Hydroécol. Appl. (1992) Tome 4 Vol 1, pp. 1-11

Power generation on the british coast: thirty years of marine biological research

Andrew W.H. Turnpenny and Jack Coughlan Fawley aquatic research laboratories Ltd, Marine and Freshwater Biology Unit, Fawley, , , S04 lTW, UK

Abstract. - Industry-based marine biologists have investigated a wide range of issues relating to coastal power generation since its expansion in Britain in the 1950s. Early fears of wide-scale ecological damage arising from discharge of heated effluent proved to be unfounded. The removals of fish and other natant organisms by cooling abstraction have also been shown to be of no consequence, either ecologically or to the fishing industry. Biofouling of cooling systems, once a crippling problem for the in- dustry, has been largely brought under control by low-level chlorine application. Marine dumping of ash (PFA) is due to cease shortly, and novel opportunities for use of solid by-products for marine habitat enhancement are being investigated. Studies in al1 areas continue, so that the industry can pursue improving environmental practices.

Key words. - Marine biology - Power generation - Heated effluent - Removals of or- ganisms. Chlorine application - Dumping of ash - Marine habitat enhancement.

Résumé. - Les investigations des biologistes marins quant à l'impact des centrales électriques remontent aux années 1950 en Grande-Bretagne. Les premières craintes de dommages écologiques à grande échelle résultant du rejet d'effluents échauffés se sont avérées infondées. II a aussi été montré que les disparitions de poissons et autres organismes aquatiques par aspiration avec les eaux de refroidissement n'avaient pas de conséquence écologique ni d'impact sur I'industrie de la pêche. L'encrassement bio- logique des systèmes de refroidissement, qui était un problème majeur pour I'industrie, a été réglé par l'utilisation de chlore à faibles doses. Les rejets en mer de cendres de charbons (PFA) vont cesser très prochainement, et de nouvelles opportunités pour I'u- tilisation de produits de recyclages solides pour la valorisation de l'habitat marin sont à l'étude. Les recherches se poursuivent dans tous les domaines, prouvant la motivation des industriels en matière de protection de l'Environnement.

Mots-clés. - Biologie marine - Centrales électriques - Rejets thermiques - Entraîne- ments des organismes - Chloration - Emissions de cendre - Valorisation de l'habitat marin. 2 Andrew W.H. Turnpenny and Jack Coughlan

INTRODUCTION tuarine and coastal generation was prompted by a number of factors. First, the 1956 Clean Air Act had ef- Today, of 80 GWe installed electricity fectively ruled out the redevelopment generating capacity operated by the of urban sites. Second, the increasing main producers in Britain, some 46% size of generating units necessitated is sited on open coasts or estuaries larger sites with substantial volumes (fig. 1). of cooling water, neither of which were available in urban areas. Third, Until the 1950s, the majority of Bri- a growing energy gap ushered in the tain's thermal generating capacity was first civil nuclear programme and early located inland, in and around urban nuclear stations were built away from centres, using river water for plant co- population centres. Finally, expansion oling purposes. The shift towards es- of oil refining capacity made available

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Fig. 1. - Coastal and Estuarine Power Stations in Britain. Power generation on the British Coast 3 large volumes of heavy fuel oit at low holding the most productive oyster cost; major new stations were sited (ustrea edulis) grounds in the country. alongside the new refineries at Pem- After giving consent for the Bradwell broke, Fawley and in the Thames Es- station, the lnspector recommended tuary. These stations could take that biological studies should be un- advantage of large available areas of dertaken to allay the fears of the fis- low-lying, level land of little monetary hing industry. This gave rise to the value. team of marine biologists, formerly wi- thin the CEGB and subsequently part The need for marine biological stu- of the Research and Technology De- dies was recognised at an early partment of National Power, based at stage. Proposals to build the first two Fawley (Hampshire). stations at Berkeley and Bradwell sparked immediate op- Much has been written about the position which, at Bradwell, led to a marine biological consequences of four day Public Inquiry. There were power generation. In this paper we re- deeply held views about the possible view some of the key issues from an effects of the new station on the local historical perspective leading to the fishing industry, an area at that time current position.

