At Carbon Concepts we have been interested in renewable and sustainable energy for several years.  Since the technical requirements of the wind turbine and its associated systems are a very close match to the technology that we have already evolved in other sectors, we decided to develop a competitive wind generator rated at 2.5 kw at a the industry standard wind speed of 12 m/s (force 5).

SMALL SCALE WIND AND WATER POWER

Carbon Concepts 2.5 KW wind turbine generating set

click here to see short  video

The vertical axis turbine offers two major advantages over the more conventional axial configuration:

•       Almost totally silent operation - even at high speed and load.

•       Perception of lower visual impact - improved public acceptance.

The disadvantages are that the engineering is more complicated, it is very intolerant of poor aerodynamics and the blade stresses are higher.  We believe that the advantages are critical to the acceptability of small wind turbines, particularly when mounted on or close to buildings.  This is of particular importance for urban installations where local authorities are seeking to meet current energy targets. 

The first wind turbine has now completed its initial performance evaluation.  It is currently undergoing endurance and structural testing while the final control system is optimised. 

TECHNOLOGY

The performance and cost effectiveness of the wind turbine derive from the advanced technology generator and the aerodynamics and structure of the rotor set.  The rotor has been designed in accordance with the best available low speed aerodynamic technology and is fully optimised for the unusual conditions of the vertical axis wind turbine.  The turbine currently drives an electrical generator, but would equally support water or hydraulic pumps and heat pumps.

The advance tip technology improves efficiency and minimises noise.  Testing has confirmed that, even at high speed and load, the rotor is effectively silent.  Attempts to measure the noise of the rotor showed that perceived noise was dominated by the wind and adjacent trees.

2.5K.W. wind generator set - fixed installation

DESIGN AND COMPONENT INTEGRATION

The design of the first installation was completed in conjunction with the University of Nottingham.  The work was carried out as a fourth year Group Development Project by four students completing their M. Eng. degree.  The design brief was that the installation should be fully portable.  It can be erected by two people without the need for special tooling or lifting equipment and is transported on a small boat trailer.

  We believe that the complete portability of this turbine makes it unique. 

For maximum stability, the generator is mounted at the bottom of the tower and is driven by a shaft.  Both electrical and mechanical breaking systems are employed to allow a controlled emergency stop. This turbine is set up as an electrical generator.  With appropriate processing it is suitable for battery charging, mains connection and direct heating. 

Fixed Installations

For fixed installations the same generator and rotor will be mounted as an integrated unit at  the top of the tower (typically 5 metres).  This installation is illustrated on the left.  The low weight of our assembly means that this can also be assembled and erected on site without special equipment or lifting gear. 

RESEARCH

The design and development programme has been supported by a programme of modelling, simulation and wind tunnel testing.  This has given us invaluable data, particularly in support of the self starting behaviour of the turbine.

The photograph on the right shows the quarter scale model mounted in the wind tunnel at Durham University.  In addition to the starting performance, it is being used to derive the power coefficient characteristics.  This is particularly difficult on the full size turbine due to the variability of "real" wind.

The 25% model in the wind tunnel at Durham

note the alternative rectangular blade form

FURTHER DEVELOPMENT.

In addition to the 2.5 kw wind turbine that we have been testing over the past two years, we wre actively working on two new turbines.

1) 1.5 kw wind turbine.  We have already run the current blade design on the smaller, 1.5 kw generator.

2) 5 kw wind turbine.  Following the very successful testing of the 5 kw generator, we have started to work on a blade set to match.  This will be of a slightly different design due to the different structural considerations of the larger machine.

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