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Alternative ways of biomethane production - a SWOT analysis

May 2014

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Authors: Sabine Strauch, Tim Schulzke, Oliver Jochum

Contact: Fraunhofer UMSICHT

Research Group »Biogas Technology«

Osterfelder Strasse 3

46047 Oberhausen, Germany

www.umsicht.fraunhofer.de

Note on legal topics

All legal topics published in this report exclusively serve the purpose of general

information and do not refer to individual legal concerns. The authors and other

parties involved assume no liability regarding the correctness, timelines,

completeness or usability of the information made available. The assertion of claims

of any kind is excluded.

Page 3 of 19

The Biomethane Guide for Decision Makers has been created within the project

GreenGasGrids supported by the Intelligent Energy - Europe programme (contract

number IEE/10/235/S12.591589).

Webpage: www.greengasgrids.eu

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THE GREEN GAS GRIDS PROJECT PARTNERS

German Energy Agency - dena (Germany)

Fraunhofer UMSICHT (Germany)

Austrian Energy Agency (Austria)

Energetski Institut Hrvoje Požar -EIHP (Croatia)

Agence de l’Environnement et de la Maîtrise de

l’Energie - ADEME (France)

Renewable Energy Agency – REA (UK)

University Szeged (Hungary)

European Biogas Association

Consorzio Italiano Biogas (Italy)

Agentschap NL (The Netherlands)

Krajowa Agencja Poszanowania Energii – KAPE

(Poland)

Slovenská Inovacná Energetická Agentúra - SIEA

(Slovakia)

Natural Gas Vehicle Association - NGVA

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TABLE OF CONTENTS

INTRODUCTION ............................................................................................. 6

Alternative ways of producing biomethane ...................................................... 6

What is a SWOT analysis? ............................................................................. 6

Synthetic Natural Gas production from biomass (BioSNG) ................................... 8

The technical process ................................................................................... 8

Plants in operation – examples ...................................................................... 9

SWOT analysis .......................................................................................... 11

Power to bioGas – biological methanation of renewable hydrogen ....................... 12

The technical process ................................................................................. 12

Plants in operation – examples .................................................................... 14

SWOT analysis .......................................................................................... 15

Comparative analysis and conclusion .............................................................. 16

LITERATURE ................................................................................................ 18

ABBREVIATIONS .......................................................................................... 19

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INTRODUCTION Alternative ways of producing biomethane

Biomethane is a gas mixture obtained from cleaning and upgrading biogas. As its

name suggests, its main component is methane (CH4); in this context biomethane

is defined here as a renewable gas that is either sourced from biogenic materials

(organic matter) or is generated through biological processes. Due to its high

methane content and its gas condition biomethane is appropriate to substitute

natural gas.

Conventionally, biomethane results from the anaerobic digestion of organic matter

such as manure, bio-waste or energy crops. During this process wet biomass is

biologically digested to some residuals full of nutrients (digestate) and a gas

mixture known as biogas, which will be subsequently upgraded to biomethane.

Apart from this production way, biomethane can be obtained from other processes

that work under different circumstances and with different sources.

The main two alternative processes to obtain biomethane are

� the production of Synthetic Natural Gas from biomass (BioSNG) from

woody biomass by thermo-chemical conversion, and

� the Power to BioGas process on the basis of biological methanation of

renewable hydrogen and carbon dioxid.

This document is based on our general experience and knowledge at the time of

publishing this report. It is intended to give information about biomethane and its

sources to decision makers in policy and business and to provide a rough overview

on the characteristics of the single technologies.

What is a SWOT analysis?

SWOT is a flexible concept that can be used in various scenarios from assessing

projects or business ventures, making decisions, solving problems to strategy

formulation. In the Green Gas Grids project we use it to analyse the state of

development and the capability of biomethane production pathways.

Concept of the SWOT analysis, which is presented on the graphic below, contains

four sections,

� Strengths,

� Weaknesses,

� Opportunities,

� Threats,

which describe positive or negative, internal or external characteristics of the

respective biomethane production technology.

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SWOT analysis has been chosen to serve as an initial assessment of technical and

economical risks for biomethane production technologies. The analysis aims to

identify internal strengths and weaknesses of the production pathways BioSNG

production and Power to BioGas as well as examining the external opportunities

and threats which can endanger the feasibility of a biomethane project.

