Renewables First - storage - Chris Elliott final version
1. The value of storage
Chris Elliott
Senior Hydropower Engineer
8th November 2016
2. Overview
1
• Stroud, Gloucestershire
• Hydro is largest part of the business
• High and Low head systems
• Design
• Install
• Maintain
• Screening systems
3. Aims of Presentation
• Outline of the type of schemes FiT has encouraged
• Aside from FiT, where does a scheme’s income come from?
• To what extent can water storage be added to a scheme to increase
• Energy capture
• Income per MWh generated
• Trends in prices leading from changes to generation mix and demand
responsivity
• TRIADs
• Wholesale prices
• New battery storage technology
4. What types of scheme have been built under FiT
under 15kW
schemes
•2MW
•194 schemes
15kW to 100kW
schemes
•25MW
• 362 schemes
100kW to 500kW
schemes
•54MW
•137 schemes
500kW to
2000kW schemes
•83MW
•70 schemes
2000kW to
5000kW schemes
•4MW
•1 scheme
Output<15kW
1%
15kW<Output<100kW
15%
100kW<Output<500kW
32%
500kW<Output<2000kW
50%
2000kW<Output<5000kW
2%
TOTAL INSTALLED CAPACITY BY PLANT SIZE
Mainly simple high head, no storage
5. What types of scheme have been built
focus on high head, no storage
Drivers
• Digression time pressures push developers to simple consents
• Lower impoundment heights
• Hard engineered intakes
• Fine screens
• Space constraints
• FiT income predominates – storage is peripheral to economics
Most FiT schemes don’t have storage
6. Scheme income examples –
FiT payment does not have any time sensitive element
Site pre accredited
before 2014, 99kW
size
• 75% FiT,
• 25% Other (Electricity, DUoS, TRIAD, REGO)
Site pre accredited
2015, 500kW+ size
• 59% FiT
• 41% Other (Electricity, DUoS, TRIAD, REGO)
Site pre accredited
late 2016, 500kW+
size
• 47% FiT
• 53% Other (Electricity, DUoS, TRIAD, REGO)
7. Non FiT income
typical PPA, example 500kW scheme
Electricity export
• c. 5p/kWh with time
sensitivity
• £88,000 p.a. for 500kW
scheme
TRIAD avoidance benefit
• £45/kW typically with
time and location
sensitivity
• £18,000 p.a. for a
500kW scheme hitting
90% TRIADs @ 90%
GTPS
GDUoS credits
• Var. p/kWh location
specific, but potentially
time sensitive
REGO
• neg.
If you have no storage:
• You are not able influence how well you hit TRIADs or maximise sale price intra
day on a STOD tariff
• You are unable to avoid spilling once at capacity
Therefore storage may increase both energy capture and £/MWh
8. Energy capture improvement with active upstream
storage
500kW plant, 150m head, 10000m3 storage
0
100
200
300
400
500
600
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Power with no storage /kW
9. Energy capture improvement with active upstream
storage
500kW plant, 150m head, 10000m3 storage
• Potentially look to introduce
separate storage at convenient
point upstream
• Topology
• Ownership
• Ecology
• No change to FiT accredited
scheme
• Relatively small impoundment,
modest volumes
• May avoid Reservoirs act
• Generally lower risk
structure
• Analogous to a mill pond rather
than large dam
10. Energy capture improvement with active upstream
storage
500kW plant, 150m head, 10000m3 storage
0
200
400
600
800
1000
1200
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Storage effect from summer storm
Power /kW Stored volume /m3 Total power /kW
11. Energy capture improvement with active upstream
storage
500kW plant, 150m head, 10000m3 storage
Extra capture – calculated to be 102MWh, value £17.1k p.a.*
*=2015 pre accreditation
Major pro – certainty that this benefit will remain for life of FiT
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50
100
150
200
250
300
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extra energy capture /kWh
12. Production time shifting with active upstream storage
500kW plant, 150m head, 10000m3 storage
Jan
Mar
May
Jul
Sep
Nov
0
1
2
3
4
5
6
7
8
9
Typical STOD tariff structure (weekday)
0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9
13. Production time shifting with active upstream storage
500kW plant, 150m head, 5000m3 storage
0
1
2
3
4
5
6
7
8
9
10
0
1000
2000
3000
4000
5000
6000
0 10 20 30 40 50 60 70 80 90 100
April flow duration and production from stored water
Stored volume /m3 Movable production /kWh River Flow /m3s-1
14. Production time shifting with active upstream storage
500kW plant, 150m head, 5000m3 storage
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0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12
Peak time capacity factor
Monthly capacity factors 1600h to 1900h No storage Monthly capacity factors 1600h to 1900h With storage
15. Production time shifting with active upstream storage
500kW plant, 150m head, 10000m3 storage
Value of shifting production
£1300 p.a
Derived from aiming at
maximising production
1600h – 1900h on an all
export STOD tariff
Electricity
value
£1300 p.a.
