SINTEF Energy Research Jens Hetland a, Ping Yowargana b, Sylvain Leduc b, Florian Kraxner b a SINTEF...

SINTEF Energy Research

Jens Hetlanda, Ping Yowarganab, Sylvain Leducb, Florian Kraxnerb

a SINTEF Energy Research, Kolbjorn Hejesvei 1A, N-7465 Trondheim, Norway, b Ecosystems Services and Management (ESM), International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria

Carbon-negative biopower via direct conversion and co-firing: Systemic impacts of capture and storage

of CO2 applied to Indonesia

TCCS-8 16-18 June 2015, Trondheim, Norway

Corresponding author's e-mail address: [email protected]

mailto:[email protected]


Relevance of carbon-negative emissions

About half of the scenarios of the IPCC, constraining the atmospheric concentration of greenhouse gases to 430-480 ppm CO2 equivalents, feature bioenergy with CCS (BECCS) (1).

As these scenarios jointly account for more than 5% of the global primary energy supply (2), it is necessary to further assess the potential for CO2 mitigation from a systemic perspective.

2

(1) Cf. the 5th assessment report of the IPCC (WG 3)(2) Fuss, S., Canadell, J. G., Peters, G. P., Tavoni, M., Andrew, R. M., Ciais, P., Yamagata, Y. (2014).

Betting on negative emissions. Nature Clim. Change, 4(10), 850–853.


Components to consider

Localisation and size of the plant vis-à-vis the biomass feedstock and grid connection Life-cycle emissions

3

Case-specific studies conducted from the perspective of biomass availability and technology selection are required, pursuant to local and regional demands for electricity as well as affordable pricing.

Primary energy/feedstock

Primary/secondary conversion Market / end usage

• Biomass sources• Other feedstock

• Plant size• Power cycle technology; dedicated BECCS or co-firing with coal• CO2 intensity and life-cycle emission• Carbon pricing

• Grid connection• Market demand• Electricity tariffs• Competitive price level

SINTEF Energy Research 4

1772 - 1950sCO2 emissions: 1772: 35 kg/kWh1950: 1.1 kg/kWh

Brief history of solid-fuelled power

ESP

1970sCO2 emissions: 955 g/kWh

9

ESPDESOx

DENOx

End-product recovery and use

TodayCO2 emissions: 770 g/kWh

9

ESPDESOx

DENOx

CCS

FutureCO2 emissions: 42 g/kWh (90% CO2 capture)

U: CO2 usage

S: CO2 storage


Biopower 800 MWe reaching 40% efficiency (LHV) seems feasible, provided abundant biomass

in the vicinity of the plant Would require 700 tonne biomass per hour (1) 24 lorries per hour, 30 tonne each

200 000 deliveries per year From a logistic point of view, deployment of such plants is a challenge Additional firing options will be needed to offset investments ( co-firing)

5

(1) Air dried biomass with [C,H,O,N,S,moisture,ash]=[0.3028,0.0352,0.2563,0.0704,0.0000,0.4014,0.00352] with LHV 10.55 MJ/kg

BECCSCoal

Oil

Natural gas

Gasification/

reforming

Water shift

reaction

CO2 capture

(H2

separation)

Power cycle

Hydrogen-

enriched fuel

Power cycle

Air separtion

unit(de-nitrogenation)

Water

removal

(condenser)

Power cycle CO2 capture

(scrubbing)

CO2

conditioning,

compression

and transport

H2 + CO H2 + CO2

H2

O2

CnHm + O2 <=> nCO2 + m/2 H2O

Exhaust, 0.3-0.5% CO2

Exhaust, 0.1-0.5% CO2

SINTEF Energy Research/

Jens Hetland 2006

CO2 storage

(geological

formations,

EOR/EGT)

2

3

1

Water

Biomass


Trajectories depending on plant size (net power output)

Co-firing of biomass in modern coal power plants offers higher efficiency than smaller biopower plants.

Replacing a portion of coal with biomass seems to be the most economic near-term solution for employing biopower at large.

6

0 40 80 120

16

20

24

28

32

BECCSBECCS (lower efficiency level)

BECCS (medium efficiency level)

BECCS (higher efficiency level)

Fuel:Palm Kernel Shell (Indonesia)Bituminous coal (Pittsburgh No. 8)

0 40 80 120

Net power output [MWe]

16

20

24

28

32

Ne

t e

ffic

ien

cy

[%

, L

HV

]

Co-fired biomassCo-fired biomass

20 40 60 80 100 120

Biopower plant size (without CCS) [MWe]

16

20

24

28

32

Bio

po

wer

ne

t ef

fici

en

cy (

wit

ho

ut

CC

S)

[%]

Biopower

Higher efficiency level

Medium efficiency level

Lower efficiency level

Fuel:Palm Kernel Shell (Indonesia)

Biopower plant efficiency without CCS Resulting efficiency of co-fired biomass and biopower with CCS (BECCS)


Combustion characteristics and typical feedstock compositions of Indonesian biomass sources

The biomass is converted either in existing large-scale coal power plants available for co-firing, or in smaller decentralised BECCS.

