloons-
- Use of it only in daylight conditions.
- Floating it at high altitudes may cause damages to airplanes, commercial aircraft (7 miles high), and jet aircraft.
- For energy production, through Solar balloons, we require long cables to attach it.
Solar balloons have a bright future as they use to produce energy and are free from emission which is not hazardous to the environment. It can be used to identify Hurricanes. The use of Solar balloons for transportations in standard conditions.
Written by Akshay Pawar. (LinkedIn Profile)