Broadview

The amount of electricity generated by an individual wind turbine will vary depending on the size of the turbine and the amount of wind available. Typically, modern wind turbines, of the type that are currently being installed across the UK, will have a maximum output of between 2 and 3MW. Although wind turbines will not operate at their maximum output at all times, modern turbines start generating at low wind speeds and will typically be producing electricity for between 70 - 85% of the time (Ref BWEA, Wind Power and Variability, Nov 2009). The proportion of electricity that a power station actually produces as a percentage of the theoretical maximum in each year is known as a capacity factor. The average capacity factor across all onshore wind energy sites in the UK is 27% (Ref DECC, DUKES 7.4, 2008). Hence, a 2MW turbine installed on an 'average' wind speed site in the UK will generate around 4,730MWh each year. This is enough electricity to meet the needs of 1,146 average UK homes.

In March 2007 the Royal Institute of Chartered Surveyors commissioned Oxford Brookes University to undertake a study into the impact that wind farms have had on property prices in the UK. The report states that 'apparent changes in value disappear when examined more closely' and goes on to conclude: '...the threat of a wind farm may have a more significant impact than the actual presence of one'. Furthermore, a study completed in December 2009, by Berkeley National Laboratory on behalf of the US Office of Energy Efficiency and Renewables, concludes that '...neither the view of the wind facilities or the distance of the home to those facilities is found to have any consistent, measurable, and statistically significant effect on home sale prices.'

Shadow flicker occurs when the shadow of a wind turbine's blades passes over a small opening in a building such as a window, creating a flickering effect within the building. It is a rare event which can only be caused by the culmination of a set of very specific weather conditions: there must be an unobstructed path between the sun and the wind turbine's blades i.e. no intervening cloud cover; there must be enough wind for the wind turbine to be turning and it must be blowing from such a direction that the blades of the turbine are positioned in such a way that they can cast a shadow over a nearby building; and finally, the sun must be low enough in the sky and positioned such that the shadow of the blades can fall on nearby buildings. Wind turbines can be fitted with complex weather sensors to detect exactly when the rare culmination of these conditions occur and in this event the turbines can be immediately shut down. Employing this mitigation measure can ensure that no residents living near a wind farm experience shadow flicker.

Broadview Energy believes that the future of UK electricity generation lies in a diverse portfolio of different generating technologies, including both onshore and offshore wind. Although there are obvious benefits to siting wind turbines offshore there are also significant commercial and technical drawbacks. The current government driven support mechanism for renewable energy in the UK is the Renewables Obligation (RO). The RO places a requirement on all electricity supply companies to source a percentage of the electricity that they supply to consumers from renewable power plants, with any electricity suppliers that fail to meet this obligation facing fines. Renewable power plants are entitled to claim one Renewables Obligation Certificate (ROC) for each MWh of electricity generated. The electricity and related ROCs are then sold on to supply companies who in turn present the certificates to OfGEM in order to demonstrate compliance with the RO. The cost of purchasing the ROCs from generators is factored into domestic electricity prices and passed on to the consumer by supply companies. In 2009 the government recognised that investment in offshore wind was drying up due to the high cost compared to other forms of generation. In order to address this the ROC entitlement of offshore wind was doubled to 2ROCs per MWh generated, making offshore wind twice as expensive as onshore wind to the electricity consumer.

Individual wind turbines like all other types of generating plant have a maximum instantaneous power output or ‘rated power’. It is true that wind turbines do not deliver their rated power at all times, due to maintenance down time and variations in wind speed. However, the same is also true of fossil fuel power stations which are also subject to periods of maintenance down time and regulate the fuel input to control the amount of power generated, thus accommodating for the fluctuating nature of electricity demand. On average, daytime periods are windier than nights and therefore wind turbines are likely to produce the majority of electricity during daytime when demand is also greatest. Wind turbines typically start generating electricity at wind speeds of over 6 – 9 mph. Due to the way that the wind reacts with the ground, the further from the ground that a wind speed is measured the higher it will be. Modern wind turbines typically have hub heights in the region of 80m from the ground. At this height, in most locations, wind speeds rarely fall below those required for the wind turbines to operate. As a result, modern turbines typically generate power for approximately 70 – 85 % of the time* (Ref. BWEA, Wind Power and Variability, Nov 2009).

The fuel used to power wind turbines is the wind, which we all know is abundant and free. This means that subsequent to the initial capital cost of the plant, the operational costs are minimal. Furthermore, due to the introduction of national and international emissions reduction targets through the Kyoto protocol, the emergence of carbon markets has led to an additional monetary value being ascribed to electricity generated from non-fossil fuel sources. As fossil fuel prices rise due to diminishing supplies, the cost of generating electricity in fossil fuel power stations will also rise. Conversely, due to the emergence of carbon markets and economies of scale, the cost of wind energy generation is likely to fall. The cost of generating electricity from the wind will be dependent on a number of variables, including, the price of steel, the wind resource available at a particular site, the size of the wind farm, government fiscal policy, etc. However, as an average figure, a report by the Sustainable Development Commission in November 2005 states: ‘The generation costs of onshore wind power are around 3.2p/kWh, with offshore at around 5.5p/kWh – this compares to a wholesale price for electricity of around 3.0p/kWh’(Ref. Sustainable Development Commission, Wind Power in the UK, Nov 2005).

The efficiency of any power station is a proportional measure of the amount of energy contained within a fuel that is converted by the power station into electrical energy. In the case of fossil fuel power stations, it is the percentage of the heat energy released in the combustion of the fuel that is turned into useful electrical energy. The fuel for a wind turbine is not the heat energy released by burning coal or gas, it is the kinetic energy that causes the wind to flow. The efficiency of a wind turbine can therefore be expressed as the percentage of the kinetic energy present in the wind that the wind turbine converts into useful electrical energy. Although the efficiency of a wind turbine will vary depending on wind speed, in modern turbines it can reach up to 59% (Ref. Enercon GmbH, E82 product brochure, Aug 2010), which, when compared with average thermal efficiencies of 36 - 47% for fossil fuel power stations (Ref. Digest for UK Energy Statistics, 2009), is actually very high.

The benefits of wind energy developments manifest themselves in many different ways, some being restricted to the local community in the area of the development and others benefiting not only the local community, but also the wider national and international communities. The local benefits will be realised in the creation of a community fund that will feed some of the revenue generated by the wind farm back into the local community, to be managed and distributed locally, funding community schemes. Furthermore, the coalition government intends to allow local communities to keep the business rates paid by wind farm operators, which, in the case of a 10MW wind farm, would result in approximately an additional £72,000 (Ref. Renewable UK, Community Benefit Strategy Paper, Aug 2010) being made available locally. The benefits realised by not only the local community but also the national community are in the form of a reduction in our reliance of imported fossil fuels and therefore an increase in energy security. Similarly, the inherent reduction in green house gas emissions effected by the production of clean, green renewable energy, will have the benefit of combating climate change, a benefit that will be felt by local, national and international communities alike.