Micro-Hydroelectric Power and the Historic Environment On 1st April 2015 the Historic Buildings and Monuments Commission for England changed its common name from English Heritage to Historic England. We are now re-branding all our documents. Although this document refers to English Heritage, it is still the Commission's current advice and guidance and will in due course be re-branded as Historic England. Please see our website for up to date contact information, and further advice. We welcome feedback to help improve this document, which will be periodically revised. Please email comments to [email protected] We are the government's expert advisory service for England's historic environment. We give constructive advice to local authorities, owners and the public. We champion historic places helping people to understand, value and care for them, now and for the future. HistoricEngland.org.uk/advice Micro-Hydroelectric Power and the Historic Environment PLANNING AND HISTORIC BUILDING LEGISLATION Installing a renewable power generation scheme can be both financially and environmentally rewarding. It is important to ensure that the historic significance of any feature that may be affected by the scheme is fully understood before physical work commences. In deciding how best to incorporate a low-carbon or renewable technology, the principle of minimum intervention and reversibility should be adopted whenever and wherever possible. 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 listed and traditional buildings, conservation sites and areas, terrestrial and underwater archaeological sites, designed landscapes and historical aspects of the landscape as a whole. For our policy statements on climate change and energy, refer to English Heritage’s website. TEXT CONVENTION Technical terms that appear in bold when first mentioned in the text are explained in the Glossary. The information in this publication is based on current knowledge. Whilst every effort has been made to ensure the accuracy of the advice given, English Heritage does not accept liability for loss or damage arising from the use of this information. This publication is intended only as a guide. It has no statutory authority, and should not be used as a substitute for professional advice. The guidance provided here deals only with the practical aspects of installing the equipment. The acceptability of the installation will depend on the historic significance of the building or site being adapted. You are strongly advised to discuss the proposals informally with historic environment staff from your local authority and to contact English Heritage and Natural England where Scheduled Monuments, Sites of Special Scientific Interest and Protected Species are involved. More broadly it should be assumed that historic ponds, leats and buildings are likely to contain important historic and archaeological remains and that protected species and their habitats may be present. The inclusion in this publication of any company, group or individual, or any product or service, should not be regarded as either a recommendation or an endorsement by English Heritage or its agents. COVER IMAGES top left - © JN Bentley Ltd/Morgan O’Driscoll photography bottom left - © Stephen Bartlett top right - © JN Bentley Ltd/Morgan O’Driscoll photography middle right - © MannPower Consulting Ltd bottom centre - © MannPower Consulting Ltd bottom right - © Bilfinger Water Technologies Ltd 02 Content Introduction 04 01 What is Hydroelectric Power? 06 HISTORIC OVERVIEW 06 02 How do Hydroelectric Systems work? 08 AMOUNT OF POWER 08 SYSTEM OPTIONS 09 Infrastructure 09 Intake 10 Forebay Tank 10 Trashrack 10 Penstock 10 Weir 10 Wheel or turbine 10 Wa t e r w h e e l 11 Archimedes Screw 11 Turbines 12 Powerhouse/Electrical Generation 13 Tailrace 14 DECIDING WHETHER HYDROELECTRICITY IS AN OPTION 15 Potential Sites 15 Conservation considerations 18 03 Planning the Installation 20 CONSENTS AND LEGISLATION 22 PLANNING AND HISTORIC ENVIRONMENT LEGISLATION 22 CHOOSING AN INSTALLER 24 MAINTENANCE 26 04 Costs and Grants 28 05 Glossary 30 06 Useful Contacts 32 07 English Heritage Local Offices 34 08 Acknowledgements 35 03 Introduction The energy used to heat, light and run our homes accounts for around 24 per cent of the UK’s greenhouse gas emissions – 130.5 million tonnes (2011)1. Carbon dioxide is a by-product of the burning of fossil fuels to supply energy, and emissions have spiralled upwards as our demand for energy has increased. Energy-efficiency improvements, such as increased levels of insulation and the use of energy- efficient boilers, can reduce a household’s carbon emissions. Water has been used as a source of power for thousands of years. The earliest watermills in England date to the Romano-British period. The most common design had a wheel on a horizontal axle. The number of watermills increased as they became important parts of the medieval economy. The industrial revolution gave rise to new