Anaerobic Digestion (AD) process for waste treatment?

An integrated approach for a dynamic energy and environmental system analysis of biogas production pathways

F. Pierie MSc. B Eng. PhD. candidate W. Liu PhD.

R.M.J. Benders PhD. Prof. W.J.T. van Gemert PhD.

Prof. H.C. Moll PhD.

This project is part-financed by the municipality of Groningen, province of Groningen, the European Union, European Regional Development Fund, the Ministry of Economic Affairs “Pieken in de Delta” and “Samenwerkingsverband Noord-Nederland”, and is supported by Energy Valley.

Outline

1. Introduction

2. Method and model

3. Case study and results

4. Conclusions

Introduction

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

Within this presentation sustainability is defined as

“strong sustainability”

(Elkington 1999; Christodoulou 2012).

Definition sustainability

Profit People

Planet

Main findings

From a “strong sustainability” perspective:

• Use AD for waste treatment

• Use byproducts to power process

• Use remaining byproducts locally

In this presentation I will discuss the main findings

What we found using the integrated approach and the model

Method and model

Methodology in model

This methodology includes

• Modular approach

• Material and Energy Flow Analysis

• Attributed Life Cycle Analysis

An integrated approach for a dynamic energy and environmental system analysis of biogas production pathways

Modular approach Used to lower complexity and create flexibility in model

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

Sub-module Within each sub-module the impact of a specific process is determined (for instance the digester)

Variables

(P)EROI

Carbon Footprint

EcoPoints

Impact factors

Material Flow Analysis

Direct Material and Energy Flow Analysis

Indirect Material and Energy Flow Analysis

Attributed Life Cycle Analysis (SimaPro / EcoInvent)

Biomass Biogas

Electricity use

Electricity production

Constructions

t

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

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

3) EcoPoints

Human health

Resources

Eco-systems

System boundary

Useful energy produced

Environmental impact overall (ReCiPe) in EcoPoints Pt/GJ

𝐸𝑐𝑜𝑃𝑜𝑖𝑛𝑡𝑠 = 𝐼𝑚𝑝𝑎𝑐𝑡

𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑗𝑒𝑐𝑡𝑒𝑑 =

𝑃𝑡

𝐺𝐽

Model The sub-modules were combined into a model (Excel)

Sub-module

Module

Case study

The AD process used for energy production

vs.

The AD process used for waste management

The biogas pathways

80%

20%

50 km

50%

50%

50 km

1) Pathway with energy maize and manure

2) Pathway with road side grass and manure

Scale: Farm scale digester of 10000 to 20000 tonne/year

Scenarios

1) AD as energy producer

2) Improving the AD process

3) AD as waste treatment

Replacement of waste treatment

pathays

Waste feedstock production

Offset of mineral fertilizer or other

benefits to digestate use

Processing of excess digestate

Syst

em

bo

un

dar

y

System boundary

AD as energy producer The AD process used for green gas production

(P)EROI GWP EcoPoints

Ref

Ref

Ref

Ref = Is (Groningen) Natural gas use + production NL G

rass

Mai

ze

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Lowering impact AD Using a CHP unit running on biogas from the AD process to provides power and heat for the AD process

Improving AD Increasing efficiency through energy recycling

(P)EROI GWP EcoPoints

Ref

Ref

Ref

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Gra

ss

Mai

ze

AD as waste treatment

1) Replacement of current manure treatment at farm

2) Replacement of current roadside grass management

Replacement of current waste treatment scenarios

AD waste The AD process used for waste management

(P)EROI GWP EcoPoints

Mitigation of energy use reference scenarios

Gra

ss

Mai

ze

Ref

Re

f

Ref

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Discussion

• AD process complex to model

• Range sensitive values are large within literature

• Economical values not taken into account

• There are still emissions from biogas chain, only less due to replacement scenarios

Conclusion

• The goal of AD should not be limited to producing green gas

• Internal energy use improves impact AD process

• The goal of AD should be waste treatment, with use of byproducts (gas, heat, electricity and digestate) for internal and local consumption.

Are there QUESTIONS?

