Buying a Wind Turbine - FAQs"Excellent communications. Excellent knowledge. Couldn't have asked for any better". Steve & Jill Polglase, Cornwall - Evance Iskra R9000 Small Wind Turbine Would you like to Create Your Own Electricity and Laugh at Rising Energy Prices while Saving the Environment and having the Electricity Company Pay You? 1. Why buy a Wind Turbine? - to reduce or eliminate electricity bills Greenthinking source what we consider to be the best Wind Turbines available and use suppliers that, in our opinion, provide a highly professional service. 2. What is the specification of the Wind Turbines that Greenthinking sell? Greenthinking sell three main wind turbines*, all of which are leaders in their class. The Evance Iskra R9000 is a 5kW wind turbine, the Gaia 133 is an 11kW wind turbine and the Endurance E-3120 is a 55kW wind turbine. All three turbines are capable of outperforming other wind turbines of a higher kW rating. Return to Frequently Asked Questions. 3. What size Wind Turbine will I need? Before we look at physical size and what you actually require lets consider how we should compare wind turbines. Firstly you should not just compare the power ratings (maximum kW output) of a wind turbine as these ratings are determined at a certain wind speed which is often above that at which the turbine usually operates. In this case size is not always better! All other things being equal (in terms of tower height, efficiency etc) the size of the area ‘swept’ by the blades as they turn is one of the best ways to compare wind turbines. This is known as the ‘swept area’ and is clearly related to the size of the rotors. The Gaia 133 has a large swept area of 133 m2. This is remarkable for a small wind turbine and it allows the Gaia to outperform some 20kW wind turbines at typical wind speeds. Regarding the Iskra, whilst the swept area remains important it manages to outperform its nearest competitors (including a 6kW wind turbine) because of its unique blade design and exceptional efficiency. The Evance Iskra R9000 is the most efficient 5kw wind turbine currently available on the market. So, as you can see, rated power is not the best indicator when recommending a small wind turbine. What really matters to you is the energy that the wind turbine will generate each year, which is a factor of many different things, and not just the rated power. To determine whether an Iskra or a Gaia would be the most suitable wind turbine for you, Greenthinking will take into account such factors as your intended use of the electricity generated, current and future electricity usage, site and naturally your budget. 4. How much electricity will the turbine generate? The amount of electricity that you generate from your wind turbine will vary depending on which turbine you have and the annual mean wind speed at your site. Please contact Greenthinking for an estimate. The average household uses approximately 4MWh of electricity annually and more if heated by electricity. A community centre, school farm or commercial premises could use more than 20MWh. 5. What wind speed do I need and what is a good site for a Wind Turbine? Wind Speed The important measurement for wind speed is the Annual Mean Wind Speed (AMWS). For an estimate of your AMWS please click here or alternatively contact Greenthinking and provide us with your postcode and we will advise you of the estimated wind speed at your site. For best results and acceptable payback times an Iskra requires a AMWS greater than 4.7 m/s (10.5 mph) and the Gaia requires an AMWS greater than 4.2m/s (9.6 mph) and the Endurance an AMWS greater than 5.0m/s (11.2 mph). Site Buildings and trees cause wind turbulence and this is undesirable for any wind turbine. It is therefore important to site the wind turbine as far away as is possible from any obstruction(s) that cause turbulence, especially obstructions downwind in the prevailing wind direction (usually south westerly). The diagram below shows the area affected as the wind flows over a building:
Some manufactures claim that vertical axis wind turbines overcome the problem of turbulence by having blades designed to capture the wind from any direction. Greenthinking are far from convinced of this. For any given size of wind turbine a Vertical-axis Turbine will produce less energy than a Horizontal-axis Turbine. In addition, with the air flow close to the ground producing turbulent flow this introduces issues of vibration noise and bearing wear in Vertical-axis Wind Turbines which is likely to cause an increase in maintenance over a shorter period of time. Where practicable, wind turbines should be installed on towers tall enough to take advantage of the stronger, less turbulent winds. Greenthinking will advise in the best height of tower for your wind turbine during the site survey. Usually we would recommend the highest tower possible as the extra benefits, in terms of increased electricity generated, far out ways the extra cost. However there are other factors we will take into account including the visibility of the turbine from the surrounding area and neighbours properties. *Shadow Flicker: Sunlight passing through the blades of a wind turbine, especially when the sun is low in the sky, can cause a light flickering effect. This is also taken into account in site selection. The turbine blades are coated in a way as to minimise reflection of the