8/9/2019 IEW2005_Kaya

1/29

8/9/2019 IEW2005_Kaya

2/29

Objective of the studyComparison of two future energy systems

Hydrogen system (HS) vs.All electric system (AES)

Point 1: in terms of efficiency, not the cost

Point 2: primary energycase 1 fossil fuels

case 2 non-fossil fuels

8/9/2019 IEW2005_Kaya

3/29

Fig.1 HS and AES

primary

energy

transportation

networkP.E.H2 FC E demand

electricity

wasteheat

power

generationtransportation

network

E demand

Heat demandHP

solar energy

COP

Hydrogen System(HS) Heat demand

electricity

H2

heat

exchangeable

All Electric System(AES)

8/9/2019 IEW2005_Kaya

4/29

primary

energy

transportationnetwork

bombe

motor

power

generationmotor

ft fr fFC fm

hg ht hB h

electricity

fb

Hydrogen System (HS)

All Electric System (AES)

Fig.2 transportation system

in case ofFCV and pure EV

batterytransportation

network

exchangeable

8/9/2019 IEW2005_Kaya

5/29

Main elements

in efficiency assessment

1. Conversion from primary energy

to secondary energy ( H2, electricity )

2. Fuel cells

3. Heat pumps ( Coefficient of performance)

4. Battery ( charging and discharging )

8/9/2019 IEW2005_Kaya

6/29

Conversion of primary energy

to hydrogen1. Primary energy = fossil fuels: present reformer

2. Primary energy = non fossil fuels

1) nuclear / biomassburning electric catalysis

P.E electric power H2

2) nuclear

high temp.gas reactor thermo-chemical conv.P.E. high temp.heat H2

3) biomass direct conversion to H2

8/9/2019 IEW2005_Kaya

7/29

present future

Production cost

of H2

Conversion

efficiency

ConversionEfficiency

(with CO2 capture)

Table 1: Reformer efficiency

(ct. US academy of science, LHV)

8/9/2019 IEW2005_Kaya

8/29

on fossil fuels H21. P.E. elec.power H2

not competable with AES

reason: elec.power H2 elec. Power

is less efficient than AES

2. Therefore the following two are candidates.

1) P.E. high temp. heat H2

2) direct conversion of biomass to H2

8/9/2019 IEW2005_Kaya

9/29

Fig.3 production of H2 from nuclear power- thermo-chemical conversion ( IS method) -

High temp.

gas reactor

H2+I22HI

2HI+H2SO4

I2+H2O+S2O+H2O

H2SO4

SO2+H2O1/2O2

SO2+H2O

900

heat400

heat

HI H2SO4

I2

H2O

H2

hydrogen

8/9/2019 IEW2005_Kaya

10/29

HIILFLHQF\

Temp. Fig.4 Efficiency of IS method

source national academies press, Hydrogen Economy 2004,p.215

8/9/2019 IEW2005_Kaya

11/29

Within

Several years

Future

(2015-2020)

Stationary FC

HHV

Present situation

47 %

32 %

55 %

Mobile FC

LHV

58 % 65 %

Table 2. Efficiency Targets forFC

- government of Japan -

8/9/2019 IEW2005_Kaya

12/29

Assumptions1. In HS heat demand canbe satisfiedby waste

heat ofFC and afterburning of H2 if necessary.

2. Time variability of demands is neglected. Inother words demands are assumed to be

constant throughout the period.

3. Loss in transportation of H2 is neglected.

No.2 and 3 are optimistic assumptions for HS.

8/9/2019 IEW2005_Kaya

13/29

Primary energy demands for HS and AES

- in case of stationary demand -

Without after-burning

FHS =D

t FC(1)

FAES =

D+H/COP

g(2)

With after-burning

FHS

=t

1D/

FC

+HD/FC

(1-FC

) (3)

8/9/2019 IEW2005_Kaya

14/29

Case A Case B Case D Case E

HS is alwayssuperior

HS is relativelysuperior

HS and AES in total efficiency5 cases

AES is relativelysuperior

AES is always

superior

F

F:primary energy demand

heat / electric power ratio of the demand

: Hydrogen system(HS)

: All Electric system(AES)

