Executive Summary

Summary – Bent Engineering, DBA Revoltwind

Bent Engineering has developed a revolutionary type of wind driven electric generator that hangs instead of being mounted atop a tower. The hanging wind turbine (HWT) was invented because city code prohibited windmill towers. The windmill blades and alternator had already been hand built. The only way to try it was to hang it on a tree branch. It required a rigid hanger and hinge with stop to prevent the spinning blades from striking the hanger. A counter balance to keep the alternator with blades attached from facing straight upwards was required. It could be short and heavy or long and lighter weight. A vane was added to make it point into the wind quickly. It was originally named the Gooseneck Alternator because it looked like a goose in flight. The little windmill was spinning at near ground level and ran a string of LED lights attached to the line from which it hung. They brightened when the wind blew harder. The neighbors were curious where they could get one and the hobby became a startup. The design can be fitted to any existing windmill blade/alternator combination. A design for manufacture was under construction when final US patent approval came in 2019. Field measurements of power output combined with the known costs to build it allowed us to accurately determine the cost per watt at various wind speeds. The results indicate that the HWT makes electricity at a significantly lower cost than any other technology. And in a convenient and portable form that requires no land ownership or permits on the part of the owner. It need not be made large or located in high wind speeds to justify its cost. If it can be placed in high wind it can pay for itself in under a year and run for 20 making power for only the cost of maintenance. Maintenance is performed at ground level with simply hand tools by lowering it to the ground. The global electric power market is measured in quadrillions of dollars and needs to expand to many times its current size to meet growing demand. The HWT is now the lowest cost method for making electric power. All we need to do is figure out how to use this invention and let it go to work.


Green electric power is critically needed to sustain our growing population and protect the environment. Fossil fuels are being used up and phased out. Nuclear power requires large expenditures decades in advance and hazardous materials that must be stored securely for years into the future. Wind and solar farms consume real estate in amounts that are not available to meet the expected demand. Land acquisition, environmental studies and permitting require that these projects be paid for in advance. The payback period is measured in decades. They produce low voltage that is not compatible with the high voltage grid. The electricity they produce must be converted to high voltage by high tech electronic devices and high voltage transformers cooled with toxic oils in substations. The large farms do not operate when the grid goes down because they need grid power to operate.

To date the solar and wind farms in operation around the globe have had varying degrees of success. Many financial investments were made that did not produce the expected returns. The variable power output of green energy sources that are tied to the grid reduces the efficiency of the primary fossil fuel burning plant. If this effect is large enough the power being made by the wind farm may be dumped entirely.

Our HWT invention can be made in sizes small to large using everything from bamboo to carbon fiber and suspended on existing infrastructure to produce power immediately at the point of use. They can act alone or be networked into the grid using grid tie in electronics. With an onboard rechargeable battery each windmill can act as an independent WIFI hot spot or cellular communication node. Thus allowing networks anywhere there is wind even if grid power is not available and expansion of coverage into all areas of the globe that have some wind.

Because the device naturally produces low voltage power, it is ideal for charging any rechargeable battery. They will be paired with everything from mobile phones to electric vehicles. Drone delivery of parcels is extremely energy intensive. Clusters of HWT’s will be set up and used to charge batteries for drones. This will make drone delivery inexpensive and sustainable. They will be used to build electric vehicle charging stations in homes and along the roadside across the country. The HWT is a godsend to any disaster relief effort. And they can bring power into mountainous terrain where there is often no way to carry in and set up heavy generating equipment.

Growth through partnerships in all nations is the fastest way to get this device into the hands of the people who will use it to help solve one of the greatest challenges in human history. We can no longer exist on only food, clothing, and shelter. Without electric power we cannot physically sustain our growing population.

Advantages of Hanging

Removal of the tower and the land required for the tower from the windmill system saves over 90% of the cost and 99% of the weight. The HWT can be lowered to the ground for maintenance. This eliminates the need for specially trained experts that are often flown in by helicopter and cannot work until the weather cooperates. Users will decide where to position windmills to capture the greatest amount of wind and can easily relocate them. Tower mounted wind turbines must be large in diameter and tall to justify the cost of the land and tower. Differences in wind speed across the giant rotor area create large bearing stresses and vibration that causes fatigue cracking in blades and structural supports. Hanging the turbine will reduce the stress on the bearing significantly and allow for less expensive material substitutions in these expensive components.

While there is some scale advantage in cost and efficiency to building the HWT in a large size, many small HWT’s will perform the same duty as a large one and are easier to maintain. They can be installed on rugged terrain with no earth moving equipment or massive concrete footers. They can be lowered to the ground and parked when storms are seen approaching. Large tower mounted windmills can only be built where specially designed trucks can get in to deliver the 100 plus foot long blades. Heavy equipment and concrete are required that must be hauled uphill to get to the construction site from a nearby town with enough oil and gas to make concrete in quantity. The HWT has no such requirements. In fact the HWT is the first windmill electric generator that most people can actually own. It is not surprising that fewer than 1 million tower mounted windmills exist today given the land restrictions created by the need for a tower. We expect that demand for the HWT will be in the billions of units as people learn to use it.


The six inch blade RW-Mini weighs ¼ pound and can make up to 5 watts. As a smartphone charger that can be carried in a backpack and deployed instantly anywhere there is wind it could reach a large fraction of the smartphone market and will likely be used by the mobile phone makers to promote the sale of their products in a sustainable form and expand their market into off grid communities. Though small in size it can trickle charge or maintain batteries in laptop computers, vehicles, marine equipment and security systems. In quantity the ReVolt Mini will cost under $10 to build. There are over 5 billion smartphones at the present time.

