What is a small wind turbine?
The definition differs, depending upon which organisation you ask. It is either based upon the swept area (max. 200 m2) exposed to the wind, or upon the power that a wind turbine delivers to a house. We have used the definition relating to the power class at the building and will develop and manufacture product solutions with power ratings between one and six kilowatts.
What advantages do vertical-axis small wind turbines offer in comparison to conventional horizontal-axis wind turbines? Which are better?
Over 90% of all wind turbines sold are horizontal-axis small wind turbines (i.e. small wind turbines that rotate about a horizontal axis), and their success can be attributed to their high efficiency and light weight. Their efficiency is based upon the principles of fluid mechanics and is largely due to the Bernoulli effect, which ensures there is lift at the blades and thus torque at the drive shaft.
However, this also characterises the main disadvantages: this physical process generates measurable flow-related noise and shadow flicker. Both these effects can be detrimental to the health and wellbeing of those living near wind turbines, thus giving rise to significant opposition amongst the population and licensing authorities. In contrast, Savonius-type rotors, which work purely on the principle of air resistance, are almost silent and their movement is perceived similarly to that of a wind chime. It is also important to note that laminar air flow rarely exists at low heights (under 10 metres). Thanks to its design, a vertical-axis rotor can spontaneously take up wind from any direction without having to reorient itself. It can operate from almost 360 degrees, and can convert even strong and turbulent gusts into electricity. Which principle offers the greatest advantages for a customer, is above all a question of the envisaged application (the user’s goals) and the site.
What are the advantages of the new shape of the LuvSide in comparison to existing vertical-axis solutions?
The double-helix shape of the new lightweight Savonius blade from LuvSide means that a uniform torque curve can be achieved at the generator shaft. The design also incorporates an innovative slat, which uses the incoming air more efficiently than previous designs can. In the conventional Savonius geometry, the blades pass through an “air void” three-quarters of the way round, where no power is delivered. In the LuvSide the slat provides assistance during this phase and further accelerates the generator. This is similar to the use of an additional spinnaker to increase forward propulsion when sailing with a tailwind.
What further innovations does the LuvSide offer?
A wind turbine basically consists of three main components: blades, generator and power electronics. One problem in the industry is that development often begins with a good idea for one of these three components, and then the other two are not properly adapted to the system as a whole. This reduces the (already low) energy yield that can be obtained from wind close to the ground and delivered to your power socket.
In the LuvSide turbine the three components – rotor, generator and power electronics – were developed and thoroughly tested by an interdisciplinary team made up of materials scientists from aviation and aerospace, electrical engineers, physicists and production specialists from the wind energy sector. Only then were manufacturers and suppliers selected that excel in providing good quality, well-priced components. The manufacture and assembly takes place to an industrial standard. We were therefore able to construct a vertical-axis wind turbine in this demanding environment that redefines both the economic ratio of purchase price to energy yield and the technical standard for a series product.
How does the LuvSide increase its efficiency?
As already mentioned, the first major innovation is the patent-protected rotor shape with the slat arrangement. In addition, friction and vibrations in the system as a whole have been reduced by the selection of a special bearing concept. This means that a very high proportion of the kinetic energy from the wind is transmitted to the generator in the form of torque. The generator takes the form of an external rotor with 48 poles and 80 magnets and, thanks to this elaborate construction, achieves high efficiency even at low wind speeds. With this slow-rotating generator, the unit can feed efficiently into the grid even at approx. 50 rpm, thereby outdoing the high-speed generators from the standard ranges of most suppliers. Nevertheless, the generator can also process gusts or storms of 100 km/h and above and operate at speeds of 200 rpm.
Which target group is the LuvSide solution aimed at?
Our appearances at the New Energy trade fair in Husum in March 2015 and the Hanover trade fair in April 2015 will yield further information about which target groups are most interested in this product solution. LuvSide has targeted both home owners and users from trade and industry. The LuvSide offers a diverse range of possibilities. It even opens up entirely new design options in the field of “building art” that did not exist before.
What costs/extra costs are associated with the purchase of a LuvSide?
The ultimate purchase price will be decided after the final stage of development. The internal objective, however, is to price the product at significantly less than 7000 euros for the power class up to 1 kW. Additional components such as mast construction, roof construction, monitoring equipment and service contracts will also be offered when sales begin.
