Tag Archives: tidal energy

Environmental History of Tidal Power in the Severn Estuary

Plan for Severn Barrage

Thomas Fulljames’ watercolour of his plan for the Severn Barrage, 1849.
Source: Wikimedia Commons

In recent decades the interest in renewable energy from sources such as wind, solar and tidal power has steadily increased. However, this interest in harnessing “mother nature’s” energy is not new. Over the past 160 years the Severn estuary has been the focus of numerous proposals to provide a transport route over the estuary, improve navigation and to exploit its large tidal range to generate electricity. As a potential source of predictable, renewable and carbon-free power with the potential to supply up to 5 per cent of current UK electricity needs, such interest is understandable. Despite its potential, the latest proposals, like all its predecessors in the past century and a half, have failed to secure government and public support to build a barrage in the Severn estuary.

How is it that a barrage still has not gone beyond the drawing board? And why are companies, scientists and politicians still willing to invest time, effort and money in further proposals?  Alexander Portch, a PhD candidate in the Department of History at Bristol University, investigates these two questions. Although the past 150 years is the main focus, Alexander also investigates earlier efforts to harness tidal power of the Severn and how the activities of people whose lives were bound up with the estuary’s daily tides have shaped the estuary and lands bordering it. This episode of the podcast features an interview with Alexander Portch and his work on the history of the Severn Estuary.

 

Further reading and resources

Blog posts by Alexander Portch on the Power and the Water website.

Severn Barrage Tidal Power”, The Renewable Energy Website

The Severn Bore website

Charlier, R.H., Menanteau, L., ‘The Saga of Tide Mills,’ Renewable and Sustainable Energy Reviews, 1:3 (1997), 171 – 207.

Godbold, S., Turner, R.C., Hillam, J., Johnson, S., O’Sullivan, A., ‘Medieval Fishtraps in the Severn Estuary,’ Medieval Archaeology, 38:1 (1994), 19 – 54.

Video showing example of tidal mill: Craftsmen: The Tide Miller, 1951 Woodbridge, Suffolk.

 

Music Credits

Stockholm” by timberman, available from ccMixter

Begin (small theme)” by _ghost, available from ccMixter

Easy Killer (DGDGBD)” by Aussens@iter, available from ccMixter

Exploring environmental History podcast

 

This podcast was simultaneously published on the Environmental History Resources website as part of the Exploring Environmental History podcast series.

Tidal Power: A Question of Scale?

By Alexander Portch

Whilst the remarkably well preserved site of Nendrum Monastery on the western shores of Strangford Lough in Northern Ireland may feature the earliest known example of a tidal mill in the world – and, by extension, effectively the starting point for the process of technological evolution that has resulted in today’s tidal energy devices like barrages, lagoons and tidal stream turbines[1] – it suffers from an issue encountered frequently in archaeology: namely that of incomplete evidence and the need to interpret what survives, with the likelihood that any interpretation will be fraught with inaccuracy and conjecture.

This may be familiar to viewers of Channel Four’s Time Team (now sadly also confined to the depths of the past) where, almost on a weekly basis it seemed, entire settlements were reconstructed in astounding detail seemingly on the basis of little more than a handful of pottery shards, the occasional pit, and perhaps the odd wall or two. Admittedly it is in fact possible to say a great deal about a site even if the items listed above comprise the sum total of all features and objects uncovered; not least the fact that a structure existed, its likely whereabouts and possible form and function, and – using the pottery – a likely date for its occupation. The pottery could even hint at possible trade links with faraway places. In order to present this assemblage and any resulting interpretations to a lay audience, however, some form of visual reconstruction is usually necessary and this is where imaginations begin to play a more prominent role, as demonstrated by the often spectacular 3D (re)creations of roundhouses, Roman villas and other assorted ancient monuments, through which Tony and the team could stroll at their leisure.

It is quite likely that many of these efforts are reasonably close to the truth, and even if they fall short of the mark, they do at least succeed in providing entertainment for some, and even inspiration for others (myself for one). Thus, the numerous reconstruction illustrations encountered in the museum at Nendrum Monastery, including a rather impressive physical model of the whole site, served to provide valuable insights into what the location may have been like throughout the duration of its occupation. This included the tide mill, which, despite its sophistication was also a wonderfully simple way of extracting usable energy from the regular rise and fall of the water in the Lough. Such mills may well also have existed around the shores of the Severn Estuary throughout the latter half of the 1st millennium AD; although, as yet, no examples have been identified.