The RW-1 that is coming into production weighs only 16 pounds and can produce 200 watts. In 15 mph wind it makes 50 watts. A typical cell tower could be powered by 20 of them. If hung from the cell tower they would be mounted on the lower part of the tower just above tree tops and roof lines. They would not increase the wind load on the cell tower substantially. The cost would be about 10 thousand dollars. A power line run to the same cell tower from the grid will cost hundreds of thousands or more. It may pass through land owned by others who are paid a right of way fee. The HWT will allow cell towers to be placed far from grid power on a small patch of real estate. Bridges, highway signs, billboards and remote monitoring equipment can be powered inexpensively by them. If the faces of a skyscraper were blanketed with many small HWT’s they could produce a tremendous amount of power without increasing the wind load to the building and be mounted higher than a tower can reach.

The RW-1 can be hung on existing infrastructure without major disruption. One on each power pole for instance. There could be a windmill on every power pole, cell tower and skyscraper today. But for a device that makes a small amount of power and gets hit by lightning frequently the maintenance cost is too high. By comparison, the RW-1 can be hung on a cable with an electronic winch. Maintenance is performed with the push of a button at ground level where there is no fall hazard. The HWT cannot be struck by lightning if hung on a grounded hook or line.

Tower mounted wind turbines have reached a size where blade length is limited by tower height. Using the HWT design it is possible to build a wind turbine with blades longer than existing tower mounted technology can achieve. If hung beneath a blimp, a standard large wind farm turbine would cost 1/10th as much and operate nearly 100% of the time in high wind at high altitude beneath the blimp. It would produce hydrogen gas to be stored in the blimp using water extracted from the atmosphere by condensers mounted on the blimp. The tether that holds the blimp fixed to the ground would deliver electricity, hydrogen to burn as fuel, pure oxygen, and pure water safe for drinking. All generated by power made from the windmill and water extracted from the air. It could be flown into any desert. If the windmill requires maintenance it can be lowered to the ground. Storage of hydrogen gas at altitude is preferable to storage on the ground.

People will figure out how to use buildings, slopes, trees, etc. to channel wind towards an HWT hanging close to the ground and many advances will be made as engineers gain experience with them.

There are as many uses for the HWT as there are users of the HWT!


Portable power generation can be accomplished using gasoline, kerosene, diesel and natural gas. The systems are well understood, available in quantity and reliable. Solar panels that are portable are growing in popularity and reasonably priced. And there are many small wind turbine designs that rely on clamps to secure them to structures. To get the same power as the RW-1 out of solar panels will require 2- standard size (39” X 65”) solar panels that must be secured to the ground and protected from strong wind, shade, dust, hail, and debris. Solar panels typically operate for 6 hours during the day and cannot operate at night. The grass beneath a solar panel must be cut. Animals, insects and fungi that make their homes beneath a solar panel will require removal or poisoning. And solar panels require removal of ice and snow as well as occasional cleaning to remove the thin film of grime that accumulates and reduces efficiency. Our product is unique because it has the ability to capture a lot of power on a small footprint and is located above the heads of people, and moving machinery. They will not prevent the sun from striking the ground beneath them. Small windmills do not harm birds and bats. They do not throw off heavy ice as large wind turbines do. So the land beneath them is safe for other uses.


The technology is new and unfamiliar to engineers, developers, architects and city planners. The claims made in this summary cannot be supported beyond the limited testing performed by the inventor. There are a large number of unknowns that must become known for large scale acceptance. We feel that these unknowns will be quickly answered by early adapters of the technology because the savings potential is too compelling to ignore. The machine is attractive and will garner attention from green energy enthusiasts worldwide. It is its own advertising bill board and is highly visible. Many people will not like the way they look. As when America was electrified and people did not want to look at power lines everywhere. Now we have come to accept them because we are dependent on electric power.

Our biggest recognized opportunity is the growing awareness by the people of the magnitude of the energy problem and rising demand in nations that have no oil or fossil fuel. In the US commitments are being made to go green by some future date and there are sustainability mandates on most new construction. Most states do not have the land required to go green using wind and solar farms and have not done the research needed to identify unintended costs associated with going green. The HWT allows the states to meet their green energy objectives at a significant cost reduction over other technologies without a massive up front effort. We are in the beginning stages of learning to live without fossil fuels. The HWT provides electric power at a cost so low that the work required to make use of it will get done. And many new inventions will be developed into products that allow HWT’s to be installed and used productively on existing infrastructure.

Global warming is accelerating as thermal momentum builds in the ecosystem. If we have a means to eliminate one of the causes of global warming at a cost savings we must move quickly to find out if it will work on a large scale. The economy needs a boost, billions of people need power immediately and we need to take back control of the chemistry of the atmosphere. Our plan is to license the HWT technology to manufacturing partners around the globe. This will allow existing windmill producers and electronic device makers to compete and grow the technology rapidly. Large utility companies and network providers will learn to incorporate it for the savings and benefits it provides through new products and public/private partnerships. By scaling the number and size of HWT’s purchased, any green energy budget can be utilized to complete a project.

We believe that relief agencies around the globe will provide HWT’s to people who cannot afford them and that emergency supply warehouses will be stocked with them.

Management Team

The management team is led by Chief Executive Officer Stephen Cowap who founded his company, Bent Engineering, in July of 2011. He has a Master of Science degree in ceramic engineering from the University of Illinois, 1984. He was a glass technologist for Owens Corning and Philadelphia Quartz. He is the author of several patents. Was a member of ASTM C08, and is a member of the honorary engineering fraternity, Tau Beta Pi.