Small-Scale Wind for Hydrogen Production

for Rural Power Supplies:

HyLink System at Totara Valley

MUCER Energy Postgraduate ConferenceWellington 3-5 June 2008

presented by Peter Sudol (Massey University)

Totara Valley• Demonstration site for Massey University and Industrial Research Limited on distributed generation

Aims: - design a renewable hybrid micro-power system at the end of 11 kV distribution line - provide network support

HyLink System

Demonstration on hydrogen as a means of balancing and transporting the fluctuating wind power

System implementationby IRLSystem analysis by Massey University

Massey University’s 2.2 kWwind turbine incl. control system will be used in conjunction with a larger electrolyser currently being developed at IRL.

Characteristic HyLink System Power Line Initial cost incl. labour

NZ$55,000 - current configuration - incl. pipeline mole ploughing

NZ$60,000 -NZ$100,000- underground wiring requires a trench- overhead wiring complicated due to difficult terrain

Cost ofconversion devices

NZ$17,000- electrolysis setup

NZ$16,000- fuel cell system

2 x NZ$2,500- step up and step down transformers

Energy loss atconversiondevices

ηe/conv = 60%- converter/electrolyser subsystem

ηpemfc/inv = 35% (electr.)- fuel cell/inverter subsystem

2 x 200 W power loss- power consumption at both transformers

Lifetime 50 years- MDPE gas pipeline

4,000 operational hrs- ReliOn PEM fuel cell

10,000 operational hrs- PEM electrolyser

60 years

Energy Storage Hydrogen pipeline/tank- easy to scale up

Batteries- expensive for large-scale storage

Hylink in the IRL Laboratory

Electrolysis setup

Hydrogen was stored in 150m MDPE pipeline located in a container filled

with sand, outside of the lab.

Alkaline Fuel Cell DCI 1200 Setup

Source: IRL

The electricity produced was used to charge batteries or was inverted to the grid.

Electrolyser Stack Connection

hydrogenoutlet

water inlet

positive electricalpotential

water and oxygen outlet

negative electricalpotential

hydrogen pressure meter

Distilled water is pumped just through the anode compartment (oxygen side) of the electrochemical cells

which is not pressurised.

Lynntech Electrolyser Stack

catalysedmembrane

metal flow field

The right stainless steel endplate (+ electronics) was used for a previous application and was replaced by a titanium

endplate.

Source:LynntechIndustries

active area of 33 cm2

Electrolyser Stack - VI Curves

1.2

1.4

1.6

1.8

2.0

2.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Current Density (A*cm-2)

Ave

rage

Cel

l Vol

tage

(V)

8.2ºC17.4ºC22.5ºC30.1ºC36.4ºC60ºC Lynntech

At higher stack temperature there is a higher electr. current flow (higher hydrogen production) at the same voltage due to improved reaction kinetics.

System Efficiency Estimation• Electrolyser: η = 65.3% electricity (+heat)/hydrogen conversion efficiency (at a current flow of 23,5 A)

- Not considered: hydrogen pressure energy output, power consumption of the 12W water pump, heat transfer with circulating water

The above efficiencies were calculated using the lower heating value (LHV) of hydrogen.

Hydrogen production/consumption was estimated by measuring the pressure increase/drop in the pipe.

• Alk. FC DCI 1200: η = 41.1% hydrogen/electricity conversion efficiency (at 650 W electrical power output)

- Not considered: thermal energy output (approximately 20% combined heat and power efficiency over 60%)

Proven Wind Turbine• Rated power output: 2.2 kW• Zebedee furl (+ cone) system allows for dynamic balance between the rpm and the pitch of the airfoil. During stormy winds turbine doesn’t stop, instead, keeps generat. at nearly rated power.

Drawing: Proven Energy Limited

Air-X400 W

Wind Power Control and Electrolysis Container

Distilled water tankfor the electrolysis

3 x 48 W solar panels for additional battery charging

Hydrogen pipeline- the top riser

Source: IRL

Electrolyser in the Container

Deionisation columnRecombiner

Flash arrestor

Dehydration unit

Water pump

Electrolyser stack

Circulating water reservoir

Source: IRL

Hylink Transition to Totara Valley

Pipeline mole ploughing (60 cm deep)

Electrofusion joint betweenthe pipeline sections

MDPE Internal diameter: 16 mm Outer diameter: 21 mm Wall thickness: 2.5 mm Length: 2 km Volume: 402 L

Welder for electrofusion Source: IRL

Fuel Cell Connection in the Woolshed

IRL controller

IRL grid-connected inverter

PEM fuel cell ReliOnIndependence 1000 (J48C)

Pressure sensor

Source: IRL

The batteries power the control and data logging equipment as well as provide a necessary buffer for the fuel cell and inverter.

Operating PEMFC supplies the inverter and the controller as well as charges the batteries.

48 V gel battery bank

Hydrogen Diffusion Rate Estimation

zptAP

Q mean

The pipeline was pressurised with 4.1 barg hydrogen and then the pressure drop was recorded.

Result:Hydrogen loss: 42.5 kPa/week 7.5mol/week 15 g/week 0.5 kWh/week at LHV 3 W

Currently, the fuel cell operates at pipeline pressure between 1 barg and 2 barg, so at average 2.5 bar abs.

