Frequently asked questions
Click on the adjacent boxes below to reveal, below, some of the questions that are often asked about onshore wind power.
Aren’t wind turbines inefficient?
Wind farms typically generate electricity around 70-85% of the time and the kinetic energy of the wind is converted to electricity very efficiently, with none of the thermal waste inherent in fossil fuel plants. Wind power is therefore an efficient way to generate electricity, using an energy source that will never run out.
Over the course of a year, a turbine will typically generate about 30% of its theoretical maximum output. This is the capacity factor, NOT the efficiency of the turbine. The capacity factor of fossil fuel power stations is on average 50% because of stoppages for maintenance or breakdowns or because the power from that plant simply isn’t needed at that point in time. No power plant generates power for 100% of the time.
In order to compare turbines with the capacity factors of other energy sources the following figures have been extracted from The Digest of UK Energy Statistics (DUKES) for 2013 based on average capacity factors between 2007 and 2012:
- Photovoltaic power Stations 8.6%
- Wind 27.5%
- Hydroelectric 33.7%
- Coal-fired power stations 44.7%
- Combined cycle gas turbine power stations 56.65%
- Nuclear power stations 61.9%
Are wind turbines noisy?
The noise emitted from wind turbines has been reduced significantly over the last 10 to 15 years. Improved design has drastically reduced the noise of mechanical components so that the most audible sound is that of the wind interacting with the rotor blades. Even in quiet rural areas, the sound of the blowing wind is often louder than the turbines.
Noise effects from wind turbines are rated by a standard recognised in National Planning Guidance called ETSU-R97. Under this standard it is accepted that the higher the wind speed, the greater the noise emissions from a wind turbine (because it is working harder) but generally speaking the higher the background noise as well from the wind moving around obstacles in the landscape. Where a minimum standard of noise at a property cannot be met (35 decibels, approximately equivalent to the background noise in a quiet bedroom) based on sophisticated computer modelling and as agreed with the Council, it is necessary to measure background noise levels at a property. This allows examination of how noise levels increase with wind speed at a property to establish how the windfarm design should respond to the noise environment in an area.
Noise limits are set by the planning conditions attached to almost every planning consent and are strictly controlled by planning authorities to ensure wind farms do not cause unacceptable noise impacts.
Do wind turbines affect wild life and birds?
RSPB has indicated that, as long as a wind farm is situated appropriately, it will not pose a significant hazard to birds. Indeed R SPB has stated on record that, “Climate change poses the single greatest long-term threat to birds and other wildlife, and the RSPB recognises the essential role of renewable energy in addressing this problem.” They further state that, “Wind power has a significant role to play in the UK’s fight against climate change and we will work with Government and developers to ensure this outcome” (Source: http://www.rspb.org.uk/forprofessionals/policy/windfarms/).
As part of the comprehensive environmental impact assessment which is carried out on all of our wind turbine developments, Force 9 consults with relevant statutory consultees, the RSPB and, where appropriate, other environmental bodies, to make sure that any impacts on wildlife are fully mitigated. Where possible we look for opportunities to actively enhance the environment for protected birds and other wildlife.
Do wind farms affect tourism?
There is no evidence that tourism numbers have been damaged by the growth of renewable energy projects in Scotland; in fact there is recent evidence that (i) tourist numbers and spending are growing and (ii) confidence levels amongst accommodation providers is at a high, and increasing, level: 780,000 international visits to Scotland were recorded during the second quarter of 2014, the second best quarter since 2007, and 17% up on the same period in 2013, with overall spending up 7.8% on the second quarter of 2013. (Source: Visit Scotland Trends Dashboard (October 2014).
There has been no evidence of actual negative impacts on tourism and research from 2012 by Visit Scotland has illustrated “that the presence of wind farms had no influence on decision making of the vast majority of tourists” (source: Revised Oct 12 Insights Wind Farm Topic Paper). Many wind farms have themselves become tourist attractions such as Whitelee and Scroby Sands in Norfolk. Wind farms have the potential to encourage tourism by bringing infrastructure, for example funding improvements to path networks, and creation of, or improvements to, tourist facilities.
Are offshore turbines more effective?
Onshore wind turbines are inherently more economical to build and operate than offshore wind turbines due to the harsh marine environment and the cost of servicing offshore operations. Offshore wind farms also take considerably longer to develop and require a significant maintenance regime once operational. It would therefore be impractical, and very significantly more expensive to rely wholly on off shore wind for our renewable energy requirements. As the technology matures offshore windfarms may become more competitive but on-shore wind will always be cheaper, quicker to deploy and easier to maintain.