HS

AES

Case C

8/9/2019 IEW2005_Kaya

15/29

Technologies stagnant case progress case

H2 reformer r 0.72 0.79

H2 transport t 1 1

Fuel cell FC 0.40 0.55

Heat utilization

Ratio

1 1

Power generation

g

0.50 0.55

Power transmission

t

0.90 0.90

COP of heat pump 3 3

Table.Efficiency values of system elements:fossil fuel case

8/9/2019 IEW2005_Kaya

16/29

Hydrogen tech

stagnant case

Hydrogen tech

progress case

Power tech

stagnant case

Case E

AES is always

superior

Case D

AES is relatively

superior

Power tech

progress case

Case E

AES is always

superior

Case D

AES is relatively

superior

Table. Comparison of HS and AES: stationary demand

- fossil fuel case -

8/9/2019 IEW2005_Kaya

17/29

Primary E

HS

AES

HS is better

in efficiency

Case D

HS

AES

AES is always better

in efficiency

Case E

Fig. Cases D and E

Hydrogen tech progress case Hydrogen tech stagnant case

8/9/2019 IEW2005_Kaya

18/29

Technologies stagnant case progress case

H2 reformer r 0.50 0.60

H2 transport t 1 1

Fuel cell FC 0.40 0.55

Heat utilization

Ratio

1 1

Power generation

g

0.30 0.35

Power transmission

t

0.90 0.90

COP of heat pump 3 3

Table.Efficiency values of system elements:nuclear case

8/9/2019 IEW2005_Kaya

19/29

Hydrogen tech

stagnant case

Hydrogen tech

progress case

Power tech

stagnant case

Case E

AES is always

superior

Case B

HS is relatively

superior

Power tech

progress case

Case E

AES is always

superior

Case B

HS is relatively

superior

Table. Comparison of HS and AES: stationary demand

- nuclear case -

8/9/2019 IEW2005_Kaya

20/29

Primary E

HS is better

in efficiency

Case B

HS

AES

AES is always better

in efficiency

Case E

Fig. Cases B and E

AES

HS

Hydrogen tech stagnant caseHydrogen tech progress case

8/9/2019 IEW2005_Kaya

21/29

Fuel charging of EV and FCV1. Charging the battery takes hours, while

charging H2 takes only several minutes.

= Fundamental disadvantage of EV

2. However,with revolutionary change in charging

tech ( including those of capacitors ), EV will

obtain muchbetterposition in future.

At this moment FCV is much advantageous.

8/9/2019 IEW2005_Kaya

22/29

primary

energy

transportationnetwork

bombe

motor

power

generationmotor

ft fr fFC fm

hg ht hB

electricity

fb

Hydrogen System (HS)

All Electric System (AES)

Fig.2 transportation system

in case ofFCV and pure EV

batterytransportation

network

exchangeable

hm

8/9/2019 IEW2005_Kaya

23/29

HS vs. AES: automobile demand

- (1) efficiency data -1. reformers and fuel cells

power generation and transmission

the same as in case of stationary demand

2. automobilebattery

present: 0.80 future: 0.85

3. motorsame for EV and FCV

for convenience efficiency = 1

8/9/2019 IEW2005_Kaya

24/29

Hydrogen tech

stagnant case

Hydrogen tech

progress case

Power tech

stagnant case

fFCV = 0.29

fEV = 0.36

EV is superior

fFCV = 0.43

fEV = 0.36

FCV is superior

Power tech

progress case

fFCV = 0.29

fEV = 0.42

EV is superior

fFCV = 0.43

fEV = 0.42

EV and FCV

compatible

Table. Comparison of HS and AES: automobile demand

- fossil fuel case -

8/9/2019 IEW2005_Kaya

25/29

Hydrogen tech

stagnant case

Hydrogen tech

progress case

Power tech

stagnant case

fFCV = 0.20

fEV = 0.22

EV is relatively

superior

fFCV = 0.33

fEV = 0.22

FCV is superior

Power tech

progress case

fFCV = 0.20

fEV = 0.27

EV is superior

fFCV = 0.33

fEV = 0.27

FCV is superior

Table. Comparison of HS and AES: automobile demand

- nuclear case -

8/9/2019 IEW2005_Kaya

26/29

Summary of findings

- stationary demand (1) -1. In case that primary energy is of fossil fuels hydrogen

system (HS) is superior

only with advancement of related technologies, ifrequired afterburning is less than a certain limit.

However several assumptions about efficiencies of relatedhydrogen system elements being rather optimistic we

should recognize that HS can survive only withdesperate efforts for substantial improvement ofsystem efficiency.

8/9/2019 IEW2005_Kaya

27/29

Summary of findings

- stationary demand (2) -2. In case that primary energy is nuclear,

HS is superior again only with remarkable

improvement of efficiencies of related systemelements.

The position of HS is relatively better when

compared with the case of fossil fuels being

primary energy sources.

8/9/2019 IEW2005_Kaya

28/29

Summary of findings

- in case of automobile demand -FCV is mostly superior in system efficiency to

pure EV if related system technologies

remarkably advance.

Taking into account that FCV has much less fuel

charge time than EV, we may say that use of

hydrogen will be more advantageous and

realistic in transport sector than in stationary

demand sector.

8/9/2019 IEW2005_Kaya

29/29

Fig. Remaining Issue: How to transfer from

Present decentralized system to Future centralized system

Primary

Energy

Distribution

network

City gas

Petro productsCokes gas

Gas pipeline

Petro station network

Large scale

Hydrogen network

PE: fossil fuels PE: nuclear / biomass

Small scale

biomass

Large scale

biomass

Nuclear energy

Decentralized

system

Centralized

system

present future