What did exist in more recent times, however, were far larger and more complex structures, such as those at Berkeley and Westbury-on-Severn, both in Gloucestershire. These were certainly in operation from the 18th century, and possibly earlier. Whilst the basic mode of operation differed little from the early medieval tide mills of Northern Ireland, including Nendrum, involving the impounding of water at high tide within a pond, and its subsequent release through waterwheels as the tide ebbed, they also made full use of more modern forms of milling technology, such as vertical wheels, and gearing mechanisms. The latter could enable multiple millstones to be operated by only one or two wheels, whilst simultaneously providing the necessary power to hoist sacks of grain into the upper storeys of the building.

In the case of the example at Berkeley much of the machinery remains in situ within the building (so I have been informed), now derelict following the demise of the last commercial enterprise there in 2004. This may, however, have little to do with tidal power as the mill was converted during the 20th century, first to steam power and then to electricity, whilst the millpond and tailrace have since silted up. In order to fully understand how such facilities operated, therefore, and, in turn, their significance within the context of local communities for whom the tidal cycle of the Severn may have functioned as a focus of livelihood and identity, it seemed necessary to see a tide mill as it might have existed a century or more ago.

There are presently only five restored tidal mills in the British Isles. This may seem like a good number for those who are unfamiliar with such features, as I was only two years ago; however, considering that more than 700 mills were once in existence around the Atlantic coasts of Europe, including many in the British Isles,[2] the remaining examples can hardly be seen as representative. Nonetheless, those that do survive have been restored with care and attention to detail, enabling at least two of them to function once again as they may have done during their working lives. The closest mill to Bristol, where I am currently based, is that at Eling near Southampton which, until it closed for refurbishment earlier this year, produced its own flour on an almost daily basis. Beyond that, the other options were either an expedition to the coast of Suffolk and the working mill at Woodbridge or the slightly more accessible example at Carew Castle in Pembrokeshire. From an archaeologist’s perspective the choice wasn’t difficult to make, and without further delay I headed west.

Carew Cross

The 11th century Carew Cross stands, tall and imposing, facing the eastern entrance to the castle (with the well-positioned Carew Inn visible behind). Photo: Alexander Portch.

The castle at Carew has stood on its promontory overlooking the nearby Carew River, a tidal arm of the Cleddau Ddu, since the beginning of the 12th century when the Norman rulers of England sought to extend their influence into Wales; however, a defensive settlement has been shown to have existed there from the Iron Age. The nearby Celtic cross, one of the finest in Wales, may even hint at the location’s status as a royal centre for the Welsh Kingdom of Deheubarth prior to the arrival of the invaders from the east. It is also likely that a mill existed nearby to supply the castle during the medieval period; however, documentary records for a tide mill date from the 16th century with the present structure being of 19th century construction.[3]

Carew Castle

The West Range of Carew Castle, with its two 13th century drum towers, occupies a commanding position overlooking the still waters of the impounded mill pond. Photo: Alexander Portch.

The building comprises four floors, in addition to the under storey which houses the two vertical waterwheels, and functioned primarily as a corn mill, grinding grain into flour. After a relatively long period of use (longer than most modern power stations at least), the mill ceased operation in 1937 until its restoration in the 1970s. Initially the machinery was put back to use for demonstration purposes; however, now it stands dormant – clean, tidy, well-organised, but too fragile to resume operation. Recent feasibility studies have investigated the potential for breathing new life back into the now arthritic cogs, wheels and gears, in addition to the possibility of installing a modern turbine for generating electricity but, much like the great majority of tidal energy proposals, it remains little more than a report rather than any determined action.

Carew Mill

Carew tidal mill, visible in the distance from a vantage point high up in the nearby castle. Now largely abandoned (with the exception of the occasional wedding party and the regular stream of visitors and re-enactment groups) the castle now provides the ideal habitat for a diverse range of flora and fauna, including more than half of the species of bat found in Britain. Photo: Alexander Portch.

