How Wind Machines Work
Intro
Many millions of dollars have been spent throughout history trying to reinvent the wheel. Perhaps no other concept, however, has induced the shear amount of explicative language in the heat of frustration, as the concept of harnessing free fuel from the wind. The contents of this page should answer many of the questions surrounding the basic concepts behind a few championed designs.
It is noteworthy for any person researching this incredibly fascinating subject to realize that our forefathers struggled with the technical aspects of harnessing wind, whereas, now days the struggle is about pushing back on the failed political and social policies of the past.
It is also very important to make the distinction between centralized power distribution and Distributed Generation. Centralized power is old fashioned coal, gas, or nuclear power designed to allow regulated monopolies to enslave us every month. Distributed Generation allows the person or entity to provide (for themselves) the power needed to operate their business, farm, or home while also exporting to the existing grid. That is not to say that alternative energy can't be centralized because it can be and is already being used this way.
The former distinction, and the unbalanced policies regarding DG is at the heart of most every renewable energy stakeholder. This is the precise driver for so much of the historical cynicism that one uncovers while talking to former and current industry gurus. Consider that to be your disclaimer until your eyes are opened to the true benefits of Distributed Generation (DG), and the countless other positive effects it offers the world.
Marcellus Jacobs
Harnessing the Wind
We are not talking about grinding grain. Sometimes those old contraptions are referred to as wind v1.0. While they served their purpose, one of the most phenominal acts of physics is in fact the lift principle which allows the right shaped blades to develop the forces necessary to increase power at a rate proportional to the velocity of the wind, while simultaneously generating electricity being matched to an alternator.
A true representation of the technological progress of the time. -photo thnx Dale Hughes
The trials and tribulations of many teams of individuals over time has given us a vast array of different renditions of wind energy conversion devices, some better than other. The shape of the blades, the orientation of the rotor (vertical or horizontal), and the tower configuration are some of the main visual differences that can tell you a lot about what the creator(s) were trying to accomplish. Different styles do in fact have names based first upon the configuration of the rotor.
Rotor Configurations
Savonius
Vertical Axis
Drag device
The old savonius style config. is a low speed high torque unit. It uses very old somewhat crude technology to convert energy from the wind. The efficiency is very low (around max 30%). Such low tip speed doesn't allow for good electric production and adding gear boxes always increases costs and maintenance issues. Due to the fact that an apparent advantage is perceived through having shorter towers, this design has tempted many entrepreneurs and engineers alike to chase after something that literally fights against itself every 1/2 rotation.
Physically scaling up the size of the unit begins to add stress to components very quickly. Obvious stability of the rotor is a concern with no support from the top. Although the Helix and others were a joke there is an argument that they may yet serve a purpose if they can find a way to "stack" them on the sides of existing structures. That all depends on costs and will most likely never become below solar.
Darrieus
Vertical Axis
Lift Device
The darrieus style configuration has the same tower issues as the savonius however it varies in that it is a lift device. The rotor does not "catch" wind but rather takes off in it. The enemy of this configuration however is fatigue from a lift- no lift cycle that is a negative force on the blades.
The speed control of the rotor is very critical in this setup. While drag devices fight against themselves and don't require as much attention to governing, the lift principle makes this more difficult for darrieus rotors. A vertical axis wind turbine (VAWT) in a 20mph wind rating of 2kW, in a 40mph wind it would want to produce 16kW. If you try to capture that with a bigger generator then you waste capacity as most of the time the wind is only generating 2kW.
Bergey
Direct Drive Up-wind
Horizontal Axis
Lift Device
Wind energy production started in concept with this type of design during the 1920's, in Minnesota. The benefits of direct drive units have allowed these style of machines to survive for decades without failure and with relatively low maintenance. The rotor bearings and blades are your prime moving parts thus should be designed to last.
Most common generator designs are radial for both up-wind and down-wind direct drive units, although there are down-wind turbines that use a radial generator design.
When buying a wind turbine, or designing one for that matter, it is important to realize how many moving parts the machine has. In all cases, a wind turbine's moving parts are naturally hard to access to maintain or change if needed.
Generally speaking, any turbine rated at 10kW or less should use a direct drive alternator design. It limits the amount of maintenance issues and costs over the lifetime of the unit. At this scale, a machine requiring a lot of maintenance can squash the economical benefits you acquire by harnessing the wind.
Timeline
First Century AD –
Heron of Alexandria created with a wind-wheel design to power grain
700-800 AD– Europe
Sistan region of Iran, wind-wheels used to grind grain (reportedly). The available research from large website's claim they ground CORN!! Which we know has to be an error or lie.
1000AD – China, Sicily
Wind to make sea salt from coastal areas from pumping mechanisms
1180 AD – Europe
VAWT's used in NW Europe to grind grains into flours.