Strengths

Opportunities Threats

Weaknesses

SWOT SWOT

Figure 1: Principle of a SWOT analysis

Page 8 of 19

Synthetic Natural Gas production from biomass (BioSNG) SNG is referred to as Synthetic Natural Gas and is a substitute for natural gas that

can be derived either from fossil coal (brown coal, black coal), municipal solid waste

or from renewable biomass. In this report only renewable SNG sourced from

biomass is considered which is also referred to as BioSNG. In contrast to anaerobic

digestion, the BioSNG production requires organic matter with low water content

and with woody characteristic (lignocellulosic material). The large amount of

appropriate biomass, ranging from e.g. agricultural and forest residues,

lignocellulosic content of energy crops or municipal paper waste, is a reason why

this production pathway is considered to be able to contribute significantly to green

the natural gas grid. The resource potential of biomass that is accessible for BioSNG

production in the EU27 has been estimated by Thrän to exceed 2500 PJ per year

[1].

The technical process

BioSNG production is based on the gasification of biomass. Gasification is a partial

oxidation process in which biomass is transformed into carbon monoxide (CO),

hydrogen (H2) and carbon dioxide (CO2) using high temperatures. This mixture of

gases will at a later stage be upgraded to a high quality natural gas substitute:

BioSNG.

BioSNG production process consists mainly on five steps (Figure 2) which will be

described in the following.

Figure 2: BioSNG production process

Drying: During this step biomass has to be dried to remove water and

lower the moisture content; this allows a reduction of energy

input at elevated temperature during the gasification process and

increases its efficiency. The most widely applied drying

techniques are steam drying, flue gas drying and low

temperature air drying.

Gasification: Once the biomass is dried, it is ready to be gasified. The solid

material is converted to a gaseous phase and gasification is

achieved due to partial oxidation at temperatures of around

700-900°C. The usable technologies depend on the biomass to

be fed in; the most common technologies are fixed bed, fluidised

bed and entrained flow gasification. In contrast to gasification

plants with direct CHP utilisation which are often using air as

gasification agent, BioSNG production suffers from the input of

inert gases such as N2 due to its negative effect on the heating

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value of the product gas. For this reason, biomass is gasified by

using gasifying agents such as pure oxygen or water steam.

Gas cleaning: The product of gasification is a gas containing mainly CO, H2,

CO2, CH4 , higher carbons and some impurities (e.g. dust, tars);

reason for which this gas must be cleaned. To achieve the

desired gas quality and composition, cyclones, fabric filters and

scrubbing separators are used.

Methanation: During the methanation step CO2 and CO are converted to CH4

according to the following reactions

��� + 4�� → ��� + 2���

�� + 3�� → ��� + ���

The methanation process requires a catalyst while most often

nickel catalysts are used. Fixed bed reactor can be considered as

the state of the art technology. However, there are other

technologies using fluidised bed or slurry reactors as well.

Gas upgrade: The received product gas is to be upgraded by CO2 and CO

removal. Depending on the grid specification and the product gas

quality H2 is to be separated and moisture is to be reduced by an

appropriate drying technology.

The comprehensive gas treatment technology, which is required when producing

BioSNG, results in high investment costs. These costs contribute significantly to

BioSNG production costs whereas plants with high gas production capacity benefit

from scaling effects. Urban estimated BioSNG production costs for a 60 MW plant

(fuel capacity) and resulted in roughly 58 €/MWhHi,N considering investment

conversion and fuel costs1 [2],. Recent publications result in a cost estimation for

production costs for a plant capacity of 100 MWth to be 63 €/MWhHi,N for BioSNG

production with steam reforming and 68 €/MWhHi,N with oxygen reforming [3].

Plants in operation – examples

Gasification plants representing a pre-stage and pre-requisite of BioSNG production

have been implemented in several projects all over Europe. Especially Austria is one

of the very active countries (Table 1).

BioSNG production itself is considered to be in demonstration status. There are only

a few BioSNG projects in planning or in inauguration stage [4], [5]. In 2008 at the

European Center for Renewable Energy in Güssing, Austria the first methanation

plant in the world (1 MW) was built in Güssing. This project successfully

demonstrated the methanation of gas sourced from woody biomass. It transformed

the wood gas from the neighbouring biomass power plant into synthetic natural gas

and produced 300 Nm³ of wood gas from 360 kg of wood, which was converted into

120 Nm³ natural gas at the methanation step. As a first step, a small part of the

synthesis gas stream obtained from the fluidised bed gasification was taken from

1 year of commissioning 2010, 70€/t of wood

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the Güssing plant. In the second step, methane was synthesised from this synthesis

gas. The methanation reactor was a stationary fluidised bed, which was operated in

a pressure range from 1 to 10 bar [6]. The project has been supported by the 6th

RTD Framework Programme in the time from 2006 to 2009. After sucessful

demonstration the plant has been taken out of operation [7], [8].

