U Pumped Hydro Energy Storage (UPHES): A pre … BUsiness Dialogue...1 Underground Pumped Hydro...

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Underground Pumped Hydro Energy Storage (UPHES):

A pre-feasibility study from South Africa

Sustainable Use of Abandoned Mines in the SADC Region

Indaba Hotel, Johannesburg (South Africa), 28-30 Nov 2017

F Winde, E Erasmus, F Kaise r

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Contents

(0) Summary

(1) Background and core idea

(2) Technical feasibility

(3) Economic viability

(4) Research needs/ uncertainties

(5) Conclusions

Surface mine area

Access shaft

Pressure pipe

Upper storage reservoir

Ventilation

Mine void =

lower storage reservoir

Turbine chamber

reservoir

Karstified dolomite

Tailings dams

Wind/solar power

not to scale

Engine/ generator

Pump/ turbine

Shutting device

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Summary

UPHES in deep level GMs are:

(1) … technically feasible due to favourable conditions in SA

very deep shafts

stable hard rock

water-rich dolomites

large voids

existing infrastructure

accessibility

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(2) … economically viable and affordable

…on national economy level (government)

- no flooding no perpetual pump-and-treat of AMD

- no last-man-standing problems (extend life of marginal mines)

- no ghost-town scenario sustainable economic development

- protection of large groundwater resources (karst)

- aids decarbonisation of current energy base

…on investor level (business case)

- different revenue streams

- possible added revenue in future

- currently low interest rates

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(1)

Background

Background Technical feasibility Economic viability Research needs Conclusions

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Karst

JHB

100 km

WEST RAND

FREE STATE

EVANDER

EAST RANDKOSH AREA

CENTRAL

RAND

FAR WEST RAND

operational

closed/ flooded

dolomitic compartments =

several x Vaal dam


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Water- water deficit Gauteng latest drought 2016- AMD threat in FWR- karst aquifers of strategic importance to Gauteng- water for E (SA): 821 Ml/d(2017)

AMD- high costs for pump-and-treat: R 10 bn/ 130 Ml/d short-med term+ R 12bn long-term (RO) + R 9 bn Rand Water eventually: ~ 360 Ml/d indefinite costs

Energy - 2008-2016: peak load gap

now overcapacity (Medupi/ Kusile…)

- steep tariff increases- limited black start capacity - decarbonisation: increase

RE (grid stability)

UPHES

Mining - deepest mines worldwide high pumping cost threaten viability- last-man standing problem- post-closure requirements- mines now liable for legacy costs** Mine Water Management Policy July 2017

- mine void as asset: fully equipped shaft: R 10bn ($1bn) 270 mio. m³ total permanent void volume

Situation in South Africa


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Pump / Turbine

Grid

E-output (turbine) (expensive, day)

E-input (pump)(cheap/ night)

E-input

(pump)

E-output

(turbine)= 0.80

consume 20% more energy than is produced

upper reservoir

lower reservoir

mature, tried and

tested technology

The concept


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UPHESV: 1 Mm³

h: 2500 m

P: 1240 MW (5h/d)

Eff. 77%

…3800 m

Burj Khalifa

(839m, $1.5bn )

+ 1

/2

Drakensberg(3480 m)

+ 3

00

m

2016 (R 28bn)

V: 26 Mm³

P: 1340 MW (for 16h/d)

Eff: 78%

Ingula

460 mP/T

P/TFully equipped

shaft (2016):

R 14bn ($1bn)

South African conditions


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UPHES consortium

Research Mining Energy

multilateral MoU signed

RDT


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Existing studies/ projects

RAG + UDE (2012-2018): Ruhrgebiet (operating hard coal mines)

Eskom (1997-2006): Central Rand Au-mines

Patton Engineering (2013): KOSH: AGA Au-mines

Genex (2014-2019): Kidston Au-mine

Pyhäsalmi (2014-2020): Cu/Zn-mine

EFZN (2009-2011) : Harz, Erzgebirge (closed old ore mines)

Germany

Finland

Australia

South Africa


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(2)

Technical feasibility

Background + core idea Technical feasibility Economic viability Risks Conclusions Background Technical feasibility Economic viability Research needs Conclusions

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Selecting a suitable mine

Blyvoor # 4/6

Driefontein #7

Ezulweni shaft (Cooke #4)

24 100

70

Tautona South Deep

Cooke #3

Deelkraal

Blyvoor

Venterspost

REGMt

DRD

Luipaardsvlei/Cham d‘Or

- significant water ingress (resource protection, pumping infrastructure …)

- last-man-standing setting

- still accessible but no production

- sufficient depth


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Driefontein GM 7# (Far West Rand): UPHES layout

