The document summarizes a feasibility study conducted by the UK government to assess the viability of constructing tidal power schemes in the Severn Estuary. It outlines the background and objectives of the study, as well as the 10 options originally considered and the 5 options shortlisted after public consultation. The shortlisted options include barrages and lagoon schemes. Decisions on whether to support a scheme are expected in late 2010 after further environmental assessments and public consultation. The study is evaluating the options across technical, economic, environmental and regulatory dimensions to inform the government's decision.

1. Severn Tidal Power Feasibility StudySevern Tidal Power Feasibility Study
Severn Estuary Forum 2009Severn Estuary Forum 2009
Juliet Austin – Environmental workstream lead, STP study,Juliet Austin – Environmental workstream lead, STP study,
Department of Energy & Climate ChangeDepartment of Energy & Climate Change

2. Background: Two-year
Government Feasibility study
• Government decision in response to Sustainable Development
Commission’s 2007 report ‘Turning the Tide’ and increasing UK
need for renewable energy
• To enable Government to decide whether it could support tidal
power scheme in the Severn Estuary, and if so, on what terms?
• 10 long-listed options – 5 shortlisted after 2009 public consultation
• 3-5 year planning and, if consented, 5-10 year construction periods
• Issues being addressed:
- strategic case for Severn power compared with alternatives, and in
what timescale (2020/2050…?)
- impacts and benefits, and balance between the two?
- costs and risks, who bears them, legal compliance
- preferred scheme/s? Multiple options under consideration

3. Map of 10 originally-
proposed options

4. 5 Short-listed schemes
… Following 2009 public consultation…
Beachley Barrage (625 MW, £2.3bn construction cost)
Shoots Barrage (1.05 GW, £3.2bn)
Cardiff-Weston Barrage (8.6 GW, £20.9bn)
Welsh Fleming Lagoon (1.36 GW, £4bn)
Bridgwater Bay Lagoon (1.36 GW, £3.8bn cost)
… individually, and some potentially in combination

5. Short listed options

6. Decisions next year
• Advice to ministers April 2010, subject to election
• Public consultation (in addition to one in Jan-April 09)
• Decision late 2010 – either:
- to offer package of support for preferred scheme/s to
go ahead, and move to full feasibility work leading to
planning application OR
- to wait until uncertainties are clearer, and potentially
for new technologies to be deployable in the Severn OR
- not to support a scheme

7. Public consultation
Issues for consultation – Jan-April 2009
1. Shortlist of scheme options
2. Scope of Strategic Environmental Assessment (SEA)
3. Scope of overall work of feasibility study
What replies did we get?
Good response – over 730 replies:
• Lots of views, full range of views
• How assessing environmental impact?
• Short-listing – questions on why and how
• Regional economic DTZ report – assumptions made?

8. Government response
• Explains how scheme options are being considered
• Confirms shortlist of 5 schemes for impact assessment
• Confirms £534,000 funding for 3 new Severn Estuary
technology schemes (SETS):
- Atkins/Rolls Royce: low head barrage
- Severn Tidal Fence Consortium – tidal stream
- VerdErg: tidal stream array
• ‘Feedback loop’ – apply learning and shortlist SETS and
non-shortlisted schemes if feasibility study criteria met
• Confirm SEA scope, with minor changes
• Peer review of DTZ study

9. Non short-listed
Schemes
Apply learning and
short-list if feasibility
criteria are met
Embryonic
Schemes
Develop and assess via
SETS. Short-list if feasibility
criteria are met. Consider in
study conclusions if not.
Short-listed
schemes
Feasibility study conclusions
Developing evidence base/
optimisation of scheme design and operation
Consideration of scheme options –
feedback loop

10. Embryonic technologies
3 schemes being funded: less environmentally damaging/cost
effective?
Low head barrage – Rolls Royce/Atkins
– ‘low head’ barrage with new types of turbine than traditional barrage design
– Draws on both tidal stream and range technology
– Tides held back for less time = should reduce potential impact on intertidal/fish
Severn tidal fence – Severn tidal fence Consortium
- Tidal stream array
- Does not hold back water to generate electricity – turbines use movement of
water rather than height difference
Severn tidal fence - VerdErg
- Radical new fence design using tidal stream technology – water passes through
tubes that in turn drive turbines
- Minimal moving parts – potentially less damage to fish and intertidal habitat

11. Wider context
• Government’s Low-carbon Transition Plan and Renewable Energy
Strategy
• Aim: 40% low carbon electricity, 30% renewables by 2020
- renewable electricity - mainly offshore wind
- Severn tidal power?? Depends on wind – plus cost of energy,
certainties, impacts, cost and risk
• Longer term:
- 80% decarbonisation electricity supply by 2050. Demand will rise
- include mix of renewables, nuclear, carbon capture and storage
- Severn tidal power?? More work needed on longer term, also on
Severn power options

12. Work areas…
Economic & Commercial
• Strategic and economic case
• Impact assessment
• Risk assessment and risk management
• Subsidy mechanism, public role & costs, delivery
timescale
• Transfer of risk – public vs private?
• Timing implications
• Cost – environment, compensatory measures
• Affordability / impact on consumers
• Regional economic impact

13. Environmental studies
(more detail later)
• Gathering evidence for Strategic Environmental Assessment (SEA)
of environmental and regional impacts – report in 2010
• Impacts on flooding, birds, fish, other habitats and species,
water quality, geomorphology (shape of estuary and moving
sediments)
• Series of technical workshops in the autumn comprising specialists
to advise on the SEA studies
• Environmental legislation – can we comply? Studies include
Habitats Directive, Water Framework Directive
• Ecosystem valuation report – to illustrate the value of the
environment to society, in monetary terms
• All part of consultation in 2010

