1 -

Hvor står afsaltning energimæssigt?

Chefingeniør Christian Stamer

Krüger A/S

DWF temamøde Vand og energi-effektivisering

torsdag den 28. april

Energi til afsaltning omfatter i bredere forstand både anlæg og

drift. Vi behøver en fælles standard for at kunne sammenfatte

det totale energikoncept.

I Veolia har vi valgt at benytte begrebet Carbon Footprint, som

udtrykker den ækvivalente mængde CO2, som aktiviteten

belaster kloden med set over en lang årrække.

Veolia har udviklet et særligt værktøj til dette formål, som jeg

vil anvende i det følgende.

2 -

3 -

Which tools to calculate the Carbon Footprint?

Computes the GHG emissions based on basic process models

Excel spreadsheet dedicated to Carbon Footprint

Other impact indicators

Human Health (human toxicity, respiratory effect…)

Biodiversity (aquatic and terrestrial ecotoxicity…)

Resource depletion (e.g. « water footprint » under development)

Ai * EFi

i1

n

Emissions Factor (in kg.CO2eq per)

Activity Data (tons of steel, KWh elec…)

Perimeter (construction, operation, decommissioning)

Carbon Footprint =

Ai * EFi

i1

n

Emissions Factor (in kg.CO2eq per)Emissions Factor (in kg.CO2eq per)Emissions Factor (in kg.CO2eq per)

Activity Data (tons of steel, KWh elec…)

Perimeter (construction, operation, decommissioning)Perimeter (construction, operation, decommissioning)Perimeter (construction, operation, decommissioning)

Carbon Footprint =

Gas GWP over 100 years

(CO2eq)

Carbon dioxide (CO2) 1

Methane (CH4) 25

Nitrous oxide (N2O) 298

Hydrofluorocarbons 12 to 12,000

Perfluorocarbons 5,700 to 11,900

Chlorofluorocarbons 4,600 to 14,000

Conversion factor: Global Warming Potential (GWP) over 100 years

One single unit, ton CO2eq,

reflecting the impacts of all GHG

4 -

Life Cycle Inventory

How to assess the Carbon Footprint ?

Decommissioning

Production

of concrete

Construction

Operation

Intake pumping

Water treatment

Water distribution

Inventory of

intermediates

INPUT FLOWS

Fossil fuels

Minerals

OUTPUT FLOWS

Indirect GHG

Emissions

Production

of chemicals

Production

of electricity

Background processes

LCA scope

Ecoinvent database For Emission Factor

Technical modeling

of process units

Raw water

Potable water

Direct GHG

emissions

Plant perimeter

5 -

Emission Factors

Construction

Concrete: 260 kg.eq CO2/ m3

Steel: 2770 kg.eq CO2/ t

Power – impact of local energy mix

Operation

FeCl3 40%: 719 kg.eq CO2/ t

Ca(OH)2: 750 kg.eq CO2/ t

NaOCl 15%: 813 kg.eq CO2/ t

Polymer: 1.57 kg.eq CO2/kg

France: 0.09 kgCO2/kWh

Spain: 0.35 kgCO2/kWh

Saudi : 0.75 kgCO2/kWh

Australia: 0.92 kgCO2/kWh

6 -

SWRO desalination plant

0

0,5

1

1,5

2

2,5

3Membrane renewal

Plant and piping network construction

Disinfectant NaOCl production

Remineralization chemicals production

CIP chemicals production

Antiscalant production

Coagulant / Flocculent production

Electricity production for water treatment

Electricity production for intake and distribution

Green House Gases emissions

in kg CO2-eq/m3

of potable water

Construction < 2% of GHG emissions

RO pumping needs > 75% of GHG emissions

7 -

Impact of local energy mix

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5UAE grid mix

Saudi Arabia grid mix

Australian grid mix

Spanish grid mix

Nuclear thermal plant

Wind turbine

Photovoltaic cells

Combined cycle gas turbine

Oil fired plant

Coal thermal plant

GHG emissions in kg CO2-eq/m3 of potable water Power supply

UAE grid mix: 99% gas turbines, 1% oil fired plants Saudi Arabia grid mix: 47% gas turbines, 53% oil fired plants Australian mix: 75% coal, 20% gas, 5% hydro/wind Spanish grid mix: 22% coal, 30% gas turbines,

