Tidal Power Projections

Tom Beagan

24th February 2005

The Tidal Resource

The UK has a significant proportion of the world’s tidal power

It can be harnessed in 2 forms:

• Tidal Barrage

• Tidal Stream

Tidal Barrage• Requires a tidal basin

– at least 5m tidal difference

• Few suitable sites in the world

• La Rance (right) only large one, 240MW capacity

• Potential for an 8460 MW barrage across the Severn

Tidal Barrage

Benefits• Continuous electricity source• Pollution free (except construction)• Low cost after completion

Limitations• High capital cost (resulting in high cost of electricity)• Environmental impact: sediment flows, species migration• Hinders navigation• Visual impact• Can’t control peak generation time

Tidal Stream

• The newer method of tidal generation

• Devices placed in strong tidal streams around UK

• Possible devices: – ‘Seagen’ (right) up to

1MW– Stingray (aerofoil)

150KW

Tidal Stream

Benefits• Small environmental and visual impact• Large Potential resource in UK waters• No pollution

Limitations• Technology in early stage of development• Devices expensive = expensive electricity• Tidal streams are a long way from large populations• Electricity loss through transmission• Low load factor 39% average (carbon trust)

The Future for Tidal Barrage

Artists impression of the proposed Severn barrage

Hmmm!

The Future for Tidal Barrage

There are 3 large barrage proposals in UK• The Severn – 8640 MW by far the largest in UK• The Mersey – 700MW• Orkney Churchill Barriers – 300MWSeveral smaller proposals• Duddon estuary (Cumbria) – 100MW• Wyre estuary (Lancashire) – 63.6 MW• Conwy (North Wales) – 33.4 MW• Loughor (Swansea) – 5 MW

Why aren’t they being built?• Mainly financial reasons

– Severn 8.6GW scheme ‘uneconomical’– High capital costs and few jobs after completion– Electricity will be too expensive

• Environmental reasons– Large opposition from pressure groups– Extent of possible damage unknown– Big risk

• Turn towards Tidal Stream– Interest is building– Acquiring more funding and investment

What can we expect from barrage?

• Unlikely to be any sizeable schemes between now and 2030 except maybe Orkney (existing barrier)

To increase likelihood• Need a reduction in capital costs• Improvement in power capture efficiency• Possible tidal lagoon in Severn? FOEProjection• 2010 – 0 MW• 2015 – 0 MW• 2020 – Up to 300 MW if Orkney gets go ahead• 2030 – 300 MW

The Future for Tidal Stream

The Future for Tidal Stream

The future is bright!• Size of resource 22 TWH/yr most recent prediction• Most advanced design is double turbine ‘seagen’ capable

of over 1 MW capacity• 300 KW single turbine being tested in Bristol Channel

currently outperforming expectations by 27%

Problem?• High cost of technology currently over £2M for a single

unit• Funding gap, businesses can’t afford to build prototypes

The Future for Tidal Stream

Solution• Aug ’04 Marine Renewables Development Fund

to be set up• Grants of £5M to suitable investors

Result• 1 MW prototype Tests and technological improvements• Grid connected ‘farm’ of 3-5 devices Tests• Tidal farm will grow to 20+ devices Tests• Several farms will be created in different sites • Improved technology will bring prices down, large growth

Tidal Stream Projections

Tidal Stream Projections

Carbon trust total tidal stream extractable:• 22 TWh/year• That requires a 2.5 GW supply• This will need 6435 double turbines (LF 39%)

Can we do this by 2030?• That’s 257 Seagen a year from now until 2030

I don’t think so!!!

What can we expect?• 2010 – 1 Seagen (1MW) probably grid installed

– 0.39 MW = 0.01 PJ

• 2015 – 25 Seagen grid operational– 9.75 MW = 0.31 PJ

• 2020 – 100 operational– 39 MW = 1.23 PJ

Capital cost cheaper, Each unit now 1.5 MW • 2025 – 350 operational (around 50 per year)

– 205 MW = 6.46 PJ

• 2030 – 750 operational (around 80 per year)– 439 MW = 13.8 PJ

Stream plus Barrage

• Orkney tidal barrage (300MW) likely by 2020

• Load factor around 23%• Therefore 69 MW = 2.18 PJ

2020 – 3.14 PJ2025 – 8.46 PJ2030 – 16 PJBut this is an optimistic projection!

Conclusion

• Large margin for error• Projections rely on

results of testing• Transmission costs not

accounted for• Hydrogen?• Main barrier FINANCIAL