machines for industrial processes that needed ever larger amounts of power to drive them. Increased knowledge, skills and fabrication techniques meant the creation of materials that had previously not been available. Water wheels could be made in larger dimensions to fulfil the growing need for power. In the mid nineteenth century, with increasing research and development into harnessing electricity, different methods of electrical generation were explored. Electricity generated though the mechanical rotation of a shaft, could be achieved using a waterwheel. A faster spinning shaft could generate electricity more efficiently than one that span more slowly. The slow and powerful rotation of large waterwheels was sometimes geared up to a faster shaft rotation, and smaller turbines were made which would spin at a faster rate. Electricity created from the kinetic and potential energy of water is known as hydroelectricity. This is a zero-carbon technology, as no carbon is emitted in the generation of the electricity. The total hydroelectric installed generating capacity in the UK in 2011 was around 1676MW (megawatts). This accounted for 1.9% of the total power generation in the UK and 14% of the renewable energy generation. Most of the power is generated in large-scale schemes, which are those producing more than 5MW (enough power for around 1,000 homes). A study funded by the Department for Energy and Climate Change and the Welsh Assembly Government in 2010 determines that there is between 130MW to 185MW of potential capacity for hydroelectric power in England that could be exploited. This guidance looks at micro-hydroelectricity. These are systems with a power output of less than 50kW. Smaller systems are likely to be around 5kW, which, with other power saving measures and an appropriately sized battery pack, should be suitable for powering an average domestic property. Hydroelectric generation is often well-suited to sites with historic significance. These sites may contain; i. buildings such as watermills with existing mill wheels; ii. buildings which were once mills but have since been converted to other uses, and so only remnants of the original use are visible; iii. sites with existing infrastructure suitable for a hydroelectric scheme, or; iv. other sites where potential for hydroelectric generation has been identified. The sites can be located in isolated areas, where on-site generation can cost less than installing a connection to the National Grid. 1 2012 UK Greenhouse Gas Emission, Provisional Figures and 2011 UK Greenhouse Gas emissions, final figures by fuel type and end-user. 04 21’ x 5’ Overshot Wheel at Hythe Mill in Kent (Photo courtesy of Stephen Bartlett) 05 01 What is Hydroelectric Power? HISTORIC OVERVIEW Watermills were in use in Britain during the Roman period though their numbers were small (about five sites are known). A resurgence in water engineering seems to have occurred in the mid Anglo-Saxon period, from about the eighth century on. The most famous example is the mill excavated at Tamworth, which had a wheel on a vertical axle. The Domesday Book, a survey undertaken for the purposes of taxation in 1085-86 that gives a snapshot of England at the end of the Anglo-Saxon period, lists over 6000 mills. ‘Mills’ here refers to machinery rather than buildings (of which it is estimated there were over 5000), nearly all being water-powered, with a small proportion powered by animals. Windmill technology appeared in the twelfth century. Many of these would have been established milling sites, perhaps in use for centuries prior to the survey, and some were to remain in use right up to the nineteenth century and even the present day. It is not known how many of mills listed utilised waterwheels on a horizontal axle and how many used waterwheels on a vertical axle. The existence of extensive water supply systems, although not mentioned explicitly, can be inferred from the listing of mills. An implication of the sheer number of mills listed in Domesday is that river systems in England were already heavily engineered and under a high degree of control by the eleventh century. Wheel before refurbishment at Knockando Wool Mill (Photo courtesy of Hugh Jones) Throughout the medieval period watermills were an important part of manorial and monastic economies. A typical mill belonged to the Lord of the Manor, with all corn grown on the manor required to be milled there, by payment of a toll. Many mills were turned to other uses such as fulling cloth, sawing wood, crushing stone and sharpening tools or weapons. It has been argued that a medieval version of the industrial revolution took place, having watermills and their associated water supply systems at its heart. Certainly the existence of the material infrastructure of milling (the heavily engineered river and leat systems as well as the mills themselves) laid part of the foundation for the Industrial Revolution of the late eighteenth and nineteenth centuries.