Derived from increasing
likely TRIAD capacity
factor from 91% to 99%
TRIAD
value
£variable –c. £6300 p.a.
in 22 area
The presence of storage
allows access to a
banded DUoS tariff and
optimisation of capacity
factor in the red band.
GDUoS
value
Significantly higher where
there is on-site demand
16. Total current value of storage
500kW plant, 150m head, 10000m3 storage
Constraints
• If you have a FiT accredited site designed to have Qdesign ≈ Qmean you
cannot scale up the plant because you lose FiT accreditation
• Reservoirs act volumes
Capacity
factor
increase
£17.1k
Minimise wasted
flow
Marginal
opportunity to
eliminate start up
volume as
turbine can run
efficiently
intermittantly
Generate
at peak
time
£1.3k
Generate at peak
times
Optimise
hitting
TRIADs and
GDUoS
£7.6k
£26.0k Total benefit
Minimise
production
loss from
plant
maintenance
17. Other situations where storage is significantly more
valuable
Existing storage
• If there is existing storage which can be adapted with relatively little additional regulatory and
operational burden the benefit of storage can be enhanced
On site usage
• Larger differentials between off peak export and import prices, and more time at this differential make
this more attractive than working simply on export price differentials
Flashy catchment
• Flashier catchments would usually lead to more than average spill and can benefit disproportionately
from attenuating this
Large design flow
•
Grid services
• Potentially STOR market via aggregator
18. Batteries
• How come batteries are the in thing if we show that the business case for
water storage is largely driven by gathering more FiTs
• Current storage capacity dominated by Hydro, but lots of hype around
batteries and other storage technology
19. Storage – revenue streams
Response
• Enhanced
Frequency
Response
• Firm Frequency
Response
Reserve
• Fast reserve
• Short Term
Operating
Reserve
• Capacity
Market
Price / Time shift
• Transmission or
Distribution
cost avoidance
/ payment
• Own use
• Curtailment
Avoidance
• Price arbitrage
20. TRIAD changes
• OFGEM open letter
• TRIADs – the three max demand HH / year – result in apportionment of
TNUoS charges
• TRIADs encourage demand reduction, but prediction “getting too good”,
high users perceived to avoid fair share
• TRIAD avoidance via embedded diesel Distributed Generation (DG) at
high users, and incentive not to just reduce on site demand, but export
as much as possible
• Government would like to encourage new CCGT via capacity Market
which is currently outcompeted by diesel DG
• But TRIADs are established and do lead to peak reduction, DNOs not
clear on what latent demand there is
• Conclusion –
• probably difficult to change
• probably hydro would not be badly hit by a broader base to
transmission network charging
21. Overall conclusion on storage
• A combination of improved energy capture, plus
better value for units generated makes storage on
100m head + sites worth considering
• Water storage based storage can be cost effective
especially with
– High head, flashy watercourse
– On site demand
• If you are considering a project Renewables First
are a capable partner for assessment, design,
delivery
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