Using: 1.5 W mean power loss due

to H2 diffusion through pipe walls during fuel cell operation

Hydrogen Permeability through PE - Comparison

Massey University (at 20°C) :Industry (at 23°C):

PasmmmolP

2

151045.1

Totara Valley (at 10°C):

PasmmmolP

2

16105.5

RTEP

ePP

0

General rule of thumb for Arrhenius equation: for every 10°C increase the reaction rate doubles.

0ln1ln PTR

EP P

Or EP and P0 can be estimated by measuring P at different T and solving:

Frictional Pressure Drop Estimation at Fuel Cell’s max. Output

• According to the manufacturer, the fuel cell consumes at 1 kW 15 stdL H2 /min mean H2 velocity is 1.24 m/s

• Due to the gas flow is laminar, and hence, the friction factor f independent of roughness .

• Then the frictional pressure drop can be calculated using the Darcy-Weisbach equation as follows:

• Considering that the fuel cell requires low H2 pressure for operation, the calculated pressure drop can be neglected.

1057Re idV

061.0Re64

lamf

barkPafVdLp lami

026.06.22

2

HOMER Simulation of the current HyLink System Configuration

Selected Results

Data Inputs• Batteries’ task is not to store energy to meet community’s

load requirements. They cover the system internal electricity needs, and PV panels can be thought as the power source for that. For this reason batteries as well as PV panels were excluded from the simulation.

• Wind resource data was taken from the NASA website, however the four wind parameters (Weibull shape factor etc.) derive from the previous study at Massey University.

• The average of one of the eight monitored sites at Totara Valley was used as the primary load data.

• Furthermore, factual and not projected data was used e.g. for the ReliOn fuel cell the lifetime of 4,000 operational hours and not 40,000 operational hours.

HyLink System Schematics used in HOMER

grid-connected stand-alone

Providing Back-up Power for Peak Loads (May)

May9 10 11 12 13 14 15

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Pow

er (k

W)

AC Primary LoadPEMFC ReliOn Pow erGrid PurchasesCapacity Shortage

- Grid purchase capacity constrained at 2.3 kW- max. hourly peak load throughout a year: 3.3 kW- 1 kW fuel cell

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Pow

er (k

W)

AC Primary LoadPEMFC ReliOn Pow erGrid PurchasesCapacity Shortage

Providing Back-up Power for Peak Loads (July)

- Grid purchase capacity constrained at 2.3 kW- max. hourly peak load throughout a year: 3.3 kW- 1 kW fuel cell

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5Po

wer

(kW

)Air-XPEMFC ReliOn Pow erCapacity Shortage

Providing Back-up Power for Peak Loads

Due to small system configuration, esp. wind turbine/electrolyser,very dependent on the prevailing wind conditions.

Daily Pipeline Filling Process Fluctuations due to changing Wind

0.0

0.1

0.2

0.3

0.4

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5

Pow

er (k

W)

Stor

ed H

ydro

gen

(kg)

PEMFC ReliOn Pow erCapacity ShortageStored Hydrogen

Scenario for HyLink with added Massey University’s

2.2 kW Wind Turbine and IRL’s 1 kW Electrolyser

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Pow

er (k

W)

AC Primary LoadPEMFC ReliOn Pow erGrid PurchasesCapacity Shortage

The previous capacity shortageon 24th July is compensated dueto improved systemresponse.

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5

2.0

2.5

Pow

er (k

W)

Proven/Air-XPEMFC ReliOn Pow erCapacity Shortage

Scenario for HyLink with added Massey University’s

2.2 kW Wind Turbine and IRL’s 1 kW Electrolyser

0.0

0.1

0.2

0.3

0.4

July23 24 25 26 27 28 29

0.0

0.5

1.0

1.5

Pow

er (k

W)

Stor

ed H

ydro

gen

(kg)

PEMFC ReliOn Pow erCapacity ShortageStored Hydrogen

Scenario for HyLink with added Massey University’s

2.2 kW Wind Turbine and IRL’s 1 kW Electrolyser

Outcomes• Low durability and high replacement cost of electrochemical

conversion devices represent the main barrier in introducing the HyLink system

• Small-sized system very dependent on the prevailing wind conditions – low energy buffer capability

• The 36%-efficient fuel cell/inverter subsystem consumes the full pipe content (3.3kWh at 3bar pressure difference) in ca. 1 hr at 1kW ac output.

• The wind turbine/electrolyser subsystem needs ~9hrs at its rated power (80 stdL/hr, 360 W) to provide this hydrogen content – at optimal wind conditions

• Hence, the fuel cell/inverter efficiency (36% electr.) constrains the overall system performance and the small wind turbine/electrolyser size slows the system’s response.

General Outcome• Successful demonstration of a new energy

concept – in operation since May 2008• The HyLink system reveals barriers and

opportunities of hydrogen based energy systems.

• The HyLink system proves, that an energy carrier can be produced from a renewable resource high efficiently.

• The HyLink system proves that this energy carrier can be transported via cheap pipelines.

• The HyLink system proves that this energy carrier can be converted to electricity high efficiently (not Carnot Cycle constrained), carbon neutral and noiseless in fuel cells.

Acknowledgements

• Prof. Ralph Sims (Massey University)• Attilio Pigneri (Massey University)• Steve Broome (IRL) • Edward Pilbrow and Eoin McPherson (IRL)• Jim Hargreaves (Massey University), Phil

Murray, Mark Carter• Totara Valley residents• and many others at Massey