solar hydrogen the value of saving sunshine for a rainy day phil grÜnewald

Solar Hydrogen

The Value of Saving Sunshine for a Rainy Day

PHIL GRÜNEWALD

The mother of all sustainable energy

SUN

WIDELY DISTRIBUTEDFREE AT POINT OF USEPLENTIFUL 125W m-2 500 kW per person (UK)

10% efficiency and 2% of land mass

1 kW per person

bar tidal, geothermal and nuclear

Heat Wind Hydro Biomass Fossil

EMBODIED TIME / CONVERSIONSEMBODIED TIME / CONVERSIONS

The mother of all sustainable energy

(bar tidal, geothermal and nuclear)

Heat Wind Hydro Biomass Fossil

The mother of all sustainable energy

Photons

Direct conversion of photon energyAlready reality with PV +

-

-

A sustainable energy vector

HYDROGEN

CARBON : HYDROGENDEVELOPMENT

•ABUNDANTLY AVAILABLE (WATER)

•STORABLE •GAS•LIQUID•HYDRIDE

•EFFICIENT CONVERSION (FUEL CELL)

Conversion technologies

1. Thermal• 2500 K, 0.05 bar for 25% H2

2. Thermo-Chemical-Cycles• Oxidise/Reduce Metal

3. Photo-Biological• Grow algae and extract H2

+-

Electrolyser

PV

4. Photo-Electro-Chemical• Combines Photovoltaic and Electrolyser

Conversion technologies

+-

4. Photo-Electro-Chemical• Combines Photovoltaic and Electrolyser

Conversion technologies

PV + Electrolyser

4. Photo-Electro-Chemical• Combines Photovoltaic and Electrolyser

PEC device

PEC device

H2

e-

Q

hν

e-

Q

Heat as by-

product

Heat as by-

product

1.229V to split water

1.229V to split water

External assistance

External assistance

ExternalLoad ?

ExternalLoad ?

Heat aids Process (?)

Heat aids Process (?)

Poly-generation

Conversion technologies

PEC device

• Suitable for small scale applications

Centralised Decentralised

INFRASTRUCTURELARGE INVESTMENTSUPPLY DEMAND –

CATCH22

SMALL SCALE BUILD UPSCALABLEDEMONSTRATION PROJECTS

- +++

--

Infrastructure

But does it make economic sense ?

SUN HYDROGEN ECONOMICS

1. How to model a PEC device?2. Which parameters matter?3. What configuration is best?4. How does PEC compare to alternatives?

OBJECTIVES

The trouble with the sun• Irradiation not on demand• Poor temporal correlation with demand• PV / solar thermal don’t displace generation capacity

???Can H2 storage

help?

Irrad

iatio

n

Dem

and

24h 24h

The trouble with (average) humans

24h

kWh

5min

-1

Data: Courtesy of Adam Hawkes24h

30 days of one month 1 day (high and low res.)

Temporal resolutionThe drawback of limited ramping and finite power rating is only revealed with high temporal resolution data!

The drawback of limited ramping and finite power rating is only revealed with high temporal resolution data!

18%

8%

ModelModel

ThermalDemandProfile

PowerDemandProfile

IrradiationProfile

η el.η th.η H2

…

η el.η th.η H2

…

Input Data Parameters

Gen

erati

on H2 – el

£ kW-1

…

H2 – el

£ kW-1

…

Conv

ersi

on η charge

£ Wh-1

…

η charge

£ Wh-1

…Stor

age

Commercial

El. RateFITGas priceIRR

…

El. RateFITGas priceIRR

…

NPV

Mod

el s

truc

ture

ThermalThermal H2H2 Electr.Electr.

Available Demand

DemandStorageStorage

Fuel CellFuel Cell

Unmet

Available Demand

Demand

Excess Unmet

Output

StorageStorage

ElectrolyserElectrolyser

Gas boilerGas boiler Feed inFeed in GridGrid

20%

15%

10%0, 5%

Net

Pre

sent

Val

ue [£

]

H2 conversion efficiency

Thermal conversion efficiency

Conversion Efficiency

PRELIMINARY RESULTS - EXAMPLE

How does a PEC device compare to- PV- PV + electroyser- Solar Thermal

THE BIG QUESTION…

Installation cost [£ kW-1]

NPV

[£ k

W-1

]

Optimum Storage Capacity

H2 Storage [kWh]

Thermal Storage Capacity [kWh]

0 kWh

10 kWh

20-40 kWh

Net

Pre

sent

Val

ue [£

]

PRELIMINARY RESULTS - EXAMPLES

To get meaningful model outputs we need good input data- More detailed analysis of storage parameters- Understand PEC efficiency trade offs

FUTURE WORK

1. How to model the performance of a PEC device?2. Which parameters matter?3. What configuration is best?4. How does PEC compare to alternatives?

OBJECTIVES

CONCLUSION

Model produces meaningful results• NPV with respect to base case• Comparison with solar technologies• Automated processing with 2 control variables• Good data available for demand and generation

But• Many parameters are not well understood