The project GoBiGas is the first demonstration project for SNG production at

industrial scale. It is located in Göteborg, Sweden, and the owner of the plant, the

Swedish energy company Göteborg Energie, celebrated the inauguration of the

plant in March 2014. The gas production capacity is 20 MW at its first scale. A

second phase with a capacity of 80 MW is planned [9].

An additional Swedish project for BioSNG production at industrial scale (200 MW) is

announced by E.on [8].

In France 11 partners investigate together the production of BioSNG under the

umbrella of the R&D project Gaya. The project aims at demonstrating the vehicle

fuel production from lignocellulosic biomass by thermo-chemical conversion [10].

Table 1: Location and status of gasification plants in Europe, no

claim to be complete [source: [5], [7], [9], own research]

LOCATION UTILISATION/

PRODUCT

FUEL/PRODUCT

[MW]

START OF

OPERATION

STATUS EQUIPMENT

SUPPLIER

Austria

Güssing Gas engine 8.0fuel / 2.0el 2002 Operating AE&E / Repotec

Güssing BioSNG 1methane 2008 Out of operation Repotec

Oberwart Gas engine/ORC 8.5fuel / 2.8el 2008 Operating Ortner Anlagenbau

Villach Gas engine 15fuel / 3.7el 2010 Out of operation Ortner Anlagenbau

Klagenfurt Gas engine 25fuel / 5.5el 2013 Stopped

Vienna Hydrogen 50fuel / 30hydrogen 2015 Planning Repotec

Germany

Neu-Ulm Gas engine/ORC 14fuel / 5el 2013 Commissioning Repotec

Sweden

Göteborg BioSNG 33fuel / 20methane 2014 Operating

(gasifier) /

Commissioning

(methanation)

Metso / Repotec /

Haldor Topsoe

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SWOT analysis

POSITIVE

NEGATIVE

STRENGTHS WEAKNESSES

IN

TER

NA

L

• Large resources of lignin containing biomass are available.

• Very good space-time-yield compared to conventional biomethane plants

• Small spatial footprint • Small amounts of residues and

wastes

• High technical effort and challenging process conditions in terms of process temperature and pressure

• Comprehensive gas cleaning is necessary for several process steps and has impact on plant availability

• Nutrient recycling is only possible to a very limited extent (e.g. ash extraction)

EX

TER

NA

L

OPPORTUNITIES

• Large scale plants offer the possibility of an increase in energy efficiency

• The used biomass resource is not in conflict with food production.

THREATS

• Further research is required e.g. to increase plant availability

• Under the current market conditions, BioSNG production costs are not competitive with fossil gas. Support schemes are required.

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Power to BioGas – biological methanation of renewable hydrogen

Efficient concepts for storage of electric power are crucial for the success of the

energy transition in addition to the expansion of renewable energies. The energy

storage concept “power to gas” converts the excess electrical power into hydrogen

or methane. In this way on sunny and windy days renewable electricity from PV or

wind can be stored and later used in times when they are needed.

Integrating the natural gas grid and its cavern storages, the concept of power to

gas has the greatest capacity among all other storage technologies and is today

considered as the only option to store electricity in order of several TWh over a long

period of time (Figure 3) [11].

Figure 3: Demand for storage solutions will rise with the increase

of fluctuating renewable energies. The natural gas grid offers

interesting options via biomethane and PtG solutions. (source ZSW

2009)

The technical process

The conversion of carbon dioxide (CO2) and hydrogen (H2) into methane (CH4) and

water (H2O) is described by the following reaction:

��� + 4�� → ��� + 2���

This conversion can take place by means of thermo-chemical or biological

processes. In thermo-chemical processes, metal catalysts are used to enable the

chemical reaction of CO2 and H2. Most often nickel catalysts are used which requires

highly pure starting gas streams.

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This thermo-chemical conversion runs at temperatures of about 340-500 °C and

pressure conditions in the range of 10 bars. Due to the strong exothermic nature of

the reaction cooling is essential to ensure proper operating.