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Fig. 2. - Summary of Potential Interactions between Thermal Power Stations and the Marine En- vironment. 4 Andrew W.H. Turnpeniny and Jack Coughlan

INTERACTIONS BETWEEN and establishment or elimination of THERMAL POWER STATIONS species, to non-thermal effects arising AND THE MARINE ENVIRONMENT from biocide discharge, modification of water currents and deoxygenation of the sea bed and water column. The principal interactions between an estuarine or coastally-sited power sta- tion and the marine environment are shown in Figure 2. These can be pla- EFFECTS OF THERMAL ced in three broad categories: DISCHARGES 1. effects arising from engineering construction and site occupation; By 1950 thermal discharges were 2. effects arising from solid and firmly established as an important en- liquid waste disposal; and vironmental issue on inland sites. It was not surprising, therefore, that 3. consequences of cooling water thermal stress in estuarine and ma- (CW) system operation. rine ecosystems was quickly taken up The last of these requires some by objectors, particularly commercial further explanation. A direct-cooled fishermen who stood to lose their li- 1000 MWe conventional velihood if the catastrophes predicted requires 30 cubic metres of cooling by 'experts' should materialise. During water each second. For a Pressurised the 1956 Bradwell Inquiry, this Water Reactor this rises to more than concern was summed up in emotive 40 m3s-l. As this water enters the in- headlines such as 'Dead Sea' and 'Ri- take, it draws with it any suspended ver of Death'. It is a matter of history weed and debris, as well as fish and now that such fears of wide-scale and other aquatic animals that cannot es- profound alteration of marine ecosys- cape the flow. To prevent blockage of tems resulting from thermal dis- the heat exchangers this material is charges at Bradwell and elsewhere in removed by small-mesh (8-10 mm) Britain proved to be unfounded. For- screens and is normally rejected to tuitously, the commissioning of Brad- trash bins. Smaller organisms pene- well in 1962-63 coincided with one of trate the screens and pass through the coldest winters on record. The the CW system where they are sub- Blackwater froze over, with vast mor- jected to stresses including mechani- talities of organisms. One result vf im- cal shock, abrupt temperature mediate significance was that oysters changes and, when in use, exposure living near the cooling water outfall to biocides such as chlorine. Beyond had avoided the almost complete the point of discharge, a variety of ge- mortality suffered elsewhere in the es- neric and site-specific issues have tuary [Il. Periodic surveys of the Bla- been raised by objectors. These ckwater undertaken by MAFF and range from thermal effects on the phy- CEGB since the commissioning of siology and behaviour of organisms Bradwell have continued to show es- Power generation on the British Coast 5 sentially the same community struc- induce stress but it was never de- ture as that recorded prior to monstrated that this would increase construction of the power station [2]. Bonamia susceptibility. Other work [4] has demonstrated that temperature The question of the impact of ther- rises typical of power stations opera- mal discharges on commercial oyster ting in British coastal would populations continues to attract de- bate. The Solent oyster fishery deve- push oysters towards, rather than beyond, their optimum growth tempe- loped shortly after the commissioning ratures. The plans for Fawley 'B' were in 1970 of , a 2000 MWe oil-fired plant which dis- eventually withdrawn and these is- charges warm water into the Solent. sues were never fully resolved. By the late 1970s it had become Eu- rope's largest self-sustaining commer- Thermal discharge effects on other cial fishery for 0. edulis, with a peak marine benthos were investigated in annual yield in excess of 1000 tonnes an intensive three year study at [3]. It is clear that this fishery has flou- , [5]. rished, despite its intimate exposure This station is well suited to the in- to the discharge and yet, when in vestigation of thermal effects, since 1988 the CEGB published proposals the outfall discharges into the head of for the construction of an 1800 MWe a canallcreek system and exhibits 'B' station on the same site, the oyster clearly defined temperature gradients, issue was again raised, this time by thermal fronts and cyclical tempera- both local fishermen and regulators. ture fluctuations. Animal communities were investigated over a 4km reach The position of the regulators was of the creek; the temperature rise at set by EEC Directive 791923lEEC on the head was around 10 OC and at the 'The Quality Required of Shellfish Wa- lowest (reference) site 3 OC. The main ters'. Areas inclusive of the existing effect was a 40% reduction in the and proposed thermal discharge had number of species in the upper part been designated EEC Shellfish Wa- of the creek compared with the refe- ters and were subject to a maximum rence site. This was accounted for by recommended temperature rise of the absence of stenothermal species 2 OC above ambient. The fishermen (e.g. the molluscs Petricola pholadi- raised several new objections, inclu- formis and Cerastoderma edule). In- ding the possibility that thermal stress tertidal species (e.g. the annelids might increase susceptibility to Bona- Tubificoides amplivasa tus and Caule- mia infection. Bonamia is a protozoan riella zetlandica) being tolerant of parasite which has reached epidemic thermal shock, spread opportunistical- levels and wiped out populations in ly into subtidal areas to produce vety European and some English South dense populations. Langford [6] noted coast fisheries. A study commissioned a similar reduction in fish species di- by CEGB into stress in oysters de- versity in the upper part of the creek monstrated that thermal shock could but with very large numbers of warm- 6 Andrew W.H. Turnpenny and Jack Coughlan water species such as sea bass (Di- around power station outfalls [8]. It is centrarchus labrax) and grey mullet interesting to speculate on the effects (Liza auratus). The main conclusion of decommissioning power stations in that can be drawn from these studies bass nursery areas, or indeed of lo- is that, whilst increased temperatures wering the water temperature by the may reduce species diversity, effects addition of chilled water arising from, are local and restricted essentially to for example, gasification plant. the area of direct impingement of the warm water plume onto the sea bed.

