Honors Program Thesis Proposal
Feasibility of a Contra Rotating VAWT Powered Home Heating System
Mark F. Czajkowski
Objective:
The objective of this thesis is to determine if a small Contra Rotating Vertical Axis Wind
Turbine (CR-VAWT) is an economically sound way of heating water to supplement the
heating systems in a typical home.
Problem:
As society and economies grow, the amount of fossil fuels taken from the environment
has grown with them. Fossil fuels have allowed for the growth that has been seen in the
past century. However, there are dangers with having fossil fuels as the back bone of our
culture. Fossil fuels are created very slowly over thousands of years. People are using
fossil fuels faster than they are being made, making fossil fuels a finite resource that will
not be around forever; once our supply is depleted other sources of energy will have to be
found. Another problem with using fossil fuels is associated with the pollution that is
generated when the fuel is burned. Gases and particulates that are put into the
atmosphere are blamed for global warming, acid rain, health problems, etc. It will be
necessary to develop alternative energy sources that come from a sustainable or
renewable source and do not pollute the environment in order to sustain the current
lifestyle.
Background:
Most people would be willing to break away from our dependence on fossil fuels,
especially if it was economically advantageous. With the recent increase in the price of
fuels the idea of renewable energy is looking even greener. In upstate New York, a
significant portion of the energy needs of a home come from heating water. If there were
an economical, clean, and renewable way to heat water, people could save money while
helping to save the environment.
Proposed solution:
As the sun heats the earth’s surface, different parts heat up at different rates, this causes
pressure differences and wind. Therefore, wind will be around for as long as the sun is
heating the earth. If there was an economically sound way to harness the energy in wind
that could be used to heat water for use in a home, the dependence on fossil fuels could
be cut dramatically.
A CR-VAWT could be a viable candidate to provide the energy needs at the home level.
The advantages of a vertical axis wind turbine compared to the more common horizontal
axis turbine (HAWT), include, a relatively simple design with no need to track the wind
direction, the generator and associated equipment are near the ground where it would be
easily accessible for a homeowner, and a CR-VAWT used to heat water could work
without an expensive control system.
A CR-VAWT is like the combination of two anemometers, if looked at from above, one
set of cups or blades spins clockwise and the other set spins counter clockwise (Figure 2).
The contra concept is used on many airplanes and boats to increase efficiency while
eliminating the asymmetrical torque faced by conventional rotors.
Figure 1: Contra example - Convair XFY (Wikipedia)
There are two main types of CR-VAWT, lift driven (figure 1) and drag driven (figure 2).
An example of a drag driven type device is an anemometer used to measure wind speed.
A lift driven device uses the flow of wind over the blades to develop lift which turns the
turbine. Lift driven VAWT usually need to be started manually to get the flow of wind
over the blades and initiate lift. As a result a control system would be needed to start the
turbine. However a drag driven CR-VAWT will start whenever the wind is strong
enough to overcome the frictional and electromagnetic forces in the generator and
assembly. The control system makes up a significant financial portion of a homeowner
wind turbine, if this could be eliminated the overall cost of electricity (COE) from the
turbine could be reduced.
Methodology:
The first step of the process would be to search for relevant literature. Historical
information on max power output, design, and efficiency for drag and lift driven CRVAWT will be gathered. Further, literature and data on energy needs of an average
household, particularly energy to heat water in a home will be collected. Various heating
methods will be researched including oil, and gas. For example, natural gas is the most
used source of heat for homes in the Northeast portion of the United States. In the 2001
census, 59.1 million out of the 107.0 households use natural gas. (Energy Information
Administration) The cost per BTU can be calculated by dividing the cost per 1000 cubic
feet, by the cost of 1000 cubic feet of natural gas.
Cost per BTU 
Price per 1000 ft 3 $15.57

 $.001557 / BTU
1000
BTU per 1000 ft 3
This is only part of the total cost of energy (COE). The COE can also be calculated for
the various energy sources using method below.
TIC
 FCR  AOM  CBTU  ABTU
COE  DL
(Adapted, Spera,1998)
AF  AEO
where : COE  unit cost of energy delivered to the customer ($/kWh)
TIC  total initial cost of the system; includes complete
cost exposure for land, equipment, and start - up operations ($)
DL  design life of turbine (y)
FCR  levelized fixed charge rate; includes return on capital income tax,
property t ax and insurance ($/y)
AOM  annual cost of perations and maintenanc e of the system ($/y)
CBTU  fuel cost, cost per BTU ($/BTU)
ABTU  annual amount of heat used (BTU/y)
AF  availabili ty factor accounting for system downtime, partial or total
AEO  net annual energy output of the system without downtime (kWh/y)
By comparing the COE for a CR-VAWT and the various traditional heating methods, it
will be determined if a CR-VAWT is an economically efficient solution. Furthermore,
the length of time it will take to start seeing Return on Investment (ROI) will be
calculated.
If after our analysis, a drag driven CR-VAWT seems like an economically sound solution
to heat water in a home, a drag driven CR-VAWT model will be designed, built and
tested. The physical model along with wind tunnel testing will allow for greater
confidence in our proposed solution to the diminishing fossil fuel and pollution problem.
Experimental Procedure:
The goal of testing will be to determine the amount of heat that can be generated from a
CR-VAWT at various wind speeds. The setup will consist of a CR-VAWT with a
generator connected to a resistor in a tank of water. As the wind turns the CR-VAWT
and generator, an electrical voltage difference and current is created. The voltage
difference and current can be applied to a resistor in a tank of water, the heat generated
per unit time will be the power ( P  V  I ). By looking at how well a CR-VAWT can
generate heat, an appropriate size can be chosen to supplement the energy needs for the
average house. An advantage over turbine systems that are used to produce electricity to
be tied with the grid or power appliances is the resistance heater can operate with
unregulated levels of voltage and frequency. (Iowa Energy Center)
Conclusion:
A CR-VAWT may be an ideal solution to help alleviate our dependence on fossil fuels.
If the total COE of a CR-VAWT is comparable or less than the COE for conventional
fuels then a CR-VAWT is an economically sound solution, thus savings the homeowner
money. Furthermore, any diversion from fossil fuels and the dangers associated with
them could help the future of the humans and our planet.
Figure 2: Sandia National Laboratories 34 meter tall lift driven VAWT (US DOE)
Figure 3 - Concept of a drag driven CR-VAWT
Reference:
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Energy Information Administration, “Table HC3-9a. Space Heating by Northeast
Census Region” http://www.eia.doe.gov/
Energy Information Administration, “Average Retail Price of Electricity to
Ultimate Customers by End-Use Sector” http://www.eia.doe.gov/
Iowa Energy Center, “Wind Energy Systems, Main Components of a Wind
Turbine” http://www.energy.iastate.edu/renewable/wind/wem/wem07_systems.html
Sandia National Laboratories, Vertical Axis Wind Turbines Brochure
Spera, D. 1998. Wind Turbine Technology, Fundamental Concepts of Wind
Turbine Engineering. ASME
U.S Department of Energy, Sandia National Laboratories, American Wind Energy
Association, Vertical Axis Wind Turbines, The History of the DOE Program
Wikipedia “Convair XFY ” http://en.wikipedia.org/wiki/Convair_XFY