The option that is discussed in this report is the conversion of CO2 to methane via

the biological pathway, called “Power to BioGas”. In contrast to the thermo-

chemical process, the metabolic reactions of biological methanation occur naturally

when specialised microorganisms are present. Methanogenic archaea use hydrogen

and carbon dioxide as source for their metabolism – as a product methane is

produced.

photovoltaic and windenergy

maize

electrolysis biological methanation

O2

biogas upgrade

CO2

H2

biogasbiomassbiogas plant

excesselectr.current

CHP

H O2H O2

O2

manure

electr. current

heat energy

O2

H O2 CO2

natural gas vehicle

mobility

H O2 CO2

gas grid

CH4

CH4

Figure 4: Power to gas concept with biological methanation

(source: Fraunhofer UMSICHT 2013)

These are the same microorganisms that are responsible for the methane-forming

step in biogas, landfill gas and sewage gas production. Power to BioGas is at a

development stage, however, from the current point of view it offers certain

benefits such as described in the following:

� Mild process conditions with low temperature and pressure conditions

(35-70 °C; reaction already at ambient pressure) ease the engineering and

operation. These conditions are very similar to the ones in biogas plants.

� Cost-effectively because of the use of microorganisms from freely available

by-and waste products such active biomass from digestate from biogas

plants

� High tolerance against contaminants. Hydrogen sulfide as a nutrient source

is even beneficial to the process; therefore in contrast to the thermo-

chemical pathway the biological methanation does not require

comprehensive gas treatment.

� High reactivity results in fast start and stop operation [13].

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� High selectivity of the microorganisms which means that methane is

produced without intermediate products.

Whereas the implementation of biological methanation into an existing biogas plant

is not expected to involve extraordinary financial efforts, the production of

renewable hydrogen is considered to be the most important economical challenge.

The high investment costs for an electrolyser of 800 to 1500 €/kW 2 [12] make up

a significant part of the production costs. The exploitation of the biological

methanation technology will therefore strongly depend on the development of

electrolysis technology for low costs. Production costs are estimated to range from

ca. 80 to 150 €/MWhHs, provided excess electricity is delivered without charge3.

An additional challenge will be to optimise the conversion rate of biological

methanation. The conversion rate is strongly linked to the accessibility of the feed

to the bacteria which is limited by the solubility of the feed gases. More research is

needed to further investigate and optimise the process of biological methanation

before it reaches maturity for being realized at industrial scale.

Plants in operation – examples

Biological methanation is considered to be at development stage and there has

been little experience with larger scale applications. There are some pilot projects in

operation (Table 2), whereby the largest pilot plants have been set up by

Electrochaea in Foulum, Denmark [14], and another one by Microbenergy in

Schwandorf, Germany [16]. A new project aiming at scaling up to a capacity of 1

MW has been recently announced by Electrochaea [14].

Table 2: Location and status of plants for biological methanation in

Europe (no claim to be complete) [source: [14], [16], own

research]

2 only alkaline electrolysers are considered here, since invest costs for PEM electrolysers are

even higher

3 further assumptions: 2000 operation hours, capital costs 12% p.a.

LOCATION FERMENTER SIZE

[CUBIC METER]

BEGINNING OF

OPERATION

SCALE OPERATOR

Germany

Allendorf 2012 pilot Microbenergy

Schwandorf 100 2012 pilot Microbenergy

Oberhausen 0,005 2012 laboritory Fraunhofer UMSICHT

Denmark

Foulum 10 2012 pilot Electrochaea

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SWOT analysis

POSITIVE

NEGATIVE

STRENGTHS WEAKNESSES

IN

TER

NA

L

• Mild process conditions regarding required temperature, pressure and purity of the educt gas streams

• Easy switch on and off behaviour of the process has been reported.

• Easy integrating into biogas / biomethane plant concepts is possible without major hurdles.

• The process is still at research and pilot plant stage

• Still high investment costs for electrolysis facility ca. 1000 €/kW]

• Rate of conversion is strongly linked to the solubility of hydrogen in water.

• The handling of hydrogen bears some challenges (e.g. security, technical leak tightness)

EX

TER

NA

L

OPPORTUNITIES

• Renewable storage for renewables.

• Biogas / biomethane plants are able to offer the levelling of excess electricity as a service and therefore take a new role in the energy supply and grid stabilisation

• Increasing economical feasibility if costs for electrolysis can be lowered.

• Countries with high percentage of fluctuating RES can benefit from this technology.

THREATS

• Further research is required e.g. to investigate and optimise the process

• Under the current market conditions not competitive with fossil gas. Support schemes are required.

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Comparative analysis and conclusion The analysis shows that there are several ways available for producing biomethane.

A large range of biomass substrates can be used to generate biomethane, and even

excess electricity and appropriate CO2 sources can be converted via the Power to

BioGas technology.