Are licensing procedures needed for the installation of the LuvSide?
Specific laws and decrees relating to licensing exist in each of Germany’s ‘Länder’ and sometimes in each individual district. The most important information on the various regulations is provided on the LuvSide website. To sum up: it depends greatly upon the people who deal with the subject of wind turbines in the region in question. If the responsible authorities already have experience with small wind turbines, the licensing of every further turbine will be significantly easier.
Is the LuvSide a suitable small wind turbine to supply power to an off-grid installation?
There is a fundamental difference between systems supplying direct into the grid and those used to charge a battery. The LuvSide is primarily designed for grid operation (230 V/3 phase) and aims to reduce the individual consumption of a residential unit or business. Off-grid installations or independent power supplies generally require a battery charger, and the power electronics need to be adapted to suit this. Efficiency depends largely upon how well the components are matched to one another. If there is enough demand for off-grid solutions, LuvSide will collaborate with a reputable battery manufacturer.
What sizes and power classes will the LuvSide be produced in?
LuvSide develops SWTs in the power classes 1 kW, 3 kW and 6 kW. The first LuvSide product will be 200 cm high with a diameter of 140 cm, and will have a nominal power of 1 kW at a wind speed of 14 m/s. This means the swept area of 2.8 m2 will extract the highest amount of energy yet achieved by any vertical-axis SWT.
As a potential customer of LuvSide, what factors do I need to consider?
The best way to ensure that the potential at the planned site is accurately predicted is to take a wind measurement in-situ. All factors, such as planning permission, structural surveys, installation and price, should be discussed with your chosen dealer or installer. Those interested can find further information on the LuvSide website.
Is my site or plot suitable for a small wind turbine?
Certain site conditions must be fulfilled if a SWT is to supply energy in the long term. It helps to look at the environment in detail. The more freely the wind can flow over the turbine, for example at a height of between 8 and 10 metres, the better. Nearby buildings and trees can disrupt the wind flow. The power generated by a wind turbine increases disproportionately with the wind speed. For example, locations where the airflow is accelerated in certain weather conditions can represent attractive sites for a vertical-axis wind turbine. Likewise, the edge of a tower block can be a suitable position for achieving good results even at low wind speeds.
Is the wind speed at my site high enough? How can I find out?
Specialist dealers for SWTs generally have measuring equipment they can loan out to produce long-term wind measurements over a period of six months. The wind speed should be measured at the precise position at which the turbine is to be situated. This allows the expected energy yield to be determined relatively precisely.
How much electricity can I generate with a LuvSide of a given power rating?
We recommend assessing a site to determine whether it fulfils your personal goals. For example, a four-person household consumes between 4000 and 5500 kilowatt hours per year. At an average wind speed of 4-5 m/s, e.g. at average altitudes, the 1 kW LuvSide unit will provide a saving in energy costs of around 750 kW/h. In northern Germany and the low mountain ranges, output can rise to 1000 kW/h. It is a platitude, but it is true: it depends on the wind. As a rule of thumb, if the wind speed doubles, the mechanical output increases eight-fold.
What additional benefits does the attractive design of the turbine offer?
The LuvSide wind turbine is characterised not only by its high efficiency but also by its attractive double-helix rotor. The design of the blades attracts a lot of attention at installation sites and is perceived as a visually attractive advertising space. Therefore, in addition to its function as an innovative and forward-looking energy source, the LuvSide also serves as a modern advertising medium that has a positive influence upon our customers’ corporate image. Two-thirds of respondents to a survey we carried out amongst staff of technical companies see the use of renewable energies as living proof that a company is taking a responsible attitude towards the future. This, in its turn, has a beneficial effect upon the company’s image and prompts the conclusion that the company is offering forward-looking products and services.
In meetings with potential users from trade and industry, proposals were made for using the rotor as advertising space to evoke positive emotions (active energy saving, environmental protection, CO2 reduction).
When will the LuvSide be available for sale?
Comprehensive long-term tests are currently underway, allowing us to make the turbine a little better every day. If everything goes to plan, we will be putting the LuvSide into series production at the start of 2016. The decisive factor for us is that all quality requirements are 100% fulfilled before series production begins.