Why not have hydro, wave or tidal energy instead?
We need all of these technologies and the government is supporting them all. In fact wave and tidal energy receives significantly higher levels of support than onshore wind – as they are not yet close to commercial viability (there is a big challenge in developing equipment that can survive long term in the hostile marine environment). For now onshore wind remains, by some margin, the most cost effective form of renewable energy.
Doesn’t the wind industry get large subsidies from the government?
ALL forms of energy production receive government support – such as tax relief for decommissioning North Sea oil and gas; or reduced corporation tax rates (10% for 10 years) and tax relief on exploration activities for fracking. If Government did not regulate the energy market – and instead penalised creation of carbon emissions – many wind farms would be built without government support.
The level of support from the government has been steadily reduced in recent years and will continue to reduce under Electricity Market Reform. This will make wind power increasingly better value for bill payers as the wholesale price of fossil fuels continues to rise in the longer term.
This concern was highlighted by Lord Stern who wrote an influential global review of climate change economics and who said that the UK’s dependence on fossil fuels had generated three quarters of the increase in costs for households, that “there is a concerted campaign to mislead the British public about the factors that are driving up consumers’ electricity and gas bills” and that “if the campaign succeeded in getting cuts in support for renewables, consumers would face even higher bills in the future as the cost of fossil fuels continued to rise.” (source: Energy Firms and Media conspiring to mislead public BBC 16.10.13)
Why do wind turbines sometimes not turn when it’s windy?
Wind turbines start operating at wind speeds of 3 to 4 metres per second (7-9 mph) and reach maximum power output at around 15 metres/second (33 mph). At very high wind speeds, i.e. storm force winds, (25 metres/second or 55mph) wind turbines are shut down. However we should keep in mind that these sort of extreme wind speeds cause damage to a wide variety of structures and typically cause schools and businesses to close. This only happens on a very few days in the year. All forms of generating plant have to be shut down sometimes for maintenance or for health and safety reasons.
Turbines are sometimes switched off at times of ‘overcapacity’ on the national grid, ie there is too much generation in relation to demand at that specific moment. See more on this under the ‘Pointless?’ FAQ.
Why build wind farms when we always need 100% back up when the wind isn’t blowing?
Our electricity supply is designed to have some ‘overcapacity’ at all times. All generation plant needs backup in case another part of the system goes off line – e.g. the major fire at Didcot gas Power Station in October 2014 or the August 2014 shut down of four nuclear reactors (two at Heysham 1 and two at Hartlepool) for eight weeks.
The National Grid constantly balances supply and demand for electricity. They liaise with large electricity users and monitor and predict domestic electricity use based on patterns established over years. They can ask most systems to ramp up or down production at any time to maintain a steady supply on the grid. When wind farms are generating (and this can be predicted with sufficient accuracy for the National grid at about 12 hours’ notice) they can ask other generators, typically gas plants, to ramp down electricity production. So wind farms help National Grid balance supply and demand in a much more flexible and cost effective way than other forms of generation. And of course, they help us use less fossil fuels, reducing emissions and conserving resources for future generations.
Why do windfarms sometimes get paid money NOT to operate?
National Grid chooses to ask wind farms to switch off because it is the cheapest and most flexible way of balancing supply and demand: much more cost effective than shutting down other forms of generation.
National Grid contracts with supply companies to supply electricity on to the grid in a planned way. If there is over-supply on the grid, beyond predicted need, NG will ask plant to shut down and is contractually obliged to pay compensation to the generator. It is often windfarms which are asked to shut down because they are the most flexible and cost effective means of achieving balance on the grid. However it is not exclusively windfarms which are asked to shut down in this way : all forms of generation receive ‘constraints payments’ : between 2011 and 2012 National Grid reported that wind farm operators received 10% of constraint payments paid to all generators – and this represented only “a few pence a year on a typical electricity bill”.
How much does it cost to build a large turbine?
Taking into account development costs plus all civil engineering works (roads, bridges etc) a cost of approximately £3m per turbine is typically anticipated. However all of this is privately invested money: there are no grants or subsidies (or tax relief) for developing and building wind farms. The risks are therefore high particularly since developers have to write off the costs of developing sites that do not proceed to planning applications or which are not consented and built.