Concerning stage of development, it can be stated that biomethane from AD is the

most developed pathway. More than 230 plants are in operation, almost all of them

produce renewable gas at industrial scale. Compared to that state, the other two

presented options Power to BioGas and BioSNG production are regarded to be at

demonstration status. Trials at laboratory and pilot stage have been carried out to

investigate the process and technical feasibility has been proven. The first real

industrial scale BioSNG project has just recently been commissioned. One large

scale Power to BioGas project is already in the pipeline.

The three pathways have their specific characteristics concerning the appropriate

technical and economical scale. BioSNG production is considered to be appropriate

for large scale projects due to issues such as availability of substrates and cost

degradation effects; Biomethane from AD projects in practise experienced that

plant size is driven by the fermentation unit and the availability of appropriate

substrates. Specific production costs benefit from scale-up effects up to a plant size

of 2000 Nm³/h. Larger plants are most often built in parallel production lines [14].

Due to the connection of Power to BioGas projects with biogas plants, their scale

are expected to be linked to the size of Biomethane from AD projects.

The costs for biomethane production range from 53 – 63 €/MWhHs for BioSNG [5],

over 65-83 €/MWhHs for biomethane from AD [15] and even higher for biomethane

received from Power to BioGas processes. Under the current economical conditions

(e.g. low natural gas price of ca. 24 €/MWhHs) these renewable gases can only

compete with fossil natural gas, if appropriate support mechanisms are available.

These schemes should value the benefits of biomethane – its renewable nature and

the fact that it can be stored and can be flexibly used for climate protection.

To sum up, the comparison shows that each biomethane production pathway has

its specific strengths. Due to the flexibility in production and utilisation biomethane

is worth to be considered in a lot more energy concepts.

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Page 18 of 19

LITERATURE

[1] Thrän D, Müller-Langer F (2011): Potenziale in Deutschland und Europa; In: Biogas: Erzeugung, Aufbereitung, Einspeisung; Oldenbourg Industrieverlag, München; pp 17 – 40; Graf F, Bajohr S (editor)

[2] Urban W et al (2009): Abschlussbericht BMBF-Verbundprojekt Biogaseinspeisung, Band 3; www.biogaseinspeisung.de

[3] Simell P et al (2014): Techno-economic study on bio-SNG and hydrogen production and recent advances in high temperature gas cleaning. In: Regatec 2014, Conference Proceedings; pp 39; Held J (editor)

[4] Kopyscinski J et al (2010): Production of synthetic natural gas (SNG) from coal and dry biomass – a technology review from 1950-2009; Fuel 89 pp1763-1783

[5] Webpage of European Biofuels Technology Platform http://www.biofuelstp.eu/bio-sng.html (accessed 15 of May 2014)

[6] Webpage of the European Centre for Renewable Energy http://www.eee-info.net/cms/EN/

[7] Seiffert M et al (2009): Final report: Bio-SNG – Demonstration of the Production and Utilisation of Synthetic Natural Gas (SNG) from Solid Biofuels

[8] Webpage of Transport Research and innovation Portal: http://www.transport-research.info/web/programmes/programme_details.cfm?ID=35788 (accessed 15th of May 2014)

[9] Webpage of GoBiGas project http://gobigas.goteborgenergi.se (accessed 20th of May 2014)

[10] Webpage of the Gaya project www.projectgaya.com (accessed 20th of May 2014)

[11] Specht M et al (2009): Speicherung erneuerbarer Energien im Erdgasnetz

[12] Dena (2013): Power to Gas. Eine innovative Systemlösung auf dem Weg zur Marktreife. (Brochure)

[13] Krajete A et al (2013): Benefits of biological methanation. Presentation at DBI http://www.dbi-gti.de/fileadmin/downloads/5_Veroeffentlichungen/Tagungen_Workshops/2013/H2-Fachforum/14_Krajete_KrajeteGmbH.pdf (accessed 20th of May 2014)

[14] Hofstetter D (2013): Biomethane Production via Power-to-Gas In: UK Biomethane Day 2013 http://www.r-e-a.net/images/upload/events_133_10_-_Dominic_Hoffstetter_-_Power-to-Gas_-_UK_Biomethane_Day_2013.pdf (accessed 20th of May 2014)

[15] Beil M et al. (2014): Final project report BIOMON

[16] Albrecht U et al. (2013): Analyse der Kosten Erneuerbarer Gase, BEE Plattform Systemtransformation

Page 19 of 19

ABBREVIATIONS

AD Anaerobic digestion

BioSNG Synthetic natural gas from renewable biomass

MW Megawatt

PJ Peta Joule

R&D Research and Development

RES Renewable Energy Sources

SNG Synthetic natural gas

SWOT Analysis on strengths, weaknesses, opportunities and threats

WP Work package