Hydropower ‘Good Practice Guide’Supplement to EA Hydropower manual

Dr John Aldrick

HO Water Resources Regulation manager

Environment Agency Policy on Hydropower

The slides showing hydrographs and flow duration curves were prepared to illustrate the impact a hydropower scheme may have on flows in the depleted reach. A range of different river types were used, as indicated in the title of each slide.

The hydrograph shows the gauged flow, without hydropower, the flow in the depleted reach with abstraction for hydropower, and the flow for hydropower (and other amenity purposes in the hydropower leat etc).The percentile flow values (Q50,Q95 values) used are for illustrative/investigation purposes.

This work has shown that there are further principles that can be drawn out and developed regarding the setting of hydropower abstraction/flows in the depleted reach. These will be developed further as part of the 'Good Practice Guidance'.

PRESENTATION CAVEATS

Environment Agency Policy on Hydropower

The Agency strongly supports the Government’s targets for the use of renewable energy. (10% - 2010, 20% - 2020)

BUT The Agency recognises both potential benefits &

environmental impacts of small-scale hydropower The Agency seeks to work constructively with the

hydropower industry to balance the benefits/impacts of hydropower

“We’re only borrowing the water, so what’s the big deal”

Agency regulatory regime

Strong legislative and environmental constraints which guide us

Range of matters to take into account e.g. water resources, fisheries, flood risk, water quality, navigation,

Water Resources permit Abstraction Licence/Impoundment licence/sec 158 agreement

Hydropower proposals test the Water Resources mandate to balance the needs of the developer and the environment

Abstraction Licence

Quantity that can be abstracted Max. Instantaneous, hourly, daily, annual

Residual flows in deprived reach measurement/control of abstraction & flows

Operating/control agreement Time limited licence (normally 12 years to CAMS Common End Date)

Fish Screening requirements Fish Pass requirements Derogation agreement ?- (quirk of legislation?)

Allows some further upstream abstraction

No abstraction charge if < 5Mw

Hydropower issues

Location environmental sensitivity

Volume/timing local impact

Residual flows deprived reaches flow measurement

Fisheries turbines screens fish-passes

Good Practice Guide

Appendix to Agency Hydropower Manual

To provide starting point for evaluating schemes

Checklist for criteria that may require EIA work Principles for setting Residual flow Flow measurement Screen/turbine relationship Principles of screen design

Hydropower Good Practice Guide

Being developed by EA/Hydropower Working Group Aims to :

provide Agency/developers with a consistent approach, common language and practical advice

clarify the Agency position and promote awareness But it won’t :

answer all your Hydropower development issues Agency Hydropower Manual(2003) available on website

Environmental site list audit

Red boxes need further work

Notes provide further guidance

Water Resources Conservation Chemical/physical

water quality Biological Water

quality Fisheries Flood Defence

tick box A Water Resources Checklist Note No.

YES NO

Is the scheme non-consumptive i.e. will 100% of any water abstracted be returned to the water course from which it was taken?

1

Is the scheme being built on existing infrastructure? 2

Will the turbine be placed directly within the weir / water course rather than in a separate channel?

3

Is there a flow-depleted channel? 4

Is there a flow-depleted weir? 4

Is it intended to increase the height of the impoundment? 8

Do surveys reveal any existing abstractions, including unlicensed ones, which will be derogated by the proposal? (1)

5

Is there an EA gauging station in the depleted reach or nearby that is likely to be affected by the scheme?

5

Will the developer accept a derogation consent within the proposed licence? 7

Checklist indicates factors that need to be considered

Deprived reach Flow

Flow to be left in deprived reach between intake and discharge - (how much?)

To meet fisheries, ecological, amenity, riparian, navigation needs

Dependant on environmental sensitivity May depend on the length of the deprived reach May vary with flow or season (eg migratory fish) Flow measurement or control Decisions impact on economics/viability of scheme

HydropowerLarge river Q50-Q95 Q50/Q95 2.01

Don hydropower

100

1000

10000

Oct

-89

Dec

-89

Feb

-90

Apr

-90

Jun-

90

Aug

-90

Oct

-90

Dec

-90

Feb

-91

Apr

-91

Jun-

91

Aug

-91

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-91

Dec

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-92

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92

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Jun-

93

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-93

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Feb

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Apr

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Jun-

94

Aug

-94

Date

Flo

w (

Ml/

d)

Long Term Natural

Qn50

Qn95

Hydro 1

Gen vol 1

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

?

Hydro 1

Hydro 2

1.00 8808.610.00 2922.520.0 1762.130.0 1220.4

40.00 956.350.00 787.460.0 674.2

70.00 586.880.00 503.190.0 431.6

95.00 392.298.00 349.499.0 327.5

100.00 275.2

HydropowerLarge river Q50-Q100 Q50/Q95 2.01 141% more hydropower

Don hydropower

100

1000

10000

Oct

-89

Dec

-89

Feb

-90

Apr

-90

Jun-

90

Aug

-90

Oct

-90

Dec

-90

Feb

-91

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-91

Jun-

91

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-91

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Feb

-92

Apr

-92

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92

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Jun-

93

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Feb

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Jun-

94

Aug

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Date

Flo

w (

Ml/

d)

Long Term Natural

Qn50

Qn95

Hydro 1

Gen vol 1

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

?