Studies carried out by the GIZ(1) conclude that residues of palm oil, rice paddy and sugar cane are the most dominant resources of bioenergy feedstock in Indonesia, due to the large volume of crops production.

7

Parameter Unit Palm

Mesocarp Fiber

Palm Kernel Shell

Palm Empty Fruit

Brunch

Rice Straw

Rice Husk

Bagasse E.Camal-dulensis

E. Globulus

Higher Heating Value

MJ/kg 19* 16.3* 16.8* 15.84 15.09 18.1 19.42 19.23

Lower Heating Value

MJ/kg - - - - - - 18.23 18.03

Volatile Matter

wt. % 73.03 73.77 77.1 63.52 65.47 79.9 81.42 81.6

Fix Carbon

wt. % 16.13 15.15 16.8 16.22 15.86 18 17.82 17.3

Ash wt. % 10.83 11.08 6.1 20.26 18.67 2.2 0.76 1.1

Carbon wt. % 51.52* 48.68* 47.65* 38.83 38.24 44.6 49 48.18

Hydrogren wt. % 5.45* 4.77* 5.2* 4.75 5.2 5.8 5.87 5.92

Nitrogen wt. % 1.89* 1.17* 1.82* 0.52 0.87 0.6 0.3 0.39

Oxigen wt. % 40.91* 45.27* 44.97* 35.47 36.26 44.5 43.97 44.18

Sulphur wt. % 0.23* 0.202* 0.36* 0.05 0.18 0.1 0.01 0.01

* Dry ash free basis

(1) Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH


Fuel characteristics of Indonesian palm kernel shell and a references coal (Pittsburgh No. 8)

Composition of Indonesian palm kernel shell used in this study, and reference coal (Pittsburgh No. 8).

8

Palm Kernel Shell [%, bw] Pittsburgh No.8 [%, bw] Carbon 48.680 69.36 Hydrogen 4.770 5.18 Oxygen 45.270 11.41 Nitrogen 1.170 1.22 Sulphur 0.202 2.89 Water 0 6 Ash 11.080 9.94 CO2 0 0 Lower heating varlue (LHV) [MJ/kg] 16.300 25.174


Fuel characteristics

Hydrogen (H) and oxygen contents (O) as well as carbon (C) of the Indonesian palm kernel shell (left), and reference coal (right, Pittsburg No. 8), presented in accordance with van Krevelen.c

9

0

0,5

1

1,5

2

2,5

3

3,5

4

0 0,2 0,4 0,6 0,8 1

H/C

O/C

0

0,5

1

1,5

2

2,5

3

3,5

4

0 0,2 0,4 0,6 0,8 1

H/C

O/C


Power plant assumptions Assessments are based on independent biomass-fired power plants and co-firing of biomass

in conventional coal power plants, comparable to the current Indonesian situation. The efficiency of biopower plants forming the basis for BECCS has been assumed to follow

three efficiency trajectories (low, medium and high), essentially corresponding to three classes of biopower capacity: 10, 50 and 100 MWe.

For the co-firing alternative, a conventional 660 MWe coal power plant with an initial efficiency of 38% (LHV) has been chosen (i.e. sub-critical steam conditions).

Generic bituminous coal (Pittsburgh No.8) is used for co-firing with Indonesian biomass (palm kernel shell). Up to 16% biomass can be co-fired without essential modifications of the plant. The condenser pressure is assumed to be similar for the BECCS and the coal-power plant (0.003 bara, 36°C).

The flue gas is cleaned via an absorption process using an amine-based solvent requiring 3.24 GJ/tonne CO2 to be regenerated. For both alternatives, the heat is provided by steam extracted from the medium-pressure turbine at 5 bara and 160°C. The captured CO2 is compressed to meet a pipeline pressure of 146 bara for delivery in dense phase at the wellhead.

The estimation of the coal-power plant is made on the assumption that the plant is fully equipped with environmental control systems (ECS) removing 99% of the sulphur contained in the flue gas, whereas the BECCS alternative is without ECS.

The calculations are based on ISO conditions.

10


Impact of biomass depending on technology and feed rate

The combustion is provided with 5% excess oxygen. Estimations are based on complete reactions, and typically 85% full operational availability.

The initial plant efficiency (without CCS) and the rate of CO2 capture has been used as parameters characterising the fully integrated CCS-based power cycle.

11

0 10 20 30

Biomass feed [kg/s]

120

160

200

240

CO

2 e

mit

ted

[g

/kW

h]

Resulting from co-firing

BECCS Higher efficiency level

BECCS Medium efficiency level

BECCS Lower efficiency level


0 5 10 15 20 25

Biomass demand [kg/s]

0

40

80

120

Ne

t p

ow

er

ou

tpu

t [M

We]

BECCS (lower efficiency level)

BECCS (medium efficiency level)

BECCSBECCS (higher efficiency level)

Biopower without CCS


Cofired biomass with CCS38% initial efficiency

40% initial efficiency

42% initial efficiency

Net power output CO2 emitted

Impact on power generation plant efficiency The power generation efficiency will drop by roughly 10%-points (essentially the same

whether CCS is applied to the coal power plant or to the smaller dedicated BECCS plant).


