How a New Class of Wind Turbine was Developed
What do you do when you want a wind turbine, but it is not possible because of local planning regulations? Most people would just give up and look elsewhere for their renewable energy, but not Win Keech. Win lives in the North York Moors National Park, a beautiful part of northern England, with extremely rigorous planning requirements, so much so that in the 1,500 km2 park (which is in one of the windiest parts of the UK) there is only one wind turbine installed. To Win, the solution was obvious, he decided to invent his own wind turbine that would be acceptable to the planners.
By Dean Gregory, Co-founder, The Power Collective Ltd, UK
The brief was simple – the turbine had to be as unobtrusive as possible, efficient at all wind speeds, work well in the urban environment, and be silent, vibration free and inexpensive.
Background
With a background as a jet turbine blade designer for Rolls Royce, Win knew that wind speed increased as it passed over the ridge of a building and decided to use this to his advantage, designing a cross-flow horizontal axis wind turbine installed on the ridge to maximise the energy available to the turbine. The idea of a roof-ridge-mounted turbine was not new, but it had never previously been commercialised due to a number of inherent problems: noise, vibration and efficiency. When a turbine is fixed to a roof, it needs to be silent and vibration free as it produces its energy. With his experience in designing noise limitation systems for military aircraft, Win was convinced that the problems could be solved.
First Steps
With the concept in mind, Win approached Dean Gregory, friend and serial entrepreneur, to look at forming a company and commercialising the product. One of the first things the company did was to approach the North York Moors National Park Authority to make sure that the design, which they called the RidgeBlade, would be acceptable in protected areas, an approach that resulted in the authority providing a small grant to develop a prototype. The authority also requested that Win design a larger version of the RidgeBlade, now called the RB2, for installation on commercial and agricultural buildings.
Early Success
With a clear development path, and a ready customer base, the company expanded the core team by recruiting Bernie Cook, an experienced company director and businessman from the IT sector, and Simon Pringle, an expert in sustainability. Shortly after the team was put together, the company entered the Green Challenge, a competition to find and reward the best new carbon reducing technologies from around the world. The company beat over 300 entrants to take the first prize of €500,000, which helped to fund the development of the RidgeBlade.
Since then, The Power Collective has continued to develop the RidgeBlade MicroGeneration System – an innovative and unique, affordable, simple and effective way of harnessing the wind’s power to produce electricity.
Design Criteria
The RidgeBlade has been designed to produce electricity in a wide range of wind conditions (including low wind speeds) while maintaining a low visual impact. This makes it suitable for the majority of installation locations, including urban houses as well as environmentally sensitive sites such as National Parks and rural locations. Given the urgent need to improve the energy and carbon performance of existing building stock, the RidgeBlade has been developed to be retrofitted into the existing built environment. In addition, the unit has been designed to be low cost, in terms of manufacture, installation and maintenance. It is highly efficient at all wind speeds, effectively silent and vibration free in operation, low cost, robust and easy to produce and is also protected from overspeed running through patent-pending aerodynamic features.
Installation and Operation
The RidgeBlade was designed to be easy to install with existing skill sets, having been designed to use the same installation methods as solar photovoltaics. It is also planning friendly, adding very little to the height of the roof, and suitable for most roof types (flat and pitched roofs). The RidgeBlade operates in low and medium wind speeds to generate electricity, and is designed to accept wind that is turbulent (e.g. in built-up areas) over a wide range of wind directions.
Specifications
The system is modular, consisting of 1.2-metre sections that connect together mechanically to the required length, and therefore the generation figures depend on the size of the installation, but the maximum output per rotor is 400 watts (installed capacity). Like all wind turbines it does not reach peak output very often, but unlike other turbines, the RidgeBlade is designed to operate best in low and medium winds (i.e. most of the time). The units also accept wind from a wide wind rose of ±75 degrees. While the design is extremely sophisticated, the technology is relatively simple, making the RidgeBlade very suitable for manufacture or assembly in developing nations. In such areas it is expected that the cost to the consumer would be in line with local economic conditions – in a word, affordable.
Output
Because of the modular nature of the RidgeBlade, the output depends not only on the prevailing wind conditions but also on the number of rotors installed. As an example, a five-rotor installation (RB1 Domestic) produces in the region of 3,200kWh per year where the mean wind speed is 5.7 m/s. For a ten-rotor RB2 installation the figures are about 6,100 kWh per year at the same mean wind speed.
Next Steps
Since 2009, Win and The Power Collective have continued to refine, develop and test the RidgeBlade, to a point where there are now two variants, the RB1 and RB2, differing only in size for domestic and commercial installation.
So, did Win achieve his objectives? Well, the turbine is unobtrusive, only adding between 0.55 and 0.92 metres to the height of a roof, a property which has pleased planning authorities both in the UK and Europe.
Testing has shown the design to be very efficient, with a start-up speed of only 1.2 metres per second, before the wind can even be felt on your face! The units are also designed to self-limit aerodynamically, so operate in very high wind speeds as well as very low, making the ‘generation envelope’ as wide as possible. What astounds most people though, is the silent operation of the RidgeBlade – any noise that is created is always below the level of ambient background noise.
The final hurdle for Win and the team is the commercialisation and rollout of the RidgeBlade, and in 2014 Libra Energy BV were chosen to partner as distributors for Western Europe. A manufacturing partner has also been chosen, and full-scale manufacturing is intended to commence in the second quarter of 2015.
One obvious question is cost, and while no cost has been finalised, every indication is that the price per kilowatt will be roughly equivalent to that of solar photovoltaics. Because the units are modular in construction, they are inexpensive to manufacture, and the use of common components makes ongoing maintenance inexpensive and easy.
For Win and The Power Collective, it is the culmination of a dream to make small-scale, low-cost wind generation a reality for customers around the world, especially in areas where traditional wind turbines are not suitable, such as protected landscapes and urban sites. It has been a long journey, but hopefully the benefits will be seen by thousands of people throughout the world in the coming years.
Biography of the Author
Dean Gregory has had a varied career including the founding of a number of start-ups including the Power Collective, (developers of the RidgeBlade wind turbine). Whilst with the Power Collective, Dean won the 2009 Green Challenge, a global competition rewarding the best carbon reduction technology, and was also a finalist in the Climate Week Awards and the Ashden Awards