Perhaps the most striking thing about the mill at Carew is the causeway linking the mill building on one side of the river channel with the far bank and housing both the wheels beneath the building, and the sluice gates which allow water to enter during the flood tide. In effect this is a barrage. A very small barrage, at least in contrast to those proposed for the Severn, but a barrage nonetheless, and probably not much smaller than the Annapolis Royal tidal barrage in Nova Scotia.[4] It comprises a solid wall built laterally across the width of a river, thereby effectively cutting off an arm of the waterway from the “natural” operation of the tides. The tides do still affect the millpond created by this structure, but they now rise and fall at the whim of the mill owner or operator (presently the Pembrokeshire Coast National Park Authority). Essentially this could be seen as merely a small-scale version of what might have come to pass on the Severn if a barrage had ever been built. And on that basis, would it have been such a bad thing? At Carew during my visit it was the mill pond that provided the most conspicuous habitat for wading birds, including shell duck and heron, sustained no doubt by the schools of fish that could be seen swimming in the relatively clear waters. The flow of the incoming tide was also discernible, whilst the scent of the salty waters still pervaded the air.

Causeway

The causeway at Carew Castle Tidal Mill: an early tidal barrage? Source: Alexander Portch

But then, the Carew River has no tidal bore, which would be entirely eradicated by a Severn Barrage, and its populations of fish are almost certainly less substantial and diverse than the much larger and more complex Severn. Five hundred years ago the mill pond causeway may have been relatively expensive and could have taken months to build, but that contrasts starkly with the billions of pounds and close to a decade required for the Cardiff-Weston barrage proposals of recent years. In many respects the issue of tidal power is very much a question of scale. Small-scale developments, in terms of size of the buildings and structures, the geographic space they occupy and influence, and the time they take to build have generally been more popular and successful; as demonstrated by the many hundreds of tide mills, the few successful examples of tidal barrages and the current trend towards investment in small-scale tidal turbines and tidal lagoons. Meanwhile, despite the unwavering faith of some its advocates, the comparatively massive Severn barrage continues to flounder. A large-scale fish in a relatively small sea.

 

Notes

[1] http://powerwaterproject.net/?p=562

[2] W.E. Minchinton, ‘Early Tide Mills: Some Problems,’ Technology and Culture, 20:4 (1979), 777 – 786.

[3] For more on the cross, tide mill and castle see: J.R. Kenyon, ‘Carew Cross, Castle and Mill,’ Archaeological Journal, 167 (2010), 29 – 33.

[4] http://www.nspower.ca/en/home/about-us/how-we-make-electricity/renewable-electricity/annapolis-tidal-station.aspx

Saints and Sea Power in the Tidal Waters of the Irish Sea

By Alexander Portch

In 2008 the Bristol-based renewable energy developer, Marine Current Turbines[1] (MTC), installed the world’s first grid-connected tidal stream turbine in the waters of Strangford Lough on the eastern coast of Northern Ireland. Known as SeaGen S and capable of generating up to 1.2 GW of electricity from the kinetic energy of the Lough’s fast-flowing tidal currents, the device represented a significant step forward in the development of commercially-viable tidal power technologies. The recent near-collapse of MCT following the decision of Siemens, their owners, to sever their connection with the wave and tidal energy industry, served, however, as a reminder of just how much still needs to be achieved before tidal stream and tidal range devices start to receive the same level of investment and support as that enjoyed by other, more prolific renewable energy initiatives like wind and solar[2].

Nonetheless, SeaGen remains in situ, its blades rotating in unison with the twice daily rise and fall of the tide and, thanks to a 24 hour monitoring system, continuing to generate power with minimal adverse impacts on nearby marine fauna[3]. Furthermore, with the recent announcement that Atlantis, another wave and tidal energy company, is to throw MCT a lifeline, the future of tidal power in the Lough would appear to be secure[4]. A rare tale of success, which stands in stark contrast to the on-going saga of failed enterprises in the Severn Estuary.