Results (assessing the impact of biomass per se)

Concentration of species resulting from the two alternatives using the same feed rate for biomass.

It has been assumed that the biomass per se is completely dry, which is usually not correct. The true humidity of the fuel will affect the dew point.

GWh denotes net power output.

g/g denotes mass fraction of species in the flue gas.

12

Co-firing BECCS Net el. power without CCS [MWe] 67.681 49.87

Net el. power with CCS [MWe] 49.95

32.14

Plant efficiency / no CCS [%] 38.00 28.00 Plant efficiency with CCS [%] 28.04 18.04 Biomass demand (kg/s) 10.927 10.927 Flue gas composition formed (referred to base plant without CCS)

g/GWh g/g g/GWh g/g

CO2 905 0.1954 1 266 0,2238 H2O 197.3 0.0426 311,5 0,05510 SO2 18.6 0.0040 2,9 0,00051 O2 231.3 0.0499 275,6 0,04875 N2 3222.4 0.6954 3730,4 0,65977 Ar 58.8 0.0127 68,1 0,01204 Flue gas composition at stack (with CCS, 90% capture rate)

g/GWh g/g g/GWh g/g

CO2 126.4 0.0238 196,4 0,0280 H2O 311.0 0.0519 483,4 0,0690 SO2 0.029 4.898E-05 4,4 0,0006 O2 275.2 0.0608 427,7 0,0611 N2 3724.5 0.8478 5788,7 0,8262 Ar 67.9 0.0155 105,6 0,0151 Elementary sulphur removal (g S/kWh) 9.2 0 Acid dew point (°C, Okke) 140.1 155.1 Acid dew point (°C, Verhoff) 146.8 162.8 Water dew point [°C) 39.4 44.4


Negative carbon emission resulting from the two plants in g/kWh net power output

The table compares the impact on emissions termed neutral and negative. Since the conversion of biomass by definition is carbon neutral, the amount of CO2 released to the atmosphere is deducted from the plant's emissions. With CCS, the amount of CO2 generated from biomass and permanently stored represents negative emissions.

With BECCS, an additional amount of 37% CO2 must be captured and stored than the CO2 captured and stored from the co-firing alternative.

Due to the higher efficiency, the emission of CO2 from co-fired biomass is lower than that of a biopower plant.

With reference to the net electric energy supplied to the grid, the neutral and negative emissions from the BECCS plants will be from 27% to 75% higher than those from a very large power plant equipped with CCS, where the biomass is co-fired with coal. The reason is that the efficiency ratio between the co-firing and the BECCS options ranges from 1.27 for the largest and most efficient BECCS plant (100 MWe) to 1.75 for the smallest and less efficient BECCS plant (10 MWe).

13

Co-firing with biomass BECCS Comments Neutral emission (g/kWh) 126.4 196.4 Released to the atmosphere Negative emission (g/kWh) 778.6 1069.6 Captured and stored


Conclusion

1. Significant advantages of co-firing over independent bioenergy power plants when CCS is applied. Provided that an operational coal-power plant is at hand, more net electric energy can be

generated from the biomass than would be the case in a dedicated BECCS plant, although the amount of CO2 captured and stored will be identical.

2. Independent bioenergy power plants with the same electric energy must burn roughly 27-75% more biomass and will generate a corresponding amount of additional CO2 (dependent on the size and complexity of the plant).

Nevertheless, in the context of Indonesia, where the feedstock mainly comes from existing agriculture residues, biopower plants are still seen as an attractive option despite the lower efficiency. This interest is backed by resource availability and limited access to electrification in areas with dominant agriculture activities.


Conclusion

3. Without a high initial efficiency, CCS will not become economically viable, simply because of the limited amount of electricity to sell.

Most likely, a sufficiently high efficiency can only be ensured in large plants with advanced steam parameters (preferably in super-critical steam power cycles). Future material development is expected to enhance the efficiency considerably, which may have an impact also on smaller plants, whereby the range of differences may become smaller.

4. When it comes to safeguarding the energy supply, which is important in countries with power

scarcity such as Indonesia, the use of available biomass resources for co-firing in coal power plants will be preferable. Clearly, this has a considerable limitation as concerns the logistics of providing the required

biomass feedstock.

5. In a regulatory regime with a sufficient price on carbon emissions, independent biopower plants may be preferred to the co-firing alternative mainly due to the CO2 which is accountable either as negative or neutral emission.

In this case, an accounting system capable of handling negative CO2 emissions is mandatory.


Concluding remark

The above insights should lead to further investigations, especially to cost-benefit analyses pertaining to electricity tariffs, and carbon pricing within a limited national context. Such analyses will be useful for the identification of patterns maximising carbon emission reduction.

SINTEF Energy Research Jens Hetland a, Ping Yowargana b, Sylvain Leduc b, Florian Kraxner b a SINTEF...

Documents

Transcript of SINTEF Energy Research Jens Hetland a, Ping Yowargana b, Sylvain Leduc b, Florian Kraxner b a SINTEF...