The effects referred to so far are CONTROL OF BlOFOULlNG al1 'near-field', i.e. occurring within the mixing zone of the thermal discharge. Whilst the Bradwell lnquiry was consi- Of increasing interest are the 'far-field' dering the possible effects of a power effects, that is the elevation of water station on oysters, mussels (Mytilus temperature by perhaps only a frac- edulis) were crippling stations from tion of a degree over a wide area. Camarthen to Blyth. Between 1957 This concept is valid principally within and 1964, Power Station a semi-enclosed body of water such (Hampshire) alone suffered 4000 as an estuary. For most species, the condenser tube failures from mussels. effect will be insignificant compared The problems arose from mussels with natural temperature fluctuations. settling and growing on hard surfaces Organisms most likely to be affected within the water intakes where they are those living at the northern (warm- could take advantage of the supply of water species) or southern (cold water plankton from the incoming water. If species) limits of their distribution. dislodged they could become wedged Whilst there are no definitive data, the in condenser tubes causing potential for this effect can be inferred blockages or, at worst, perforation, from reports of 'warm-water' fishes of leading to boiler feed water contami- Mediterranean origin (e.g. sea bass nation, boiler corrosion and turbine and red mullet Mullus surmeletus) pe- blade damage. At Poole, 300 tonnes netrating further north into British wa- of mussels and barnacles were remo- ters during warm years. After a series ved during one annual overhaul. of increasingl~ warm winters from 1986 to 1990- exceptionally high re- Although chlorine was being used cruitment was observed in a number at these stations, application was in- of such species in the Bristol Channel termittent. At one station, continuous, [7]. It is also well established that suc- low level chlorination was tried and cessful sea bass recruitment is in part proved to be successful. Further ex- dependent upon warm winters (Hen- perimental work by biologists at Poole derson and Holmes, pers. comm.) Power Station showed that the low- and a recognised fact that young bass level technique prevented mussel congregate in the warm waters settlement, reduced growth in mus- Power generation on the British Coast 7