Interest in the potential inherent in the tidal cycle of Strangford, and other similar environments around the coast of the British Isles, is, however, nothing new, with the achievements of the SeaGen device reflecting similar trends dating back more than a thousand years. In 1999 excavations at the site of Nendrum Monastery on Magee Island, the largest such landmass in Strangford Lough, resulted in the re-interpretation of linear wall structures in the waters to the east of the monastic complex as mill dams, rather than fish weirs as had hitherto been believed. Over subsequent seasons of fieldwork, the well-preserved remains of three successive phases of milling activity were revealed, with dendrochronological dating providing confirmation that this was the site of the earliest example of a tide mill in the world[5].

The first mill was shown to have been constructed between AD 619 and AD 621 and comprised a large dam, 110m in length, which served to impound water within a triangular millpond, 6,500 m2. The pond would fill at high tide and be retained as the tide receded outside the embankment, thereby providing a source of motive power to drive a horizontal waterwheel as it was released back into the Lough. This wheel would have been located in a wheelhouse positioned at the southern corner of the millpond. In the late 7th or early 8th century the first mill fell out of use and was replaced by a second complex of features on the same spot. The most marked change was a reduction in the size of the mill pond, with a new dam forming a smaller, rectangular area of impounded water adjacent to the shore. This was then largely destroyed by the final imposition of a third mill, again in the same location and dating to the end of the 8th century AD. Alongside a wealth of stone and waterlogged wooden artefacts, including a variety of stone slabs marked with crosses, the excavations yielded the almost intact upper millstone from this later development.

Remains Tidal Mill Pond

The surviving remnants of the mill pond embankments now lie largely submerged beneath seaweed and vegetation spreading from the shoreline. In the centre is the long, straight wall associated with the second and third mills, demarcating the boundary of a narrow millpond adjacent to the shore, whilst in the distance to the left is the embankment for the first millpond. Photo: Alexander Portch

Within the remarkably extensive literature on the history and archaeology of tide mills and early water mills, Nendrum has since become an icon of this site-type. Further fieldwork in Ireland is increasingly revealing just how commonplace such structures were in the early medieval period but, at present at least, Nendrum would appear to be where it all began. With my own interest in the recent and much deeper history of the interactions between humans and the non-human process of the tidal cycle, Nendrum has long been a source of some fascination and it was thus with great anticipation that I finally arrived there on a bleak and blustery day in late April. Despite the unseasonal weather conditions and the overcast leaden skies, the atmosphere of the place was tangible and it was a thrill to see the still imposing remnants of the mill pond walls in person. Thankfully a respite from the cold was provided by a superb, if somewhat modest, visitor centre which included a balanced array of written information, artefacts excavated from the site itself, interpretative reconstruction illustrations, a model of the site and an engaging, if rather dated, television documentary (great for someone nostalgic for the 90s, but otherwise in need of updating!).

Model medieval monastery

The fascinating and highly detailed interpretative model of Nendrum located in the centre of the monastery’s visitor centre. It pre-dates the discovery of the tide mills but provides a good insight into what the site may have been like a millennium and a half ago. Photo: Alexander Portch

In many respects this is the real antecedent of the ill-fated Severn Barrage. Whilst recent proponents of tidal range technology frequently tout it as an advanced technology of the future, a means by which to harness an apparently un-tapped source of endless and predictable energy, and an alternative to “old-fashioned” or “out-dated” forms of electricity generation like coal and nuclear, in reality it is nothing of the sorts. Its origins lie in the ingenuity and hard work of people living centuries earlier driven both by their need to extract power from whatever sources were available and their devotion to a power somewhat more intangible. Their lives seem almost impossible to comprehend in the fast-paced, digital age in which we now live, being bound up with cycles of day and night, ebb and flood that have long since been rendered obsolete through modern innovations. Nonetheless, with the recent proposals for a tidal lagoon near Swansea Bay only one step away from receiving government consent[6], it may soon come to pass that the tidal cycle regains some of its former importance as a source of power and sustenance at the heart of our own society.

N.B. For those interested in reading in far greater detail about the excavations at the Nendrum tide mills, a comprehensive archaeological monograph is available: T. McErlean, T. & N. Crothers, Harnessing the Tides: The Early Medieval Tide Mills at Nendrum Monastery, Strangford Lough (London: The Stationery Office, 2007).

