Wind Energy and the Historic Environment
English Heritage is the Government’s adviser on the historic environment. Central to our role is the advice we give to local planning authorities and government departments on development proposals affecting historic buildings, sites and areas, archaeology on land and underwater, designed landscapes and the historic aspects of the landscape as a whole. We also manage an estate of over 400 historic properties open to the public. This guidance is intended for developers of wind energy projects which may affect any of these aspects of the historic environment. It is also aimed at those, including local authority planners and their historic environment advisers, involved in strategic planning for renewable energy and the determination of project specific applications.
Alongside this guidance on wind energy, English Heritage has also produced guidance on climate change and other renewable energy technologies and the historic environment.
Climate Change and Renewable Energy
The Earth’s climate is changing. The average global temperature has risen by 0.6 degrees Celsius since the beginning of the 20th century, taking the northern hemisphere outside the range of average temperatures it has experienced over the last 1,000 years. Globally, all of the 10 warmest years on record have occurred since the beginning of the 1990s, and the effects of recent warming can be seen in an increased incidence of heat-waves, storminess and flooding, the retreat of glaciers and ice sheets, and altered responses in plants and animals.
Although climate change is a natural and constant process, there is a strong scientific and political consensus, internationally and within the UK, that the current increase in average temperatures results mainly from increasing atmospheric concentrations of carbon dioxide and other greenhouse gases and that these increasing concentrations are the result, in part at least, of human influences. There is also general agreement that average temperatures are likely to rise even faster, particularly in the second half of this century, unless action is taken to limit and reduce greenhouse gas emissions.
Under the terms of the Kyoto Protocol, the UK pledged to reduce greenhouse gas emissions by 12.5 per cent below 1990 levels by 2008–12, with a further undertaking to reduce CO2 emissions by 20 per cent by 2010. The European Union has also endorsed the need to reduce carbon dioxide levels in order to limit future temperature rise to 2 degrees Celsius.
Within this framework of international obligations and targets, the Government set out its energy policy, including its policy on renewable energy, in the 2003 Energy White Paper, Our energy future – creating a low carbon economy. The White Paper aims to put the UK on target to cut its carbon dioxide emissions by some 60 per cent by 2050, with real progress made by 2020, while maintaining reliable and competitive energy supplies.
The generation of energy from a variety of renewable sources is intended to make a major contribution to achieving this target, as well as providing a response to the depletion of fossil fuels and the need to promote security of energy supply within the UK. The Government has previously set a target to generate 10 per cent of UK electricity from renewable energy sources by 2010.The White Paper set out the Government’s aspiration to double that figure by 2020 and suggested that an even greater proportion of energy requirements would be needed from renewable sources beyond that date.
English Heritage Policy on Renewable Energy and the Historic Environment
On the basis of the most widely accepted predictions, future climate change is likely to be detrimental to the historic environment. Despite the fact that most historic buildings, sites and landscapes have experienced a changing climate in the past, many may be at risk, together with the important contribution they make to the UK economy:
- Rising sea levels will endanger the preservation of historic maritime landscapes, structures, buildings and archaeology.
- Increasing frequency and severity of flooding may damage the historic fabric of towns and cities.
- Higher temperatures, drier summers, changing patterns of vegetation and altered distributions for pests and disease may pose significant challenges for the long-term maintenance of historic landscapes, including designed landscapes.
- Potential increases in rainfall, storminess and weather intensity together with greater risk of ground subsidence may threaten the continued stability and weather resilience of many historic buildings.
- Changes in hydrology and cropping regime and increasing soil erosion as a result of weather extremes may make it more difficult to conserve buried archaeological remains.
Recognising these threats to the historic and natural environments and to our national prosperity, English Heritage welcomes the Government’s commitment to reduce the emissions which contribute to global warming. We support measures to reduce fuel consumption, increase energy efficiency and exploit renewable energy sources. In addition, through our own sustainable development strategy, we are committed to reducing the environmental impact of our own activities. Nevertheless, we also recognise that some renewable energy technologies have the potential to cause serious damage to irreplaceable historic sites, which are themselves an integral part of the wider environmental and sustainability agenda.
A truly sustainable approach to renewable energy generation needs to secure a balance between the benefits it delivers and the environmental costs it incurs. English Heritage therefore supports an approach to renewable energy generation which:
- acknowledges the need for society to invest in a wide range of renewable energy generation technologies;
- recognises the potential environmental impacts of different technologies, including their implications for the historic environment;
- keeps the balance of environmental benefits and disadvantages of each technology under continual review; and
- continually seeks to limit and mitigate adverse impacts.
English Heritage believes a pro-active and strategic approach to the land-use planning system will maximise the benefits of renewable energy projects, while minimising their adverse effects on the historic environment. This should be achieved by considering the cumulative effects of projects as well as their specific impacts and by ensuring that the implications of renewable energy developments are adequately reflected in national, regional and local planning policy and at all stages of the environmental impact assessment process.
We also believe that high quality design should play a key role in minimising any adverse effects of projects, whether this is directed at the disposition of wind turbines and energy crops in the landscape or the positioning of photo-voltaic cells on historic buildings. Fundamental to achieving high quality design will be a sound understanding of the character and importance of the historic asset involved, whether at the scale of individual buildings and sites or more extensive historic areas and landscapes.
Given the rapidity with which renewable energy technologies are evolving, considerable weight should be given to ensuring the reversibility of renewable energy projects and their associated infrastructure. English Heritage therefore believes that where sensitive greenfield land is used for renewable energy developments, it should not subsequently be regarded as brownfield land once installations are redundant.
Wind Turbine Technology
By converting wind energy into electricity, wind turbines reduce the environmental impact of power generation. Wind energy is currently the most developed of a number of renewable energy technologies, with more than 1,000 wind turbines already operating across the UK, producing around one quarter of one percent of the country’s energy.
Wind turbines can be deployed individually, to power a single site or installation, but are most commonly grouped together as ‘wind farms’ to provide power to the national grid. The energy output from turbines has increased dramatically over the past decade from 200 KW to 3 MW and with 5 MW turbines now under evaluation. Their greater energy yield means that the number of turbines needed to produce a given amount of energy has been reduced by at least a factor of five. Over the same period, however, the tower height and rotor diameter of turbines has doubled. Large modern wind turbines have rotor diameters ranging up to 65 metres. Towers range from 25 to 80 metres in height and, when a blade is vertical, some of the larger modern wind turbines can reach a total height in excess of 100 metres. Larger-scale wind energy developments are also becoming increasingly common as turbine ratings increase. In 2003, around a third of completed developments were above the 50MW threshold, and wind farms may now include up to 24 turbines and cover a total area of around one square kilometre.
As technical advances increase its cost effectiveness, offshore wind generation is beginning to play an increasingly important role in achieving renewable energy targets. By 2006, the installation rate for offshore generation is predicted to overtake that onshore. Currently, fifteen wind energy developments are planned in three strategic sea areas identified by government off the UK’s eastern and western coasts. Offshore wind farms are generally large installations. Current turbine hub heights range from 40 to 100 metres and rotor diameters from 44 to 110 metres, with turbines likely to increase further in size and capacity. Although this increase in scale could intensify the visual impact of offshore installations when seen from the land, parallel improvements in technology which allow them to be located further from the shore may tend to mitigate this effect. A major expansion of offshore capacity is, however, likely to require a significant strengthening of the national grid at the coast where it is currently poorly developed.
The full English Heritage policy statement on Wind Energy includes information on evaluating the impact of offshore and onshore wind turbine projects on the historic environment.
You can order a hard copy through customer services (Product code 51099): How to Order Hardcopies.