Vertical Axis Wind Turbines for Micro-Generation

Bob became a Non-Executive Director of 4Navitas Ltd a company on 1st June 2013. 4Navitas Ltd has developed their first Vertical Axis Wind Turbine (VAWT).

A very exciting world-first, this mid-size Wind Turbine has a 30-100KW output. It’s made from green composite materials, and is bird-, bat- and radar-friendly with a payback time of around 4.5 years.

Vertical Axis Wind Turbine from 4Navitas
The 4N-55 is designed & manufactured in the UK specifically for UK winds.

About Vertical Axis Wind Turbines

Vertical Axis Wind Turbines offer a very reliable, efficient and cost-effective alternative to conventional Horizontal Axis Wind Turbines. Vertical Axis Wind Turbines are less intrusive visually, even in areas such as National Parks and Areas of Outstanding Natural Beauty. These turbines are quieter, more bird and bat-friendly and are less expensive to maintain compared to horizontal turbines.

The UK has some of the best wind resources in Europe, so it is hardly surprising that businesses throughout the UK are looking at small wind turbines (under 100KW) to produce their own energy requirements and thus reduce their energy bills. In addition, micro-generation now offers businesses a real income stream and makes wind energy a commercially viable option. Correctly sited, a wind turbine can provide a substantial return on Investment, significantly higher than current returns from the banks.

Introducing the 4N-55

The 4N-55 is a 55kw rated turbine. Three years in development, the radical new design is manufactured in the UK and incorporates a wealth of patented design features, which greatly enhance power generating output at low wind speeds, and significantly reduce the total costs of ownership. The design team includes world leading aerodynamics and electronic consultants.

Full details, specifications and more info are at


2 thoughts on “Vertical Axis Wind Turbines for Micro-Generation”

    1. Thanks for your interest and comment. We have this information from 4Navitas:

      It is true that dead bats, some of which are apparently un-injured, have been found on wind farms. There are two reasons for the deaths, strike by a blade and low pressure vortex of the blades.

      To cover each one:

      Strike, the heat at the nacelle of a wind turbine is visible to insect life, this causes flying insects to congregate around the nacelle, this congregation of insect life attracts feeding bats who are sometimes then struck by the blades.

      Another issue is that bats have a pressurised lung, very different from birds, they can suffer huge internal haemorrhage caused by the low pressure vortex at the tip of a fast moving HAWT blade, remembering that these blade tips are moving in some instances at several hundred miles per hour. This was noted when apparently un injured bats were being found dead on wind farms.

      The mortality of birds and bats is hardly effected by the wind industry in any instance if you study the figures.

      Our turbine has the heat created by the motor at ground level, therefore insects congregate at ground level and away from the wings, so any hunting bats will be similarly attracted to ground level. The maximum rotational speed of our wing is 55 mph, and so we do not create a low pressure vortex, so the other cause of bat death is also mitigated.

      The reason birds are struck, is due to the fact that they are caught out by the fast moving wing tips, birds accustomed to a migratory route may fly close to wind turbines, they will fly around the tower or the nacelle, but are caught out by the very large swept are (over 6400 sq M)

      Our swept are is 198sq M, therefore the birds can see the full mill in rotation as they approach, to them it appear to be a solid square object.

      Hope that explains,


      Dominic M’Benga
      4 Navitas (Green Energy Solutions) Ltd

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