 

Notes

[1] http://www.marineturbines.com/

[2] http://www.theengineer.co.uk/news/-siemens-hunts-for-buyer-to-take-on-marine-current-turbines/1019559.article

[3] Keenan, G., et al. “SeaGen Environmental Monitoring Programme Final Report.” Royal Haskoning: Edinburgh, UK, January (2011).

[4] http://www.imeche.org/news/engineering/atlantis-buys-marine-current-turbines-29041502

[5] McErlean, T.C. et al, ‘The Sequence of Early Christian Period Horizontal Tide Mills at Nendrum Monastery: An Interim Statement,’ Historical Archaeology, 41:3 (2007), 63 – 75.

[6] http://www.tidallagoonswanseabay.com/

 

Environmental History in the Making in Portugal and the Severn Sea

By Alexander Portch

Guimaraes

After a week of continuous conference sessions, some fresh air and open space was greatly needed. Thankfully, the UNESCO world heritage city of Guimaraes is situated amongst a truly spectacular landscape; one that could be easily enjoyed thanks to a cable car running direct from the urban centre to the summit of the nearby Montahna da Penha. Photo: Alexander Portch

And so the conference season continues. Whilst a new experience for me personally, the extensive programme of talks and panels circulated in advance of the 2nd World Congress of Environmental History at the University of Minho in Guimaraes, Portugal, which took place between the 8th and 12th of July, provided an insight into what to expect from the one of the year’s most prestigious gatherings of environmental historians, and the subsequent event didn’t disappoint. With presentations and discussions covering a multitude of subject areas, geographic locations and sub-disciplines – from marine cultural environments to the intersections between environmental histories and visual culture; encompassing the Americas, Australasia, India, Africa, and even the comparatively humble Tyne valley in northern England; and drawing upon the work of historians, geographers, zoologists and artists – WCEH 2014 demonstrated quite clearly just how far the practice of environmental history has advanced since the early days of the mid-late 20th century. Nonetheless, despite being daily immersed in a wealth of world-class scholarship disseminated by some remarkably knowledgeable, outgoing and enthusiastic individuals, I still could not help but be distracted by further developments back home in my own area of interest: the Severn Estuary.

Alongside the excitement of meeting and engaging with students, academics and scholars from around the world; listening attentively to discussions on topics as relevant to my interests as the remaking of North American rivers through the construction of hydroelectric dams and as fascinating as the emergence of Earth Art in the 1960s; sampling the many delights of Portugese café culture; and witnessing the tidal wave of destruction that was Germany’s assault on an unsuspecting Brazil in their 7-1 semi-final victory earlier in the week; the news that the Crown Estate have recently agreed seabed rights for a host of new wave and tidal energy demonstration zones, in addition to five new wave and tidal current sites, at various locations around the British coast, couldn’t fail to attract my attention. This includes three sites to be operated by Cornwall-based company WaveHub, encompassing wave testing zones in North Cornwall and South Pembrokeshire and a tidal stream array off the north coast of Devon near Lynmouth. The latter has been announced as the test site for Pulse Tidal’s Pulse-Stream system, which employs an alternative approach to harnessing the power of tidal stream currents to that employed by the majority of developers. Rather than creating the equivalent of an undersea wind turbine, as has been the case for MCT Siemens with their SeaGen design and Open Hydro with their Open Centre technology, the pulse-system exhibits a vertical up-and-down motion akin to the flaps on an aircraft which enables it to be deployed in relatively shallow water.

Equally distracting was the news that, despite the apparent finality of the UK government’s decision last year to reject proposals by Hafren Power for a tidal barrage along the Cardiff-Weston route (from Lavernock Point on the Welsh side of the Severn Estuary to Brean Down on the English side), the newly formed Severn Tidal Energy have recently succeeded in negotiating up to £200m of investment for a renewed attempt at securing support for an identical scheme. The investor, who is reported to be experienced in funding global infrastructure projects, has yet to be formally identified; however, it seems evident that STE are intent on pursuing a similar strategy to that of Hafren Power who made it clear that their project would be dependent on significant financial support from a private investor.