From a “strong sustainability” perspective:

• Use AD for waste treatment

• Use byproducts to power process

• Use remaining byproducts locally

Frank Pierie

Also check out presentation Flexigas from Jan Bekkering

(Wednesday session 27 room 9 from 15:15 to 15:35h.) This project is part-financed by the municipality of Groningen, province of Groningen, the European Union, European Regional Development Fund, the Ministry of Economic Affairs “Pieken in de Delta” and “Samenwerkingsverband Noord-Nederland”, and is supported by Energy Valley.

Contact details

Frank Pierie PhD Researcher f.pierie@pl.hanze.nl Hanze Research Centre – Energy

This project is part-financed by the municipality of Groningen, province of Groningen, the European Union, European Regional Development Fund, the Ministry of Economic Affairs “Pieken in de Delta” and “Samenwerkingsverband Noord-Nederland”, and is supported by Energy Valley.

Additional slides

System boundaries

System boundary energy

Waste feedstock production

Harvesting of waste feedstock

Transport of feedstocks

Storage and pre-treatment of feedstocks

Maize feedstock production

Harvesting of Maize feedstock

Anaerobic digestion of feedstocks

Upgrading to green gas and injection into

national gas grid

Biogas Digestate

Offset of natural gas and end use

Primary construction materials and

embodied energy

Direct and indirect Process

energy Transport of digestate

Emissions from digestate use as fertilizer

Offset of mineral fertilizer or other

benefits digestate use

System boundary

Processing of excess digestate

Offsetting of waste treatment

scenarios

System boundaries for energy production scenario

System boundary waste

Waste feedstock production

Harvesting of waste feedstock

Transport of feedstocks

Storage and pre-treatment of feedstocks

Maize feedstock production

Harvesting of Maize feedstock

Anaerobic digestion of feedstocks

Upgrading to green gas and injection into

national gas grid

Biogas Digestate

Offset of natural gas and end use

Primary construction materials and

embodied energy

Direct and indirect Process

energy Transport of digestate

Emissions from digestate use as fertilizer

Offset of mineral fertilizer or other

benefits digestate use

System boundary

Processing of excess digestate

Offsetting of waste treatment

scenarios

System boundaries for waste treatment scenarios

System boundary waste

Waste feedstock production

Harvesting of waste feedstock

Transport of feedstocks

Storage of manure 6 month

Primary construction materials and

embodied energy

Direct and indirect Process

energy

Transport of digestate

Emissions from digestate use as fertilizer

Offset of mineral fertilizer or other

benefits digestate use

System boundary

Processing of excess digestate

Waste feedstock production

Mulching of grass

Transport of material and men

Primary construction materials and

embodied energy

Direct and indirect Process

energy

Emissions from grass mulched

Offset of mineral fertilizer or other

benefits digestate use

System boundary

Man

ure

G

rass

The system boundaries of current waste scenarios

System boundary ref

Production of natural gas

Cleaning of natural gas

Distribution of natural gas

Combustion as end use

Primary construction materials and

embodied energy

Direct and indirect Process

energy

System boundary

Mitigation of earthquakes in

Groningen

The system boundary of (Groningen) natural gas per GJ

Sensitivity

analysis

(P)EROI

0

2

4

6

8

10

12

(P)EROI (GJ/GJ)

GWP100

0

10

20

30

40

50

60

70

80

90

100

GWP(100) (kgCO2eq)

EcoPoints

0

2

4

6

8

10

12

14

16

18

20

EcoPoints (ReCiPe 2012 Pt.)

Results Specific

Compare Energy invested in process (MJ)

GWP 100 emissions from process (kgCO2eq)

Compare

ReCiPe environmental impact from process (Pt)

Programed scenario in model

Maize scenario in model

Grass scenario in model

Green gas chain Results of three scenarios for green gas production

(P)EROI GWP EcoPoints

Replacing waste reference scenarios

Gra

ss

Mai

ze

Ref

Ref

Ref

Ref = Is (Groningen) Natural gas use + production NL

Waste With CHP

Energy

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Waste With CHP

Energy

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Waste With CHP

Energy

Gra

ss

Mai

ze

Gra

ss

Mai

ze

Using a CHP for internal energy production

Base case scenario