20% nuclear electricity, 18% hydro / wind

Australian

model

But, energy mix is not within the scope of the suppliers of water

technology

Need to look at the C footprint of the water treatment schemes

8 -

Greenhouse Gaseous emissions in kg CO2 eq/m3

for desalination plants

0

0,5

1

1,5

2

2,5

3

3,5

4

FUJAIRAH OMAN SUR SYDNEY

Projects

kg

CO

2 e

q/

m3

po

tab

le w

ate

r

Membrane renewal

Plant and piping network construction

Sodium hypochlorite / sodium bisulfiteproduction

Sulfuric acid, sodium hydroxide, CO2production

Antiscalant and cleaning chemicalsproduction

Coagulant and polymer production

Electricity production

Results from Eolia TM

February 2009

François Vince

3.78 kWh/m3 @

39 g/L TDS 28°C

3.84 kWh/m3

average per year

3.92 kWh/m3

average per year

Energy mix:

98% gas

2% oil

Energy mix:

82% gas

18% oil

Energy mix:

79% coal

12.14% gas

6.36% hydro

9 -

Salinity/ temperature impact on 1st pass RO pressure Pressure 1 st Pass

min 58 bars

max 64,5 bars

50,0

55,0

60,0

65,0

70,0

75,0

80,0

15 20 25 30 35 40 45

Temperature

Pre

ss

ure

38

39

40

41

42

45

50

55

TDS g/l

28

Gap: 6,5 bars

32

Case Study: Oman

10 -

Concentrate

Reverse

osmosis

Booster

Permeate

Post

treatment

Drinking

Water Pretreatment

Intake

Seawater

ERD

Variable

frequency drive

HP pump

Where is the electricity consumption the highest: 1st pass

Variable Frequency Drive on RO booster pumps allows

flexibility to adapt to pressure variations

Case Study: Oman

11 -

Electrical consumption Breakdown on RO 1st pass

0,00

0,50

1,00

1,50

2,00

2,50

1 -HP RO Booster pumps 2 -DWEER Booster pumps 4-1st PASS HP pumps 5-Recirculation pump for DWEER

type of pump

kw

h/m

3

Kg

CO

2 e

q/ m

3

0.46

0.92

1.38

1.84

2.3

0

Case Study: Oman

HP RO Booster DWEER Booster HP Pump DWEER Recirculation

Emission factor at Oman: 0.92 kg CO2eq/ kwh

DWEER =

Dual Work Exchanger Energy Recovery

12 -

Example at Oman Sur : up to 76.5% of electrical consumption on the

first pass

Electrical consumption Breakdown on Oman Sur

1 -HP RO Booster pumps

2 -DWEER Booster pumps

4-1st PASS HP pumps

5-Recirculation pump for DWEER

6-Second pass RO pumps

7-Intake pumps

10-Existing plant

11-Others

1st pass RO 67-76,5%

Pretreatment 5%

Where is the electricity consumption the highest?

Case Study: Oman

13 -

HYDRANAUTICS DOW

1st PASS

Pressure at maxi conditions - worst case

(TDS max / T°C min - 4,5 years) 60,0 62,5

Boron in permeate 1st pass - worst case

(4,5years - 35°C) 3,23 2,01

2nd PASS

Pressure at maxi conditions

(TDS max / T°C min - 4,5 years) 12,0 10,2

Feed pH max 10,4 10,2

Boron in permeate 2nd pass - worst case

(4,5years - 35°C) 0,37 0,39

Impact of the choice of membrane on electrical consumption

14 -

Impact of Energy Recovery Device

Pelton Turbine: 80% DWEER - ERI: 95%

0

0,5

1

1,5

2

2,5

3

3,5

Power Consumption (kWh/m3) Carbon Footprint (kCO2eq/m3)

kW

h/m

3 -

kg

CO

eq

/m3

DWEER - ERI - 95%

Pelton - 80%

15 -

CONCLUSIONS

Tools available:

Compare water supply scenarios and main process trains

Excel spreadsheet to get into more details in the calculation

Carbon footprint of SWRO plants: 80-90% from energy

consumption

How can we reduce the Carbon footprint

Use the most efficient ERD – optimal pump

Find new membrane system configurations

Use the most energy-efficient membranes => e.g. NanoH2O

Desalination systems powered by renewable energies