sels which had already settled, and EFFECTS OF WATER controlled microfouling (slimes) on ABSTRACTION ON FlSHERlES heat exchangers. Today, low-level chlorination is still the preferred option at most coastal power stations. The capture of predominantly small fish on CW intake screens is one of Environmental concern over the the more evident environmental ef- discharge of residual chlorine has fects of power generation and has prompted constant review of alterna- been a recurring source of contention, tive methods but, to date, no better especially with commercial fishermen. alternative has been found. Current It is acknowledged that this is an ad- research at Fawley is aimed at redu- ditional cause of mortality, like the cing the amount of chlorine required, wastage of discarded undersized fish thereby reducing discharges. In prac- in the fishing industry, which should tise, very little free chlorine persists be put into its proper context. beyond the point of discharge, on ac- A programme of CW screen sam- count of chemical reactions taking pling has been carried out over many place within the cooling system and years at different power station sites. discharge zone. Typically, and initial The surveys are statistically designed dose yielding 0.2 mg CI 1-l at the to overcome sampling bias caused by condenser inlet will have decayed to tidal and seasonal influences. At Hin- around 0.1 mg CI 1-l at the point of kley Point 'B' Power Station, monthly discharge, and by a further factor of sampling has been maintained now ten within 1000 m along the plume for eleven years. Though not al1 co- axis [9]. astal power stations have been sam- No adverse effects have been pled over this length of time, identified in Britain as a result of such information has been gathered from discharges, though for non-target or- enough sites representative of diffe- ganisms (plankton), exposure to the rent marine habitats and intake des- higher chlorine levels within the co- igns to develop models which can be oling system represents a risk addi- used to predict fish catch at other tional to the physical hazards of sites and even for 'green field' sites. transit [IO].The consequences for the The PISCES expert system develo- majority of planktonic species are ne- ped at Fawley allows the non-expert gligible since the nutrients released at to predict at-risk fish communities, death are quickly reassimilated by the and catch rates at proposed water in- ecosystem. The risk of high mortali- takes, for any point around the British ties amongst the eggs or larvae of coast. Such tools are valuable aids to commercial fish and shellfish has led environmental impact assessment. to lengthy studies to ensure that water The first attempt to place fish intakes are placed well away from catches by power stations into the spawning grounds of such species context of stock sizes and commercial [Ill. landings was made for Sizewell 'A' 8 Andrew W.H. Turnpenny and Jack Coughlan

Power Station in 1983 [12]. Local fis- upon fish and shrimp populations. The hermen were objecting to the propo- central idea is to establish the size of sa1 to build Sizewell 'B', on the the population frorn which the anirnals grounds that the catch of undersized are cropped. This is straightforward fish would be increased substantially for major commercial stocks for which with two stations operating. It was estirnates are made regularly under shown that the catches by the 'A' and the auspices of the International 'B' stations would amount to only a Council for the Exploration of the Sea small fraction of the commercial catch (ICES) (see Table 1) but for many (Table l), equivalent to the catch of species such data are not routinely a single srnall trawler, and would be available. indistinguishable amongst natural At Fawley Power Station, recorded fluctuations. Sirnilar findings have captures of the sand smelt (Atherina been reported 1131 for estuarine po- boyer~),a small inshore fish, were of wer stations, where catches of juve- the order 1O5 individuals per year. The niles could be expected to be higher population structure over the first ten due to the presence of fish nursery years operating life of the station sho- areas. The long time series of catch wed no significant alteration by this data collected from Hinkley Point pro- sustained level of cropping [15]. Such vide a direct demonstration that sus- findings indicate a high degree of na- tained cropping by several power tural resilience in inshore fish popu- stations in the Severn Estuary and lations. Bristol Channel has not led to any In a study of the brown shrimp sustained depression of fish or shrimp (Crangon crangon), morphometric nurnbers [14]. characteristics were used to distin- Population studies hold the key to guish population boundaries of understanding the nature of impacts shrimps taken from different coastal

Table 1. - Comparison of fish loss due to Sizewell 'A' Power Station with loss due to commercial fishing vessels, as % of North Sea stock (Year: 1983) [12]. - . . ICES Stock Size Power Station Commercial Species (millions) % %

Sole 21 O 0.01 3 23

Dab 4 900 0.00034 ?

