Improving the sustainability of the farm-scale Anaerobic Digestion (AD) process through modeling

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Improving the sustainability of the farm-scale

Anaerobic Digestion (AD) process through

modeling

F. Pierie MSc. B Eng. PhD. candidate

R.M.J. Benders PhD.

Prof. W.J.T. van Gemert PhD.

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Outline

1.Introduction

2.Method and model

3.Case study results

4.Conclusions

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Goal: Researching the integration

of biogas production and use in a smart, flexible and decentralized (bio)gas grid. Gas canister market Consumers Waste producers Gas canister truck Gas upgrading Greenhouse

Gas injection point

Farm Biogas production Smart monitoring Solar PV Wind

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Within this presentation sustainability is defined as

“strong sustainability”

(Elkington 1999; Christodoulou 2012).

Definition sustainability

Profit

People

Planet

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Research question / findings

How to improve sustainability of AD

green gas production pathways?

Main findings:

1) Not all local biomass sources can be used

2) There is a gap between energy potential and

energy gained from biomass

3) Use local biomass byproducts for AD process

4) Symbiotic systems can be sustainable and

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The AD green gas

pathway

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In theory

Green gas production Anaerobic Digestion Transport Feedstocks Green gas injection

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In theory

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In theory

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Theory

and

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Methodology in model

Measuring the sustainability of biogas

production pathways

• Modular approach

- Material and Energy Flow Analysis

- Attributed Life Cycle Analysis

- Financial analysis NPV

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Method: Modular approach

Example of

Sub-module

BIOMASS Manure Maize TRANSPORT Tractor Truck PRODUCTION Co-digestion UPGRADING Scrubbing Membranes MODULE Sub-module Truck Grass Gasification Alternative Sub-modules Absorption

Main route Alternative route

Source: Pierie et al., 2016

Energy

Biomass

Materials

Emissions

Digestate

Biogas

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Method: Sub-module

NPV (P)EROI Carbon Footprint

Sustainability expressed in

Material Flow Analysis

Direct Material and Energy Flow Analysis

Indirect Material and Energy Flow Analysis

Attributed Life Cycle Analysis (SimaPro / EcoInvent)

Biomass Biogas

Energy use

Energy production

Constructions Source: Pierie et al., 2016

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1) (P)EROI

(Process) Energy Returned on Invested in GJ/GJ

Energy in

biomass

Process

energy

consumed

Process

Useful

energy

produced

Internal

energy use

System boundary

𝑃 𝐸𝑅𝑂𝐼 =

𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑗𝑒𝑐𝑡𝑒𝑑 𝑖𝑛 𝑔𝑎𝑠 𝑔𝑟𝑖𝑑

_{𝑃𝑟𝑜𝑐𝑒𝑠𝑠 𝑒𝑛𝑒𝑟𝑔𝑦 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑}

=

𝐺𝐽

_𝐺𝐽

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2) GWP(100)

Carbon footprint GWP(100) in kgCO2eq/GJ

CO2 CO2

Fossil emissions

Increase in GWP

BIOMASS

System boundary

Useful energy

produced

𝐺𝑊𝑃(100) =

𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛

𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑗𝑒𝑐𝑡𝑒𝑑

=

𝑘𝑔𝐶𝑂2𝑒𝑞

𝐺𝐽

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3) EcoPoints

Human health

Resources

Eco-systems

System boundary

Useful energy

produced

Environmental impact overall (ReCiPe) in EcoPoints Pt/GJ

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Scenario: Biogas pathway

Green gas production AD

Transport Feedstocks

Locations

Within this scenario:

1) Anaerobic Digestion process is used

2) Biogas is upgraded to bio-methane at gas grid quality (green gas)

3) The green gas is injected into the gas grid

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Scenario: Biomass location

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Scenario: Feedstock and transport

Locations

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Results:

Local bio-energy availability

and green gas production

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0%

2%

4%

6%

8%

10%

Theoretical bio-energy

yield

Energy in feedstock

Green gas

Results: Local bio-energy availability

Loca

l demand

(%)

1) Low quality biomass

2) Conversion

losses

1) There is a gap between energy potential and energy gained from biomass

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Results: Effect of additional manure input

Source: Pierie et al., 2016

1) Not all local biomass sources can be used

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-1.2 -1 -0.8 -0.6 -0.4 -0.2 0

NP

V (

million

€

)

Results: Green gas pathway

0 1 2 3 4 5 6 7

(P)E

R

OI

(GJ

/GJ)

0 10 20 30 40 50 60

G

WP (kgC

O2eq

/GJ)

0 1 2 3 4 5 6 7 8

Ec

oP

oin

t

(P

t/GJ)

