2nd International Conference on Smart Energy Systems and 4th Generation District Heating Aalborg, 27-28 September 2016

An integrated gas grid model for upgraded biogas in future renewable energy system

Abid Rabbani SDU Life Cycle Engineering University of Southern Denmark

Feasibility study on utilizing natural gas grid for upgraded biogas

– Are there any bottlenecks due to flow capacities of the gas

grid?

– Can the low pressure distribution grid be used only for raw

biogas and medium pressure grid for upgraded gas only?

– To what extent can these grids balance the supply and

demand?

– How much raw & upgraded biogas contribute to the

electricity, heat and transport demands?

– How much gas would be exported/ imported? And under

what operating conditions?

The Funen Case

Adequate system size for analyses

Developed natural gas network

Could be replaced entirely by biomethane

Availability of feedstock

Modelling approach: An integrated grid model in “SIFRE” tool Balancing supply and demand for electricity, DH, Industrial process heat & transport sector

03 October 2016 3

Biogas Plants

10/3/2016 Abid Rabbani

DH Networks 80 bar pipeline 17 bar pipeline 4 bar pipeline

Bio-Methane Potential for Fyn

Feedstock Biogas production

(mio Nm3)

Manure 2 PJ 86

With Straw 5,7 PJ 214

No. of plants 10

Estimated size of plant

28 mio Nm3/y

Supply

Funen gas demand

Data from NGF Nature Energy

00,10,20,30,40,50,60,70,80,9

1

Jan

uar

y

Feb

ruar

y

Mar

ch

Ap

ril

May

Jun

e

July

Au

gu

st

Se

pte

mb

er

Oct

ob

er

No

vem

be

r

De

cem

be

r

PJ

Large Consumers Small Consumers

IPH Demand Color graduation: light to dark for % of total energy

Funen gas demand 5,62 PJ

Industrial demand 2,84 PJ

% of total 51%

Convertibility to el. 50-75 %

80 bar pipeline 17 bar pipeline 4 bar pipeline

03 October 2016 5

Compressed Biomethane Refilling stations

Transport Demand

Area CNG

stations

Annual Demand

(PJ)

Peak Load (MW)

West Fyn 2 0,38 36

North Fyn 1 0,19 18

Central Fyn 3 0,58 55

East Fyn 2 0,38 36

Southwest Fyn 3 0,58 55

Southeast Fyn 2 0,38 36

Total 13 2,5

LNG Terminal

Total 1 2,5 158

MR Stations CNG stations DH Networks 80 bar pipeline 17 bar pipeline 4 bar pipeline

03 October 2016 6

MR Stations CNG stations DH Networks 80 bar pipeline 17 bar pipeline 4 bar pipeline

West Fyn

North Fyn

East Fyn

Southwest Fyn

Central Fyn

Southeast Fyn

Total 6 units of supply and Demand

Each unit mainly consisting of 17 & 4 bar gas grid

All units connected to 80 bar transmission line

Different supply and demand characteristics

Localized gas grid of Funen

03 October 2016 7

Decentralized CHPs mode with H2 assisted upgrading

West Fyn

18 MWgas

7 MWe

31 MWgas

(@1 bar)

15 MWgas

43 MWe 2x18 MWgas

Supply units

Low pressure grid 4 bar

Demand units

Compressor

High pressure pipeline 80 bar

Medium pressure grid 17 bar

North Fyn

18 MWgas

7 MWe

31 MWgas

(@1 bar)

12 MWgas

43 MWe 18 MWgas

East Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

9 MWgas

2x43 MWe 2x18 MWgas

Southwest Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

40 MWgas

2x43 MWe 3x18 MWgas

Central Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

34 MWgas

2x43 MWe 3x18 MWgas

Southeast Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

27 MWgas

2x43 MWe 2x18 MWgas

150 MWgas

8 03 October 2016

Local biogas CHPs and 1 Central CHP plant

Supply units

Low pressure grid 4 bar

Demand units

Compressor

High pressure pipeline 80 bar

Medium pressure grid 17 bar

West Fyn

18 MWgas

7 MWe

31 MWgas

(@1 bar)