Cardiff-Weston Line

The “Cardiff-Weston Line” with Weston to the left and the islands of Steep Holm and Flat Holm marking the route to Lavernock Point on the Welsh coast near Cardiff. What will this view be like by the middle of the 21st Century? Very different if the newly-formed Severn Tidal Energy succeeds in its renewed attempt at securing permission for a Severn Estuary tidal barrage. Photo: Alexander Portch

As part of my work into the history of tidal energy and the exploitation and harnessing of the tides in the Severn Estuary and Inner Bristol Channel, it is my intention to employ the insights gained from my study of the past to enable the development of informed predictions and imaginings of future scenarios for such activity in the region. Could for example, the now derelict tide mill at Berkeley be resurrected as a small-scale hydro-electricity power station capable of servicing the local community? However, the activities of companies like WaveHub and organisations such as RegenSW serve as a reminder that such a future is already in the process of being envisioned. Perhaps, in place of older technologies such as tide mills or barrages, electricity will be generated through the widespread establishment of vast undersea tidal stream farms, supplemented in places by tidal lagoons such as that proposed for Swansea Bay. Alternatively, the recent establishment of Severn Tidal Energy and the renewed effort by its supporters to realise the potential for generating 5% of the UK’s electricity supply through construction of a single large-scale piece of infrastructure could still result in the designs from the past being made manifest in the future. Only time will tell, but whatever comes to pass, regardless of where I am in the world, at which conference I am presenting or which major sporting event is taking place, I will be sure to remain abreast of developments in the Severn Sea.

 

Sources/Relevant Website Links (all accessed on 14/07/14):

http://pulsetidal.com/pulse-tidal-plans-commercial-demonstration-at-lynmouth.html

http://www.bbc.co.uk/news/uk-wales-28204423

http://www.openhydro.com/technology.html

http://www.pulsetidal.com/our-technology.html

http://www.tidallagoonswanseabay.com/

http://www.walesonline.co.uk/business/business-news/company-behind-tidal-barrage-project-7373290

http://www.wavehub.co.uk/news/crown-estate-unlocks-further-uk-wave-and-tidal-current-opportunities/#more-1185

From the Bristol Channel to the Outer Hebrides: The politics, economics, social consequences and environmental effects of harnessing the power of the seas in the 21st Century

A report from the 6th Bristol Tidal Forum and the 2nd Environmental Impacts of Marine Renewables (EIMR) Conference in Stornoway, Isle of Lewis, Scotland.

By: Alexander Portch

The sun is shining, the grass is green, blossom adorns the cherry and the hawthorn, and the mornings are filled with a cacophony of birdsong: the conference season has clearly arrived. Whilst the much anticipated 2nd World Congress of Environmental History in Guimaraes, Portugal, is still several weeks away, the interdisciplinary nature of my research into tidal power in the Severn Estuary is such that it seemed appropriate to attend the 6th session of the Bristol Tidal Forum on 24 April at the University of Bristol, before packing my bags and embarking on a more extended expedition to the farthest reaches of the British Isles to join the 2nd Environmental Impact of Marine Renewables (EIMR) Conference in Stornoway.

sailing away from Ullapool

The soaring peaks of the Scottish Highlands near Ullapool fade into the distance as the Caledonian MacBrayne ferry MV Isle of Lewis departs for Stornoway (Photo: Alexander Portch).

Whilst my research mainly adopts an historical perspective to study the various ways in which people have harnessed the power of the tidal cycle in the past, it is also my intention to consider how that practice may continue into the future, particularly if a barrage is never constructed. With the UK still faced with the need to massively reduce its reliance on fossil fuels by the end of the decade, thereby meeting targets imposed by the EU, and the likelihood that without further investment in new facilities for electricity generation the population, even in developed areas, could suffer from energy shortages, interest in the potential offered by wave and tidal power remains high.