Efficiency

Emissions

Impact

NPV

2) Use local biomass byproducts for AD process

Reference natural gas

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-1.2 -1 -0.8 -0.6 -0.4 -0.2 0

NP

V (

million

€

)

Results: Green gas pathway

0 1 2 3 4 5 6 7

(P)E

R

OI

(GJ

/GJ)

0 10 20 30 40 50 60

G

WP (kgC

O2eq

/GJ)

0 1 2 3 4 5 6 7 8

Ec

oP

oin

t

(P

t/GJ)

Efficiency

Emissions

Impact

NPV

However…

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Preliminary results:

Improvement of performance

using symbiotic systems

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Scenario: System optimization

Internal fuel Liquid fertilizer Solid fertilizer 1 6 6 4 5 2 Improved insulation Leakage repair Internal electricity Internal heat Additional biogas Manure bypass Heat exchanger Heat pump

Green fertilizer production Green fuel production

Locations

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-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

NP

V (

million

€

)

Results: System optimization

0 5 10 15 20 25

(P)E

R

OI

(GJ

/GJ)

-50 -40 -30 -20 -10 0 10 20 30 40

G

WP (kgC

O2eq

/GJ)

-8 -6 -4 -2 0 2 4 6

Ec

oP

oin

t

(P

t/GJ)

Efficiency

Emissions

Impact

NPV

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-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

NP

V (

million

€

)

Results: System optimization

0 5 10 15 20 25

(P)E

R

OI

(GJ

/GJ)

-50 -40 -30 -20 -10 0 10 20 30 40

G

WP (kgC

O2eq

/GJ)

-8 -6 -4 -2 0 2 4 6

Ec

oP

oin

t

(P

t/GJ)

Efficiency

Emissions

Impact

NPV

However…

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Conclusions

From a “strong sustainability” perspective:

• The goal of AD should not be limited to

producing maximum green gas output

• Symbiotic systems can improve the overall

sustainability of the AD process

• Locally available biomass is a scarce resource

which should be used wisely

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Discussions

• AD process complex to model

• Range sensitive values are large within

literature

• There are still emissions from biogas chain,

only less due to replacement scenarios

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QUESTIONS?

Hanze University of Applied Sciences

Research Centre Energy

Frank Pierie

PhD. Researcher

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1) (P)EROI

(Process) Energy Returned on Invested in GJ/GJ

Energy in

biomass

Process

energy

consumed

Process

Useful

energy

produced

Internal

energy use

System boundary

𝑃 𝐸𝑅𝑂𝐼 =

𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑗𝑒𝑐𝑡𝑒𝑑 𝑖𝑛 𝑔𝑎𝑠 𝑔𝑟𝑖𝑑

_{𝑃𝑟𝑜𝑐𝑒𝑠𝑠 𝑒𝑛𝑒𝑟𝑔𝑦 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑}

=

𝐺𝐽

_𝐺𝐽

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2) GWP(100)

Carbon footprint GWP(100) in kgCO2eq/GJ

CO2 CO2

Fossil emissions

Increase in GWP

BIOMASS

System boundary

Useful energy

produced

𝐺𝑊𝑃(100) =

𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛

𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑗𝑒𝑐𝑡𝑒𝑑

=

𝑘𝑔𝐶𝑂2𝑒𝑞

𝐺𝐽

(43)

3) EcoPoints

Human health

Resources

Eco-systems

System boundary

Useful energy

produced

Environmental impact overall (ReCiPe) in EcoPoints Pt/GJ

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4) Net Present Value

Inflation

Cost of capital (R)

Time (25 years)

System boundary

CAPEX (C

₀

)

Analysis of profitability scenario in Net Present Value (NPV) in (€)

𝑁𝑃𝑉 =

𝑇

_𝑡=1

_1+𝑅

𝐶

− 𝐶

₀

= €

OPEX

TAX

(NL)

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Sensitivity

analysis

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(P)EROI

0 2 4 6 8 10 12 (P)EROI (GJ/GJ)

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GWP100

0 10 20 30 40 50 60 70 80 90 100 GWP(100) (kgCO2eq)

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EcoPoints

0 2 4 6 8 10 12 14 16 18 20 EcoPoints (ReCiPe 2012 Pt.)

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Main scenarios

Green gas production AD Transport Feedstocks Locations Internal heat Internal electricity

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Use of local biomass waste flows

Locations

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System optimization

Locations

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Combination of technologies

Internal heat Internal electricity Internal fuel Liquid fertilizer Solid fertilizer Feedstocks Manures 3 1 6 6 4 Feedstock / Digestate Green gas Biogas Electricity Heat Legend Location of farms 5 2