14. Technical & Engineering
- Optimisation of shortlisted barrages and lagoons – getting best
out of options against different feasibility study objectives (cost,
environmental impact, amount of energy)
- Mitigation against environmental damage: cross-checking
against SEA impacts
- Grid Study
- Supply Chain Study
- Severn Estuary Embryonic Technology Schemes assessment

15. Regional impact assessment
• Commissioned independent peer reviewer to look at
DTZ report (strategic-level assessment of economic and
social impact) in light of public consultation comments
• Conclusions of review expected this Autumn
• SEA, supply chain study and ecosystems valuation work
contribute to picture on regional impact
• Will take a view on whether more work is necessary after
peer review

16. • Regulatory overview:
assessment of compliance with
relevant regulations and policies
• Assessment of various potential
consenting procedures
• Analysis of the methodology of
consenting compensatory
habitats
• Analysis of risk and who bears it
Consenting
Route /
Risk Analysis
Consenting
Compensatory
Habitats
Regulatory
Overview
Timeline
Planning And Consents

17. Engaging stakeholders & public
• Public consultation Jan-April 2009
• Regular stakeholder meetings, multilateral and bilateral
• SEA workshops for technical experts
• Sciencewise public dialogue sessions:
– Intended to provide early view on priority issues for people and
how best to communicate information in the consultation
– Small scale meetings for invited members of the public
• Information on DECC website and regular e-mail bulletins
• Encouraging organisations to communicate to your stakeholders
• Public consultation (likely to be in 2010)
– Include public meetings on both sides of the Estuary

18. Environmental studies (more
detail)
• Strategic Environmental Assessment (SEA) – high-level social and
environmental impacts – a requirement of large project plans.
Majority of scientific evidence base.
• Pre-consultation – high-level. May09 – Jan10 – more detailed.
• Engaging stakeholders: Decc environmental workstream
(Environment Agency, Natural England, Countryside Council for
Wales, Defra, Welsh Assembly Govt), SEA Steering Group (NGOs,
regional interests incl. Bristol Port), individual stakeholder meetings

19. High level
environmental issues
• Environmental benefit - annual saving of up to 11Mt CO2.
• Range of effects on estuarine, marine and freshwater
ecosystems.
• Studies on the value of the services they provide – eg
fishing, flood defence, aggregates.
• Severn Estuary, River Wye and River Usk (and beyond)
– protected international importance for their biodiversity.
• Compliance with Habitats Directive, Water Framework
Directive, other environmental legislation, policies.
• Uncertainty in results given short timescales, whether
desk or field-based, different specialist opinions.

20. Impacts?
Hydraulics and geomorphology
• H&G: Shape/ structure of estuary, currents, sediment
movements
• High tidal range = complicated environmental system
• Sediment deposition in channels, build up on foreshore or
erosion, flood risk?
• Estuary is extreme high energy environment.
• Removing energy changes environment.
• Understanding physical response drives many other
topics – water quality, flooding, biodiversity; affects
engineering
• Looking at range of potential complex physical scenarios

21. Other impacts?
• Reduced tidal range – loss of salt marsh and mudflat habitats.
Effects on habitats and their value as flood defence?
• Flood risk?
• Birds – displacement, loss of birds from Severn, national effects?
• Fish and fishing – declines and/or local extinctions?
• Water quality – salinity, pollutants, temperature.
• Other sea users – aggregate, other energy production, tourism and
recreation.
• Historic environment/seascape?
• Navigation?

22. Environmental studies
- SEA
SEA
ENVIRONMENTAL
REPORT
Physico-Chemical
THEME
Society & Economy
THEME
Landscape &
Historic Env
THEME
Biodiversity
THEME
Carbon Footprint,
Resources &
Waste THEME
Hydraulics and
Geomorphology
Marine Water
Quality
Freshwater Env. &
Assoc. Interfaces
Flood Risk and
Land Drainage
Society &Economy
Navigation
Other Sea Uses
Noise & Vibration
Marine Ecology
Ornithology
Migratory &
Estuarine Fish
Terrestrial &
Fresh. Ecology
Historic
Environment
Landscape and
Seascape
Carbon
Footprinting
Resources and
Waste

23. Habitats Directive compliance
and compensatory measures
• Following steps laid down in EU Regulations
• Process: Scoping and Appropriate Assessment on
designated sites, assessing for likely significant adverse
effects. If so, look to mitigate. Is the project of IROPI?
If so, determine feasibility of providing compensatory
measures.
• Investigating feasibility / cost of different types of
compensatory measures. E.g. managed realignment for
lost mudflat/saltmarsh, impacts on fish.
• Do not yet know enough to say whether compensatory
measures possible for any of the habitats/species lost
under short-listed schemes.

24. 2010: Phase 2 public consultation on recommendations
Scheme assessment: Individual costs, benefits, risks, impacts
of each scheme against key areas identified in study objectives
(regional, economic, environmental, regulatory requirements,
energy and climate change goals) using quantitative and
qualitative data from evidence gathered across feasibility study
Decision by Ministers: Stop, wait, go ahead?
Response to phase 2 consultation
2009/10 - environment:
Results of SEA studies, impact on
environmental legislation, ecosystem
valuation
Strategic case
Results of Severn
Embryonic
Technology
Schemes

25. Contact information –
getting in touch
Web:
www.decc.gov.uk/severntidalpower
Email:
severntidalpowerunit@decc.gsi.gov.uk