Solar Hydrogen Project Group Update 14 th July 2009.

Solar Hydrogen Project

Group Update

14th July 2009

Progress

To Do- efficiency trade off between PEC inputs / outputs (with SD - maybe Zachari?)- costs of prototype (with CC) and costing down exercise- review the model methodology (with Adam Hawkes)- economics of storage (mostly from literature at the moment)

Storage system

PECProduction rate

Compressor Cost (ΔP,KW)

Tank Cost (P,Capacity)

Installation Cost (V, A, P?)

Operation Cost (P, turnover)

Storage system


Thermal Storage Capacity [kWh]

0 kWh

10 kWh

20-40 kWh

Net

Pre

sent

Val

ue [£

]Initial model prediction:Limited benefit above 40 kWhe

Tank diameter 0.83 m

“Worst case”- Half annual demand <1500 kWhe

- Hydrogen equivalent: 11.1 m3 @ 20 MPa- Tank diameter: 2.7 m

Storage system

PECProduction rate


0

5

10

15

20

25

30

35

40

45

0 20 40 60

Pressure [MPa]

Cost

[£/k

Wh

]

Higher pressure increased embrittlement

Storage system

Operation Cost (P, turnover)Operation Cost (P, turnover)

Compression energy

0

10

20

30

40

50

60

70

80

0 20 40 60 80 100

Pressure [MPa]

Den

sit

y [

kg

m-3

]

ideal gas

Hydrogen

Storage system

Compressor Cost (ΔP,KW)Compressor Cost (ΔP,KW)

Literature figures:<10 kW >6600 $ kW−1 >250kW <1000 $ kW−1

Usually based on large scale systems Power dominant over pressure

For small systems, maximum pressure assumed to be critical, but no reliable figures in literature.Any experts????

Model assumption: 10 £ MPa-1



Land cost factor 300 £ m-2

Installation cost 650 £ m-3

Optimum Storage Pressure

-

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 10 20 30

Pressure [MPa]

Cost

[k£

]

100 kWh50 kWh10 kWhMinSeries5Series6

H2 Specific Energy 33.3 kWh/kgR 8.314472 J K^-1 mol-1H2 atomic weight 1.00794 g mol^-1T 300 K

Tank capacity 10 kWh /dayAverage daily turnover 100%Total Energy stored 36500 kWh

Economic life 10 yearsIRR 10%Discount factor 6.14Energy price 0.1 £ / kWh

Generation Pressure 0.1 MpaStorage Pressure 20 Mpa

CapEx parametersLand cost factor 300 £ m^-2Installation cost 650 £ m^-3Tank cost 96.31 £Compressor 10 £ /Mpa

OpExCompression Energy 7%Cost to compress 160.42 £

Tank capacity 0.30 kg H2Tank volume 0.04 m^3Tank diameter 0.41 mTank area (+ 25% contingency) 0.17 m^2

Cost of land 50.48 £Cost of installation 24.15 £

Total cost 235.06 £

IrO2 Deposition

• Tried electrodepositing Ir on WO3

• Heat treatment increases current remarkably

• Cannot conclude whether heat treatment affect WO3 or Ir

Solar Hydrogen Project: SD

• Fe2O3 work:

– Steph/Monica: material produced by ultra-sonic spray pyrolysis

– Comparative study of different types of Fe2O3:

• EPFL CVD (new samples received)• EPFL USP (from Monica)• Hydrogen Solar spray pyrolysis• other?

Solar Hydrogen Project: SD

• The following slides were added post-meeting. Data for:

– EPFL CVD (old sample): photocurrent-potential plots, showing large increase with chopping frequency. (Due to ?)

– HS SP (poor performing): photocurrent-potential plot shows increase in photocurrent due to greater contribution from the transient photocurrent at short times. (NB: real current density has not been calculated.)

Fe2O3: HS (poor!)

-5.0E-05

0.0E+00

5.0E-05

1.0E-04

1.5E-04

2.0E-04

2.5E-04

-0.5 -0.25 0 0.25 0.5 0.75 1

Potential vs qre / Volt

cd /

Acm

-2

Dark 450 nm

Fe2O3: HS Photocurrent-potential

-5.0E-07

0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

3.0E-06

-0.5 -0.25 0 0.25 0.5 0.75 1


Ph

oto

curr

ent

den

sit

y /

Acm

-2

87 Hz 279 Hz

Fe2O3: EPFL CVD (better)

-2.5E-05

0.0E+00

2.5E-05

5.0E-05

7.5E-05

-0.5 -0.25 0 0.25 0.5 0.75 1


Cd

/ A

cm

-2

Fe2O3: EPFL Photocurrent-potential

0

0.025

0.05

0.075

0.1

0.125

0.15

-0.5 -0.25 0 0.25 0.5 0.75 1


Ph

oto

curr

ent

den

sity

/ A

rb U

nit

s

87 Hz 279 Hz

FZ update

• Membrane Permeation and selectivity study

• Update on sartorius reactor fittings/ tubing

Modeling of Photocatalytic Reactors

Zachary Ulissi

Steve Dennison

Geoff Kelsall

Top plateSpacer (fluid)Spacer (fluid)Bottom Plate

Membrane

Electrolyte Inflow

Electrolyte Flow(with H2 or O2)

Light Source(monochromatic)

Mesh Cathode

Electrolyte Inflow

Electrolyte Flow(with H2 or O2)

Photo-Anode

MembraneFluid ChamberFluid Chamber

Mesh Cathode(Conductor)

Membrane

Photo-Anode

Absorption, α e-h+

2e

2H+

H2

+

Diffusion

Kinetics

Fluid Flow+Diffusion

Diffusion

Fluid Flow+Diffusion

H2O+ 2H+O2

Kinetics

Absorption,Diffusion (2),Band Bending

Electrolyte Flow(if laminar)(1)

(1)

(2)

(2)

(3)

(3)

(4?)

log(

Velo

city

/ C

ente

rline

Vel

ocity

)

log(Velocity / Centerline Velocity)Flow=3.5ml/min

log(

Velo

city

/ C

ente

rline

Vel

ocity

)

log(Velocity / Centerline Velocity)Flow=3.5ml/min → 700ml/minLaminar → Turbulent at ≈200ml/min

log(Velocity / Centerline Velocity)Flow=300ml/min

Next Steps

• Determine whether inlet corners should be removed

• Couple diffusion in flow to constant flux on surfaces

• Identify approximate rates of diffusion of e/h and degree of band bending in photo-anode

• Approximate kinetics of surface reactions (most difficult portion)

Solar Hydrogen Project Group Update 14 th July 2009.

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