3000 m

sub-vertical shaft

tertiary shaft

Karst aquifer (1000 Mm³)

machine cavern

(turbine, pump)

ingress

pump

P

lower reservoir (1 Mm³)T

upper reservoir (1000 Ml)

discharge +

access shaft

emergency

shaft

Pemergency sump

Shaft - diameter: 10 m

Pressure pipe – diameter (1 Mm³/5h at <7m/s): 3.6 m

Shaft elevator – max width: ~5 m: <largest part of machinery

bottom ingress: ~10 Ml/d

=1% circulated volume

~100 Ml/d ingress(90% captured)


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0.5

-2 k

m

Shaft

Drive (10 km)

10 km x (5x3) 15m² = 0.15 Mm³

Shaft cross-cut (4 km)

1000 m x 15m² x 4/reef= 0.06 Mm³

100 m 100 m

Au-reef

Reef cross cuts (50 km)

total volume per level: 500 m

x (3 x 3) 9 m² x 100/level =

0.45 Mm³

5-2

000 m

Storage volume per level:

100 x reef cross cuts: 0.45 Mm³ (68%)

1 x main drive: 0.15 Mm³ (23%)

4 x shaft cross cuts: 0.06 Mm³ (9%)

Total: 0.66 Mm³ per level

lease

bo

un

da

y

lease

bo

un

da

y

Driefontein GM 7# (Far West Rand): estimating storage volume


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P = (V * * g * h * T ) : t

Epot

water Volume= storage space

[Mm³]

height diff.

= shaft depth [m]

time of

operation

[h/d]

Power = energy

outpout [MW]

Energy storage

capacity [MWh]

T/P

V [m³]

da

y

nig

ht

- density of water (1t/m³)

g – gravitational pull (9.81 m/s²)

T – efficiency of turbine (91%)

Th

S M L XL Ingula

h [m] 1000 2000 3000 4000 470

V [106 m3] 1 1 1 2 26.3

Epot [MWh] 2725 5450 8175 21900 21440

t [h] 4 8 16 4 8 16 4 8 16 4 8 16 16

P [MW] 620 310 155 1240 620 310 1860 930 465 4960 2480 1240 1344

Driefontein: possible UPHES dimensions


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Parameter Pilot UPHES(R ? bn*)

77% efficiency

h [m] 2500

V [Mm3] 1 (1000 Ml)

Epot [MWh] 6 800

t [h] 5 8 16

P [MW] 1230 770 335

Proposed dimensions of pilot plant

Complementary add-ons

+ Geothermal energy(T: 10 K, 100 Ml/d): 1 160 MWh/d

direct use of heated water (e.g.

green houses, central heating)

Sibanye Gold Ltd. total need: ~500 MW/d

planned solar system (R 3bn) : 200 MW/d

Wind power

turbines on tailings dams/ Gatsrand)

storing wind energy

*Eskom (2000): 18%...40% cheaper than on surface

Patton Engineering (2013): R 4.5 bn (300 MWh)

overestimate (excavations): R 2-4 bn (6.8 GWh)

at 1 cycle /d: required pumping volume

1000 Ml/d, currently installed ~ 400 Ml/d


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Ezulweni mine

Blyvoor # 4/6

Driefontein #7

Ezulweni shaft

(Cooke #4)

24 100

70

Tautona South Deep

Cooke #3

Deelkraal

Blyvoor

Venterspost

REGMt

DRD

Luipaardsvlei/Cham d‘Or

Background + core idea Technical feasibility Economic viability Risks Conclusions

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Ezulweni U-mine

- closure application pending

- 66…88 Ml/d ingress (2016)

- pumping costs: ~R 15m/ month

+ staff and shaft maintenance

- large installed pumping capacity

- relatively low depth (1500 m)

- underground drop: 600 m

- storage volume per level currently determined

underground dams indicate suitability of tunnels

as storage reservoirs

7m

6m

…and pump chamber (50A level)current water pipes…

… pumps

Shaft barrel


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Ezulweni U-mine

60

0m

underground dam at pump chamber

1500m

Option 2:

upper reservoir

on surface


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(3)

Economic viability


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Business case: Selling peak-load electricity

Eskom Megaflex Tariff (2015)[cent ZAR per kWh]

Peak(5h/d)selling

Standard(11h/d)selling

Av.(16h/d)selling

Off-peak(8h/d)buying

Winter: June-Aug (3 months) 223.63 67.74 116.45 36.79

Ratio selling : buying priceprofit margin

6.0 +460%

1.8 +38%

3.2+243%

Summer: Sep-May (9 months) 72.96 50.2 57.31 31.86


2.3 +77%

1.5 +15%

1.8+38%

Average year (240 weekdays/a) 110.62 54.58 72.09 33.09


3.3+257%

1.7+27%

2.2+68%

- Efficiency of 80% can currently be achieved (reduced by pumping ingress to 77%)