15 MWgas

2x18 MWgas

North Fyn

18 MWgas

7 MWe

31 MWgas

(@1 bar)

12 MWgas

18 MWgas

East Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

9 MWgas

2x18 MWgas

Southwest Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

40 MWgas

3x18 MWgas

Central Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

34 MWgas

500 MWe 3x18 MWgas

Southeast Fyn

2x18 MWgas

2x7 MWe

2x31 MWgas

(@1 bar)

27 MWgas

2x18 MWgas

150 MWgas

9 03 October 2016

Upgraded biogas

60% biogas upgraded

1% 61%

61%

100%

100%

0

100

200

300

400

500

600

700

800

900

IPH DH EL CNG LNG

GW

h

Share of upgraded gas

Biomethane

Biogas

0

5

10

15

20

25

30

35

40

09-02-2050 09-02-205015:00

10-02-205006:00

10-02-205021:00

11-02-205012:00

12-02-205003:00

12-02-205018:00

Pro

du

ctio

n (

MW

)

CF-BG => CF-CHP-BGCF-BG => CF-IPH-BGCF-BG => CF-UP

CHP

IPH Boiler

Upgrading

53% 47%

CH4 upgrading Biogas H2

• Medium pressure grid in stress during Centralized CHP production

Central Fyn East Fyn North Fyn SEast Fyn SWest Fyn West Fyn

-600

-400

-200

0

200

400

600

800

1000

Central FynEast FynNorth FynSEast FynSWest FynWest FynM

Wh

x10

00

CH4 flows within areas

Decentralized Central CHP

0 10 20 30 40

Compression for LP injection

Compression for MP injection

Compression for HP injection

24%

46%

29%

MWh

Electricity consumption of compressors

• High consumption in MP grid ~ upgraded gas volume

• Different compression levels depending on the upgrading technology

03 October 2016 12

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

0,0 5,0 10,0 15,0 20,0 25,0

Tota

l pre

ssu

re lo

ss

Min

imu

m P

ipel

ine

Pre

ssu

re (

bar

)

Gas demand (MW)

Maximum Biogas Capacity in low-pressure grid

Junction Pressure (P1) Bar Pressure at outlet (P2) Bar Total pressure loss (DP) %

33 MW Biomethane

(18 MW)

Pipeline characteristics

Material: PE Plastic

Diameter: 107 mm

Friction factor: 0,01

Length: 1 km

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0,00

10,00

20,00

30,00

40,00

50,00

60,00

0 200 400 600 800 1000 1200 1400

Tota

l pre

ssu

re lo

ss

Min

imu

m P

ress

ure

(b

ar)

Gas demand (MW)

Minimum Biomethane pressures Junction Pressure (P1) Bar Pressure at outlet (P2) Bar Total pressure loss (DP) %

Pipeline characteristics

Material: Steel

Diameter: 312 mm

Friction factor: 0,015

Length: 20 km

(500 MW) CHP

0

500

1000

1500

2000

2500

3000

3500

4000

IPH DH EL CNG LNG

100% 21% 24% 100% 100%

MW

h x

100

0

Energy in different sectors

Production

Demand

52% 30%

3% 15%

Primary Energy Supply

Biogas Electricity Compression Imported Gas

• Biomethane grid fully catering to Transport sector

• Though gas import is 15% in volume, import actually occurs 38% of time

Concluding remarks

The system is capable of balancing the supply & demand majority of the time

60% of biogas is upgraded to biomethane

More strain is observed on MP biomethane grid

Improvements through: – Optimization of the storages to increase flexibility

of upgrading

&

– Operational strategies for compressors to minimize gas imports

2nd International Conference on Smart Energy Systems and

4th Generation District Heating, Aalborg, 27-28 September 2016

Thank you