Hydro 1

Hydro 2

1.00 8808.610.00 2922.520.0 1762.130.0 1220.4

40.00 956.350.00 787.460.0 674.2

70.00 586.880.00 503.190.0 431.6

95.00 392.298.00 349.499.0 327.5

100.00 275.2

HydropowerSpaty river Q50-Q95 Q50/Q95 6.86116% more hydropower if Q100

Kilgram hydrograph

0

100

200

300

400

500

600

700

800

900

1000

Oct

-89

Oct

-90

Oct

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Oct

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Date

Flo

w (

Ml/

d)

Long Term Natural

Qn50

Qn95

Hydro 1 Q50 - Q951831590

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

GES A2

Hydro 1

Hydro 2

Qn95

Qn50

1.00 10583.210.00 3603.220.0 2116.230.0 1407.2

40.00 957.050.00 657.160.0 471.7

70.00 316.480.00 200.690.0 127.1

95.00 95.898.00 70.699.0 55.7

100.00 33.4

HydropowerLarge Chalk river Q50-Q95 Q50/Q95 1.75

Chalk hydrograph

0

100

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1000

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Flo

w (

Ml/

d)

Long Term Natural

Qn50

Qn95

Hydro 1 Q50 - Q95gen Q

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

GES A2

Hydro 1

Hydro 2

Qn95

Qn50

1.00 1350.310.00 841.120.0 736.730.0 658.1

40.00 583.350.00 529.760.0 468.4

70.00 420.580.00 374.090.0 330.8

95.00 303.398.00 274.199.0 259.9

100.00 218.2

HydropowerLarge Chalk river Q50-Q100 Q50/Q95 1.75152% more hydropower

Chalk hydrograph

0

100

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1000

Oct

-89

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Flo

w (

Ml/

d)

Long Term Natural

Qn50

Qn95

Hydro 2Q50 - Q100genQ

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

GES A2

Hydro 1

Hydro 2

Qn95

Qn50

1.00 1350.310.00 841.120.0 736.730.0 658.1

40.00 583.350.00 529.760.0 468.4

70.00 420.580.00 374.090.0 330.8

95.00 303.398.00 274.199.0 259.9

100.00 218.2

Hydropower50-50 flow split2/3rds of power

Hydropower Chalk hydrograph

0

10

20

30

40

50

Oct

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Date

Flo

w (

Ml/d

)

Long TermNatural

Qn50

Qn95

Hydro 1 Q50 - Q95

gen Q

50%split

0

10

20

30

40

50

0 10 20 30 40 50 60 70 80 90 100Flow Excedence %ile

Flo

w M

l/d

Long Term Natural

GES A2

Hydro 1 Hydro 2Qn95Qn5050% split

1.00 53.610.00 32.720.0 24.830.0 19.7

40.00 15.650.00 12.760.0 10.5

70.00 8.880.00 7.590.0 6.3

95.00 5.598.00 4.899.0 4.4

100.00 3.3

Deprived reach Flow – principles?

Q90-95 default Hands Off Flow Q30/50 – HOF potentially available for hydropower Length of deprived reach 50/50 flow split?

Limited impact on flow variability 2/3rds of hydropower

Q50/Q95 < 3 (high baseflow) may have economic advantage of using Q100 if very short deprived reach

Fisheries

Turbines screens Migration spawning Habitats Directive

Turbines, screens, conservation

Conservation issues (HD, SSSI etc) impact on overall scheme

Fish friendliness of turbines Screen specification

Fish friendly turbines?

Crossflow Francis Kaplan Archimedean screw Waterwheel

Fish screens

Mostly physical wedge wire, mesh,bar

Fish screens are expensive

Recent R&D Mesh size flow velocities

Fish Screen - principles

Inlet velocity – ideally 0.25-0.3m/sec (at an angle to the flow) – leading to a

By-wash – to enable fish to escape Mesh size/turbine type

Tail race screens on salmonid rivers

1 3 6mm 16 25 50Crossflow Kaplan/ Screw/

Francis Waterwheel

10/ 12.5

Fish migration

Fish passes may involve retro-fit also likely to be costly New weirs Salmonid rivers first

Applicants should expect the Agency to:

Provide clear guidance on the licensing process Highlight key issues for environmental assessment Have an understanding of hydropower Provide information it has available Be consistent Provide timely responses, with explanations

Applicants should not expect the Agency to:

collect and analyse supporting data carry out the environmental assessment accept inadequate data or assessments give a binding view based on incomplete information design the scheme contravene its statutory duties

The Agency expects the applicants to:

to know their site, its environment and their objectives for the scheme (background)

consider and design their proposals carefully consider options/alternatives make early contact with the Agency and continue such

throughout the process appreciate the legislative and other constraints provide quality, focused environmental assessments provide appropriately detailed plans and drawings to

support any applications

Conclusions

Good Practice Guidance has not had final sign-off Will not answer all questions Provides ‘starting point’ for decision making Requires trialling/evaluation The Agency will move to National Permitting in 2008