This is particularly so in some of the more remote parts of the British Isles, where strong tidal currents and energetic wave environments are commonplace, such as the Orkney Islands and the Outer Hebrides. In the latter’s case, the scattered villages and isolated crofts are subject to the highest levels of fuel poverty in the UK and, being so far removed from the coal-fired power stations and nuclear power plants that provide the greater part of the mainland’s power, are in a precarious position with regards to their present and future electricity supply. In more recent times, small arrays of wind turbines have been built across much of Lewis; but wind is widely known for its fickle and unreliable nature, even in one of the most windswept places in Europe. It is in response, therefore, to the increasing demand for alternative sources of renewable and reliable energy in places like the northern and western isles of Scotland, and their possession of an unparalleled wave and tidal resource, that an embryonic industry has sprung up in the region and is rapidly increasing in scale and sophistication. In the southwest, too, the combination of a high tidal range in the Severn estuary, powerful tidal currents around the north Devon coast and Cornish peninsula and the high energy waves rolling in from the Atlantic, in addition to the strong winds that drive them, has been recognised through the creation of the South West Marine Energy Park. This is an initiative which seeks to foster collaboration and engagement amongst a variety of companies and organisations, including consultancies, think-tanks and tidal turbine developers.

All such developments have implications for the future of the Severn estuary. Will a barrage be constructed after all? Or will the estuary be divided up into a series of tidal lagoons, as may already be taking place with the recent plans for a lagoon in Swansea Bay? Alternatively, will the estuary be left unmodified to facilitate the widespread exploitation of the waves, winds and tidal currents further out to sea in the Bristol Channel? These are all options to be considered, particularly as each has significant implications for both humans and the non-human environment. With these thoughts and questions in mind, I took my first tentative steps into this year’s conference season.

The Bristol Tidal Forum is a relatively small-scale affair. Taking place over the course of a single day, the event was composed of a linear sequence of talks given by key individuals involved in the south west’s burgeoning tidal energy industry. As quickly became clear, these were mostly people working in the development and financing aspects of the sector, including the directors of engineering firms responsible for designing and building the devices themselves, representatives of organisations tasked with providing the financial support necessary to make such technology economically viable, and policymakers whose remit it is to ensure that the industry continues to develop in line with relevant guidance and government priorities. The environmental aspects of the technology were thus rarely touched upon, whilst the barrage was evidently far from most people’s minds. In fact, one speaker even went as far as to express frustration with the obstacles that have arisen in response to the deployment by their company of turbines in Puget Sound, in the Pacific Northwest of the USA, resulting from the need to monitor the resident orca (killer whale) populations. In many respects, the tone was set from the very beginning by Andrew Garrad of DNV-GL. In his opening address he laid the blame for any delays and difficulties in developing the industry on a combination of political and economic factors, rather than environmental concerns. Perhaps there is some truth in this assertion, and it is something I will be testing through my own historical study of the Severn barrage.

In marked contrast to the Bristol Tidal Forum, the EIMR 2014 conference, as the title implies, was very much focussed on the real and predicted impacts that tidal and wave energy generation may exert on “the environment”. With delegates arriving from as far afield as Oregon, Washington state, France and Spain, and bringing with them expertise in disciplines as diverse as social science, underwater noise propagation, monitoring of marine mammals and diving seabirds, maritime archaeology – and, in my case, environmental history – the resulting presentations, posters and coffee-break discussions proved to be enjoyably eclectic and adopted an open-minded perception of “the environment” as encapsulating human and non-human elements, as well as sentient and inanimate agents. Of particular interest were talks on community engagement as part of the development of tidal power in Nova Scotia, an area now favoured for tidal stream turbines, but also recognised for possessing one of the few operational tidal barrages in the world; a monitoring project centred on salmon around the coasts of Scotland which employed a combination of contemporary and historical tagging data, including some dating back to the mid-19th century; an overview by representatives of Historic Scotland of recently published historic environment guidance for wave and tidal energy developers[i]; and a poster which sought to demonstrate that construction of barrages around the UK, including one in the Bristol Channel, would significantly alter the tidal range as far afield as the Bay of Fundy and the coast of Maine.