1887 – Glascow, Scotland
The first claimed wind electric machine in the world. Professor James Blyth at Andersons College (Modern day Strathclyde College).
The crude 10M blades featured cloth. The machine was not a lift device but supposedly charged accumulators that powered lights in their cottage. This is the claimed first utilization of the tech.
Winter 1888 – Ohio, US
Professor Charles F. Brush builds a 12kW wind turbine to charge 408 batteries stored in the cellar of his mansion. The turbine, which ran for 20 years, had a rotor diameter of 50m and 144 rotor blades.
1890s – Askov, Denmark
Scientist Poul la Cour begins his wind turbine tests in a bid to bring electricity to the rural population of Denmark. In 1903, Poul la Cour founded the Society of Wind Electricians and in 1904 the society held the first course in wind electricity. La Cour was the first to discover that fast rotating wind turbines with fewer rotor blades were most efficient in generating electricity production
1900 – Europe
An Estimated 30Mw of total power equivalent used to directly power mills, pumps, threshing, and sawmill operations across Northern Europe. The total approximate turbine count was roughly 2500.
1927 – Minneapolis, US
Joe and Marcellus Jacobs open the Jacobs Wind factory, producing wind turbine generators. The generators are used on farms to charge batteries and power lighting.
1931 – Yalta, former USSR
A precursor to the modern horizontal wind generator is used in Yalta, generating 100kW. The turbine has a 30m tower and a 32% load factor, meaning it provides 32% of its potential energy output, pretty good even by today's standards.
1931 - Europe
The first vertical axis wind turbine, the Darrieus turbine, is invented by Frenchman George Darrieus who in 1931 has it patented in the US. The design, often referred to as the "eggbeater windmill", due to the appearance of its two or three blades, is still used today.
1941 – Vermont, US
The world's first megawatt wind turbine is built and connected to the power grid in Castleton, Vermont. The turbine has 75-foot blades and weighs 240 tons.
1956 – Gedser, Denmark
The Gedser wind turbine is built by Johannes Juul, a former student of Poul la Cour. The 200kW, three-bladed turbine inspired many later turbine designs, and Juul's invention - emergency aerodynamic tip breaks – is still used in turbines today. The turbine operated until 1967 and was refurbished in the mid 1970s at the request of Nasa.
1970s – Ohio, US
The United States government, led by Nasa, begins research into large commercial wind turbines. Thirteen experimental turbines are put into operation and the research paves the way for many of the multi-megawatt technologies used today.
1978 - North Wind
Awarded DOE Grant for the development of the HR2. This and the larger HR3 were sold for over 20 years.
1980 – New Hampshire, US
The world's first windfarm consisting of 20 turbines is built in New Hampshire. The windfarm however, is a failure as the turbines break down and the developers overestimate the wind resource.
Gear Driven Up-wind
Horizontal Axis
Lift Device
Jacobs
Many of the same principles of the direct drive turbine are present in the gear driven Jacobs 20kW. However, the scale of this turbine justifies maintenance due to the transfer case. Gears require oil and oil requires changing which means obvious maintenance and associated costs.
The direct drive manufacturers like to point out associated costs by going this route and argue the juice is not worth the squeeze in this case for an extra 10-15,0000 kWh's/year, as compared to a Bergey or similar direct drive model. The direct drive turbines have been able to achieve a higher efficiency in the past 5-10 years by switching to neodymium (rare earth) magnets, something Wind Turbine Industries (Jacobs) has not done. They are positioned well if ever neodymium hits a big spike in price.
The design of the generator and rotor is capped by the rated tower loads. This means the design is a function of matching the blades to the alternator while keeping the weight down. Jacobs over-sized their alternator but moved the weight down the tower which lowers the center of gravity.
1983 - Ok,USA
The BWC Excel 10 was introduced in 1983 and it has been installed at over 1,800 sites around the world.
1991 – Vindeby, Denmark
The first offshore windfarm is created in Vindeby, in the southern part of Denmark. The windfarm consists of 11 450kW turbines.
1991 – Cornwall, UK
The UK's first onshore windfarm is opened in Delabole, Cornwall. The farm consists of 10 turbines and produces enough energy for 2,700 homes.
Skystream
Direct Drive Down-wind
Horizontal Axis
Lift Device
Down-wind turbines do not face the wind, but passively look away and let the blades react to the direction of the wind. By using this method, the turbine manufacturer's have gotten rid of the need for a tail.
The down-wind passive yaw method is vulnerable to non production or "facing into the wind" in low wind speeds but the logic is that they are designed to yaw into the wind when the wind has power to offer.
Hope to make this page a facinating and never ending update to these intriguing ways to convert wind power