Prototype

1. Project Title: Designing and fabrication of Prototype 30W Buoyant Air Turbine
Introduction:-
Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean,
produces no greenhouse gas emissions during operation and uses little land, whereas, a wind
turbine is a device that converts kinetic energy from the wind into electrical power.
The result of over a millennium of windmill development and modern engineering, today's wind
turbines are manufactured in a wide range of vertical and horizontal axis types. The
smallest turbines are used for applications such as battery charging for auxiliary power for boats
or caravans or to power traffic warning signs. Slightly larger turbines can be used for making small
contributions to a domestic power supply while selling unused power back to the utility supplier via
the electrical grid.
There are various designs of Wind turbines, among them one is High-altitude wind power (HAWP).
This type of turbine harnesses the power of winds high in the sky by use of tether and cable
technology. Numerous Wind turbines have been developed on this technology, namely kites,
kytoons, tethered gliders, tethered sailplanes, aerostats (spherical as well as shaped kytoons), bladed
turbines, airfoils, airfoil matrices, balloons, parachutes, drogues, variable drogues, spiral airfoils,
Darrieus turbines, Magnus-effect VAWT blimps, multiple-rotor complexes, fabric Jalbert-parafoil
kites, uni-blade turbines, flipwings, tethers, bridles, string loops, wafting blades, undulating forms,
piezoelectric materials and more.
Buoyant Airborne Turbine (BAT) is one of them which integrates proven aerospace and wind
turbine technology. The BAT lifting platform is adapted from tethered aerostats, which have
reliably lifted heavy communications and monitoring equipment high into the air for decades. BAT
integrates three main components:
· Shell - A proprietary helium-filled shell made from high performance, industrial fabrics that
lifts the turbine up and stabilizes it in the air.
· Turbine - A lightweight conventional three-blade, horizontal axis wind turbine fixed within the
shell.
· Tethers – The lightweight, high strength tethers hold the turbine in place in all weather
conditions and transmit power to the ground.
Apart from above, there shall also be some Ground works, which include the setup of tethering
control mechanism.
Objective: Designing and fabrication of Prototype Buoyant Air Turbine that
converts kinetic energy of wind into electrical power. Study of turbine performance and power
output at various altitudes shall also be carried out so as to suggest the key parameters which
need to be improved for high efficiency working model of the Buoyant Air Turbine for future.

2. EXPERIMENTAL & FABRICATION WORK:-
Shell
Made of gas-tight and durable fabric, the shell shall either be inflated with lighter gas such as
hydrogen or helium. The shell will passively align into changing winds while channeling wind
through the turbine. Aerodynamic lift shall combine with buoyant lift to keep the Buoyant Air
Turbine aloft in both strong and weak winds.
· Preferably Parachute fabric could be used as a shell material
· Impure Hydrogen gas shall be preferred as it is inexpensive and non easily combustible if
exposed to sun or released in the air unless a spark is provided
Turbine
The lightweight, horizontal-axis turbine adapts conventional, proven architecture used in
the thousands of efficient wind turbines that are currently deployed around the world. The
turbine generates electricity when airborne.
· Possibly a geared DC Generator shall be used.
· For blades, Light weight readymade plastic blades could be used or thin steel sheet can be
used to fabricate the blades as per our requirement
· Another possible design of efficient turbine could be similar like the image shown below if
found feasible in its weight.

3. Tethers
Tethers are used to connect the shell and turbine to winches on the ground. Tether control is
manually adjustable to make turbine altitude variable, stabilize the turbine in the air, and provide an
electrical connection to send power from the turbine to the ground.
Electrical cables could also be used as a tethering material which could help reducing the additional
weight on the shell.
Ground Works
The ground work includes the setup of tethering control mechanism. Winches on the ground shall
be used to control tether length.
After successful fabrication of Turbine, its performance shall be observed and power output at
various altitudes shall also be noted. Measurement of power output at various altitudes
shall also be carried out. After thorough observations and analysis, suggestions would
also be provided for the key parameters which need to be improved for high efficiency
working model of the Buoyant Air Turbine for future.
Estimated Cost of Turbine Setup of various Power
Watts Cost in Rs. Rs./Watt
10 45,000 4500
20 48,000 2400
30 54,000 1800
70 84,000 1200
1000 500,000 500
Estimated Cost of 1 x Gas for 30W Turbine Setup: (H2 Gas Purchased from Market)
Cylinder of impure H2 Gas of 1000 kPa and Volume of 0.77 Cubic Ft. Rs. 1200/-
Required no. Cylinders No. 9
Total Cost of Gas Rs. 10800/-
Rent of Cylinder with labor Rs. 6000/-
Sum of above Rs. 16800/-
Cost of 2nd Gas Charging Rs. 16800/-

4. Estimated Cost of 1 x Gas for 30W Turbine Setup: (Self Manufactured H2 Gas)
Tentative Cost of Cylinder Rs. 8000/-
Required no. Cylinders No. 2
Total Cost of Gas Rs. 16000/-
Cost of Al & Castic Soda Rs. 4000/-
Sum of above Rs. 20000/-
Cost of 2nd Gas Charging Rs. 4000/-
Estimated Cost of 1 x Gas for 30W Turbine Setup: (He 99.9992% Pure Gas Purchased
from Market)
Cost of Gas 6m3 – 2000 psi Rs. 30,000/-
No. of Cylinders Required No. 1
Total Cost of Gas Rs. 30,000/-
Rent of Cylinder with labor Rs. 3000/-
Sum of above Rs. 33,000/-
Cost of 2nd Gas Charging Included above
Cylinder Deposit (Refundable) Rs. 20,000/-
High-altitude wind for power purposes
Winds at higher altitudes become steadier, more persistent, and of higher velocity.
Because power available in wind increases as the cube of velocity (the velocity-cubed
law),assuming other parameters remaining the same, doubling a wind's velocity gives
23=8 times the power; tripling the velocity gives 33=27 times the available power.
With steadier and more predictable winds, high-altitude wind has an advantage over wind
near the ground. Being able to locate HAWP to effective altitudes and using the vertical
dimension of airspace for wind farming brings further advantage using high-altitude winds
for generating energy.
High-altitude wind generators can be adjusted in height and position to maximize energy
return, which is impractical with fixed tower-mounted wind generators .HAWP systems that
are flown must climb through all intermediate altitudes up to final working altitudes—being
at first a low- and then a high- altitude device.
Enclosure: Annex-A Karachi Wind Data

5. Annex-A