IS THERE A ROLE FOR VERTICAL AXIS WIND TURBINES?

There are two types of wind turbines:  horizontal and vertical axis.  The type you mostly see, from those classical Holland windmills to utility wind farms feature blades that revolve around an axis horizontal or parallel to the ground.  The other type has an axis that is up and down or perpendicular to the ground.  Today I feature the latter variety.

Wind energy conversion systems have pros and cons.  The good:

• Non polluting.
• Domestic source.
• Relative low maintenance.
• Wind farms can continued to be farmed for agriculture.
• About the cheapest source of renewable electricity.

A few cons:

• Not reliable.  Need storage for home or farm applications.
• Thus storage costs can be a problem.  Meaning today, mostly batteries.
• A threat to wildlife like birds and bats.
• Deforestation can create an environmental impact.  Deserts are great.
• Noise.
• Unsightly.
• NIMBY:  various communities, especially Hawaii, are saying Not In My Back Yard.

Last year, wind energy produced 9.2% of all the electricity in the U.S.  Note that all of solar only was responsible for 2.8%.  Also note that petroleum was used only for 0.5% of electricity generation in the country.

Hawaii is unusual in that 60% of our electricity comes from petroleum.  We attained 38% renewables, though, which is only 20% for the nation.  Hawaii produces 8% of our electricity from wind energy, about the same as the U.S.  We have stopped using coal for electricity, and that occurred last month.  The U.S. is at 22%.

Four years ago the largest wind turbine was 8MW.  The action now heads to 20 MW.

• The world's biggest is the Chinese MingYang Smart Energy 16 MW offshore wind turbine, with a diameter of just about 800 feet.  Imagine three football fields side by side.  Just about that size.  Only one can supply electricity to 20,000 homes.
• Danish Vestas has a 15 MW turbine designed for high wind conditions.  Diameter of 775 feet.
• Here is what is expected in 2035.

Note that all the above uses horizontal axis turbines.  What about vertical axis wind turbines (VAWT)?  Germany just constructed the largest VAWT near Grevenbroich in the west by a Swiss company Agile Wind Power.  It is about 105 feet in diameter and 344 feet high (about as long as a football field including some of the end zones).  Produces 0.75 megawatts of power.

One scientific fact you should know about wind turbine power:  the energy generated increases with the cube of the wind velocity.  This means that a hypothetical wind machine powered by winds at 20 MPH produces eight, yes 8, times more energy than at 10 MPH.  20/10 = 2.  2x2x2 = 8.

A rule of thumb is that for the same circumscribed area, VAWTs produce 30% less power than HAWTs.  Also keep in mind that energy = power times time.  On the other hand, Wikipedia reports:

Computer modeling suggests that wind farms constructed using vertical-axis wind turbines are 15% more efficient than conventional horizontal axis wind turbines as they generate less turbulence.^[5][6]

In other words, VAWTs can be placed closer to each other.  Further, the noise level of VAWTs is significantly lower than HAWTs.  Parts are easier to transport, install, operate and maintain.  The crucial items are the generation equipment and gears.  For VAWTs they can be at ground level.

VAWTs can come in a variety of conformations:

I've long been a fan of VAWTs.  I got my start in the U.S. Senate when the U.S. Congress passed the first wind energy act in 1980.  I was the Senate staffer assigned to this effort, working for Senator Spark Matsunaga.  My House counterpart, who did most of the work, Tom Gray (left), went on to help found the American Wind Energy Association, while the individual who I shared an office with, Ed Ing, later on became President of AWEA.

In the 1980's VAWTs were mostly Darrieus (he is from France and got the first patent in 1925) turbines.  Sandia National Labs borrowed from the Europeans and Canadians, and here are some of these systems.  FloWind Corp was the major company involved.

The Darrieus turbine ÉOLE in 1987 in Quebec was the largest at 3.8 MW, using steel instead of aluminum blades.  It is today a tourist attraction.

Only a few years ago several VAWTs with H-rotors were installed near Krakow in Poland.  Watch how they develop.

Of course,  there is the other end of the size spectrum which today dominates in numbers.  The majority of VAWTs these days are for home use to vent attics and power farms.   Here is a good source of candidates with details on cost and supplier.   I looked at  one Amazon site and if you want something really cheap, a second location with a VAWT for $11!

More realistically, a 4kW VAWT for $1590 might be more realistic if you want to charge batteries and therefore essentially get you off the grid.  Low vibration and noise promised, with easy and quick installation.  The battery system, though, will increase the overall cost.

There are other options.  Here is an excellent article for urban applications by Eddie Robinson entitled:  The Best Vertical Wind Turbines for 2022.  Must repeat this reality, though, that the power of the wind device increases with the cube of the wind velocity.  Homes and apartments are rarely built in windy places.  One intriguing example, though, is if you have a location where the prevailing winds can be funneled to one location.  If some noise can be tolerated (although  some of those machines mentioned in the link above mention "noiseless" operation), might be worth an experiment to determine if an investment is warranted.

So to summarize the big picture, the largest VAWT projects occurred in North American in the 1980's, with a renewed interest in Europe using the H-rotor concept in the 2010's, which shows promise for offshore wind farms.  Norway's World Wide Wind indicated that their system can generate double the power of the largest HAWTs, and a 40 MW (the largest HAWT today is 16 MW) unit is in their future, like maybe 2029.  Also follow the evolution of the Agile Wind Power 750 kW VAWT in Germany, mentioned earlier.  When metal fatigue, gearbox and stability issues are all fully overcome, VAWTs should begin to make an impact in the future.  

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