Whithing 3 500 0.0087 47

Cod 845 0.00044 53

Herring -- Power generation on the British coast 9 localities [16]. The purpose of this stu- SOLID WASTE DISPOSAL dy was to establish whether catches AND UTILISATION of up to 10 tonnes per annum at po- wer stations such as Hinkley Point and Sizewell were of any significance The power industry has always had to stocks. It was demonstrated that a major solid waste disposal require- there are six major populations of ment arising from coal ash production. shrimps around the coast of From 1994, this burden will be increa- and Wales. These already support fis- sed by the commissioning of flue gas heries that are large in relation to po- desulphurisation (FGD) plants using wer station catches. Any impact would the limestone-gypsum process. For a be minor, being spread out over a po- 1800 MWe coal fired power station pulation as a whole. using this FGD process, there will be an annual production of IO6 tonnes of Some benefits arise from the cap- pulverised fuel ash (PFA) and 0.5 x ture of organisms on intake screens. IO6 tonnes of gypsum. The majority It was recognised back in the 1960s of this material, as in the past, will be that power station and other industrial sold to the constructioin industry or water intake screens offer the oppor- used for land reclamation and landfill. tunity for low-cost monitoring of fish Sea dumping has never been a major and other natant organisms. Power route for disposal. A PFA disposal site stations on the Thames Estuary pro- located off the Northumbrian coast vided evidence for the recovery of fish has received a part of the PFA pro- populations following pollution abate- duction from Stella and Blyth power ment, and this monitoring has conti- stations since the 1950s. The ecolo- nued to this day at West Thurrock gical consequences of this practise Power Station by the National Rivers have been shown to be minimal [17], Authority. Regular annual sampling limited essentially to a blanketing of from the screens of Kingsnorth and marine benthos over the immediate Oldbury Power Stations has enabled area of deposition. Despite this, ma- MAFF scientists to monitor changes rine disposal will cease by 1993. in year class strength in sea bass [8]. Following successful reports from The Il-year sampling programme at the Coal Waste Artificial Reef Pro- Hinkley Point has provided a wealth gramme (C-WARP) in the USA [18], of data on the estuarine community the CEGB in 1986 began to consider which are being used to develop more the use of consolidated blocks of PFA generalised models of estuarine and gypsum materials for habitat en- community dynamics. Such models hancement, and in 1988 commissio- help us to understand how a wide va- ned Southampton University to riety of anthropogenic impacts, ran- undertake the Poole Bay Artifical Reef ging from commercial fishing to tidal Project. The aim of this project is to power generation, might affect estua- investigate the properties of blocks of rine communities. different composition and their poten- 10 Andrew W.H. Turnpenny and Jack Coughlan tial for reef construction. Results from Environmental Effects of Cooling the first exposure season of the reef Systems at Nuclear Power Plants, International Atomic Energy Agency, indicate no loss of structural integrity, Vienna, 1975, pp. 423-448. an abundant and diverse fauna and [3] Key D. and Davidson P.E. A review flora and negligible transfer of toxic of the development of the Solent metals from the bocks to the epibiota oyster fishety, 1972-80. Laboratoty [19]. Public interest in reef construc- Leaflet No. 52, MAFF Direct. Fish. tion for leisure uses (sport angling and Res., Lowestoft, 1981, 36 pp. diving) and for mariculture is growing. [4] Buxton C.D., Newell R.C. and Fields J.G. Response surface analysis of The future of reefs made from these the combined effects of exposure materials will depend on economic and acclimation temperatures on fil- factors and licensing success. tration, oxygen consumption and scope for growth in the oyster Ostrea edulis. Mar. Ecol. Prog. Ser., 6, (l), ENVIRONMENTAL ASSESSMENT 1981, pp. 73-82. (51 Bamber R.N. and Spencer, J.F. The benthos of a coastal power station European Council Directive discharge canal. J. mar. biol. Ass. 851337lEEC requires the power in- U.K., 64, 1984, pp. 603-623. dustry to prepare environmental sta- [6] Langford T.E. The effects of a ther- tements for al1 major new mal discharge on the growth and developments. The long tradition of feeding of bass, Dicentrarchus la- research into the environmental brax (Linnaeus, 1758) in the Estuary, England. Central Electricity consequences of power generation Generating Board, Publ. No. has placed the industry at the front TPRD/U3126/R87, 1987, 50 pp. of environmental assessment deve- [7]Holmes R.H.A. and Henderson, P.A. lopments in Britain [20]. Continuing High fish recruitment in the Severn research will maintain this position Estuary: the effect of a warm year? and ensure that the best principles of J. Fish Biol., 1990, 36, pp. 961-963. environmental responsibility are [8] Pawson M.G. and Pickett G.D. The bass (Dicentrarchus labrax) and ma- upheld. nagement of its fishery in England and Wales. Laboratory Leaflet No. 59, MAFF Direct. Fish. Res., Lo- westoft, 1987, 37 pp. REFERENCES [9] Coughlan J. and Davis M.H. Concen- trations of chlorine around marine cooling water ouîfalls: validation of a [l] Crisp D.J. The effects of the severe model. In Water Chlorination: Envi- winter of 1962-63 on marine life in ronmental Impact and Health Effects, Britain. J. Anim. Ecol., 33, 1965, pp. Vol. 5, eds. Jolley, R.L., Bull, R.J, 165-21O. Davis, W.P., Katz, S., Roberts, M.H., [2] Hawes F.B., Coughlan J. and Spen- Jr. and Jacobs, V.A., Ann Arbor, MI: cer J.F. Environmental effects of the Ann Arbor Science Publishers Inc., heated discharge from Bradwell Nu- 1985, pp. 1459-1468. clear Power Station, and of the co- [IO] Coughlan J. and Davis M.H. Effect oling systems of other stations. In of chlorination on entrained plankton Power generation on the British Coast 11