23% more energy is used than generated

can only operate profitable if E-selling price (peak) is 1/0.77 = 1.3 x larger than

E-buying price (off-peak)

Av. electricity selling-buying profit margin per year at 5-hour-operating mode: 257%


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Business case: selling peak electricity and water

Peak-electricity sales Dfnt 7#(2500 m, 6800 MWh/d)

Ezulweni(1500 m; 4125 MWh/d)

Power selling (turbine)buying (pump)

5h x 1237 MWh8h x 1070 MWh

5h x 761 MWh8h x 469 MWh

Price [R/MWh] sellingbuying

1106330.9

1106330.9

[Mio R/d] sellingbuying

net-income

6.842.834.01

4.211.242.97

Electricity-income(240 weekdays/a)

R 962m/a R 713m/a

Water sales 100 Ml/d 70 Ml/d

Income/d at R5/kl R 500,000 R 350,000

Water income(365.25 days/a)

R 183m/a R 128m/a

Total revenue electricity/ water

R 1145m/a81% /19%

R 841m/a85 % / 15%

both sites may continue to be a gold mine after all…


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Economic viability

Direct revenue Added (monetary) benefits

selling peak electricty

selling clean water

geothermal heat energy use (?)

selling grid services (future?)

- power storage capacity (RE)

- black start capacity

- frequency stabilisation

- regulating/ balancing power

Mines

Eskom

Government

Communities

- no last men standing problem

- protects against future tariff hikes

- post-closure community development

- no indefinite future liabilities

- image gain (share price)

- costs deductable from rehab funds?

- adds black start capacity

- cheaper than conventional PHES

- aids decarbonisation: storing RE

- free grid services

- cuts transmission losses

- export of know how

- no AMD costs to taxpayer

- no costly ghost towns

- protects scares water resources

- allows for post-mining development

- high social acceptance


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(4)

Research needs,

uncertainties


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Research needs, risks, uncertainties

Geological aspects

- seismic effects of frequent mass shifting

- natural and mining-related seismicity

- boundary pillar integrity/ stability

- stability of void structures (life span of tunnels etc.)

- water tightness of tunnels

Water-related aspects

- karst feed flow fluctuations (floods, droughts, sinkholes…)

- silting of reservoirs (precipitates)

- pressure and temperature induced calcite precipitation (scaling)

- contamination of bottom ingress

- acidification

Engineering aspects

- pressure pipe construction (raise boring vs. shaft pipe)

- suitable machinery for very high water pressure

- remote controlled machinery/ ventilation needs

- access shaft large enough for heavy machinery

- corrosion issues (humidity, acidification)

- drainage time from long tunnels (gradient flow)


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Economic aspects

- future energy market in SA

share of renewable energy (CSIR,2017: 75%...79% by 2050?)

- exchange rate fluctuations (investment grading)

- run-away inflation

- development of interest rates…

Legal, administrative aspects

- liability issues (mining legacy)

- sterilisation of mineral resources

- regulatory uncertainty: status of UPHES and applicable fees (Germany)

Socio-political aspects

- nationalisation debate

- rapid economic transformation

- tensions between industry and government

- organised labour attitude

- others (corruption, state capture…)

General

-‘known unknowns’ vs. ‘unknown unknowns’

- conduct a pre-mortem

- SWOT analyses


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(6)

Conclusions


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(1) Favourable conditions in SA Geology: chemically inert and stable hard rock

Infrastructure: large volume, depth, pumps, grid access...

E-market: good price-spread, carbon tax savings,

Policy: decarbonisation, post-closure development, water resource

protection

High social acceptability: jobs, reuse of mining landscapes, water resource

protection ...

(2) Major potential benefits no perpetual pump-and-treat

improves energy and water security (locally and nationally)

no water pollution

aids decarbonisation of economy

no ghost towns and social disintegration

adds tax revenue

no losers

exportable knowledge


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(3) Recommendations

secure governmental support (tax breaks....)

expand feasibility study

consult regulators (NERSA, DWS, DMR...)

develop market for grid services (E-storage...)

engage stakeholders: communities, unions, farmers...

explore complementing measures (aqua- and horticulture ...)

preserve knowledge, data and expertise

identify best ownership model

select and approach investor/s


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Thank you!

U Pumped Hydro Energy Storage (UPHES): A pre … BUsiness Dialogue...1 Underground Pumped Hydro...

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