The IEA Bioenergy Technology Collaboration Programme (TCP) is organised under the auspices of the International Energy Agency (IEA) but is functionally and legally autonomous. Views, findings and publications of the IEA Bioenergy TCP do not necessarily represent the views or policies of the IEA Secretariat or its individual member countries.

State of the Art in Green Gas

Bioenergy: A critical path to carbon neutrality

Professor Jerry d Murphy, Leader Task 37

MaREI centre for energy, climate and marine

IEA Bioenergy 2 December 2021

www.ieabioenergy.com

Professor Jerry D Murphy

1. Director MaREI centre for Energy, Climate and Marine (2015)

2. Professor of Civil Engineering, University College Cork (2015 )

3. Engineers Ireland Excellence award (2015)

4. Biogas Task Leader IEA Bioenergy (2016)

5. Marine Industry award for excellence (2017)

6. Adjunct Professor University of Southern Queensland (2018)

7. Fellow of the Irish Academy of Engineers (2019)

8. Advisory Board of DBFZ (German Bioenergy Research Centre) (2020)

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www.ieabioenergy.com3

Technical Reportshttp://task37.ieabioenergy.com/technical-brochures.html

Case Stories: http://task37.ieabioenergy.com/case-stories.html

OURMOTIVATIONS

Energytransition

Climateaction

Blueeconomy

Prof Jerry Murphy

Dr Richen Lin

Director of Circular Economy, Energy & Environmental Systems (CEEES)

PI Bioenergy & Biorefinery Team

Dr David Wall

PI Advanced Fuels & Circular Economy Team

Dr Richard O Shea

PI Industrial Ecology Team

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Lecturer in Environmental Engineering

Lecturer in Transportation Engineering

Lecturer in Sustainability in Enterprise

Davis Rusmanis Omar Ibrahim Donal O Ceileachair Jorge Diaz

Nathan Gray Anga Hackula Rajas Shinde H2 - PhD

Dr Chen Deng

Dr Xihui Kang

Benteng Wu

Xue Ning

Dr Vaishali Thaore Aoife Long

Kwame Donkor

Archishman Bose

Daniel Hickey

www.ieabioenergy.com6

Anaerobic Digestion

Hydrogen production: Green, Blue and Grey

• In the EU and US, up to twice as much energy is sourced from gas grid as electricity grid.

• Ireland has ca. 8 GWe electrical capacity at 40% RES-E

• Ireland’s electricity grid has already experienced and sustained some of the highest system nonsynchronous penetration (SNSP) in any national electricity grid

• Ireland targets a further 4 GWe of offshore wind by 2030 leading to 70% RES-E

• This level of intermittency on an island grid is extremely challenging and may lead to periods of over production, negative pricing, instability and requirements for storage.

Green hydrogen: Interconnectivity of electricity and gas grids

Yearly breakdown of dispatch-down levels into constrain and curtailment on island of Ireland

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€100/MWh = €3/kgH2 ≈ €1.00/Ldiesel

Step 1: Power to hydrogen: run hours, price and sustainability

Power to hydrogen: developers perspective

• Hybrid system attractiveness increases with curtailment but need a hydrogen value above the levelized cost of €3.77/kgH2.

• H2 has an energy value of 33.33kWh/kgH2 which equates to 11.3c/kWh.

• Round cycle electricity to H2 back to electricity (at 60% electrical efficiency) equates to 18c/kWhe which is extremely expensive

• As a transport fuel, 11.3c/kWh equates to ca. €1.13 per L diesel equivalent. Even better if used in a fuel cell (greater efficiency than IC engine 50% vs 30%), equates to ca. €0.68/L per L diesel equivalent

Audi E-gas at Wertle, Germany - Catalytic Sabatier process

Sabatier Equation: 4H2 + CO2 = CH4 + 2H2O

Food waste biomethane

Production of hydrogen in 6MW electrolyser

Production of methane via Sabatier

1000 Audi NGVs

Step 2: Power to methane

Methanothermobacter Wolfeii

Biological conversion of hydrogen to methane in a batch system

Biological methanation in in-situ, ex-situ batch & continuous systems

Biological methanation in continuous systems

Potential to incorporate electrolysers at existing anaerobic digestion facilities

Potential to integrate electrolysers at wastewater treatment plants

www.ieabioenergy.com

Increased output of methane from power to methane system

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Integrating biological, thermo-chemical and power to gas systems in a circular cascading bioenergy system

Ex-situ biological methanation with addition of graphene

Direct Interspecies electron transfer : electron bridges to overcome hydrogen partial pressure in degradation of volatile fatty acids

Anaerobic digestion

CO2

CH4

O2

H2

Power to Gas

Syngas/Bio-oil

Pyrochar

Pyrolysis

CH4

Biomethanation

Integrating biological, thermo-chemical and power to gas systems in a circular cascading bioenergy system

Integration of biological, thermo-chemical and power to methane systems in a circular economy, energy and environmental system

www.ieabioenergy.com24

Anaerobic Digestion

Step 3: Power to Liquid Renewable Fuel through coupling of electricity, H2 & CO2

3CH4 + CO2 + 2 H2O = 4 CH3OH CO + 2 H2 = CH3OH

What will fuel ships, trucks and planes?

Advanced fuels for ships, trucks and planes

Low energy density of battery technology presents significant challenges for electrification of haulage, shipping and aviation

Shipping• Liquid biofuels and “drop-in” fuels → use in older vessels • Methanol and biomethane → short to medium term• Hydrogen and ammonia → long-term zero-emissions shipping

Aviation• “Drop-in” replacement fuels for jet fuel only technically feasible

pathways for emissions reductions

Haulage• Battery electric trucks feasible for short distances• Biomethane represents a mature technology for long distance

trucking• Hydrogen presents promising long-term opportunity for zero-

emissions long-distance trucks

Circular Economy Energy & Environmental Systems (WESTKUSTE 100)

Research informing renewable gas production

Biomethane• Biomethane is part of circular economy energy and environmental system and as evidenced is mature.• Research can improve process such as direct interspecies electron transfer through addition of graphene

Hydrogen• Grey hydrogen is cheap 5c/kWh while Blue hydrogen is more sustainable but more expensive 6.5c/kWh• Green hydrogen is most expensive c. 10c/kWh but can be green if and only if electricity is green• Green hydrogen can not depend on curtailed electricity only as electrolysers would not pay for themselves• Round cycle efficiency is poor for electricity to hydrogen to electricity costing c. 18c/kWeh• Hydrogen in a fuel cell presents promising opportunity for zero-emissions long-distance trucks c. 70c/Ldiesel equiv

Power to methane (P2-CH4)• Hydrogen can react with CO2 to produce methane in niche applications (biogas upgrading) • Can place electrolyser at stack of cement factory or food and beverage industry to decarbonise industry

Circular economy energy and environmental systems• Can integrate electricity, gas and water utilities such as by positioning electrolysers at WWTPs• Trucks, ships and planes need light fuel systems that do not demand space; battery is not very suitable• Compressed biomethane and/or hydrogen represent a solution to decarbonise long distance trucking• Power to liquid (such as ammonia) presents viable options for long distance haulage (ships)

Confidential - Internal Use Only Do Not Forward 30

IEA Bioenergy Task 37