What was perhaps most apparent, however, was just how substantial the impact of these new wave and tidal energy devices is likely to be for the marine and coastal environments; for both people and the rest of nature. Despite their relatively modest size in comparison to more substantial structures such as tidal barrages and lagoons, they may still pose a threat to marine mammals such as seals, basking sharks and whales, and seabirds, in addition to modifying tidal range and tidal current velocity, whilst also affecting rates of sedimentation and wave propagation. They could also pose a hazard for shipping, influence the size and frequency of waves currently enjoyed by surfers and other water users (although a talk on this subject with regards to the north Cornish coast suggested that the modifications imposed by the new WaveHub testing site near St Ives are unlikely to be particularly noticeable), and function as an eyesore for tourists and local inhabitants of coastal areas. What is also clear, however, is just how much people care about such issues and how enthusiastic they are about finding ways through which to overcome any problems inherent in the technology in order to facilitate the successful deployment of what could prove to be one of the “cleanest” and most “sustainable” forms of electric energy generation.

Delegates EIMR 2014

Delegates at the EIMR 2014 Conference in Stornoway pose for the final end-of-conference. Reused with kind permission of the organisers of EIMR 2014.

The excitement that currently surrounds the wave and tidal energy industry was perhaps most clearly demonstrated towards the end of my travels in the Outer Hebrides during a journey around western Lewis organised as part of the conference. In addition to visits to the Callanish Stones (Calanais in gaelic) – the Stonehenge of the north, according to some – the Gearrannan Blackhouse Museum and the Dun Carloway (or Dùn Chàrlabhaigh) Broch (thus satisfying my passion for all things archaeological and ancient), the trip took in the proposed site for the Siadar wave energy testing facility located on the north-west coast of Lewis. Developed by Aquamarine Power and employing their Oyster wave energy machines, this is set to become the largest single array of wave energy devices in the world, providing approx. 40 MW of energy to communities on the island. Whilst the devices will be mostly submerged beneath the water, they will nonetheless become visible at the surface during operation. Concern also surrounded the potential risks they pose for marine mammals, the important seabird population of Lewis, the area’s archaeological and historic environment resource, and any vessels that may pass nearby. Additionally, the visual aesthetics of the region were in danger of being compromised by the large number of metal objects scattered across an extensive swathe of coastline.

Lewis coast

Looking south west along the windswept Atlantic-facing coast of Lewis towards the site of Aquamarine’s proposed Siader wave energy farm. The project was awarded full consent by the Scottish government in May 2013, but as can be seen here development has yet to begin. The photograph was also taken on a particularly calm and flat day but the Isle of Lewis is nonetheless renowned for its frequent high-energy waves (photo: Alexander Portch).

In contrast to many energy generation proposals, however, the Siadar site seems to be remarkable for overcoming all such potential obstacles. Seabird and mammal surveys have indicated that the area is largely devoid of any significant populations, and certainly isn’t used as a breeding ground or for feeding; archaeological remains are few and far between; shipping tends to be located further out at sea, away from such an exposed and rocky coast; whilst the decision to paint the devices in battleship grey with only a small amount of luminous yellow facing out to sea will keep their visual impact to a minimum. Local people are largely in support of the project, which will also make use of nearby insular harbour facilities and fabrication centres, and will benefit directly from the electricity produced at the site.

Beach at Dalmore

Breakers pound the beach at Dalmore, a short distance to the south west of the Siader wave site. This demonstrates that even on a calm day the waves on the west coast of Lewis can be sizable. Many a-surfer in the south west of England would no doubt be envious! (Photo: Alexander Portch)

Indeed, as I flew back to Bristol from Inverness at the end of what had been a most enlightening and enjoyable venture, and gazed down upon the miles of offshore wind turbines sprouting contentiously from the seabed off the Lancashire coast, I couldn’t help but wish that all energy developments could be so straightforward and acceptable. On the other hand, if that were so, my doctoral research would be much less interesting! In reality even the Siadar wave site is a long way from completion, and it will undoubtedly encounter further challenges along the way. But the lessons learned from that development could prove instrumental for subsequent projects elsewhere in Britain, and further afield; including, perhaps, the Bristol Channel and the Severn Estuary. Thus, as I delve deeper into the libraries and archives, I will be sure to keep at least one finger on the pulse of the wave and tidal power industries of the 21st century.

 

[i]Firth, A. Historic Environment Guidance for Wave and Tidal Energy. English Heritage,   2013.