at several United Kingdom coastal [15] Henderson P.A., Turnpenny A.W.H. power stations. In: Water Chlorina- and Bamber R.N. Long-term stability tion: Environmental Impact and of a sand-smelt population subject to Health Effects, Vol. 4, Book 2, eds. power station cropping. J. Appl. Jolley, R.L., Brungs, W.A., Cotruvo, ECO/.,21, 1984, pp. 1-10, J.A., Cummings, R.B., Mattice, J.S. [16] Henderson P.A., Seaby R. and Marsh and Jacobs, V.A., Ann Arbor, MI: Ann S.J. The population zoogeography of Arbor Science Publishers Inc., 1983, the common shrimp (Crangon cran- pp. 1053-1063. gon) in British waters. Central Elec- [Il] Henderson P.A. The vertical and tricity Generating Board, Pub. No., transverse distribution of larval her- ESTD/U0009/R89, 1989, 16pp. ring in the River Blackwater estuary, [17] Bamber R.N. Potential environmental Essex. J. Fish Biol., 31, 1987, effects of dumped pulverized fuel .DD. . 281 -290. ash in the sea. Central Electricity Generating Board, Pub. NO. Turnpenny A.W.H., Utting N.J., Mill- RD/U3471/R89, 1989, 7Ppp. ner R.S. and Riley J.D., The effect of fish impingement at Sizewell A Po- Woodhead P.M.J., Parker J.H. and wer Station, Suffolk, on North Sea Duedall I.W. The use of by-products fish stocks. Central Electricity Gene- from coal combustion for artificial rating Board, Pub. No. reef construction. In Artificial Reefs TPRD/L3270/R88, 1988, 40 pp. - Marine and Freshwater Applica- tions. ed. D'ltri. F.M.. Lewis Publica- [13] Turnpenny A.W.H. Fish impingement tions, Chelsea, Michigan, USA, at estuarine power stations and its 1986, pp. 265-292. significance to commercial fishing. J. [19] Collins K.J., Jensen A.C. and Lo- Fish Biol., 33 (Supplement A), 1988, ckwood A.P.M., Fishery enhance- pp. 103-11O. ment reef building exercise. Chem. [14] Henderson P.A. and Holmes R.H.A. ECO/.,4, 1990, pp. 179-187. On the population dynamics of dab, [20] Bamber R.N. Environmental impact sole and flounder within Bridgwater assessment: the example of marine Bay in the lower Severn Estuary, En- biology and the UK power industry. gland. Neth. J. Sea Res., (in press), Mar. Poll. Bull., 21, (6), 1990, 270- 1991. 274.