sun from them. 6. How much does a Wind Turbine cost? The Evance Iskra R9000 costs approx. £24,000 and the Gaia 133 between £43,500 and £46,000. Prices are subject to a Site Survey/Feasibility Study and include, cable and VAT but not groundwork’s (foundations and trench work). Like any rotating machinery all wind turbines make a noise and often this is the most emotive issue for objections to wind turbines of all sizes. Unfortunately there is a lot of mis-information out in the public domain. Most people who have seen an Evance Iskra R9000 or Gaia 133 at our open days have been surprised how quiet they are; some people have even said to us that they like the noise they make! Greenthinking will provide you with detailed information on the expected noise levels and provide evidence to support your planning application. The Evance Iskra R9000 has been designed to be very quiet indeed. The rotor design, and in particular the low rotor tip speed, coupled with the direct drive system (no gearbox), all ensure quiet operation. Minimising noise was also a key objective for Gaia-Wind’s engineers. The principal source of noise originates from the turbine blades. The constant and low rotational speed of the Gaia 133 wind turbine makes it among the quietest in its class. In practice the turbine noise is often masked by background noises such as the noise of the wind blowing through the trees or traffic. Click here to watch a video (with sound) of a Gaia 133 taken by a customer at an open day in Cornwall - the customers conclusion "I am now convinced that the Gaia will not be a noise problem". 8. Are building mounted Wind Turbines recommended? No, at least not by Greenthinking! The two main problems are turbulence and possible structural damage. A wind turbine needs a steady flow of wind. Buildings deflect the wind causing turbulence so the turbine spends more time ‘looking’ for the wind and the efficiency of the turbine is compromised. Buildings are designed to take compressive loads, not lateral loads that a building mounted wind turbine would impart. The vibration of the wind turbine would be transmitted to the building on which they are mounted with possible damage to the structure of the building. 9. What are ROCs and Feed in Tariffs? Renewable Obligation Certificates are soon to be phased out for small wind turbines but please look at the ofgem website for an explanation. Feed in Tariffs (Clean Energy Cash Back Scheme) 10. Do I need Planning Permission? Yes - Planning is the all important step, as without planning permission you cannot install a wind turbine. Greenthinkingg will provide a planning support document if you choose to prepare the planning application yourself. We can also arrange for a complete planning service on your behalf by an experienced Chartered Planner. For further details of our planning service please contact Greenthinking. The planners will look at many aspects of your proposed installation that are mentioned in this FAQs section including proximity to neighbours, visibility, noise and possible effects of birds and bats. Thankfully planning permission is becoming easier, even in AONBs and SSSIs as the government has made commitments to ensure that councils give permission, unless there are credible objections rather than ‘not in my back yard’ complaints. 11. What happens to the Electricity that my Wind Turbine generates? There are 3 main types of Turbine Configuration. 1. Grid Tied Configuration 2. Battery Configuration 3. Integrated Battery Configuration Greenthinking will normally, without charge, take care of obtaining permission from your local electricity network supplier (DNO) for you to attach a your wind turbine to the national grid. Yes, if you have a Grid Tied Configuration (see above). You must seek an agreement with an electricity supplier to buy your generated electricity and claim your ROCs or FITs. For current advice on Selling your Electricity Generated please click here. Please also see details of ROCs and Feed in Tariffs above. 13. Does a wind turbine harm birds or bats? Bird strikes do happen but it is very rare for a small wind turbine. Vehicles, windows and cats kill millions more birds than wind turbines and we are unlikely to stop driving, remove our windows or ban cats! Greenthinking will take possible wildlife implications into account during the Site Survey and the local planners will also consider possible effects on wildlife. Greenthinking may propose a position for your wind turbine that is not the optimum position if we feel that the optimum position may affect the wellbeing of birds, bats or other wildlife. It is worth noting here the view of the Royal Society for the Protection of Birds: “climate change is the most serious long-term threat to wildlife in the UK and globally and, therefore, RSPB supports the Government’s target to source 15% of electricity from renewables by 2015.” 14. Does a wind turbine affect radar systems of TV reception? Small wind turbines the size of an Iskra or Gaia are very unlikely to cause detrimental effects on aviation and associated radar or navigational equipment. Neither are they likely to effect signals used for television, radio or mobile phones. 15. How can I get More Information? Please contact Greenthinking and we will gladly answer any question that you put to us regarding small or medium size wind turbines. |
Buying a Wind Turbine - FAQs |
